JPH075493B2 - Process for producing bis (2-hydroxyhexafluoro-2-propyl) benzene derivative - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a bis (2-hydroxyhexafluoro-2-propyl) benzene derivative useful as a raw material for various fluoropolymers.

[Prior Art] It is conventionally known that bis (2-hydroxyhexafluoro-2-propyl) benzene can be obtained by reacting hexafluoroacetone with benzene in the presence of aluminum chloride. .Chem., 30,998 (196
5)], When carrying out the above reaction, aluminum chloride (1 g) is added to benzene (1 mol) and the reaction temperature is 40 to 50 while refluxing.
Since the temperature was maintained at 0 ° C. and aluminum chloride was added successively during the reaction, the total amount of aluminum chloride used was 6 to 20 g, which corresponds to 4 to 15 mol% with respect to benzene.

On the other hand, in JP-A-63-33346, benzene 780
After dissolving g (10 mol) in 3.5 l of carbon disulfide, 3.65 kg (22 mol) of hexafluoroacetone was introduced, and aluminum chloride was added to start the reaction.
It is stated that the temperature is maintained at 30 to 46 ° C, and at this time, 406g (30mol) of aluminum chloride is consumed.

After completion of the reaction in both cases, water is added to decompose the aluminum chloride, the reaction product is extracted with a solvent, and then purified by distillation or another method to obtain the desired product.

[Problems to be solved] Industrially large amount of bis (2-hydroxyhexafluoro-2-
Propyl) benzene derivative, for example, bis (2-hydroxyhexafluoro-2-propyl) benzene under normal pressure requires an expensive reflux device because the boiling point of hexafluoroacetone is as low as -27 ° C. It is economically advantageous to use a closed pressure system.

When hexafluoroacetone is reacted with a benzene derivative, the production reaction of the first-stage mono-substituted product, (2-hydroxyhexafluoro-2-propyl) benzene derivative, is a violent exothermic reaction at 1 mol%. The reaction proceeds easily in the presence of aluminum chloride below, but in the reaction for producing the bis (2-hydroxyhexafluoro-2-propyl) benzene derivative in the second stage, the reaction is difficult to proceed, and as described above, the reaction It was necessary to add aluminum chloride sequentially until completion, and a considerably large amount of aluminum chloride was used as the total amount.

Thus, in the conventional method, there is a problem that a large amount of aluminum chloride is required and the reproducibility of the required amount of aluminum chloride is poor, and further, when recovering the target product after the reaction, The problem is that in the conventional method, aluminum chloride was decomposed with a large amount of water, phase extraction was performed after adding an extraction solvent such as methylene chloride, and distillation purification was performed. A large amount of solvent is required to prevent the precipitation of crystals, the separation at the interface is not good, and the product diol has a strong water-dissolving power, so that it cannot be dehydrated sufficiently with magnesium sulfate, sodium sulfate, etc. There was a problem that the initial distillation loss due to the mixing of water was large during the distillation purification.

Further, in order to avoid the problem of the above-mentioned recovery method, direct distillation after the reaction is considered to be a simple method, but in this case heating at high temperature is unavoidable, and as a result, hydrochloric acid is generated and a high boiling by-product is newly generated. The problem of doing it still remains.

[Means for Solving the Problems] Under these circumstances, the present inventors have replaced the conventional method with sufficient cooling when carrying out the reaction and maintaining the temperature at a low temperature of 30 ° C. or lower. In the second step reaction, the reaction proceeded exothermically quickly, and in recovering the target product after the reaction, aluminum chloride was decomposed with a metal hydroxide such as sodium hydroxide in a non-aqueous system. However, they have found that the subsequent distillation can be favorably performed, and have reached the present invention.

That is, the present invention has the general formula (In the formula, R ₁ represents a group selected from hydrogen, halogen and alkyl groups.) Hexafluorofluoride at a temperature of 30 ° C. or lower in the presence of a certain amount of aluminum chloride with respect to the benzene derivative. After reacting with acetone, add hydroxide of alkali metal or alkaline earth metal,
General formula characterized by distillation (However, R ₁ is the same as above, and R ₂ represents a 2-hydroxyhexafluoro-2-propyl group.) In the process for producing a bis (2-hydroxyhexafluoro-2-propyl) benzene derivative is there.

In the production method of the present invention, the aluminum chloride to be used may be added in a fixed amount with respect to the raw material benzene derivative,
It is not necessary to add them one after another. Therefore, the required amount of aluminum chloride may be the required minimum amount, and since reproducibility is excellent, a constant value may be added to the benzene derivative as a raw material. In this case, the amount of aluminum chloride is appropriately 4 to 30 mol%. When the amount of aluminum chloride is less than 4 mol%, the reaction does not proceed sufficiently and unreacted substances remain.

