JPH01117846A - Production of diacyloxybiphenyl - Google Patents

Abstract

PURPOSE:To obtain the above compound useful as a raw material for liquid crystal polymers in high purity and yield in a simple process, by acylating a crude product prepared by dealkylating 3,3',5'5'-tetra-tert-butyl-4,4'- dihydroxybiphenyl. CONSTITUTION:3,3',5,5'-Tetra-tert-butyl-4,4'-dihydroxybiphenyl (especially preferably obtained by oxidative coupling reaction of 2,6-di-tert-butylphenol) is dealkylated to provide a reaction product containing dihydroxybiphenyl. The resultant reaction product is then reacted with an acylating agent (e.g., acetic anhydride) in the presence of preferably an acidic catalyst to afford a diacyloxybiphenyl, which is subsequently separated from the reaction mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for producing diacyloxybiphenyl;
More specifically, the present invention relates to a method for producing diacyloxybiphenyl such as 4,4-diacetoxybiphenyl, which is useful as a raw material for liquid crystal polymers and the like.

Technical background of the invention and its problems As mentioned above, diacyloxybiphenyl is a compound useful as a raw material for liquid crystal polymers, etc. Diacyloxybiphenyl is produced by combining dihydroxybiphenyl and an acylating agent in the presence of a catalyst. It can be produced by reacting with.

By the way, it is known that dihydroxybiphenyl can be produced, for example, by alkali melting of sodium phenyldisulfonate or dihalogenated biphenyls, but since the production cost of dihydroxybiphenyl is high with this method, dihydroxybiphenyl can be produced by another process. It was desired to produce biphenyl. Therefore, dihydroxybiphenyl can be produced by dealkylation reaction of 3,3',5,5-tetra-1-butyl-4,4-dihydroxybiphenyl obtained by oxidative coupling reaction of 2,6-di[-butylphenol, etc. A manufacturing method is being considered by the present inventors.

By the way, 3,3", 5,5 produced by oxidative coupling reaction of 2,6-di-t-butylphenol, etc.
The present inventor discovered that when attempting to produce diacyloxybiphenyl from dihydroxybiphenyl obtained by dealkylation of -tetra-1-butyl-4,4-dihydroxyphenyl, the following problems arise. discovered by et al. i.e. 3.3', 5,5
It is difficult to obtain dihydroxybiphenyl with high purity and high recovery rate from the reaction product containing dihydroxybiphenyl obtained by the dealkylation reaction of °-tetra-1-butyl-4,4-dihydroxybiphenyl. A large loss of dihydroxybiphenyl occurs during the biphenyl purification process, resulting in 3.3',5.5'-tetra-butyl-4,4-
The yield of diacyloxybiphenyl from dihydroxybiphenyl is greatly reduced.

The present inventors conducted intensive research to solve the above-mentioned problems, and found that a product obtained by the dealkylation reaction of 3,3',5,5-tetra-1-butyl-4,4'-dihydroxybiphenyl was found. Without separating high-purity dihydroxybiphenyl from the reaction product containing dihydroxybiphenyl, the dihydroxyphenyl contained in the reaction product is reacted with an acylating agent in the presence of a catalyst to form diacyloxybiphenyl. The present inventors have now completed the present invention by discovering that by separating this diacyloxybiphenyl from the reaction mixture, cyasyloxyphenyl 18 can be obtained with high purity and high yield.

Summary of the invention The method for producing diacyloxybiphenyl according to the present invention comprises 3
, 3'', 5,5-tetra-1-butyl-4,4-dihydroxybiphenyl is obtained by the dealkylation reaction, and an acylating agent is added to the reaction product containing dihydroxybiphenyl to form dihydroxyphenyl and acyl. The method is characterized in that the diacyloxybiphenyl obtained is reacted with a curing agent in the presence of a catalyst and the resulting diacyloxybiphenyl is separated from the reaction mixture.

According to the method for producing diacyloxybiphenyl according to the present invention, 3,3',5,5-tetra-r-butyl-4,4-
The reaction product containing dihydroxybiphenyl obtained by the dealkylation reaction of dihydroxybiphenyl,
3. Since the acylating agent is added, dihydroxybiphenyl and the acylating agent are reacted in the presence of an acid catalyst, and the resulting diacyloxybiphenyl is separated from the reaction mixture.
High purity diacyloxybiphenyl can be produced in high yield from 3',5.5-tetra-t-butyl-4,4-dihydroxybiphenyl, and the process for producing sialyloxyphenyl can be simplified.

DETAILED DESCRIPTION OF THE INVENTION The method for producing diacyloxybiphenyl according to the present invention will be specifically described below.

