Title of Invention	"METHOD FOR PRODUCING 4,4'-BICYCLOHEXANEDIONE MONOKETAL"
Abstract	Provide a method for producing 4,4'-bicyclohexane dione monoketals expressed by general formula (2) by means of simple operations at high yields by reacting a 4,4'-bicyclohexane dione with a diol in the liquid phase in the presence of an acid catalyst while precipitating the produced 4,4'-bicyclohexane dione monoketal.

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Technical Field The present invention relates to a method for producing 4,4'-bicyclohexane dione monoketals, which are useful as materials for pharmaceutical drags and industrial chemicals or liquid crystal compounds used in display elements devices. Prior Art Traditionally 4,4'-bicyclohexane dione monoketals have been produced by, for example, causing a 4,4'-bicyclohexane dione to undergo dehydration and condensation reaction with a ketalizing agent such as ethylene glycol in the presence of an acid substance such as potassium hydrogen sulfate in an aromatic hydrocarbon solvent, to obtain a reaction mixture that contains unreacted materials as well as monoketal and diketal as reaction products, in order to finally obtain the target substance, or monoketal, from this reaction mixture (Japanese Patent Laid-open No. Hei 01-156935). However, this method requires cumbersome processes to separate and refine the target monoketal from the aforementioned reaction mixture, resulting in low yields (approx. 34%). Another method is known whereby a 4,4'-bicyclohexane dione is caused to undergo dehydration and condensation reaction with a ketalizing agent such as ethylene glycol in the presence of an acid substance such as potassium hydrogen sulfate in an aromatic hydrocarbon solvent hi order to produce diketal, while removing the produced water to outside the reaction system, after which the diketal is reacted with a 4,4'-bicyclohexane dione in the presence of an acid substance to produce monoketal by means of disproportionation (Japanese Patent Laid-open No. Hei 09-194473). However, this method also requires cumbersome operations to separate and refine the target monoketal from the reaction mixture that contains unreacted materials as well as monoketal and diketal, thereby resulting hi low yields (40%). As explained above, the conventional methods produce, after the reaction, a mixed reaction liquid that contains unreacted materials, diketal being a byproduct, and monoketal being the target product. For this reason, cumbersome chemical operations are needed to separate and refine the target monoketal and consequently the yield decreases. As a result, these methods have required improvements for use in industrial production applications. In view of the above, development of a production method capable of producing 4,4'-bicyclohexane dione monoketals at high yields from materials that can be obtained easily through industrial processes is desired. Patent Literature 1: Japanese Patent Laid-open No. Hei 01-156935 Patent Literature 2: Japanese Patent Laid-open No. Hei 09-194473 Summary of the Invention Problems to Be Solved by the Invention The present invention was developed to solve the aforementioned problems associated with the production of 4,4'-bicyclohexane dione monoketals. The discovery of a method that can provide the target 4,4'-bicyclohexane dione monoketals easily at high yields by using a 4,4'-bicyclohexane dione as a material and causing it to react with a diol in the liquid phase in the presence of an acid catalyst while precipitating the produced 4,4'-bicyclohexane dione monoketal, led to the present invention. Accordingly, an object of the present invention is to provide a method for producing 4,4'-bicyclohexane dione monoketals by means of simple operations at high yields by using a 4,4'-bicyclohexane dione, which can be obtained easily through industrial processes, as the starting substance. Means for Solving the Problems According to the present invention, a method for producing 4,4'-bicyclohexane dione monoketals expressed by general formula (2) below is provided, which is characterized by reacting a 4,4'-bicyclohexane dione with a diol expressed by general formula (1) below in the liquid phase in the presence of an acid catalyst while precipitating the produced 4,4'-bicyclohexane dione monoketal. [Symbol 1] (Formula Removed) General formula (1) (wherein R indicates a