| Title of Invention | "PROCESS FOR PREPARING PHENYLTRIAZOLINONE" |
|---|---|
| Abstract | Disclosed is a novel phenyltriazolinone production process which enables to produce a highly pure phenyltriazolinone in high yield in an simpler and safer manner and at a lower cost by using a more inexpensive raw material. Specifically disclosed is a process for producing a phenyltriazolinone, which comprises the steps of: reacting an aniline with a nitrite salt to produce a diazonium salt; reducing the diazonium salt with a sulfite salt or a bisulfite salt; hydrolyzing the reduced product to produce a phenylhydrazine; reacting the phenylhydrazine with formaldehyde in the presence of a catalyst at pH 5-10 to produce a formaldehyde-phenylhydrazone; reacting the formaldehyde-phenylhydrazone (3) with cyanic acid to produce a phenyltriazolidinone; and reacting the phenyltriazolidinone (4) with an oxidizing agent selected from a hypohalous acid salt and oxygen in the absence of any catalyst or in the presence of an oxidation catalyst. |
| Full Text | DESCRIPTION PROCESS FOR PREPARING PHENYLTRIAZOLINONE TECHNICAL FIELD [0001] The present invention relates to a process for preparing phenyl-1,2,4-triazolin-5-one, more particularly a process for preparing phenyl-1,2,4-triazolin-5-one which is a useful compound as a raw material or an intermediate product for synthesizing pharmaceuticals and agricultural chemicals. BACKGROUND ART [0002] Phenyl-1,2,4-triazolin-5-one (phenyltriazolinone) is a compound useful as a raw material or an intermediate product for synthesizing pharmaceuticals and agricultural chemicals, and various preparation processes have been proposed in the past. [0003] For example, PCT International Publication W098/38176 (patent document 1) describes that a phenyltriazolinone is prepared through the following reactions: [0004] (Formula Removed) [0005] wherein n is 0 or an integer of 1 to 5, and each X may be the same or different and is a halogen atom, a lower alkyl group, a lower haloalkyl group or the like. However, the process described in the patent document 1 requires isolation of phenylhydrazone (A-3) in the reaction step, and expensive dipheylphosphoryl azide (A-4) is used in the preparation, which involves high preparation cost of phenyltriazolinone (A-5). [0006] Therefore, it is difficult to say that the above preparation process described in the patent document 1 is an industrially advantageous preparation process. [0007] PCT International Publication WO02/12203 (patent document 2) discloses a process for preparing an aryltriazolinone represented by the general formula (B-l), comprising steps of reacting arylhydrazone (B-3) with an alkali metal salt of cyanic acid and an acid to form aryltriazolidinone (B-2) and then reacting the aryltriazolidinone with an oxidizing agent. [0008] (Formula Removed) [0009] In the formula (B-l) , X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other. [0010] However, "Liebigs Ann. Chem.", Vol. 635 (1960), pp. 82-91 (non-patent document 1) described that the formaldehyde-arylhydrazone represented by the general formula (B-3) is converted into a tetrazine derivative by coupling of hydrazones caused by an acid. [0011] That is to say, the formaldehyde-arylhydrazone represented by the general formula (B-3) is unstable in the presence of an acid. [0012] Therefore, the process described in the patent document 2 wherein the arylhydrazone (B-3) is reacted with the alkali metal salt of cyanic acid in the presence of an acid involves increase of side reaction, which exerts adverse influence on the yield and the purity of the desired product. Thus, it is not necessarily said that this process is preferable. [0013] Japanese Patent Publication No. 78322/1994 (patent document 3) corresponding to PCT International Publication WO91/3470 discloses a process for preparing aryltriazolinone represented by the following general formula (C), comprising treating aryltriazolidinone represented by the following general formula (C-l) with a hypohalous acid or a hypohalite, [0014] (Formula Removed) [0015] wherein n is an integer of 1 to 3, R is a halogen atom, an alkyl group, a haloalkyl group or the like, and each X is independently hydrogen, a halogen atom (CI, Br, or I), a lower alkyl group or the like, [0016] (Formula Removed) [0017] wherein n is an integer of 1 to 3, R is a halogen atom, an alkyl group, a haloalkyl group or the like, and each X is independently hydrogen, a halogen atom, a lower alkyl group or the like. [0018] National Publication of International Patent No. 503253/1995 (patent document 4) corresponding to PCT International Publication W093/23382 discloses a process for preparing aryltriazolinone represented by the following general formula (D), comprising successively treating arylhydrazine represented by the formula: Xn-Ph-NH-NH2 (Ph is phenyl, and X and n are the same as those in the patent document 3) with (i) CI to C3 aldehyde, (ii) cyanate and a weak organic acid and (iii) a hypochlorous acid, its salt or halogen in a tertiary butanol solvent, [0019] (Formula Removed) [0020] wherein R is a lower alkyl group, each X is independently halogen, lower alkyl, nitro, hydroxyl, NHS02R', -N(S02R')2 or -N(R')S02R' (R' is a lower alkyl group), and n is an integer of 0 to 3. [0021] However, the patent documents 3 and 4 neither describe nor suggest a phenyltriazolinone wherein R in the formula (C) or (D) is hydrogen (H) and its preparation process. Patent document 1: WO98/38176 Patent document 2: WO02/12203 Patent document 3: Japanese Patent Publication No. 78322/1994 Patent document 4 : National Publication of International Patent No. 503253/1995 Non-patent document 1: Liebigs Ann. Chem., Vol. 635 (1960), pp. 82-91 DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION [0022] The present invention is intended to solve the problems associated with the prior art as described above, and the object of the invention is to provide a novel process for preparing a phenyltriazolinone, which is capable of preparing a high-purity phenyltriazolinone more simply and safely at a low cost in a high Field using a more inexpensive raw material. MEANS TO SOLVE THE PROBLEM [0023] In order to achieve the above object, the present inventors have earnestly studied, and as a result, they have found that by forming a formaldehyde-phenylhydrazone (also referred to as a "phenylhydrazone") at pH of a specific range and then reacting the resulting formaldehyde-phenylhydrazone with cyanic acid to form a phenyltriazolidinone, a phenyltriazolinone can be prepared with high purity in a high yield without the aforesaid side reaction. [0024] That is to say, the present inventors have found that a phenyltriazolinone that is a desired product can be prepared with high purity in a high yield by: (1) treating a formaldehyde-phenylhydrazone at pH of a specific range in the reaction step of forming a phenyltriazolidinone from an aniline via the formaldehyde-phenylhydrazone, thereby mitigating or reducing adverse influence (production of tetrazine derivative as by-product) of a coexisting acid on the formaldehyde-phenylhydrazone, and (2) allowing cyanic acid to undergo cycloaddition to the formaldehyde-phenylhydrazone. [0025] The present inventors have further found that in the preparation of a phenyltriazolinone, an aniline which is inexpensive and has high general-purpose properties can be selected as a raw material. This has enabled to avoid storing of a chemical substance, such as phenylhydrazine, which causes concerns about risks of a fire, explosion or the like, and about harmfulness to health, when needed. [0026] Moreover, the present inventors have also found that all the steps can be continuously carried out. This has enabled to prepare a phenyltriazolinone that is a desired product more safely without a purification step accompanied with risks, and has also enabled to provide a process suitable for large-scale industrial production. [0027] As described above in detail, the present inventors have enabled to safely, efficiently and inexpensively prepare a high-purity phenyltriazolinone (5) in a high yield, and they have accomplished the present invention. [0028] Preferred processes for preparing a phenyltriazolinone according to the present invention include the first preparation process, the second preparation process, the third preparation process, the fourth preparation process and the fifth preparation process described below. [0029] The first preparation process according to the present invention is a process for preparing a phenyltriazolinone represented by the following general formula (5) , comprising reacting an aniline represented by the following general formula (1) with a nitrite to form a diazonium salt, then reducing the diazonium salt using a sulfite or a hydrogensulfite, then hydrolyzing the reduction product to form a phenylhydrazine represented by the following general formula (2) , then reacting the resulting phenylhydrazine (2) with formaldehyde in the presence of a catalyst at pH 5 to 10 to form a formaldehyde-phenylhydrazone represented by the following general formula (3), then reacting the formaldehyde-phenylhydrazone (3) with cyanic acid to forma phenyltriazolidinonerepresentedby the following general formula (4), then reacting the phenyltriazolidinone (4) with an oxidizing agent selected from a hypohalite and oxygen in the absence of a catalyst or in the presence of an oxidation catalyst; [0030] (Formula Removed) [0031] wherein X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other, [0032] (Formula Removed) [0033] wherein X and n are the same as those in the formula (1), [0034] (Formula Removed) [0035] wherein X and n are the same as those in the formula (1), [0036] (Formula Removed) [0037] wherein X and n are the same as those in the formula (1), [0038] (Formula