On the other hand, when it is more than 40 mol%, the reaction proceeds sufficiently, but the required amount of aluminum chloride increases, which is not economical.

The reaction temperature is 30 ° C. or lower, preferably 25 ° C. or lower, and in a solventless system, it is preferable to carry out the reaction at a temperature not lower than 5 ° C. or higher than the melting points of the raw materials and the product. The use of a solvent is not preferable from the viewpoint of productivity, but it is preferable to use a solvent particularly in the case of a raw material or product having a high melting point. In this case, it is preferably dissolved in a nonpolar solvent such as methylene chloride.

As mentioned above, the reaction can be carried out under reflux at normal pressure, but it is preferable to carry out the reaction in an autoclave for economical reasons.

Next, for the recovery of the target product after carrying out the reaction, as the alkali metal hydroxide or alkaline earth hydroxide added to decompose the catalyst, sodium hydroxide,
Examples thereof include potassium hydroxide, magnesium hydroxide, calcium hydroxide and the like.

The amount used is an equimolar amount to 5 times, and preferably 1.5 to 3 times the molar amount of aluminum chloride used. When the amount used is less than the equimolar amount, unreacted aluminum chloride remains, which is not preferable. On the other hand, when the amount is more than 5 times the molar amount, a large amount of alkali remains, which is economically undesirable.

As an addition method, the above powder is added to the reaction solution as it is, or is dissolved in a polar solvent and added to the reaction solution.

Upon addition, aluminum chloride becomes a salt of aluminum hydroxide and the above metal, and the desired product can be easily recovered by distillation without generating hydrochloric acid or the like and without giving a high boiling by-product.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the Examples.

Example 1 A 1.6 l autoclave was charged with 234 g (3.0 mol) of benzene and 30 g of aluminum chloride, and the reaction temperature was 20 to 24 ° C. in an ice bath.
Hexafluoroacetone (996 g) was introduced for 4 hours while maintaining the above condition, and after reacting for another 15 hours, gas chromatography analysis revealed that the reaction rate was 100%, 1,3
The selectivity of -bis (2-hydroxyhexafluoro-2-propyl) benzene was 82.1% and the selectivity of 1,4-bis (2-hydroxyhexafluoro-2-propyl) benzene was 17.9%.

Example 2 28 g (0.7 mol) of sodium hydroxide was added to the reaction solution obtained in Example 1.
l, 3.1 times the molar amount of aluminum chloride used), stir and distill under reduced pressure (102-108 ℃ / 18-20m)
mHg) and 1066.4 g of product was recovered. The recovery rate in this case was 86.7%, and 1,3-bis (2-hydroxyhexafluoro-2-propyl) benzene in the recovered solution was 83.8%,
4-bis (2-hydroxyhexafluoro-2-propyl) benzene was 16.2%.

Example 3 In the autoclave of 1, 192 g of fluorobenzene (2mo
l), 80 g (30 mol%) of aluminum chloride were charged, 708 g of hexafluoroacetone was added for 8 hours while cooling with an ice bath and maintaining at 25 to 30 ° C, and after reacting for 16 hours, gas chromatography was performed. When analyzed by graphy,
The reaction rate was 100%, and the selectivity of 2,4-bis (2-hydroxyhexafluoro-2-propyl) fluorobenzene was 100%.

Example 4 105 g of potassium hydroxide (1.88 mol) was added to the reaction solution obtained in Example 3.
l, 3.1 times the molar amount of aluminum chloride used), stirred and vacuum distilled as it is (97-98 ° C / 16mmHg)
Recovery, 761 g of product was recovered. The recovery rate in this case is 8
8.4%, and the purity of 2,4-bis (2-hydroxyhexafluoro-2-propyl) fluorobenzene in the recovered liquid was 9
It was 9.9%.

[Effects of the Invention] According to the production method of the present invention, the reaction temperature is maintained at 30 ° C or lower, and the minimum necessary amount of aluminum chloride as a catalyst is added, so that the reaction can be performed rapidly with good reproducibility. The progress of the reaction product and the subsequent recovery of the reaction product can be carried out easily and efficiently by distillation, which is an industrially extremely advantageous method.

Claims (1)

[Claims] 1. A general formula (In the formula, R ₁ represents a group selected from hydrogen, halogen and alkyl groups.) Hexafluorofluoride at a temperature of 30 ° C. or lower in the presence of a certain amount of aluminum chloride with respect to the benzene derivative. After reacting with acetone, add hydroxide of alkali metal or alkaline earth metal,
General formula characterized by distillation (However, R ₁ is the same as the above, and R ₂ represents a 2-hydroxyhexafluoro-2-propyl group.) A method for producing a bis (2-hydroxyhexafluoro-2-propyl) benzene derivative represented by the following.