straight chain, branched chain or alicyclic alkylene group with 2 to 6 carbon atoms) [Symbol 2] (Formula Removed) General formula (2) (wherein R indicates the corresponding item in general formula (1). Effects of the Invention The production method proposed by the present invention allows 4,4'-bicyclohexane dione monoketals to be produced through simple industrial operations at high yields from readily available materials. Best Mode for Carrying Out the Invention The present invention uses a 4,4'-bicyclohexane dione expressed by chemical formula (1) below, and a diol expressed by general formula (1) below, as starting materials. Chemical formula (1) [Symbol 4] [Symbol 3] (Formula Removed) General formula (I) (wherein R indicates a straight chain, branched chain or alicyclic alkylene group with 2 to 6 carbon atoms) A 4,4'-bicyclohexane dione expressed by chemical formula (1) above can be obtained easily by, for example, oxidizing a 4,4'-bicyclohexane diol in the presence of an oxidizing agent (Japanese Patent Laid-open No. Hei 4-597425), or reducing a biphenol by hydrogen in the presence of a palladium catalyst (Japanese Patent Laid-open No. Hei 11-158108). In a diol expressed by general formula (1) above, R is an alkylene group with 2 to 6 carbon atoms, where the alkylene group may be straight chain, branched chain or alicyclic and where two hydroxyl groups (oxygen atoms) are bonded with a different carbon atom, respectively. Therefore, specific examples of R include the ethylene group, propylene group, trimethylene group, butylene group, pentylene group, 2,2-dimethyl trimethylene group, hexylene group, 1,2-cyclopentylene group, 1,2-cyclohexylene group, and the like, where the propylene group, butylene group, pentylene group or hexylene group may be straight chain or branched chain, while the cycloalkylene group may have a substituent group. Therefore, specific examples of a diol expressed by general formula (1) above include ethylene glycol, 1,2-propane diol, 1,3-propane diol, 1,4-butane diol, 1,5-pentane diol, 2,2-dimethyl-1,3-propane diol (neopentyl glycol), 1,6-hexane diol, 1,2-cyciopentyl diol, 1,2-cyclohexyl diol, and the like. Diols that can be used favorably to cause the reaction are primary alcohols and secondary alcohols, among which noncyclic diols are preferred. Furthermore, those of straight chain or branched type with 2 to 4 carbon atoms are particularly preferred, and ethylene glycol is most preferred. These diols are normally used in a range of 0.8 to 1.6 molar times, or preferably in a range of 1 to 1.4 molar times, per 1 mol of 4,4'-bicyclohexane dione. In the above mol ranges, the amount of material diketone that remains unreacted is kept small and the production of byproduct diketal can also be suppressed, which is ideal. Under the production method proposed by the present invention, the aforementioned 4,4'-bicyclohexane dione and diol are reacted hi the liquid phase in the presence of an acid catalyst. Any acid catalyst can be used without limitation as long as it promotes ketalization through dehydration reaction of 4,4'-bicyclohexane dione and diol. Examples of acid catalysts that can be used include, but not limited to, hydrochloric acid, sulfuric acid, phosphoric acid and other inorganic acids; calcium chloride, ammonium chloride, potassium hydrogen sulfate, sodium hydrogen sulfate and other acid inorganic salts; selenium oxide and other metal oxides; aluminum chloride, boron trifluoride and other Lewis acids; p-toluene sulphonate, trifluoroacetic acid and other organic acids; acidic ion-exchange resins; clay and activated clay; and molecular sieves, among others. Of these, acids of medium strength are preferred and particularly phosphoric acid can be used favorably because it can be handled with ease in the liquid form and does not distill. These acid catalysts are normally used in a range of 0.001 to 0.30 molar part, or preferably in a range of 0.01 to 0.10 molar part, per 1 mol of 4,4'-bicyclohexane dione. Under the production method proposed by the present invention, the aforementioned 4,4'-bicyclohexane dione and diol are reacted in the liquid phase. To cause the reaction, the liquid phase is agitated. A reaction solvent may or may not be added as long as the reaction conditions are such that the reaction can be caused while allowing the produced 4,4'-bicyclohexane dione monoketal to precipitate. However, use of a reaction solvent at the time of reaction is preferred under the present invention. Under the production method proposed by the present invention, a 4,4'-bicyclohexane dione is reacted with a diol hi the liquid phase in the presence of an acid catalyst while precipitating the produced 4,4'-bicyclohexane dione monoketal. Traditionally, reacting a 4,4'-bicyclohexane dione with a diol in the liquid phase in the presence of an acid catalyst causes the unreacted materials, diketal being a byproduct, and monoketal being the target product, to coexist in the reaction liquid as the reaction progresses. Accordingly, cumbersome chemical operations are needed to separate and refine the target monoketal after the reaction, which makes the entire process longer and also reduces the yield. In addition, the monoketal produced by the reaction further reacts with the diol and turns into diketal, which is also a cause of lower yield. hi light of the above, the inventors studied earnestly and found that in the presence of an acid catalyst the reaction progresses hi the liquid phase as long as a diol is present, even when the material bicyclohexane dione has little dissolved, and that by allowing the produced target 4,4'-bicyclohexane dione monoketal to precipitate as soon as it is produced, and thereby discharging it to outside the reaction system, production of byproduct diketals can be suppressed and the diol can be reacted selectively with only one side of the bicyclohexane dione, thereby achieving a marked improvement in yield. One reason for this marked improvement in yield realized by the production method proposed by the present invention is presumed to be that, because the monoketal produced by the reaction precipitates quickly from the liquid phase as crystal and becomes inactive, the produced monoketal does not react further in the reaction liquid phase to become diketal. It is also presumed to be a reason that, since this reaction is an equilibrium reaction, even when diketal is produced as a byproduct, the diketal dissolved in the liquid phase becomes monoketal, and the monoketal precipitates as crystal as soon as it is produced, thereby breaking the equilibrium. As for the method to cause the reaction in the liquid phase while precipitating the 4,4'-bicyclohexane dione monoketal produced by the reaction, it suffices that the target 4,4'-bicyclohexane dione monoketal produced as the reaction progresses precipitates from the reaction liquid mixture, or from the liquid phase, as soon as it is produced during the course of reaction. This can be achieved by, for example, selecting an appropriate reaction solvent, condensing the solvent at the time of reaction, adding seed crystal of the target bicyclohexane dione monoketal, adjusting the composition of the reaction solvent, adjusting the reaction temperature, and/or adjusting the reaction pressure. To be specific, the above can be achieved by, for example, adding an appropriate amount of an aliphatic hydrocarbon, which is a poor solvent with respect to the target 4,4'-bicyclohexane dione monoketal, as a reaction solvent at the time of reaction. Among the methods conforming to the production method proposed by the present invention, those that use an aliphatic hydrocarbon as a reaction solvent are particularly favorable. These methods are explained below in details. First, the aliphatic hydrocarbon solvent to be used is a chain or cyclic aliphatic hydrocarbon, where specific examples include propane, butane, isobutane, n-heptane, n-hexane, n-pentane, isohexane, petroleum ether, ligroin and other chain aliphatic hydrocarbons; and cyclohexane, cyclopentane and other alicyelic hydrocarbons. In particular, cyclohexane, heptane, pentane, hexane and other chain or cyclic aliphatic hydrocarbons with 4 to 8 carbon atoms are preferred because they have low solubility with respect to the target monoketals. These hydrocarbons can be used alone or two or more of them can be combined. The amount of the aforementioned solvent is not specifically limited, as long as the reaction liquid phase is uniform or in a slurry state and can be agitated, and the produced target 4,4'-bicyclohexane dione monoketal precipitates quickly from the liquid phase. However, using the solvent in an excess amount is not desirable because it leads to a lower volumetric ratio and consequently lower