DD283497A7 - PROCESS FOR PREPARING TRIETHYLBENZYLAMMONIUM CHLORIDE - Google Patents

Abstract

The invention relates to a process for the preparation of triethylbenzylammonium chloride, which has meaning as a phase transfer catalyst and as a chlorination catalyst. The process is characterized in that the compounds triethylamine and benzyl chloride are reacted in a solvent mixture of toluene, acetone and dimethylformamide {triethylbenzylammonium chloride; triethylamine; benzyl chloride; inert solvent; toluene; Acetone; dimethylformamide; Solvent mixture,; Phase transfer catalyst; chlorination}

Description

Application of the invention

The invention relates to a process for the preparation of triethylbenzylammonium chloride of the formula

? 2 ^H ^

N i

Cl

This compound is an important phase transfer catalyst. Furthermore, the compound finds application as a chlorination catalyst, especially in the chlorination of complex heterocycles with PCU.

Characteristic of the known state of the art

From DD-PS 208147 a technically feasible process for the preparation of I is known. In this case, triethylamine II is reacted with benzyl chloride III.

The reaction takes place partly in a ketone, preferably acetone. Equimolar amounts of II and III are used for the reaction.

In a particular embodiment, after a certain reaction time I between isolates and the not yet reacted Ausgangegemisch cooked until complete reaction again for a long time.

The resulting I is formed in a finely crystalline form. An intermediate insulation is necessary because the resulting I severely restricts or no longer allows stirring. A considerable disadvantage of this procedure, in addition to the still long reaction time and the not inconsiderable technical operations, the intermediate isolation. Due to the Dickwerden of the reaction mixture poor mixing is achieved and the intermediate isolation acts unreacted starting material III very strong mucous membrane irritant. Working with breathing apparatus is therefore absolutely necessary.

Furthermore, the compound I is formed in a finely crystalline form, which manifests itself in the Trenrvorgang solid-liquid in long processing times. In particular, difficulties arise because of the hygroscopic properties of I in that the product becomes water-moist. A drying process is very complicated and leads to a quality-reduced I. In addition, the finely crystalline form involves the risk during drying to develop fine dusts, which in turn require special measures in the field of health and safety.

From Houben-Weyl, Methods of Organic Chemistry, 4th Edition, Volume XI / 2, pages 586ff. It can be seen that I is synthesized from ethanol. However, this achieves only a very small space-time yield. Reaction times of 10 hours and more are not efficient. The same applies to a process variant in Organic Synthesis Vol. 55.97 (1976). The variant specified here for laboratory approaches is not feasible on an industrial scale since the use of ether is problematic for safety reasons and a reaction time of up to 64 hours is necessary.

German Pat. No. 883,904 discloses the synthesis of quaternary ammonium salts from tertiary amines and an alkyl halide or aryl or aralkyl halide in aromatic hydrocarbons, principally benzene. A work in Benzen is

also from Houben-Weyl, Volume XI / 2, page 601, can be seen. A similar variant is known from DD-PS 139842, wherein the syntheses are carried out in benzene. The resulting quaternary ammonium compounds are formed as oily products, which are obtained only by re-treatment in benzene crystalline.

The disadvantage of the cited variant for the preparation of I, however, is that the target product spontaneously crystallises home Stirring of the oily phase and thus a poorly stirrable suspension is formed which contains unreacted starting material and includes. Also, a change that toluene or xylon is used, there is no improvement in that coarsely crystalline I is obtained in high quality and quantity.

CH-PS 484866 discloses benzene, xylene, toluene, chlorinated hydrocarbons, acid amides such as dimethylformamide, nitriles and ethers for the preparation of quaternary ammonium salts from tertiary amines and alkyl halides. In these solvents and diluents, the target products arise either in a finely crystalline form or as an oily substance, which is difficult to crystallize. Another disadvantage is the incomplete conversion or the formation of undesired by-products (eg in dimethylformamide or chlorinated hydrocarbons), which cause a deterioration in quality.

Object of the invention

The object of the invention is to find a process for the preparation of compound I in high yield, purity and in a technically simple and easy to control process.

Explanation of the nature of the invention

The present invention has for its object to produce triethylbenzylammonium chloride I in high yield, purity, quality and in a well crystallizable or separable manner.

According to the invention, the object is achieved by reacting triethylamine II with benzyl chloride III in a solvent mixture consisting of toluene, acetone and dimethylformamide. Particularly advantageous is a solid composition of the ratio of these inert solvents has been found. It was found that the composition of toluene, acetone and dimethylformamide in the volume ratio 1: 0.5: 0.05 is favorable. Other ratios give either lower yields or lower qualities. The molar ratio of the two feeds II and III should be 1: 1 to a maximum of 1.3: 1. According to the invention, the procedure is such that the mixture of toluene, acetone and dimethylformamide initially charged and a temperature of 30 ° C is set. To this is added the benzyl chloride III. Compound II is added in 30 to 60 minutes. During the amine addition, a slight increase in temperature to 75 ° C to 80 ⁰ C noticeable and after the addition is stirred at 85 ° C to 90 ⁰ C for 6 to 10 hours, finally cooled to room temperature, where I in coarse crystals of high purity and yield is obtained. The mother liquor contains no I and can be worked up by distillation or used for further preparations. The compound I thus obtained can be spun off well, contains no free III and must not be recrystallized.

embodiments

example 1

1000 liters of toluene are placed in a stirrer and with stirring 5001 acetone and

501 dimethylformamide added.

Then you give

379.5 kg of benzyl chloride, heated to 50 ⁰ C and dripped within 1 hour

304kg of 100% triethylamine so that the internal temperature at 75 ⁰ C to 8O ⁰ C is maintained.

Then heated to reflux and stirred for 10 hours. Upon cooling, I precipitate in coarse crystals of high purity.

I is separated from the mother liquor in a centrifuge and no longer washed.

The mother liquor is used three more times for the synthesis, without products of the compound I are obtained in poorer quality and yield.

Yield: 683 kg of triethylbenzylammonium chloride £ 100% of theory.

The target product adheres to a maximum of 1% solvent mixture.

Mp: 195-196.5 ⁰ C.

Example 2

10 000 l of toluene are placed in a stirrer and with stirring 6Ol dimethylformamide and

303 kg of triethylamine were added and slowly heated to 60 "C to 70 ⁰ C. At this temperature is added slowly benzyl 379,5kg in the 6O ⁰ C to 7O ⁰ C warm solution and heated now to 100 ⁰ C to 110 ⁰ C and stirred for doing it 10 hours after.

It is then cooled with stirring to 20 ° C and allowed to stir for 6 hours. Triethylbenzylammonium chloride precipitates in crystalline form and is filtered off with suction. The product obtained is again with

600I acetone stirred in a stirred tank at 2O ⁰ C to 3O ⁰ C and then sucked off again, then centrifuged well in the centrifuge.

Yield: 546 kg of triethylbenzylammonium chloride and 80% of theory.

Mp: 195-196.5 ⁰ C.

Example 3

1000ml toluene are placed in a sulphonation flask. With stirring, 100 ml of acetone and 10 ml of dimethylformamide are added.

Thereafter, 379.5 g of benzyl chloride, heated to 50 ⁰ C and added dropwise within 1 hour 303 g of triethylamine so that the internal temperature is maintained at 75 ° C to 8O ⁰ C.

Then heated to reflux and stirred for 10 hours. Upon cooling, the Zielprodiikt falls in coarse crystals, high purity and yield.

Yield: 615 g of triethylbenzylammonium chloride 90% of theory.

Example 4

The procedure is analogous to Example 3 with a solvent mixture of 1000 ml of toluene, 5COmI acetone and 10 ml of dimethylformamide.

Yield: 593 g of triethylbenzylammonium chloride ^ 87% of theory.

Example 5

The procedure is analogous to Example 3 with 1000 ml of toluene, 30 ml of acetone and 50 ml of dimethylformamide.

Yield: 034 g of triethylbenzylammonium chloride L · 93% of theory.

Claims (4)

claims: 1. A process for the preparation of triethylbenzylammonium chloride of the formula Oil by reacting triethylamine II with benzyl chloride III in an inert solvent, characterized in that the reaction of III with II is carried out in a mixture of the solvents toluene, acetone and dimethylformamide, which are known per se for the reaction of tertiary amines. 2. The method according to claim 1, characterized in that one uses a solvent mixture toluene: acetone: dimethylformamide in the volume ratio 1: 0.5: 0.05. 3. The method according to claim 1 and 2, characterized in that one submits III in the solvent mixture and Il slowly added at elevated temperature. 4. Process according to claims 1 to 3, characterized in that one uses II and III in a molar ratio of 1: 1 to 1.3: 1.