JPH0747553B2 - Process for producing dichloro- (2,2) -paracyclophane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a method for producing dichloro- (2,2) -paracyclophane represented by This compound is a substance known as an intermediate compound in the production of polydichloroparaxylylene resin, and this resin is formed as a film on the material surface by vacuum deposition and has excellent performance in electrical characteristics, high temperature characteristics, etc. Widely used for coating electronic components and parts for space equipment.

PRIOR ART This dichloro- (2,2) -paracyclophane is made by direct chlorination of (2,2) paracyclophane, or
From 2 or 3 (hereinafter referred to as 2 (3))-chloro-p-methylbenzyl chloride, Hofmann desorption is carried out via a quaternary ammonium salt and a quaternary ammonium hydroxide, similarly to (2,2) -paracyclophane. It is produced by a separation reaction (JP-A-63-93740, JP-A-64-45322, etc.). 2 (3)-which is the starting material of this latter production method
It is produced by chlorinating chloro-p-methylbenzyl chloride or 2-chloro-p-xylene.

Problems to be Solved by the Invention (2,2) Although the yield of the direct chlorination method of paracyclophane is good, the alpha chlorinated compound which deteriorates the performance of the polymerization product polymonochloroparaxylylene resin It is difficult to eliminate by-products and remove them.

One of the problems with the latter method via the Hoffmann elimination reaction is the production of 2 (3) -chloro-p-methylbenzyl chloride. As this manufacturing method, as described above Although there are two routes (A) and (B), the production is complicated in both methods, and furthermore, it is not possible to selectively obtain only the monochlorinated benzene nucleus by the reaction, and the starting material and polychlorinated substitution are not possible. Separation from the body mixture is required, but these separations and purifications are rather difficult, resulting in one of the reasons why cheap, pure dichloro- (2,2) -paracyclophane does not exist in the market. It has become one.

Another problem is the problem of yield in the Hoffmann elimination reaction, and various proposals have been made to solve this problem (the above-mentioned Japanese Patent Laid-Open Publication).

An object of the present invention is to solve the first problem. That is, a method for more easily and selectively obtaining a monochlorinated product is provided, and as a result, dichloro- (2,2), which is inexpensive and has high purity,
-The aim is to make the production of paracyclophane possible.

Means for Solving the Problems As a result of continuing the research for solving the problem, the present inventor was different from the conventional reaction route and the following reaction formula It was found that the chlorination of the quaternary ammonium salt selectively produces monochlorinated benzene nuclei as shown in FIG. In chlorination of this quaternary ammonium salt, p
It is a surprising finding that, unlike the chlorination of -methylbenzyl chloride or 2-chloro-p-xylene, only the monochlorinated form of the benzene nucleus is selectively formed by blowing chlorine gas into the aqueous solution. It was

This quaternary ammonium salt, that is, p-methylbenzyltrimethylammonium chloride is generally produced by blowing trimethylamine into a solution of p-methylbenzyl chloride ether or the like, but an aqueous trimethylamine solution is used. Is easy to operate. Both react by simply mixing and stirring, and when the reaction ends, a uniform liquid is formed. There is fever, so cool it depending on the situation. The reaction proceeds even at room temperature. Next, chlorine gas is introduced into this reaction solution while stirring. Since the internal temperature rises due to the heat of reaction, it is appropriately cooled. The reaction temperature is not particularly limited, but if it is too high, the decomposition reaction and the like described below will occur and the yield will decrease, and if it is too low, precipitation will occur and stirring will be hindered.

The progress of the reaction is gas chromatography (GC)
It can be traced by analysis etc. This quaternary ammonium salt has the following formula when the temperature is high. Since it decomposes like this, it is possible to know the progress of the reaction by utilizing this. When no p-methyl-benzyl chloride is detected by GC analysis, stop blowing chlorine. Excess chlorine is blown out as much as possible by blowing an inert gas such as nitrogen.

Next, dioxane and caustic are added to this solution and heated to carry out the Hoffman elimination reaction. Coloring of the product can be reduced by adding a reducing agent such as sodium borohydride (hereinafter, SBH) before the Hoffmann elimination reaction.

Examples Examples of the present invention will be shown below, but it should be understood that the present invention is not intended to limit the present invention, which is merely for showing specific examples of the present invention.

Example 1 14 g of p-methylbenzyl chloride and 24 g of a 30% trimethylamine aqueous solution were stirred while cooling with water. When the solution became uniform and transparent, chlorine gas was blown into the solution to carry out the reaction. The internal temperature rose due to heat generation, but it was controlled so that it did not rise above 20 ° C.

The end point of the reaction was the time when the peak of p-methylbenzyl chloride was not detected by GC analysis. After that, nitrogen was blown in to drive off excess chlorine, and 160 ml of dioxane was added thereto. 85% potassium hydroxide 38g / water 34ml solution was added dropwise to this while stirring while keeping the internal temperature below 40 ℃.
(Sodium borohydride 12%, sodium hydroxide 40%
2 ml of an aqueous solution, the same applies hereinafter) was added. Thereafter, the temperature was raised to 80 ° C. over about 2 hours and 30 minutes, and the reaction was continued at that temperature for 40 hours. The reaction product was poured into water, and the precipitate was collected, washed and dried. The precipitate was dissolved in 70 ml of toluene under heating to remove insoluble matter,
Toluene was distilled off to obtain dichloro- (2,2) -paracyclophane.

In addition, (2,2) -paracyclophane and trichlorinated compounds or more were not detected by GC analysis or were negligible (the same applies to the following examples).

Crude product yield 12.3 g Yield 89.1% Insoluble matter 1.7 g Product yield 10.2 g Yield 73.9% Example 2 14 g of p-methylbenzyl chloride and 48 g of 15% aqueous trimethylamine solution were mixed with stirring. When the solution became uniform and transparent, chlorine gas was blown into the solution to carry out the reaction while cooling so that the internal temperature was kept at 5 ° C or lower. During the process, a precipitate was formed and the stirring condition deteriorated, so an additional 10 ml of water was added. GC
After confirming the completion of the reaction by analysis, nitrogen was blown in to drive off excess chlorine. Dioxane (160 ml) was added to this solution, and the mixture was stirred and cooled, and granular 85% potassium hydroxide and SBH (2 ml) were added so that the internal temperature was kept at 20 ° C or lower. Thereafter, the temperature was raised to 80 ° C. over about 3 hours, and the reaction was continued at that temperature for 40 hours. The treatment after the reaction is the same as in Example 1.

Crude product yield 11.9 g Yield 86.2% Insoluble matter 1.9 g Product yield 9.8 g Yield 71.0% Example 3 Same as Example 1 except that the chlorination temperature was 50 ° C. or lower,
The following results were obtained.

Crude product yield 11.6g Yield 84.1% Insoluble matter 0.9g Product yield 10.3g Yield 74.6% Effect of the Invention According to the present invention, not only is the chlorination process significantly simplified and economical, but also the purity is easily high. Dichloro- (2,
2) -Paracyclophane can be obtained.

Claims (2)

[Claims] 1. The following structural formula In the method for producing dichloro- (2,2) -paracyclophane having, p-methylbenzyltrimethylammonium chloride is chlorinated to synthesize mono-chloro-p-methylbenzyltrimethylammonium chloride,
After that, dichloro- (2,2), characterized by being produced via a quaternary ammonium hydroxide and Hoffmann elimination reaction
-A method for producing paracyclophane. 2. The production method according to claim 1, wherein the chlorinating agent is chlorine gas.