efficiency. Therefore, the solvent should normally be added by 1 to 20 times by weight, or preferably by 3 to 10 times by weight, relative to the material 4,4'-bicyclohexane dione. In addition to the above, any other solvent can be used as long as the solvent does not inhibit precipitation from the liquid phase of the target 4,4'-bicyclohexane dione monoketal produced as the reaction progresses. Examples of such other solvent include aromatic hydrocarbons such as benzene and toluene, or esters such as ethyl acetate. The production method proposed by the present invention may adopt several methods to improve the reaction selectivity further. For example, although a 4,4'-bicyclohexane dione monoketal precipitates hi the normal reaction, crystal of a monoketal may be added as seed crystal before or during the reaction in order to promote precipitation hi situations where the combination of aliphatic hydrocarbon solvent and monoketal prevents smooth precipitation. Addition of seed crystal is also an effective way to prevent loss of a well-agitated state due to sudden precipitation of crystal, and to maintain the reaction liquid in a uniform slurry form. Also, the reaction caused by the production method proposed by the present invention is a ketalization reaction which is also a dehydration and condensation reaction. Accordingly, water is produced as a result of the reaction. To increase the speed or rate of reaction, it is therefore desirable that produced water be removed from the reaction liquid phase. To be specific, produced water can be removed using known methods, such as distilling the solvent containing produced water to separate the solvent and produced water, or causing the solvent containing produced water to undergo azeotropy to separate the solvent and produced water. Here, it is preferable in industrial settings that the recovered solvent be returned to the reaction system. This separation can be implemented in a small scale by using a Dean-Stark separator, for example. Another method to remove produced water is to use a dehydrating agent such as magnesium sulfate. Furthermore, under the production method proposed by the present invention the temperature of the reaction liquid is lowered by, for example, approx. 1 to 45 °C once the reaction of 4,4'-bicyclohexane dione and diol has roughly completed, after which post-reaction is implemented under agitation for normally 5 to 25 hours or so in order to cause the byproduct diketal to turn into monoketal, while allowing the unreacted bicyclohexane dione to also turn into monoketal, thereby resulting in precipitation of produced monoketal. In this case, it is not clear whether diketal is hydrolyzed to diol and monoketal and the produced diol reacts with the unreacted dione, or whether one diketal molecule reacts directly with one bicyclohexane dione molecule to produce two monoketal molecules. Either way, use of the above methods is preferred because the reaction selectivity can be unproved further. The aforementioned methods to further improve the reaction selectivity can be used alone or in combination. Under the production method proposed by the present invention, the reaction temperature is normally in a range of-50 to 80°C, or preferably in a range of 0 to 49°C, or most preferably in a range of 10 to 45°C. Note that even when the reaction is caused at temperatures of80°C or above where crystal does not precipitate, lowering the temperature to the aforementioned ranges subsequently to precipitate crystal and then agitating again will break the equilibrium and still improve the reaction selectivity of monoketal. As for the reaction pressure, the reaction may be implemented at normal pressure or any other pressure higher or lower than normal pressure. Although there are no limitations, attention should be drawn to the fact that the boiling point, azeotropic temperature with water and other conditions change depending on the solvent used. For example, lower the reaction pressure if the boiling point of the solvent should be lowered. If a solvent that remains gaseous at normal pressure, such as propane, is used, then the reaction can be implemented at higher pressure to liquefy the solvent gas. It is necessary to select an appropriate reaction pressure according to the need for a specific reaction operation. Under the reaction conditions described above, the reaction should normally complete in around 1 to 30 hours, and the reaction rate of material bicyclohexane dione under the production method proposed by the present invention is normally in a range of approx. 