Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF DIHYDROXYDIPHENYLMETHANES

Abstract

An improved process for the preparation of dihydroxydiphenylmethanes by reacting phenol over a microporous alumino-silicate zeolite catalyst composite material in a ratio of 5:1 to 10:1 in the presence of a condensing agent and an organic solvent at a temperature in the range of 20 to 200°C for a period in between 0.1 to 24 hours at normal pressure and separating dihydroxydiphenylmethanes by conventional methods.

Full Text

The present invention relates to an improved process for the preparation of dihydroxydiphenylmethanes. More particularly, it relates to a process for the selective preparation of 4, 4'-dihydroxydiphenylmethane by reacting phenol with formaldehyde in the presence of microporous zeolite catalyst. 4,4'- Dihydroxydiphenylmethane is useful as a starting material for the production of polycarbonate resins, polyester resin and epoxy resins. It is also used as a modifier and a stabilizer for phenol resins. In the prior art, dihydroxydiphenylmethanes are prepared by various methods described herein below: In one method condensation of phenol with aqueous formaldehyde was carried out using phosphotungstic acid which consists of 10:43:47 ratio of 2,2'-,2,4'- and 4,4'-dihydroxydiphenylmethane isomers (cf. Jpn. Kokai Tokkyo Koho JP 06 87 775; CA 121:57131). A method comprising reacting phenol with formaldehyde in the presence of an activated clay at 80°C for .2-.hoursco give 38.8% 4,4'- 15.8%2,2'- 38.4% 2,4'-dihydroxydiphenylmethane and 7.0% oligomer. (cf. Eur. Pat. Appl. EP331,173; CA 112:7160). Another method comprising reacting phenol with formaldehyde in the presence of activated clay catalyst gives a ratio 17.1: 41.4: 44.5 of 2.2'- 2,4'- and 4,4'-dihydroxydiphenylmethane (cf. Jpn. Kokai Tokkyo Koho JP 63,238,632; CA 116:75045). A method comprising reacting phenol with formaldehyde in a two phase mixture in the presence of aqueous H3PO4 at 45°C gives a ratio of 55:37:8 for 4,4'-, 2,4'- and 2,2'- dihydroxydiptenylmethane ( cf US Pat NO.4,400,554 ; GA 99:175378). A method comprising reacting phenol with formaldehyde in the presence of activated clay at 80°C under nitrogen atmosphere for two hours gives a ratio of 42.8:40.5:16.7 for 4,4'- 2,4'- and 2,2'-dihydroxydiphenylmethane [cf.US Pat. 4,937,392 (1990)J. A method comprising reacting phenol with formaldehyde in the presence of urea (cf.JP-B-39-26844). A method comprising reacting phenol with dimethylol urea in the presence of an acidic catalyst (cf. US Pat. 2,617,832). A number of methods are known for preparing dihydroxydiphenylmethane by reacting phenol with formaldehyde. Examples thereof include a method wherein an inorganic liquid acid such as hydrochloric acid, sulphuric acid or phosphoric acid is used as a catalysts (cf. JP-A-58-177928 (The term JP-A as used herein means an unexamined published Japanese patent application, British Patent No. 1,493,759 and US Pat Ser. No. 2,792,429). However, the above methods are disadvantageous from an industrial viewpoint because the selectivity for 4,4'-dihydroxydiphenylmethane is low in each case and in some cases catalyst is homogeneous. Thus the large amount of base is required to neutralize the homogeneous acid catalysts and this causes problems as regards the disposal of the resulting salts. In view of the above mentioned homogeneous catalysts and low selectivity for 4,4'-dihydroxydiphenylmethane in the prior art processes, it was found desirable during the course of the research work leading to the present invention to develop an improved process for the production of dihydroxydiphenylmethanes and particularly 4,4'-dihydroxydiphenylmethane in high selectivity from the condensation of phenol with formaldehyde in the presence of an inert solvent over solid catalyst composite material alumino-silicate zeolite catalyst. It is therefore an object of the present invention to solve the above mentioned problems by establishing a process for the advantageous preparation of dihydroxydiphenylmethane and particularly 4,4'-dihydroxydiphenylmethane in high selectivity using a solid zeolite catalyst in the presence of an inert solvent. Accordingly, the present invention provides an improved process for the preparation of dihydroxydiphenylmethanes which comprises reacting phenol over a microporous alumino-silicate zeolite catalyst composite material in a ratio of 5:1 to 10:1 in the presence of a condensing agent and an organic solvent such as here in described at a temperature in the range of 20 to 200°C for a period in between 0. 1 to 24 hours at normal pressure and separating dihydroxydiphenylmethanes by conventional methods. In one of the embodiment of the present invention the zeolite catalyst used in the reaction may be such as H-ZSM-5 or H-ZSM-12 or H-mordenite or H-Y or RE-Y or H-beta, preferably H-beta. In another embodiment of the present invention the condensing agent used may be such as aqueous formaldehyde or para-formaldehyde or trioxane, preferably aqueous formaldehyde. In yet another embodiment of this invention the ratio of phenol to the condensing agent is 5:1 to 10:1, preferably 5:1. In yet another embodiment the aromatic solvent used may be such as alcohol, aromatic or aliphatic hydrocarbons, a ketone or a chloroaromatic or nitroaromatic compounds, preferably, methyl ethyl ketone. In a feature of the present invention it is possible to selectively and efficiently prepare the 4,4'-dihydroxydiphenylmethane while separating the ortho and meta position products. The reactants and solvents which are employed in the process of the present invention are desired to be high in purity. In the present invention, the zeolite may be added to the reactant in a manner as follows: 1) The zeolite and the phenol may be combined and added to the condensing agent prior to the reaction. 2) The zeolite and phenol may be added simultaneously to the reaction system at the time of reaction. 3) The zeolite is suspended in a solvent, a predetermined amount of the phenol and condensing agent is added thereto. 4) The zeolite is suspended in the phenol and solvent then a predetermined amount of the condensing agent is added thereto. Another feature of the present invention is that the reaction is carried out at a relatively low temperature between 5 and 200°c. Yet another feature of the process of the present invention is the use of the non-hazardous solid aluminosilicate catalysts. Another feature of the process of the present invention is that it does not pose risk of explosion. Thus, the process of the present invention is suitable as an industrial process for the production of 4,4'-dihydroxydiphenylmethane in high selectivity. I In another feature of the present invention, the catalyst composite material employed is a microporous aluminosilicate, zeolite H-beta type. The proportion of phenol to formaldehyde ratio, solvent and H-beta used ranges from 5:1 to 10:1 molar ratio, 0 to 50ml and 0.01 to l00g/mol phenol, respectively The present invention is described in further detail with reference to the examples which are given by way of illustration only and therefore should not be construed to restrict the scope of the invention. Example 1 This example illustrates the procedure for the condensation of phenol with aqueous formaldehyde to 4,4'-dihydroxydiphenylmethane, 2,4'- dihydroxydiphenylmethane, and 2,2'- dihydroxydiphenylmethane. The reaction was carried out in an autoclave. 188 g (2mol) of phenol was reacted with 32.4 g (0.4mol) formaldehyde (37%) in the presence of Ig of activated catalyst composite material zeolite H-beta at 80°C for three hours. After the completion of the reaction, the reaction mixture cooled to room temperature and catalyst was filtered off. Thus the reaction mixture obtained was analyzed by gas- chromatography. The results are listed in Table 1. Tablel. Condensation of phenol with aqueous formaldehyde over catalyst composite material aluminosilicate zeolite H-beta after three hours. (Table Removed) Example 2 The example illustrates the procedure for the condensation of phenol with aqueous formaldehyde to 4,4'-dihydroxydiphenylmethane , 2,4'-dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 94 g (Imol) of phenol was reacted with 16.2 g (0.2mol) of aqueous formaldehyde (37%) in the presence of 2 g catalyst composite material zeolite H-ZSM-5 at 80°C for three hours under stirring in an autoclave. After the completion of the reaction , the reaction mixture cooled to room temperature, filtered off and analyzed by gas-chromatography. The results are recorded in Table 2. Table 2. Condensation of phenol with aqueous formaldehyde over catalyst composite material aluminosilicate zeolite H-ZSM-5 after three hours. (Table Removed) Example 3 This example illustrates the procedure for the condensation of phenol with aqueous formaldehyde to 4,4'- dihydroxydiphenylmethane , 2,4'-dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 47 g (O.Smol) of phenol was reacted with 8.1 g (0.9mol) of aqueous formaldehyde (37%) in the presence of 3 g catalyst composite material zeolite H-mordenite at 80°C for three hours under stirring in an autoclave. After the completion of the reaction, the reaction mixture cooled to room temperature, "filtered off and analyzed by gas-chromatography. The results are presented in Table 3. Table 3: Condensation of phenol with aqueous formaldehyde over catalyst composite material aluminosilicate zeolite H-mordenite after three hours. (Table Removed) Example 4 This example illustrates the procedure for the condensation of phenol with aqueous formaldehyde to 4,4'- dihydroxydiphenylmethane , 2,4'- dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 470 g (5mol) of phenol was reacted with 81 g (Imol) of aqueous formaldehyde (37%) in the presence of activated 5 g catalyst composite material zeolite H-Y at 80°C for three hours under stirring in an autoclave. After the reaction, the reaction mixture cooled to room temperature, filtered off and analyzed by gas- chromatography. The results are listed in Table 4. Table 4: Condensation of phenol with aqueous formaldehyde over catalyst composite material aluminosilicate zeolite H-Y after three hours. (Table Removed) Example 5 This example illustrates the procedure for the condensation of phenol with aqueous formaldehyde to 4,4'- dihydroxydiphenylmethane , 2,4'- dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 940 g (lOmol) of phenol was reacted with 162 g (2mol) of aqueous formaldehyde (37%) in the presence of activated l0g catalyst composite material zeolite MCM-22 at 80UC for three hours under stirring in an autoclave .After the reaction , the reaction mixture cooled to room temperature, filtered off and analyzed by gas- chromatography. The results are listed in Table 5 Table 5: Condensation of phenol with aqueous formaldehyde over catalyst composite material aluminosilicate zeolite MCM-22 after three hours. (Table Removed) Example 6 This example illustrates the effect of solvent (methyl ethyl ketone) on the conversion of phenol with aqueous formaldehyde and selectivity for 4,4'-dihydroxydiphenylmethane among 4,4'- dihydroxydiphenylmethane , 2,4'-dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 940 g (l0mol) of phenol was reacted with 162 g (2mol) of aqueous formaldehyde (37%) in the presence of 200ml solvent (methyl ethyl ketone) over 5 g activated catalyst composite zeolite H-beta at 80°C for three hours under stirring in an autoclave .After the reaction , the reaction mixture cooled to room temperature, and analyzed by gas- chromatography. The results are listed in Table 6. Table 6: Condensation of phenol with aqueous formaldehyde in the presence of methyl ethyl ketone over catalyst composite material zeolite H-beta for three hours. (Table Removed) Example 7 This example describes the effect of the condensing agent in the reaction of phenol with paraformaldehyde on the conversion of phenol and selectivihg for 4,4'- dihydroxydiphenylmethane among 4,4'- dihydroxydiphenylmethane , 2,4'-dihydroxydiphenylmethane and 2,2'- dihydroxydiphenylmethane. 30 g (0.32mol) of phenol was reacted with 20 g of para formaldehyde in the presence of 150 ml methyl ethyl ketone over 6g activated catalyst composite material zeolite H-beta at 80°C for three hours under stirring in an autoclave .After the reaction , the reaction mixture cooled to room temperature, and analyzed by gas- chromatography. The results are recorded in Table 7 Table 7 : Effect of condensing agent (paraformaldehyde) in the condensation of phenol over catalyst composite material zeolite H-beta in the presence of methyl ethyl ketone after three hours (Table Removed) Example 8 This example describes the effect of the condensing agent in the reaction of phenol with trioxane on the conversion of phenol and selectivity for 4,4 dihydroxydiphenylmethane, 2,4- dihydroxydiphenylmethane and 2,2'-dihydroxydiphenylmethane. 94 g (1mol) of phenol was reacted with 90 g of trioxane in the presence of 200 ml methyl ethyl ketone over 30 g catalyst composite material zeolite H-beta at 80°C for three hours under stirring in an autoclave .After the reaction the reaction mixture was cooled to room temperature, and analyzed by gas-chromatography. The results are listed in Table 8 Table 8 : Effect of condensing agent (trioxane) in the condensation of phenol over catalyst composite material zeolite H-beta in the presence of methyl ethyl ketone (Table Removed) The advantages of the present invention are, 1. The resulting advantages are that a corrosion free plant can be used. 2. A recyclable zeolite catalyst can be used. 3. The problem of the need to dispose of inorganic byproducts does not arise. 4. Due to the shape selectivity porous structure of zeolites and presence of solvent, these catalyst produce higher amount of 4,4'-dihydroxydiphenylmethane at the expanse of other isomer and higher oligomers. 5. The process of the present invention shows remarkably high industrial merits over prior art process for the preparation of 4,4'-dihydroxydiphenylmethane. The starting materials are easily available and easy to handle. We claim : 1. An improved process for the preparation of dihydroxydiphenylmethanes which comprises reacting phenol over a microporous alumino-silicate zeolite catalyst composite material in a ratio of 5:1 to 10:1 in the presence of a condensing agent and an organic solvent such as herein described at a temperature in the range of 20 to 200°C for a period in between 0. 1 to 24 hours at normal pressure and separating dihydroxydiphenylmethanes by conventional methods. 2. An improved process as claimed in claim 1 wherein, the condensing agent used is formaldehyde, paraformaldehyde or trioxane. 3. An improved process as claimed in 1 and 2, wherein the organic solvent used is 1,2-dichloroethane, chloroform, CCI4, benzonitrile, nitrobenzene acetonitrile, 1,2-dichlorobenzene or methyl ethyl ketone or mixture thereof. 4. An improved process as claimed in claims 1 and 3, wherein the zeolite catalysts composite material used is zeolite H-beta, H-ZSM-5, H-mordenite, H-Y orMCM-22. 5. An improved process for the preparation of dihydroxydiphenylmethane as substantially described herein before with reference to the examples .

Documents:

333-del-1999-abstract.pdf

333-del-1999-claims.pdf

333-del-1999-correspondence-others.pdf

333-del-1999-correspondence-po.pdf

333-del-1999-description (complete).pdf

333-del-1999-form-1.pdf

333-del-1999-form-19.pdf

333-del-1999-form-2.pdf

333-del-1999-form-3.pdf

333-del-1999-petition-138.pdf