In the present invention, first, 3,3',5,5°-tetra-1-
Butyl-4,4'-'': A reaction product containing dihydroxybiphenyl is produced by dealkylation of hydroxybiphenyl.

In the present invention, 3,3',5,5-tetra-t-butyl-
4,4'-dihydroxybiphenyl may be obtained by any method, but 3.3',5
,5-tetra-t-butyl-4,4'-dihydroxybiphenyl is 2,6-di-1 as shown in the following formula [I].
- It is preferable to use one obtained by an oxidative coupling reaction of butylphenol.

Such an oxidative coupling reaction of 2,6-di-t-butylphenol can be carried out under conditions such as those described in JP-A-55-72131.

Such 3.3',5.5'-tetra-1-butyl-
4,4°-dihydroxybiphenyl is represented by the following formula [II]
Dealkylation as shown in Figure 1 yields a reaction product containing dihydroxybiphenyl.

Such 3,3',5,5-tetra-t-butyl-4
, 4'-dihydrochylebiphenyl can be carried out in the presence of an acid catalyst using diphenyl ether or the like as a solvent, as disclosed in JP-A-61-200935, for example. . Also 3
The dealkylation reaction of 3',5,5-tetra-t-butyl-4,4-dihydroxybiphenyl is carried out using a saturated hydrocarbon with a boiling point of 190'C or higher such as sulfolane or tridecane, or decalin in the presence of an acid catalyst. Alicyclic hydrocarbons with a boiling point of 190'C or higher, such as Lucant HC-20, with a molecular weight of 5
Using a hydrocarbon with an iodination value of 1 or less, such as an ethylene-propylene oligomer of 150 to 30
It can be carried out at a temperature of 0'C1, preferably 170-280'C. 3.3',5.5'-tetra-1-butyl-4,4 using a solvent such as sulborane
By performing the dealkylation reaction of °-dihydroxybiphenyl, dihydroxybiphenyl can be obtained with high purity, and 3,3',5,5-tetra-1-butyl-4
, 4-dihydroxybiphenyl is hardly transalkylated into the solvent, so isobutene can be obtained in high yield, which is preferable.

3. When performing the dealkylation reaction of 3',5,5-tetra-1-butyl-4,4-dihydroxybiphenyl, examples of acid catalysts include sulfuric acid, hydrochloric acid, phosphoric acid, and boron fluoride. , methanesulfonic acid, p-toluenesulfonic acid, etc. are used.

In the present invention, diacyloxybiphenyl is produced by adding an acylating agent to the reaction product containing dihydroxybiphenyl obtained in this way, and reacting the citroquidibiphenyl and the acylating agent in the presence of a catalyst. . In this case, when carrying out the acyloxylation reaction, appropriate amounts of low-boiling substances and reaction solvents may be removed from the reaction product by distillation, if necessary.

The acylating agent is preferably added in an amount of 1 to 20 moles, preferably 2 to 6 moles, per mole of dihydroxybiphenyl contained in the reaction product.

The acylating agents used in the present invention include lower aliphatic carboxylic anhydrides such as formic anhydride, acetic anhydride, propionic anhydride, butyric anhydride, and valeric anhydride; aromatic anhydrides such as benzoic anhydride and toluic anhydride; Examples include carboxylic anhydrides and acid chlorides such as acetyl chloride.

The catalyst used in the reaction between dihydroxybiphenyl and the acylating agent is the acid catalyst used in the dealkylation reaction of 3.3',5,5°-tetra-1-butyl-4,4-dihydroxybiphenyl. A wide variety of acids similar to those can be used, and inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and boron fluoride are particularly preferably used. Ion exchange resins can also be used as solid acids.Also as catalysts other than acids.

Bases can also be used, and in addition to organic bases such as pyridine and quinoline, salts such as sodium acetate can also be preferably used. The amount of catalyst used varies depending on the type and reaction conditions, but it is usually preferably in the range of 0.01 to 10% by weight based on the total reaction product.

The reaction between this dihydroxybiphenyl and an acylating agent such as carboxylic anhydride is carried out at 0 to 200°C, preferably at 80 to 100°C.
It is carried out in the range of 40'C. Further, the reaction time is about 30 minutes to 5 hours, preferably about 1 to 2 hours.

Adding an acylating agent such as carboxylic anhydride to the reaction product containing dihydroxybiphenyl as described above,
After reacting dihydroxybiphenyl with an acylating agent such as a carboxylic acid anhydride, the resulting reaction mixture is cooled without being left to stand, diacyloxybiphenyl is obtained as a precipitate from the reaction mixture.