85 to 100%, while the monoketal selectivity is normally in a range of approx. 75 to 95%. The reaction yield of monoketal with respect to material bicyclohexane dione is normally in a range of approx. 64 to 95%. Under the production method proposed by the present invention, the reaction operation to be used is not specifically limited. However, it is possible, for example, to mix in a reaction container under agitation a material 4,4'-bicyclohexane dione, an aliphatic hydrocarbon solvent such as n-pentane, and an acid catalyst such as phosphoric acid, implement dehydration processing at a solvent reflux temperature of, for example, around 30 to 40°C, drip a diol into the obtained slurry to cause reaction, while at the same time remove the water produced by the reaction, and maintain the reaction after the entire amount of diol has been added. During this reaction, normally the produced target monoketal precipitates as crystal from the reaction liquid while diol is being added, and thus the slurry becomes whiter and denser. After produced water is removed, it is possible, for example, to lower the reaction liquid temperature by 5 to 40°C and then cause reaction further for approx. 5 to 25 hours, if necessary. Under the production method proposed by the present invention, after the reaction the target monoketal can be obtained at high purity from the mixture produced as a result of reaction, by using a standard method involving a simple, easy operation. For example, the reaction liquid may be filtered directly to isolate crystal; or the obtained reaction mixture may be mixed with an alkali such as aqueous sodium hydroxide solution to neutralize the aforementioned acid catalyst and then filter out crystal directly; or a solvent may be added or the temperature may be raised to dissolve crystal, wash the oil layer in water, separate the organic layer, cause crystallization, and then filter out and dry crystal, or condense a part of reaction solvent in the separated organic layer via distillation, and then add an aliphatic hydrocarbon, alcohol or other crystallization solvent to the condensed organic layer to cause crystallization, after which the obtained crystal is filtered out and dried, to obtain the target monoketal. For your information, the neutralization method should be preferably implemented in such a way that the reaction mixture be changed to alkaline quickly, followed by pH adjustment, because adjusting the pH when the reaction mixture is still acidic may cause the selectivity to drop due to hydrolysis triggered by an increasing amount of water as a result of neutralization. In addition, the obtained monoketal can be recrystallized to produce a high-purity refined product, if necessary. Solvents that can be used in this recrystallization process include, but not limited to, 2-butanol and other aliphatic alcohols; hexane, heptane and other chain aliphatic hydrocarbons; cyclohexane and other cyclic aliphatic hydrocarbons; toluene and other aromatic hydrocarbons; methyl isobutyl ketone and other aliphatic ketones; and mixed solvents thereof. (Examples) The present invention is explained below using examples. It should be noted, however, that the present invention is not at all limited to these examples. In the following paragraphs, results of gas chromatography analysis are indicated in area percent (%). Targets were identified by mass spectrometry and proton nuclear magnetic resonance analysis. Example 1 Into a 1-liter four-way flask, 37.5 g (0.193 mol) of 4,4'-bicyclohexane dione, 225.0 g of n-pentane and 1.26 g of 75% phosphoric acid (9.64 x 10"3 mol) were introduced. After the interior of the flask had been substituted by nitrogen, the mixture was heated to 37°C under agitation and pre-dehydration processing was performed for 1.0 hour using a Dean-Stark separator under reflux of n-pentane, to obtain a slurry of 4,4'-bicyclohexane dione. Next, 1.5 g of monoethylene ketal crystal was added at the same temperature, after which 13.29 g (0.214 mol) of ethylene glycol was drip-fed over 1.0 hour under reflux of n-pentane while removing produced water using the Dean-Stark separator. After the entire amount of ethylene glycol had been added, the mixture was agitated further for 0.5 hour at the same temperature under reflux of n-pentane while removing produced water using the Dean-Stark separator. As a result, the reaction liquid constituting the slurry became noticeably whiter as monoketal crystal precipitated. Thereafter, the mixture was agitated for 4 more hours before the reaction was completed. When the obtained reaction liquid was analyzed by gas chromatography, the reaction rate of 4,4'-bicyclohexane dione was 88.9%, while the selectivity of 4,4'-bicyclohexane dione monoethylene ketal was 81.2%. The reaction yield with respect to the material 4,4'-bicyclohexane dione was 72.2 mol%. Example 2 Into a 1-liter four-way flask, 37.5 g (0.193 mol) of 4,4'-bicyclohexane dione, 225.0 g of n-pentane and 0.76 g of 75% phosphoric acid (5.82 x 10"3 mol) were introduced. After the interior of the flask had been substituted by nitrogen, the mixture was heated to 37°C under agitation and pre-dehydration processing was performed for 1.0 hour under reflux of n-pentane. Next, 13.29 g (0.214 mol) of ethylene glycol was dripped into the white slurry over 1.0 hour at the same temperature under reflux of n-pentane while removing produced water using the Dean-Stark separator. After 25 minutes from the start of dripping ethylene glycol, the reaction liquid constituting the slurry became noticeably whiter as monoketal crystal precipitated. After the entire amount of ethylene glycol had been added, the mixture was reacted further for 40 minutes at the same temperature under reflux of n-pentane while removing produced water using the Dean-Stark separator, after which the internal temperature was lowered to a range of 26 to 31 °C and reaction was continued further for 14.7 hours. When the liquid obtained at the end of reaction was analyzed by gas chromatography, the reaction rate of 4,4'-bicyclohexane dione was 95.6%, while the selectivity of 4,4'-bicyclohexane dione monoethylene ketal was 85,4%. The reaction yield with respect to the material 4,4'-bicyclohexane dione was 81.6%. Example 3 Into a 1-liter four-way flask, 37.5 g (0.193 mol) of 4,4'-bicyclohexane dione, 225.0 g of n-pentane and 0.76 g of 75% phosphoric acid (5.82 x 10"3 mol) were introduced. After the interior of the flask had been substituted by nitrogen, the mixture was heated to 37°C under agitation and pre-dehydration processing was performed for 1.0 hour under reflux of n-pentane using the Dean-Stark separator. Next, 13.29 g (0.214 mol) of ethylene glycol was dripped into the white slurry over 1.0 hour at the same temperature under reflux of n-pentane while removing produced water using the Dean-Stark separator. After 25 minutes from the start of dripping ethylene glycol, the reaction liquid constituting the slurry became noticeably whiter as monoketal crystal precipitated. After the entire amount of ethylene glycol had been added, the mixture was reacted further for 40 minutes at the same temperature under reflux of n-pentane while removing produced water using the Dean-Stark separator, after which the temperature of reaction liquid was lowered to a range of 26 to 31 °C and reaction was continued further for 14.7 hours. Thereafter, 2.42 g (3.90 x 10-2 mol) of ethylene glycol was added and reacted further for 5 hours. When the liquid obtained at the end of reaction was analyzed by gas chromatography, the reaction rate of 4,4'-bicyclohexane dione was 99.4%, while the selectivity of 4,4'-bicyclohexane dione monoethylene ketal was 90.2%. The reaction yield with respect to the material 4,4'-bicyclohexane dione was 89.7%. Additionally, 2.91 g of 16% aqueous sodium hydroxide solution was added to the obtained reaction liquid at 20 C and the mixture was agitated for 1.0 hour, after which 30 g of water was added and the liquid was neutralized with 75% phosphoric acid. Next, crystal was filtered out at 20°C to obtain 45.7 g of coarse white crystal to which the solvent was attached, where the purity of the crystal as measured by gas chromatography was 93.6%. The coarse crystal was mixed with 2-butanol of the same quantity and the mixture was heated to 54°C to dissolve the crystal, after which crystallization was caused by lowering the temperature to 15°C. The obtained crystal was filtered out and dried to obtain 23. 5 g of white 4,4'-bicyclohexane dione monoethylene ketal crystal with a purity of 99.1% as measured by gas chromatography, at a yield of 50.6%. Example 4 Into a 1-liter four-way flask, 37.5 g (0.193 mol) of 4,4'-bicyclohexane dione, 225.0 g of n-heptane and 0.76 g of 75% phosphoric acid (5.82 x 10"3 mol) were introduced. After the interior of the flask had been substituted by nitrogen, the mixture was heated under agitation, and then the internal pressure of the reaction container was reduced to a range of 9.7 to 10.3 kPa, after which pre-dehydration processing was performed at 37°C for 1.0 hour under reflux of n-heptane using a Dean-Stark separator. Next, 13.29 g (0.214 mol) of ethylene glycol was dripped into the white slurry over 1.0 hour at the same temperature and same reduced pressure under reflux of n-heptane while removing produced water using the Dean-stark separator. After 30 minutes from the start of dripping ethylene glycol, the reaction liquid constituting the slurry became noticeably whiter as monoketal crystal precipitated. After the entire amount of ethylene glycol had been added, the mixture was reacted further for 40 minutes at the same temperature and same reduced pressure under reflux of n-heptane while removing produced water using the Dean-Stark separator. Thereafter, the internal pressure of the reaction container was returned to normal pressure and the temperature of reaction liquid was lowered to 26°C, after which reaction was continued further for 14.4 hours. When the obtained reaction liquid was analyzed by gas chromatography, the reaction rate of 4,4'-bicyclohexane dione was 94.4%, while the selectivity of 4,4'-bicyclohexane dione monoethylene ketal was 86.6%. The reaction yield with respect to the material 4,4'-bicyclohexane dione was 81.8%. [0030] Comparative Example 1 (Toluene Solvent) Into a 1-liter four-way flask, 37.5 g (0.193 mol) of 4,4'-bicyclohexane dione, 75.0 g of toluene and 0.76 g of 75% phosphoric acid were introduced. After the ulterior of the flask had been substituted by nitrogen, the mixture was heated under agitation, and then the internal pressure of the reaction container was reduced to a range of 3.3 to 3.8 kPa, after which pre-dehydration processing was performed at temperatures of 24 to 26°C for 1.0 hour under reflux of toluene using a Dean-Stark separator. Next, 13.29 g (0.214 mol) of ethylene glycol was drip-fed over 1 hour at the same temperature at a reduced pressure of 3.3 to 3.0 kPa under reflux of toluene while removing produced water using the Dean-Stark separator. When the reaction liquid was analyzed by gas chromatography 1.5 hours after the end of dripping ethylene glycol, the reaction rate of 4,4'-bicyclohexane dione was 62.8%, while the selectivity of 4,4'-bicyclohexane dione monoethylene ketal was 75.8%. After the entire amount of ethylene glycol had been added, reaction was caused for 5 hours at temperatures of 22 to 24°C under reflux of toluene while removing produced water. As the reaction progressed, the material 4,4'-bicyclohexane dione crystal gradually dissolved in the reaction liquid and the crystal virtually disappeared after 3 hours of agitation, and no crystal precipitated thereafter. When the obtained reaction liquid was analyzed by gas chromatography, the reaction rate of 4,4'-bicyclohexane dione was 83.8%, while the selectivity of 4,4'-bicyclohexane dione ethylene monoketal was 65.9%. Although the reaction rate was higher compared to the reaction liquid obtained 1.5 hours after the end of dripping of ethylene glycol, the selectivity was lower. We Claim: [1 ] A method for producing 4,4'-bicyclohexane dione monoketals expressed by general formula (2) below, characterized by reacting a 4,4'-bicyclohexane dione with a diol expressed by general formula (1) below in the liquid phase in the presence of an acid catalyst while precipitating the produced 4,4'-bicyclohexane dione monoketal [Symbol 5] (Formula Removed) General formula (1) (wherein R indicates a straight chain, branched chain or alicyclic alkylene group with 2 to 6 carbon atoms) [Symbol 6] General formula (2) (wherein R indicates the corresponding item in general formula (1)). [2] A production method according to Claim 1, characterized by containing an aliphatic hydrocarbon solvent in the liquid phase.

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8421-delnp-2007-abstract.pdf

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Abstract.pdf

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