Removed) [0039] wherein X and n are the same as those in the formula (1). [0040] In the second preparation process according to the present invention, a crude product of the phenylhydrazine (2) may be separated by removing an aqueous layer from a reaction mixture containing the phenylhydrazine represented by the following general formula (2) by filtration, decantation or the like, when needed; [0041] (Formula Removed) [0042] wherein X and n are the same as those in the formula (1). [0043] In the third preparation process according to the present invention, a crude product of the formaldehyde-phenylhydrazone (3) may be separated by removing an aqueous layer from a reaction mixture containing the formaldehyde-phenylhydrazone represented by the following general formula (3) by filtration, decantation or the like, when needed; [0044] (Formula Removed) [0045] wherein X and n are the same as those in the formula (1). [0046] In the fourth preparation process according to the present invention, the aniline represented by the following general formula (1) may be reacted with a nitrite in the presence of an organic solvent to form a diazonium salt, when needed; [0047] (Formula Removed) [0048] wherein X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other. [0049] In the fifth preparation process according to the present invention, the phenyltriazolinone represented by the following general formula (5) may be purified by treating it with an alkali after the phenyltriazolidinone represented by the following general formula (4) is reacted with an oxidizing agent selected from a hypohalite and oxygen in the absence of a catalyst or in the presence of an oxidation catalyst, when needed; [0050] (Formula Removed) [0051] wherein X and n are the same as those in the formula (1), [0052] (Formula Removed) [0053] wherein X and n are the same as those in the formula (1). EFFECT OF THE INVENTION [0054] In the process for preparing a phenyltriazolinone (5) according to the present invention, the reactions are completed in a short period of time at a relatively low temperature, and a high-purity phenyltriazolinone (5) is obtained in a high yield. [0055] In the process for preparing a phenyltriazolinone (5) according to the present invention, the preparation steps may be continuously carried out without isolating or purifying an intermediate product formed in each step, so that a phenyltriazolinone (5) is efficiently, safely and inexpensively provided with a small quantity of energy. Accordingly, the process for preparing a phenyltriazolinone of the invention is suitable also for large-scale industrial production. BEST MODE FOR CARRYING OUT THE INVENTION [0056] The process for preparing a phenyltriazolinone according to the invention is described in detail hereinafter. [0057] In the process for preparing a phenyltriazolinone according to the invention, a phenyltriazolinone represented by the following formula (5) is prepared through such a series of reaction steps as indicated by the following formula A. [0058] In this preparation process, a phenyltriazolinone represented by the following formula (5) is prepared through the following first to fourth steps using an aniline (1) as a raw material. [0059] That is to say, in the first step in the process for preparing a phenyltriazolinone (5), an aniline (1) is reacted with a nitrite to form a diazonium salt, then the diazonium salt is reduced using a sulfite or a hydrogensulf ite, and the reduction product is hydrolyzed to form a phenylhydrazine (2). [0060] From the viewpoint of improvement in yield and purity, a crude product or an aqueous suspension of the phenylhydrazine (2) may be used in the subsequent step instead of isolated phenylhydrazine (2) . The crude product and the aqueous suspension are obtained by removing an aqueous layer from a reaction mixture by filtration, decantation or the like. [0061] From the viewpoints of improvement in yield and improvement in purity, an aniline (1) may be reacted with a nitrite in the presence of an organic solvent to form a diazonium salt, then the diazonium salt may be reduced using a sulfite or a hydrogensulfite, and the reduction product may be hydrolyzed to form a phenylhydrazine (2) . [0062] In the second step, the resulting phenylhydrazine (2) is subsequently reacted with formaldehyde in the presence of a catalyst, preferably at specific pH (pH 5 to 10), to form a formaldehyde-phenylhydrazone (3). [0063] From the viewpoint of improvement in yield and purity, a crude product or an aqueous suspension of the formaldehyde-phenylhydrazone (3) may be used in the subsequent step instead of isolated formaldehyde-phenylhydrazone (3). The crude product and the aqueous suspension are obtained by removing an aqueous layer from a reaction mixture by filtration, decantation or the like. [0064] In the third step, the formaldehyde-phenylhydrazone (3) is subsequently reacted with cyanic acid to form a phenyltriazolidinone (4). [0065] The phenyltriazolidinone (4) without being subjected to isolation or purification is frequently used in the next step (fourth step). [0066] In the fourth step, thephenyltraizolidinone (4) is subsequently reacted with an oxidizing agent selected from a hypohalite and oxygen in the absence of a catalyst or in the presence of an oxidation catalyst to prepare a phenyltriazolinone (5). [0067] From the viewpoint of improvement in purity, the phenyltriazolinone (5) may be purified by alkali treatment after the reaction is completed. [0068] In the above process of the invention, the pheylhydrazine (2) may be isolated when needed, and the formaldehyde-phenylhydrazone (3) (also referred to as a "phenylhydrazone") may be isolated when needed. [0069] In the preparation process of the invention, removal of an aqueous layer may be carried out in either of the first step and the second step. Formula A [0070] (Formula Removed) [0071] In the formulas (1) to (5) , X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other. [0072] As the "halogen atom", chlorine atom, bromine atom, fluorine atom or iodine atom may be mentioned. [0073] When X in the formulas (1) to (5) is a "lower alkyl", an alkyl group of 1 to 6 carbon atoms may be mentioned as the lower alkyl group, which may be linear or branched. Examples of the alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, 2-methylbutyl, neopentyl, n-hexyl, 4-methylpentyl, 2,3-dimethylbutyl, 1-ethylbutyl, l-ethyl-2-methylpropyl, 1-methyl-l-ethylpropyl, l-methyl-2-ethylpropyl, 2-methyl-l-ethylpropyl, 2-methyl-l-ethylpropyl and 2-methyl-2-ethylpropyl. [0074] The phenylhydrazine (2) may or may not be a salt. Synthesis of phenylhydrazine (2) (first step) In the "first step", it is preferable that an aniline represented by the aforesaid formula (1) is converted into a diazonium salt using a nitrite, then the resulting diazonium salt is reduced with a sulfite or a hydrogensulfite, and then the reduction product is hydrolyzed to obtain the corresponding phenylhydrazine represented by the aforesaid formula (2). [0075] Specifically, for example, an aniline (1) that is a raw material is reacted with hydrochloric acid to form a salt. [0076] Then, sodium nitrite is added to this hydrochloride to perform diazotization, then the diazotized product is added to a solution sodium sulfite, pH of which has been adjusted to 5.5 to 8.0, to perform reduction, and the reduction product is hydrolyzed to form a phenylhydrazine (2) . [0077] In another case, an aniline (1) that is a raw material is reacted with hydrochloric acid in the presence of an organic solvent to form a salt, then sodium nitrite is added to this hydrochloride to perform diazotization, then the diazotization product is added to a solution of sodium sulfite, pH of which has been adjusted to 5.5 to 8.0, to perform reduction, and the reduction product is hydrolyzed to form a phenylhydrazine (2) . [0078] The diazotization, reduction and hydrolysis in the first step may be carried out in accordance with publicly known methods. For the purpose of describing the reactions in the first step in more detail, preferred embodiments of them in the preparation process of the invention are given below. [0079] In the diazotization in the first step, an aniline (1) is first reacted with, for example, hydrochloric acid to form a salt, or an aniline (1) is reacted with hydrochloric acid in the presence of an organic solvent to form a salt. In this embodiment, hydrochloric acid is used in excess. [0080] (Formula Removed) [0081] Next, for example, sodium nitrite is added to perform diazotization. [0082] (Formula Removed) [0083] Subsequently, the diazotized product is added to a solution of sodium sulfite, pH of which has been adjusted by, for example, sulfuric acid, to perform reduction. [0084] (Formula Removed) [0085] Next, the phenylhydrazine sulfonate formed is hydrolyzed to obtain a salt of a phenylhydrazine. [0086] (Formula Removed) [0087] The resulting salt of the phenylhydrazine may be neutralized, when needed. [0088] (Formula Removed) [0089] The diazotization reaction to form such a diazonium salt is usually carried out at a temperature of -25°C to 25°C, preferably -5°C to 20°C, for 15 minutes to 2 hours, preferably 30 minutes to 1 hour, at normal pressure. Examples of the nitrites used as diazotization agents include sodium nitrite and potassium nitrite, and preferable is sodium nitrite. [0090] The nitrite is usually used in an amount of 1.0 to 1.5 mol, preferably 1. 0 to 1.2 mol, based on 1 mol of the aniline (1). Although the nitrite may be used in the form of a solid, it is usually used in the form of an aqueous solution. [0091] In the diazotization reaction, a mineral acid is usually used. Examples of the mineral acids include hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, and preferable are hydrochloric acid and sulfuric acid. The mineral acid is usually used in an amount of 1.0 to 10.0 mol, preferably 2.0 to 6.0 mol, based on 1 mol of the aniline (1) . The mineral acid is usually used in the form of an aqueous solution. [0092] When the diazotization reaction is carried out using a mineral acid in the presence of an organic solvent, an organic solvent that is immiscible with water is usually used. Examples of such organic solvents include aliphatic hydrocarbons, such as pentane, hexane, heptane and petroleum ether; aromatic hydrocarbons, such as benzene, toluene and xylene; and halogenated hydrocarbons, such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. [0093] The amount of the organic solvent used is usually not less than 0.1 time, preferably about 0.5 to about 5.0 times, as much as the aniline by weight. The kind and the amount of the mineral acid used herein are the same as those previously described. [0094] When the diazotization reaction is carried out using a mineral acid in the presence of an organic solvent under the above conditions, the aniline is homogeneously dispersed in an aqueous solution of the mineral acid, so that the diazotization reaction proceeds in a high conversion rate, and a high-purity phenylhydrazine is formed. As a result, a high-purity pheyltriazolinone is obtained in a high yield. [0095] The subsequent reduction reaction of the diazonium salt obtained by diazotization of the aniline (1) is usually carried out at a temperature of 0°C to 80°C, preferably 10°C to 70°C, for 1 to 24 hours, preferably 2 to 12 hours, at normal pressure. [0096] Examples of the sulfites which are reducing agents used in the reduction reaction include ammonium sulfite, sodium sulfite and potassium sulfite. Of these, sodium sulfite is preferable from the viewpoints of high general-purpose properties, etc. [0097] Examples of the hydrogensulf ites which are reducing agents used in the reduction reaction include ammonium hydrogensulfite, sodium hydrogensulfite and potassium hydrogensulfite. Of these, sodium hydrogensulfite is preferable from the viewpoints of high general-purpose properties, etc. [0098] Although these reducing agents may be used in its original form, it is usually used in the form of an aqueous solution. The amount of the sulfite or the hydrogensulfite used is usually not less than 4.0 mol, preferably 2.5 to 4.0 mol, based on 1 mol of the aniline (1). [0099] The diazonium salt obtained by diazotization of the aniline (1) is added to an aqueous solution of a sulfite or a hydrogensulfite, pH of which has been usually adjusted to 5.5 to 8.0 and the reaction is carried out. The pH of the reaction system is usually adjusted to 5.5 to 8.0, preferably 6.0 to 7.5. The pH can be adjusted by the use of an acid, such as hydrochloric acid or sulfuric acid, or an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide or ammonia. [0100] The hydrolysis subsequent to the reduction reaction is usually carried out at a temperature of -5°C to 90°C, preferably 0°C to 80°C, for 1 to 24 hours, preferably 3 to 10 hours, at normal pressure. [0101] In the hydrolysis, a mineral acid is usually used, and examples thereof include hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. Of these, hydrochloric acid and sulfuric acid are preferable. The amount of the mineral acid used is usually not less than 2. 0 mol, preferably 5.0 to 30.0 mol, based on 1 mol of the aniline (1) (in the case of hydrochloric acid: number of moles of hydrogen chloride). [0102] As the phenylhydrazine (2) , the reaction mixture obtained by the hydrolysis may be subjected without any treatment to the reaction of the next second step. But the reaction mixture after neutralization with an alkali is preferably used. [0103] Examples of the alkalis include sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate. Of these, sodium hydroxide is preferable from the viewpoints of high general-purpose properties, etc. [0104] The resulting phenylhydrazine (2) in the form of a mixture in this step may be subjected without any treatment to the next step. Further, the resulting phenylhydrazine (2) may be subjected in this step to any one treatment of purification, isolation and separation by removal of an aqueous layer, and the phenylhydrazine (2) treated may be subjected to the next step. Synthesis of formaldehyde-phenylhydrazone (3) (second step) In the "second step" included in the first and the second processes for preparing a phenyltriazolinone (5) of the invention, the phenylhydrazine (2) is usually reacted with formaldehyde in a solvent in the presence of a catalyst at pH 5 to 10, preferably pH 6 to 8, to form the corresponding formaldehyde-phenylhydrazone (3) . [0105] The reaction can be efficiently carried out by, for example, iding formaldehyde to the phenylhydrazine (2) in the form of the reaction mixture obtained in the first step and mixing without subjecting to any treatment of purification, isolation and separation by removal of an aqueous layer. [0106] The reaction in the second step is carried out at a temperature of usually -10°C to the "boilingpoint of the solvent used", preferably 0°Cto+40°C, for usually 10 minutes to 24 hours, preferably 30 minutes to 5 hours, at normal pressure. [0107] In the reaction, the phenylhydrazine (2) and formaldehyde are used (reacted) in equimolar amounts theoretically, but formaldehyde is usually used in an amount of 1.0 to 2.0 mol, preferably 1.0 to 1.2 mol, based on 1 mol of the phenylhydrazine (2), and in usual, a formaldehyde aqueous solution containing such an amount of formaldehyde is used. [0108] Examples of the catalysts used in the reaction of the phenylhydrazine (2) with formaldehyde include: organic acid salts, such as ammonium formate, sodium formate, potassium formate, ammonium acetate, sodium acetate and potassium acetate; organic acids, such as formic acid and acetic acid; sulfonic acids, such as paratoluenesulfonic acid; inorganic bases, such as sodium hydroxide, potassium hydroxide and sodium carbonate; and amines, such as triethylamine, pyridine and 1,8-diazabicyclo[5.4.0]undec-7-ene. [0109] The catalyst is usually used in an amount of 0.01 to 20.0% by mol, preferably 0.1 to 10.0% by mol, based on the phenylhydrazine (2). [0110] When the reaction of the second step is carried out using a mixture containing the phenylhydrazine (2) obtained in the first step, the amount of the phenylhydrazine (2) contained in the mixture can be determined by the analysis using high performance liquid chromatography or the like. [0111] The pH of the reaction system is desirably adjusted to usually 5 to 10, preferably 6 to 8. The pH can be adjusted by the use of an acid, such as formic acid, acetic acid, hydrochloric acid or sulfuric acid, or an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide. [0112] If the reaction of the phenylhydrazine (2) with formaldehyde is carried out at pH of the above range, side reaction can be inhibited, and thus such pH is preferable. [0113] Examples of the solvents include water; alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, methoxyethyl alcohol, n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol and t-butyl alcohol; ethers, such as tetrahydrofuran and dioxane; and nitriles, such as acetonitrile and propionitrile. Moreover, mixed solvents of water and these solvents are also employable, and a mixed solvent of t-butyl alcohol and water is preferably used. [0114] The mixed solvent may be a mixture of two or more kinds. When a mixed solvent of an organic solvent and water is used, water is usually used in an amount of 1 to 500 parts by weight, preferably 10 to 200 parts by weight, based on 100 parts by weight of the organic solvent. [0115] The solvent is used in an amount of, for example, 100 g to 4000 g based on 1 mol of the phenylhydrazine (2). [0116] The amount of the solvent can be appropriately changed according to the reactants and the reaction conditions in each step, such as the following third step that is a step of the reaction of a formaldehyde-phenylhydrazone (3) with cyanic acid or the following fourth step that is a step of the reaction of a phenyltriazolidinone with an oxidizing agent. Thus, the amount thereof is not determined unconditionally. [0117] The resulting folmaldehyde-phenylhydrazone (3) may be used in the next step in the form of a mixture as such, or after any one treatment of purification, isolation and separation by removal of an aqueous layer is performed in this step, the folmaldehyde-phenylhydrazone (3) thus treated may be used in the next step. Synthesis of phenyltriazolidinone (4) (third step) In the "third step" that is preferably included in the process for preparing a phenyltriazolinone (5) of the invention, the formaldehyde-phenylhydrazone (3) is reacted with cyanic acid in a solvent to form a phenyltriazolidinone (4). [0118] The reaction in the third step can be efficiently carried out by reacting the formaldehyde-phenylhydrazone (3) obtained in the second step with cyanic acid without performing any treatment of purification, isolation and separation by removal of an aqueous layer. The reactions in the third and subsequent steps may be carried out after a reaction mixture containing the formaldehyde-phenylhydrazone (3) obtained in the second step is subjected to any one treatment of purification, isolation and separation by removal of an aqueous layer. [0119] When the reaction in the third step is carried out using a mixture containing the formaldehyde-phenylhydrazone (3) obtained in the second step, the amount of the formaldehyde-phenylhydrazone (3) contained in the mixture can be determined by the analysis using high performance liquid chromatography or the like. [0120] The reaction in the third step is carried out at a temperature of usually -10°C to +60°C, preferably 0°C to +30°C, for usually 1 to 24 hours, preferably 1 to 5 hours, at normal pressure. [0121] The folmaldehyde-phenylhydrazone (3) and cyanic acid are used in equimolar amounts theoretically, but cyanic acid is usually used in an amount of 1.0 to 3.0 mol, preferably 1.0 to 2.0 mol, based on 1 mol of the formaldehyde-phenylhydrazone (3). [0122] As the solvent, a solvent similar to that used in the second step is used from the viewpoints of handling efficiency, etc. [0123] When a mixed solvent of an organic solvent and water is used, water is usually used in an amount of 1 to 500 parts by weight, preferably 10 to 200 parts by weight, based on 100 parts by weight of the organic solvent. [0124] The solvent is used in an amount of 100 g to 5000 g based on mol of the formaldehyde-phenylhydrazone (3). [0125] The phenyltriazoldinone (4) obtained in the third step may be subjected to purification or isolation when needed, but in usual, it is used in the fourth step in the form of a mixture as such. Synthesis of phenytriazolinone (5) (fourth step) In the "fourth step" in the process for preparing a phenyltriazolinone (5) of the invention, the phenyltriazolidione (4) and an oxidizing agent selected from a hypohalite and oxygen are reacted in a solvent in the absence of a catalyst or in the presence of an oxidation catalyst to form a desired phenyltriazolinone (5). [0126] In usual in the fourth step, the phenyltriazolidinone (4) obtained in the third step is used in the form of a mixture containing the phenyltriazolidinone (4), without being subjected to isolation or purification. Inthiscase, the reaction canbe efficiently carried out by adding an oxidizing agent to the reaction mixture containing the phenyltriazolidinone (4) obtained in the third step. [0127] The reaction in the fourth step is carried out at a temperature of usually -20°C to +60°C, preferably 0°C to 30°C, for usually 1 to 24 hours, preferably 2 to 8 hours, at normal pressure. [0128] Examples of the hypohalites which are oxidizing agents include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, sodium hypobromite and potassium hypobromite. Of these, sodium hypochlorite is preferable from the viewpoints of high general-purpose properties, etc. [0129] The hypohalite may also be used in the presence of an oxidation catalyst, when needed. [0130] Examples of the oxidation catalysts used include: salts of the iron group, such as ferrous chloride, ferric chloride, ferrous bromide, ferric bromide, ferrous sulfate, ferric sulfate, cobalt chloride, cobalt bromide, cobalt sulfate, cobalt nitrate, cobalt acetate and nickel chloride; complexes of the iron group, such as iron (III) acetylacetonate, cobalt(II) acetylacetonate, cobalt (II) bis(salicylidene)ethylenediamine and hexaamminenickel(II) chloride; elements of the platinum group, such as platinum and palladium; salts of the platinum group, such as palladium chloride, palladium acetate and platinum oxide; complexes of the platinum group, such as chloro(triphenylphosphine)rhodium and dichlorobis(triphenylphosphine)ruthenium; copper salts, such as copper(I) chloride, copper (I) bromide, copper(II) chloride, copper(II) bromide, copper sulfate and copper acetate; copper complexes, such as copper(II) acetylacetonate and bisethylenediamine copper; zinc salts, such as zinc chloride; zinc complexes, such as tris(ethylenediamine)zinc; vanadium salts, such as divanadium pentaoxide; vanadium complexes, such as vanadium oxide acetylacetonate; and salts of rare earth elements, such as cerium chloride and samarium iodide. [0131] These catalysts may be used singly or in combination of two or more kinds. [0132] In the reaction, thephenyltriazolidinone (4) and the oxidizing agent are used in equimolar amounts theoretically, but the oxidizing agent is usually used in an amount of 1.0 to 1.4 mol, preferably 1.0 to 1.1 mol, based on 1 mol of the phenyltriazolidinone (4). [0133] Specifically, for example, an aqueous solution of sodium hypochlorite having a concentration of 5 to 25% (weight/weight), preferably 5 to 15%, may be used. If necessary, the oxidation catalyst is used in an amount of usually 0.01 to 10.0% by mol, preferably 0.1 1.0% by mol, based on the phenyltriazolidinone (4). [0134] When the reaction of the fourth step is carried out using a mixture containing the phenyltriazolidinone (4) obtained in the third step, the amount of the phenyltriazolidinone (4) in the mixture can be determined by the analysis using high performance liquid chromatography or the like. [0135] As the solvent, a solvent similar to that used in the second step or the third step is used, and also in the case of a mixed solvent of an organic solvent and water, the organic solvent and water are used in the same mixing ratio. Such a solvent is used in an amount of 100 g to 6000 g based on 1 mol of the phenyltriazolidinone (4). [0136] In the process for preparing a phenyltriazolinone (5) of the invention, it is preferable to stir the reaction solution at least mildly in each step of the first to the fourth steps. [0137] After the reaction is completed, the organic solvent in the mixed solvent (mixed solvent of organic solvent and water) above can be reused by distilling off from the reaction mixture by the use of a distillation apparatus or the like and recovering the organic solvent. [0138] Thephenyltriazolinone (5) that is a desired product is isolated through a usual extraction and separation operation, oris fractionated by distilling off the organic solvent, precipitating the desired product (5) in water, and subjecting the resultant mixture to filtration. [0139] Another method to isolate and purify the phenyltriazolinone (5) that is a desired product is, for example, the following method. [0140] That is to say, after the organic solvent contained in the reaction mixture is distilled off, the phenyltriazolinone (5) that is a desired product is dissolved in an aqueous solution of a base such as sodium hydroxide to form a salt, and the salt is washed with an organic solvent. [0141] Subsequently, to the solution containing the phenyltriazolinone (5) salt thus washed is added a mineral acid such as hydrochloric acid to neutralize the phenyltriazolinone (5) salt-containing solution, thereby precipitating the phenyltriazolinone (5) that is a desired product. [0142] By subjecting the crystals precipitated to filtration and washing with water, a high-purity phenyltriazolinone (5) can be obtained. [0143] Another method to isolate and purify the phenyltriazolinone (5) that is a desired product is, for example, the following method. [0144] That is to say, after the reaction is completed, an alkali is added to the reaction mixture to form an alkali salt of the phenyltriazolinone (5) that is a desired product while decomposing a side reaction product with alkali treatment. When a mixed solvent of an organic solvent and water is used as a reaction solvent, the organic solvent is distilled off, and then an aqueous mixture containing impurities and the alkali salt of the phenyltriazolinone (5) that is a desired product is washed with an organic solvent to thereby remove impurities from the aqueous mixture without loss of the desired product. [0145] Subsequently, to the aqueous solution containing the alkali salt of the phenyltriazolinone (5) having been washed with an organic solvent is added a mineral acid such as hydrochloric acid to neutralize the aqueous solution containing the alkali salt of the phenyltriazolinone (5) , therebyprecipitating the phenyltriazolinone (5) that is a desired product. [0146] By subjecting the precipitated crystals to filtration and washing with water, a high-purity phenyltriazolinone (5) can be obtained. [0147] The alkali treatment is carried out at a temperature of usually 0°C to 100°C, preferably 20°C to 90°C, for usually 1 to 24 hours, preferably 1 to 12 hours, at normal pressure. [0148] Examples of the alkalis used include sodium hydroxide, potassium hydroxide, sodium carbonate and potassiumcarbonate. Of these, sodium hydroxide is preferable from the viewpoints of high general-purpose properties, etc. The alkali is usually used in an amount of 1.2 to 4.0 mol, preferably 2.0 to 2.5 mol, based on 1 mol of the phenyltriazolinone (5) . [0149] Examples of the organic solvents used for the washing include aliphatic hydrocarbons, such as pent ane, hexane, heptane and petroleum ether; aromatic hydrocarbons, such as benzene, toluene and xylene; ethers, such as diethyl ether, diisopropyl ether and t-butyl methyl ether; and halogenated hydrocarbons, such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. [0150] Under the above conditions, the reaction by-product is decomposed by an alkali, and impurities are removed without loss of the desired product by washing the alkali-treated aqueous mixture with an organic solvent. Therefore, when the phenyltriazolinone (5) isolated and purified under the above condition, a high-purity phenyltriazolinone is obtained in a high yield. [0151] The resulting desired product may be further purified by means of washing with an organic solvent, column chromatography, recrystallization or the like, when needed. [0152] The phenyltraizolinone (5) thus obtained is preferably used as a raw material for producing agricultural chemicals or pharmaceuticals. [0153] In the present invention, the whole process may be carried out without subj ecting intermediate products that are the phenylhydrazine represented by the formula (2), the formaldehyde-phenylhydrazone represented by the formula (3) and the phenyltriazolidinone represented by the formula (4) to any treatment of purification, isolation and separation by removal of an aqueous layer. [0154] Further, each of the steps may be carried out after any of intermediate products that are phenylhydrazine represented by the formula (2), the formaldehyde-phenylhydrazone represented by the formula (3) and the phenyltriazolidinone represented by the formula (4) are, if needed, subjected to any one treatment of purification, isolation and separation by removal of an aqueous layer in each step. [0155] In this case, one of the phenylhydrazine, the formaldehyde-phenylhydrazone and the phenyltriazolidinone may be subjected to any one of the above treatments, or two of them may be subjected to any one of the above treatments, or all the three may be subjected to any one of the above treatments. [0156] As the solvent for use in each step, a solvent exerting no adverse influence on the reactions and favorably capable of well dissolving any of the aniline (1), the phenylhydrazine (2), the formaldehyde-phenylhydrazone (3) and the phenyltriazolidinone (4) is preferable from the viewpoint of reaction operations. However, the aforesaid solvent capable of at least partially dissolving any of them or being miscible with any of them is used. [0157] According to the preparation process of the invention, a desired high-purity compound (phenyltriazolinone (5) ) is obtained in a high yield in a short period of time under such relatively low-temperature reaction conditions as described above by passing through a series of reactions of the first to the fourth steps. EXAMPLES [0158] Hereinafter, the present invention is further specifically described with reference to the following examples, but it should be construed that the invention is in no way limited to those examples. Example 1 Preparation of 1-(2,4-dichlorophenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 1 liter was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 330 g of 10% hydrochloric acid and 48.6 g of 2, 4-dichloroaniline (purity>99%) were placed, and the mixture was stirred at 30°C for 15 minutes. [0159] The resulting mixture was cooled to -5°C, and 63 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0160] Separately from the above container, a four-necked flask having a volume of 2 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 97.4 g of sodium sulfite (purity: 97%) was dissolved in 350 g of water, and 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0161] This solution was cooled to 10 °C, and the diazonium salt solution previously prepared was quickly added. [0162] The resulting mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a mixture containing 2,4-dichlorophenylhydrazine sulfonate was obtained. [0163] To the resulting mixture, 200 g of toluene was added, and they were stirred at 65°C for 15 minutes to wash the aqueous layer, thereby removing an unreacted raw material and a reaction by-product. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0164] The aqueous layer obtained by the liquid separation was placed in a reaction container that is a four-necked flask having a volume of 3 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 313 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 20 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2, 4-dichlorophenylhydrazine sulfonate, whereby a mixture containing 2,4-dichlorophenylhydrazine hydrochloride was obtained. [0165] This mixture was cooled to 10 °C, and 300 g of a 50% sodium hydroxide aqueous solution was slowly added to precipitate 2,4-dichlorophenylhydrazine. Then, the resulting mixture was subjected to filtration to remove the aqueous layer, thereby obtained a 2,4-dichlorophenylhydrazine crude product. [0166] The amount of the resulting 2, 4-dichlorophenylhydrazine crude product was 55 g (purity: 90%). [0167] The resulting 2, 4-dichlorophenylhydrazine crude product was placed in a reaction container that was a four-necked flask having a volume of 1 liter and being equipped with a stirrer, a thermometer and a Dimroth condenser, and subsequently, 300 g of tertiary butanol, 50 g of water and 2 . 5 g of sodium acetate were added. While maintaining the pH of the mixture at 6 to 8 at 20°C, 27.5 g of a 36% formaldehyde aqueous solution was dropwise added over a period of 10 minutes. Thereafter, the mixture was stirred at the same temperature and at pH of the same range for 2 hours to obtain a mixture containing formaldehyde-2,4-dichlorophenylhydrazone. [0168] The reaction mixture was cooled to 10°C, then 19.4 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours to obtain a mixture containing 2,4-dichlorophenyltriazolidinone. [0169] Of the two layers (organic layer and aqueous layer) separated, the aqueous layer was removed to thereby remove unreacted formaldehyde and a salt. Thereafter, to the resulting organic layer (tertiary butanol layer) was dropwise added 162.5 g of a 11% sodium hypochlorite aqueous solution at 10°C over a period of 30 minutes. [0170] After the dropwise addition, the mixture was stirred at 10°C for 1 hour and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title substance. [0171] To the aqueous layer given after tertiary butanol was distilled off, 24 g of sodium hydroxide was added to form a salt of the desired title substance, thereby dissolving the salt in the aqueous layer. Then, 100 g of toluene was added, and the mixture was stirred to wash the aqueous layer, thereby removing a reaction by-product from the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0172] The aqueous layer obtained by the liquid separation was cooled to 15°C, and 94 g of 35% hydrochloric acid was dropwise added over a period of 15 minutes to neutralize the aqueous layer, thereby isolating the desired title substance. The crystals precipitated were collected by filtration and washed with 200 g of water. [0173] The crystals were sufficiently dried in a vacuum dryer to obtain 63.5 g of the desired title compound (yield: 92%, purity: 97%) . The siting point of the compound was in the range of 190 to 191 °C. EI-MS: M+229. Example 2 Preparation of 1- (2,4-dichlorophenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 1 liter was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 330 g of 10% hydrochloric acid and 48.6 g of 2, 4-dichloroaniline (purity>99%) were placed, and the mixture was stirred at 30°C for 15 minutes. [0174] The resulting mixture was cooled to -5°C, and 63 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0175] Separately from the above container, a four-necked flask having a volume of 2 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 97.4 g of sodium sulfite (purity: 97%) was dissolved in 350 g of water, and 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0176] This solution was cooled to 10 °C, and the diazonium salt solution reviously prepared was quickly added. [0177] The resulting mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a mixture containing 2,4-dichlorophenylhydrazine sulfonate was obtained. [0178] To the resulting mixture, 200 g of toluene was added, and they were stirred at 65°C for 15 minutes to wash the aqueous layer, thereby removing an unreacted raw material and a reaction by-product from the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0179] The aqueous layer recovered by the liquid separation was placed in a reaction container that is a four-necked flask having a volume of 3 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 313 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 20 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2, 4-dichlorophenylhydrazine sulfonate, whereby a mixture containing 2,4-dichlorophenylhydrazine hydrochloride was obtained. [0180] This mixture was cooled to 10°C, and300 gof a 50% sodiumhydroxide aqueous solution was slowly added to precipitate 4-dichlorophenylhydrazine. Then, the resulting mixture was subjected to filtration to remove the aqueous layer, thereby obtained a 2,4-dichlorophenylhydrazine crude product. [0181] The amount of the resulting 2, 4-dichlorophenylhydrazine crude product was 55 g (purity: 90%). [0182] The resulting 2, 4-dichlorophenylhydrazine crude product was placed in a reaction container constituted of a four-necked flask having a volume of 1 liter and being equipped with a stirrer, a thermometer and a Dimroth condenser, and subsequently, 300 g of tertiary butanol, 50 g of water and 2 . 5 g of sodium acetate were added. While maintaining the pH of the mixture at 6 to 8 at 20°C, 27.5 g of a 36% formaldehyde aqueous solution was dropwise added over a period of 10 minutes, and thereafter, the mixture was stirred at the same temperature and at pH of the same range for 2 hours to obtain a mixture containing formaldehyde-2,4-dichlorophenylhydrazone. [0183] The resulting reaction mixture was cooled to 10°C, then 19.4 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours . Of the two layers (organic layer and aqueous layer) separated, the aqueous layer was removed to thereby remove unreacted formaldehyde and a salt. [0184] Subsequently, to the resulting organic layer (tertiary butanol) was added 180mg of copper (II) acetatemonohydrate. While introducing an oxygen gas into the reaction mixture from an oxygen bomb at a flow rate of 10 ml/min, the reaction mixture was stirred at 10°C for 8 hours and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title substance. [0185] To the aqueous layer given after tertiary butanol was distilled off, 24 g of sodium hydroxide and 100 g of toluene were added, and they were stirred to wash the aqueous layer, thereby removing a reaction by-product. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0186] The aqueous layer obtained by the liquid separation was cooled to 15°C, and 94 g of 35% hydrochloric acid was dropwise added over a period of 15 minutes to neutralize the aqueous layer, thereby isolating the desired title substance. The crystals precipitated were collected by filtration and washed with 200 g of water. [0187] The resulting crystals were sufficiently dried in a vacuum dryer to obtain 64.2 g of the desired title compound (yield: 93%, purity: 96%). The melting point of the compound was in the range of 190 to 191°C. EI-MS: M+229. Example 3 Preparation of 1-(2,4-dichlorophenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 1 liter was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 330 g of 10% hydrochloric acid and 48.6 g of 2, 4-dichloroaniline (purity>99%) were placed, and the mixture was stirred at 30°C for 15 minutes. [0188] The resulting mixture was cooled to -5°C, then 63 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes, and thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0189] Separately from the above container, a four-necked flask having a volume of 2 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 97.4 g of sodium sulfite (purity: 97%) was dissolved in 350 g of water, and 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0190] This solution was cooled to 10 °C, and the diazonium salt solution previously prepared was quickly added. [0191] The resulting mixture was heated up to 20°C over a period of 0 minutes, then heated to 65 °C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a mixture containing 2,4-dichlorophenylhydrazine sulfonate was obtained. To the resulting mixture, 200 g of toluene was added, and they were stirred at 65°C for 15 minutes to wash the aqueous layer, thereby removing an unreacted raw material and a reaction by-product from the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0192] The aqueous layer obtained by the liquid separation was placed in a reaction container that was a four-necked flask having a volume of 3 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 313 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 20 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2, 4-dichlorophenylhydrazine sulfonate previously obtained, whereby a mixture containing 2, 4-dichlorophenylhydrazine hydrochloride was obtained. [0193] This mixture was cooled to 10 °C, and 300 g of a 50% sodium hydroxide aqueous solution was slowly added to precipitate 2,4-dichlorophenylhydrazine, whereby a 2,4-dichlorophenylhydrazine aqueous suspension was obtained. [0194] Subsequently, to the suspension was added 2. 5 g of sodium acetate. While maintaining the pH of the mixture at 6 to 8 at 20°C, 27.5 g of a 36% formaldehyde aqueous solution was dropwise added over a period of 10 minutes, and thereafter, the mixture was stirred at the same temperature and at pH of the same range for 2 hours. Then, the resulting mixture was subjected to filtration to remove the aqueous layer, thereby obtained a formaldehyde-2,4-dichlorophenylhydrazone crude product. The amount of the resulting formaldehyde-2,4-dichlorophenylhydrazone crude product was 58 g (purity: 90%). [0195] Subsequently, the resulting formaldehyde-2, 4-dichlorophenylhydrazone crude product was placed in a reaction container that is a four-necked flask having a volume of 1 liter and being equipped with a stirrer, a thermometer and a Dimrothcondenser, and300 gof tertiarybutanol was added. Themixture was cooled to 10°C, then 19.4 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours to obtain a mixture containing 2,4-dichlorophenyltriazolidinone. [0196] Subsequently, to the resulting mixture was dropwise added 162 . 5 g of a 11% sodium hypochlorite aqueous solution at the same temperature over a period of 30 minutes. [0197] After the dropwise addition, the mixture was stirred at 10°C for 1 hour and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title substance. [0198] To the aqueous layer given after tertiary butanol was distilled off, 50 g of water and 24 g of sodium hydroxide were added to form a salt of the desired title substance, thereby dissolving the salt in the aqueous layer. Then 100 g of toluene was added, and the mixture was stirred to wash the aqueous layer, thereby removing a reaction by-product from the aqueous layer. Thereafter, the reaction mixture was allowed to stand still to perform liquid separation. [0199] The aqueous layer recovered by the liquid separation was cooled to 15°C, and 94 g of 35% hydrochloric acid was dropwise added over a period of 15 minutes to neutralize the aqueous layer, thereby isolating the desired title substance. The crystals precipitated were collected by filtration and washed with 200 g of water. [0200] The resulting crystals were sufficiently dried in a vacuum dryer to obtain 62.1 g of the desired title compound (yield: 90%, purity: 96%) . The melting point of the compound was in the range of 190 to 191°C. EI-MS: M+229. Example 4 reparation of 1-phenyl-l, 2, 4-triazol-5-one A four-necked flask having a volume of 1 liter was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 330 g of 10% hydrochloric acid and 27.9 g of aniline (purity>99%) were placed, and the mixture was stirred at 30°C for 15 minutes. [0201] The resulting mixture was cooled to -5°C, and 63 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0202] Separately from the above container, a four-necked flask having a volume of 2 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 97.4 g of sodium sulfite (purity: 97%) was dissolved in 350 g of water, and 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0203] This solution was cooled to 10 °C, and the diazonium salt solution previously prepared was quickly added. [0204] The resulting mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature or 2 hours to reduce the diazonium salt, whereby a mixture containing phenylhydrazine sulfonate was obtained. [0205] To the resulting mixture, 200 g of toluene was added, and they were stirred at 65°C for 15 minutes to wash the aqueous layer, thereby removing an unreacted raw material and a reaction by-product from the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0206] The aqueous layer obtained by the liquid separation was placed in a reaction container that is a four-necked flask having a volume of 3 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 313 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 20 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the phenylhydrazine sulfonate previously prepared, whereby a mixture containing phenylhydrazine hydrochloride was obtained. [0207] This mixture was cooled to 10 ° C, and 300 g of a 50% sodiumhydroxide aqueous solution was slowly added to precipitate phenylhydrazine. Then, the resulting mixture was subjected to filtration to remove the aqueous layer, and the remainder was recovered to obtain a phenylhydrazine crude product. [0208] The amount of the resulting phenylhydrazine crude product was 34 g (purity: 90%). [0209] The resulting phenylhydrazine CYUA«- Pncw^ci was placed in a reaction container that is a four-necked flask having a volume of 1 liter and being equipped with a stirrer, a thermometer and a Dimroth condenser, and subsequently, 300 g of tertiary butanol, 50 g of water and 2.5 g of sodium acetate were added. While maintaining the pH of the mixture at 6 to 8 at 20°C, 27.5 g of a 36% formaldehyde aqueous solution was dropwise added over a period of 10 minutes, and thereafter, the mixture was stirred at the same temperature and at pH of the same range for 2 hours to obtain a mixture containing formaldehyde-phenylhydrazone. [0210] The resulting reaction mixture was cooled to 10°C, then 19.4 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours to obtain a mixture containing phenyltriazolidinone. [0211] Subsequently, to the resulting mixture was dropwise added 162. 5 g of a 11% sodium hypochlorite aqueous solution at the same temperature over a period of 30 minutes. [0212] After the dropwise addition, the mixture was stirred at 10°C or 1 hour and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title substance. [0213] To the aqueous layer given after tertiary butanol was distilled off, 24 g of sodium hydroxide was added to form a salt of the desired title substance, thereby dissolving the salt in the aqueous layer. Then, 100 g of toluene was added, and the mixture was stirred to wash the aqueous layer, thereby removing a reaction by-product from the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0214] The aqueous layer obtained by the liquid separation was cooled to 15°C, and 94 g of 35% hydrochloric acid was dropwise added over a period of 15 minutes to neutralize the aqueous layer, thereby isolating the desired title substance. The crystals precipitated were collected by filtration and washed with 150 g of water. [0215] The crystals were sufficiently dried in a vacuum dryer to obtain 42.5 g of the desired title compound (yield: 88%, purity: 96%) . The melting point of the compound was in the range of 184 to 185°C. EI-MS: M+161. Example 5 Preparation of 1-(2,3-dimethylphenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 1 liter was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 330 g of 10% hydrochloric acid and 36.3 g of 2, 3-dimethylaniline (purity>99%) were placed, and the mixture was stirred at 30°C for 15 minutes. [0216] The resulting mixture was cooled to -5°C, and 63 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0217] Separately from the above container, a four-necked flask having a volume of 5 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 97.4 g of sodium sulfite (purity: 97%) was dissolved in 350 g of water, and 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0218] This solution was cooled to 10°C, and the diazonium salt solution previously prepared was quickly added. This mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a reaction mixture containing 2, 3-dimethylphenylhydrazine sulfonate was obtained. [0219] The resulting reaction mixture was cooled to 20°C, and 313 g of 35% hydrochloric acid was dropwise added over a period of 20 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2,3-dimethylphenylhydrazine sulfonate previously obtained, whereby a mixture containing 2,3-dimethylphenylhydrazine hydrochloride was obtained. [0220] The resulting mixture was cooled to 10°C, and 300 g of a 50% sodium hydroxide aqueous solution was slowly added to precipitate 2,3-dimethylphenylhydrazine, whereby a 2,3-dimethylphenylhydrazine aqueous suspension was obtained. [0221] Subsequently, to the resulting 2,3-dimethylphenylhydrazine aqueous suspension were added 1,500 g of tertiary butanol and 2.5 g of sodium acetate. While maintaining the pH of the mixture at 6 to 8 at 20°C, 27 . 5 g of a 36% formaldehyde aqueous solution was dropwise added over a period of 10 minutes, and thereafter, the mixture was stirred at the same temperature and at pH of the same range for 2 hours to obtain a mixture containing formaldehyde-2,3-dimethylphenylhydrazone. [0222] The reaction mixture was cooled to 10°C, then 19.4 g of cyanic acid was added, and the mixture was stirred at the same temperature or 4 hours to obtain a mixture containing 2,3-dimethylphenyltriazolidinone. [0223] Of the two layers (organic layer and aqueous layer) separated, the aqueous layer was removed to thereby remove unreacted formaldehyde and a salt. Thereafter, to the resulting organic layer (tertiary butanol layer) was dropwise added 162.5 g of a 11% sodium hypochlorite aqueous solution at 10°C over a period of 30 minutes. [0224] After the dropwise addition, the mixture was stirred at 10°C for 1 hour and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title substance. [0225] To the aqueous layer given after tertiary butanol was distilled off, 24 g of sodium hydroxide was added to form a salt of the desired title substance, thereby dissolving the salt in the aqueous layer. Then, 100 g of toluene was added, and the mixture was stirred to wash the aqueous layer. Thereafter, the mixture was allowed to stand still to perform liquid separation. [0226] The aqueous layer obtained by the liquid separation was cooled to 15°C, and 94 g of 35% hydrochloric acid was dropwise added over a period of 15 minutes to neutralize the aqueous layer, thereby isolating the desired title substance. The crystals precipitated here collected by filtration and washed with 150 g of water. [0227] The crystals were sufficiently dried in a vacuum dryer to obtain 51.6 g of the desired title compound (yield: 91%, purity: 95%) . The melting point of the compound was in the range of 191 to 192 °C. EI-MS: M+18 9. Example 6 Preparation of 1-(2,4-dichlorophenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 5 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 350.0 g of 2, 4-dichloroaniline (purity>99%) and 350 g of toluene were placed, and the mixture was stirred at 30°C for 15 minutes . Thereafter, 2353 g of 10% hydrochloric acid was added, and the mixture was further stirred at 30°C for 15 minutes. [0228] The resulting mixture was cooled to -5°C, and 452 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0229] Separately from the above container, a four-necked flask having a volume of 10 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 698.9 g of sodium sulfite (purity: 97%) was dissolved in 2796 g of water, and 22.2 g of 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0230] This solution was cooled to 10 °C, and the diazonium salt solution previously prepared was added over a period of five minutes. [0231] The resulting mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a mixture containing 2,4-dichlorophenylhydrazine sulfonate was obtained. [0232] The resulting mixture was allowed to stand still to perform liquid separation into a toluene layer and an aqueous layer, and thereby an unreacted raw material and a reaction by-product contained in the toluene layer were removed. [0233] The aqueous layer obtained by the liquid separation was placed in a reaction container that is a four-necked flask having a volume of 10 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 2241 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 30 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2, 4-dichlorophenylhydrazine sulfonate, whereby a mixture containing 2,4-dichlorophenylhydrazine hydrochloride was obtained. [0234] This mixture was cooled to 10°C, and 2241 g of a 48% sodium hydroxide aqueous solution was dropwise added over a period of 30 minutes to precipitate 2,4-dichlorophenylhydrazine. Then, the resultant mixture was subjected to filtration to remove the aqueous layer, thereby obtaining a 2,4-dichlorophenylhydrazine crude product. [0235] The amount of the resulting 2, 4-dichlorophenylhydrazine crude product was 900 g (purity: 98%). [0236] The resulting 2, 4-dichlorophenylhydrazine crude product was placed in a reaction container that is a four-necked flask having a volume of 10 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and subsequently, 1904 g of tertiary butanol and 1500 g of water were added. While maintaining the pH of the mixture at 6 to 8 at 20°C, 174.6 g of a 37% formaldehyde aqueous solution was dropwise added over a period of 15 minutes. Then, to the resulting mixture, a solution obtained by dissolving 8.8 g of sodium acetate and 2.6 g of acetic acid in 44 g of water was dropwise added at 20°C over a period of 5 minutes. Thereafter, while maintaining the pH of the mixture at 5.5 to 6 at 20°C, the mixture was stirred for 2 hours to obtain a mixture containing formaldehyde-2,4-dichlorophenylhydrazone. [0237] Subsequently, the reaction mixture was cooled to 10°C, then 130.1 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours to obtain a mixture containing 2,4-dichlorophenyltriazolidinone. [0238] To the resulting mixture was dropwise added 1441 g of a 10% sodium hypochlorite aqueous solution over a period of 45 minutes while maintaining the temperature of the mixture in the range of not higher than 10°C. After the dropwise addition, the mixture was stirred at 10°C for 1 hour and further stirred at 25°C for 5 hours to obtain a mixture containing the desired title compound. [0239] Subsequently, to the resulting mixture was added 359 g of a 48% sodium hydroxide aqueous solution, and they were stirred at 80°C for 2 hours. Thereafter, tertiary butanol was distilled off from the mixture. To the aqueous mixture containing a sodium salt of the desired title compound and impurities was added 990 g of dichloroethane, and washing by stirring was performed to remove impurities from the aqueous layer. Thereafter, the resulting mixture was allowed to stand still to perform liquid separation. The aqueous layer obtained by the liquid separation and containing the sodium salt of the desired title compound was cooled to 20°C, and 1660 g of 18% hydrochloric acid was dropwise added over a period of 60 minutes to neutralize the aqueous layer, thereby isolating the desired title compound. The crystals precipitated were collected by filtration and washed with 2000 g of water. [0240] The crystals were sufficiently dried in a vacuum dryer to obtain 472 g of the desired title compound (yield: 95%, purity: 99%) . The melting point of the compound was in the range of 190 to 191 °C. EI-MS: M+229. Example 7 Preparation of 1-(2, 4-dichlorophenyl)-1,2,4-triazol-5-one A four-necked flask having a volume of 5 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container, and 350.0 g of 2, 4-dichloroaniline (purity>99%) and 350 g of toluene were placed, and the mixture was stirred at 30°C for 15 minutes . Thereafter, 2353 g of 10% hydrochloric acid was added, and the mixture was stirred at 30°C for 15 minutes. [0241] The resulting mixture was cooled to -5°C, and 452 g of a 35% sodium nitrite aqueous solution was dropwise added over a period of 30 minutes. Thereafter, the mixture was stirred at -3 to 0°C for 1 hour to obtain a diazonium salt solution. [0242] Separately from the above container, a four-necked flask having a volume of 10 liters was equipped with a stirrer, a thermometer and a Dimroth condenser to prepare a reaction container. In this reaction container, 698.9 g of sodium sulfite (purity: 97%) was dissolved in 2796 g of water, and 22.2 g of 95% sulfuric acid was added to adjust the pH of the solution to 7.2. [0243] This solution was cooled to 10 °C, and the diazonium salt solution previously prepared was added over a period of 5 minutes. [0244] The resulting mixture was heated up to 20°C over a period of 30 minutes, then heated to 65°C and stirred at the same temperature for 2 hours to reduce the diazonium salt, whereby a mixture containing 2,4-dichlorophenylhydrazine sulfonate was obtained. [0245] The resulting mixture was allowed to stand still to perform liquid separation into a toluene layer and an aqueous layer, and thereby an unreacted raw material and a reaction by-product contained in the toluene layer were removed. [0246] The aqueous layer obtained by the liquid separation was placed in a reaction container that was a four-necked flask having a volume of 10 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 2241 g of 35% hydrochloric acid was dropwise added at 20°C over a period of 30 minutes. Thereafter, the mixture was stirred at 75°C for 3 hours to hydrolyze the 2, 4-dichlorophenylhydrazine sulfonate, whereby a mixture containing 2,4-dichlorophenylhydrazine hydrochloride was obtained. The mixture was cooled to 10°C, and 2241 g of a 48% sodium hydroxide aqueous solution was dropwise added over a period of 30 minutes to precipitate 2,4-dichlorophenylhydrazine, whereby a 2,4-dichlorophenylhydrazine aqueous suspension was obtained. [0247] Subsequently, to the suspension was dropwise added 174.6 g of a 37% formaldehyde aqueous solution over a period of 15 minutes while maintaining the pH of the mixture at 6 to 8 at 20°C. To the resulting mixture, a solution obtained by dissolving 8.8 g of sodium acetate and 2.6 g of acetic acid in 44 g of water was dropwise added at 20°C over a period of 5 minutes, and thereafter, while maintaining the pH of the mixture at 5.5 to 6 at 20°C, the mixture was stirred for 2 hours. Then, the resulting mixture was subjected to filtration to remove the aqueous layer, thereby obtain a formaldehyde-2,4-dichlorophenylhydrazone crude product. The amount of the resulting formaldehyde-2,4-dichlorophenylhydrazone crude product was 400 g (purity: 95%). [0248] Subsequently, the resulting formaldehyde-2,4-dichlorophenylhydrazone crude product was placed on a reaction container that was a four-necked flask having a volume of 10 liters and being equipped with a stirrer, a thermometer and a Dimroth condenser, and 1900 g of tertiary butanol was added. The mixture was cooled to 10°C, then 130.1 g of cyanic acid was added, and the mixture was stirred at the same temperature for 4 hours to obtain a mixture containing 2,4-dichlorophenylhydrazolidinone. [0249] To the resulting mixture was dropwise added 1441 g of a 10% sodium hypochlorite aqueous solution over a period of 45 minutes while maintaining the temperature of the mixture in the range of not higher than 10°C. After the dropwise addition, the mixture was stirred at 10°C for 1 hour and further stirred at 25°C for 3 hours to obtain a mixture containing the desired title compound. [0250] Subsequently, to the resulting mixture was added 359 g of a 4 8% sodium hydroxide aqueous solution, and they were stirred at 80°C for 2 hours. Thereafter, tertiary butanol was distilled off from the mixture. To the aqueous mixture containing a sodium salt of the desired title compound and impurities was added 990 gof dichloroethane, and washing by stirring was performed to remove impurities from the aqueous layer. Thereafter, the resulting mixture was allowed to stand still to perform liquid separation. The aqueous layer obtained by the liquid separation and containing the sodium salt of the desired title compound was cooled to 20°C, and 1660 g of 18% hydrochloric acid was dropwise added over a period of 60 minutes to neutralize the aqueous layer, thereby isolating the desired title compound. The crystals precipitated were collected by filtration and washed with 2000 g of water. [0251] The crystals were sufficiently dried in a vacuum dryer to obtain 468 g of the desired title compound (yield: 94%, purity: 99%). The melting point of the compound was in the range of 190 to 191 °C. EI-MS: M+229. Comparative Preparation Example 1-(2,4-Dichlorophenyl)-1,2,4-triazol-5-one was prepared in accordance with the example as described in the aforesaid WO02/12203 (patent document 2). Preparation of 1-(2,4-dichlorophenyl)-1,2, 4-triazol-5-one In a four-necked flask having a volume of 10 liters, 51.5 g of sodium hydroxide was dissolved in 250 g of water, and 1300 g of t-butyl alcohol was added. [0252] Subsequently, 105 g of a 37 7» formaldehyde aqueous solution was added at 20 °C, and thereafter, 250 g of 2, 4-diclorophenylhydrazine hydrochloride was added over a period of 30 minutes, and the mixture was stirred at 20°C for 2 hours. [0253] Subsequently, the reaction mixture was cooled to 10°C in an ice water bath, and 127 g of 90% sodium cyanate having been suspended in 500 g of water was added at a time. Then, sodium cyanate having adhered to the container was washed off with 80g of water, and simultaneously, the wash liquid used was allowed to flow into the flask. By the addition of sodium cyanate, the temperature of the reaction mixture rose by 15°C. [0254] After the addition of sodium cyanate, the reaction mixture was cooled to 10°C, and then 119 g of acetic acid was dropwise added over a period of 15 minutes. [0255] Immediately after completion of the addition of acetic acid, a redbrown candy-like sparingly soluble matter began to form. Because a large amount of the red brown candy-like and sparingly soluble matter made stirring dif f icult, the redbrown candy-like and sparingly soluble matter was removed from the reaction system. Then, the reaction mixture left in the reaction system was further stirred at 10°C for 2 hours. [0256] Thereafter, 730 g of a 12% hypochlorous acid soda aqueous solution was dropwise added over a period of 90 minutes while maintaining the temperature at 10°C. [0257] After the dropwise addition, the mixture was stirred for 1 hour in an ice water bath and further stirred at room temperature for 4 hours. [0258] After the reaction was completed, t-butyl alcohol was distilled off from the reaction mixture under reduced pressure to concentrate the mixture. [0259] To the concentrate, 1000 g of toluene and 320 g of a 30% sodium hydroxide aqueous solution were added, and the mixture was vigorously stirred to extract the desired title compound. After liquid separation, the aqueous layer separated was washed with 200 g of toluene and the mixture was subjected to liquid separation. While cooling the aqueous layer obtained to 15°C, 260 g of 35% hydrochloric acid was dropwise added over a period of 30 minutes. [0260] The solids precipitated were collected by filtration and washed with 500 g of water. [0261] The solids were thoroughly dried to obtain 167 g of the desired title product (yield: 62%, purity: 81%) [0262] The main cause of low yield and low purity of the resulting 1-(2, 4-dichlorophenyl)-1,2,4-triazol-5-one in Comparative preparation Example may be that a part of formaldehyde-2, 4-dichlorophenylhydrazone that is unstable to an acid was dimerized because of the presence of acetic acid and sparingly soluble tetrazine was formed. INDUSTRIAL APPLICABILITY [0263] According to the process for preparing a phenyltriazolinone of the invention, a high-purity phenyltriazolinone is prepared more simply and safely at a low cost in a high yield, using a more inexpensive raw material. Therefore, the process for preparing a phenyltriazolinone of the invention is a preferred process also for large-scale industrial production. CLAIMS 1. A process for preparing a phenyltriazolinone represented by the following general formula (5) , comprising reacting an aniline represented by the following general formula (1) with a nitrite to forma diazonium salt, then reducing the diazonium salt using a sulfite or a hydrogensulfite, then hydrolyzing the reduction product to form a phenylhydrazine represented by the following general formula (2) , then reacting the resulting phenylhydrazine (2) with formaldehyde in the presence of a catalyst at pH 5 to 10 to form a formaldehyde-phenylhydrazone represented by the following general formula (3), then reacting the formaldehyde-phenylhydrazone (3) with cyanic acid to forma phenyl triazolidinone represented by the following general formula (4), then reacting the phenyltriazolidinone (4) with an oxidizing agent selected from a hypohalite and oxygen in the absence of a catalyst or in the presence of an oxidation catalyst; (Formula Removed) wherein X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other, (Formula Removed) wherein X and n are the same as those in the formula (1), (Formula Removed) wherein X and n are the same as those in the formula (1), (Formula Removed) wherein X and n are the same as those in the formula (1), (Formula Removed) wherein X and n are the same as those in the formula (1). 2 . The process for preparing a phenyltriazolinone as claimed in claim 1, wherein a crude product of a phenylhydrazine obtained by removing an aqueous layer from a reaction mixture containing the phenylhydrazine represented by the following general formula (2) is used, (Formula Removed) wherein X and n are the same as those in the formula (1). 3. The process for preparing a phenyltriazolinone as claimed in claim 1, wherein a crude product of a formaldehyde-phenylhydrazone obtained by removing an aqueous layer from a reaction mixture containing the formaldehyde-phenylhydrazone represented by the following general formula (3) is used, (Formula Removed) wherein X and n are the same as those in the formula (1). 4 . The process for preparing a phenyltriazolinone as claimed in any one of claims 1 to 3, wherein the aniline represented by the following general formula (1) is reacted with a nitrite in the presence of an organic solvent to form a diazonium salt, (Formula Removed) wherein X is a halogen atom or a lower alkyl group of 1 to 6 carbon atoms, n is an integer of 0 to 5, and when n is an integer of 2 or more, plural Xs may be the same or different from each other. 5. The proces s for preparing a phenyltriazolinone as claimed in any one of claims 1 to 4, wherein the phenyltriazolinone represented by the following general formula (5) is purified by treating it with an alkali after the phenyltriazolidinone represented by the following general formula (4) is reacted with an oxidizing agent selected from a hypohalite and oxygen in the absence of a catalyst or in the presence of an oxidation catalyst, (Formula Removed) wherein X and n are the same as those in the formula (1), (Formula Removed) wherein X and n are the same as those in the formula (1). |
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| Patent Number | 272116 | |||||||||
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| Indian Patent Application Number | 5039/DELNP/2010 | |||||||||
| PG Journal Number | 13/2016 | |||||||||
| Publication Date | 25-Mar-2016 | |||||||||
| Grant Date | 17-Mar-2016 | |||||||||
| Date of Filing | 12-Jul-2010 | |||||||||
| Name of Patentee | HOKKO CHEMICAL INDUSTRY CO., LTD. | |||||||||
| Applicant Address | 4-20 NIHONBASHI-HONGOKU-CHO 4-CHOME, CHUO-KU, TOKYO 1038341, JAPAN | |||||||||
Inventors:
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| PCT International Classification Number | C07D 249/12 | |||||||||
| PCT International Application Number | PCT/JP09/050091 | |||||||||
| PCT International Filing date | 2009-01-07 | |||||||||
PCT Conventions:
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