In the present invention, the reaction between the reaction product containing dihydroxybiphenyl and the acylating agent as described above is carried out in the presence of an aromatic hydrocarbon such as cumene, a dialkyl ketone such as methyl isobutyl ketone, or a carboxylic acid solvent. In particular, when acyloxylation is carried out using methyl isobutyl ketone as a solvent, when the target diacyloxybiphenyl is separated from the reaction mixture, impurities are extracted into the solvent and remain, so the purity of the diacyloxybiphenyl obtained is reduced. is preferable because it will be high.

In the present invention, diacyloxybiphenyl specifically includes various substituted products such as 4,4-diacyloxybiphenyl, 3,4°-diacyloxybiphenyl, 2,4'-diacyloxybiphenyl, and the acyloxybiphenyl of the compound. The group is necessarily a group represented by the general formula R-d-o- (wherein R represents a lower alkyl group or an aryl group), and specifically includes formyloxy, acetoxy, propionyloxy, butyryloxy, valeryloxy, Examples include benzoyloxy and toluyloxy. Among these, acetoxy is preferred, and 4,4-diacetoxybiphenyl and 3,4'-diacetoxybiphenyl are preferred.

The diacyloxybiphenyl thus obtained has an extremely high purity of 99% or more, and the reaction yield of diacyloxybiphenyl based on dihydroxybiphenyl is also extremely good at 99 mol%. The obtained yield is also good at 95 mol%.

However, if 19 is produced by oxidative coupling reaction of 2,6-di-t-butylphenol,
, 5°-Tetra-1-butyl-4,4-dihydroxybiphenyl from the reaction product containing dihydroxybiphenyl obtained by the dealgylation reaction. When attempting to separate and purify dihydroxybiphenyl by another method, the recovery The percentage is about 90%, and the purity of the crystals obtained is about 95%.

As described above, according to the method for producing diacyloxybiphenyl according to the present invention, the acylating agent is directly added to the reaction product without separating dihydroxybiphenyl from the reaction product, and the dihydroxybiphenyl and the acylating agent are combined. Since diacyloxybiphenyl is produced by reaction, diacyloxybiphenyl is produced with high purity and high recovery rate compared to the method of separating dihydroxybiphenyl from the reaction product and acyloxylating it to obtain diacyloxybiphenyl. The excellent effect of simplifying the process can be obtained.

Further, the diacyloxybiphenyl thus obtained can be easily converted to dihydroxybiphenyl by hydrolyzing with an acid or an alkali, if necessary.

According to the method for producing diacyloxybiphenyl according to the present invention, 3,3',5,5°-tetra-1-butyl-4,4
An acylating agent is added to the reaction product containing dihydroxybiphenyl obtained by the dealkylation reaction of °-dihydroxybiphenyl, and the dihydroxybiphenyl and the acylating agent are reacted in the presence of a catalyst. Because siloxybiphenyl is separated from the reaction mixture, dihydroxybiphenyl is separated from the reaction product and diacyloxybiphenyl is obtained by acyloxylation, which makes it possible to produce diacyloxybiphenyl with high purity in a high yield. In addition, the manufacturing process of diacyloxybiphenyl can be simplified.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 100CC equipped with stirrer, thermometer and backflow condenser
3,3',5 at a temperature of 83.8% by weight in a four-roof flask.
．． 5'-tetra-t-butyl-4,4°-dihydroxybiphenyl 10 g, n-paraffin 107! , p-toluenesulfone mo, 2 g were charged, and reacted at 180'C for 3 hours. Analysis of the reaction solution by gas chromatography revealed that 3,3',5,5-tetra-butyl-4
, 4-dihydroxybiphenyl was completely reacted, and 3.30 g of 4,4-dihydroxybiphenyl was produced in the reaction system at this time.

Next, the reaction solution was cooled to 100°C, 10ml of methyl isobutyl ketone, 6.23ml of acetic anhydride, and 0.059ml of sulfuric acid were added, and the mixture was reacted at 120°C for 1.5 hours. Analysis of the reaction solution by gas chromatography revealed that all of the 4,4°-dihydroxybiphenyl had reacted, and the reaction yield of 4,4°-diacetoxybiphenyl was 99 mol%.

The temperature was then slowly lowered to 10'C. The precipitated 4,4-diacetoxybiphenyl was filtered and dried to obtain 4.5 g of 4,4-diacetoxybiphenyl.

This was a white crystal with a purity of 99.7% and a yield of 94 mol% based on 4,4-dihydroxybiphenyl.

Claims (1)

[Claims] 1) 3,3',5,5'-tetra-t-butyl-4,4
- An acylating agent is added to the reaction product containing dihydroxybiphenyl obtained by the dealkylation reaction of dihydroxybiphenyl, and the dihydroxybiphenyl and the acylating agent are reacted, and the resulting diacyloxybiphenyl is separated from the reaction mixture. A method for producing diacyloxybiphenyl, characterized by: