CS215315B1 - Process for preparing alkylbenzyl chlorides - Google Patents

Abstract

The invention relates to the preparation of alkylbenzyl chlorides by chloromethylation of alkylbenzenes having 10 to 18 carbon atoms in the alkyl chain in the presence of a liquid catalyst system consisting of zinc chloride and/or stannous chloride and aliphatic acid, preferably acetic acid. Chloromethylation takes place either 1 (by the action of formaldehyde and hydrogen chloride and/or by the action of monochlorodimethyl ether. The concentration of water in the reaction mixture is kept at a constant level by binding either chemically, preferably by adding anhydride or orgamic acid by adsorption. The chloromethylation reaction takes place at a temperature of 40 °C to 140 °C and at a maximum pressure of 2.0 MPa. Prepared alkyl benzyl chlorides are the starting point raw material for the production of cationic, possibly non-ionic and anionic surfactants.

Description

2

The present invention relates to a process for the preparation of alkylbenzyl chlorides by chloromethylation of alkylbenzene copolymers of 10 to 18 carbon atoms in the alkyl chain by chloromethylation with either formaldehyde or substances which release formaldehyde by reaction conditions and hydrochloric acid and / or monochlorodimethyl ether under the presence of mixed acarboxylic acid complex catalysts. The concentration of water in the reaction mixture is maintained at a maximum of 10% by weight by binding the reaction water by chemical or adsorption.

Chloromethylation of short alkyl chain alkylbenzenes is described in U.S. Pat. No. 3,658,923. Chlorosulfonic acid is a catalyst. According to Japanese Patent Publication No. 74,11635, chloromethylation is catalytic with ferric chloride. In Japanese Pat. No. 74,11701, chloromethylation catalysts include AlCl 3, SnCl 4, ZnCl 2, SbCl 5.

German Patent No. 1,082,893 covers a method of chloromethylation in which the concentration of chlorohydrogen in the aqueous phase of the reaction mixture is maintained at a rate of at least 30% by introducing gaseous hydrogen chloride into a mixture of at least 30 ° C.

Alkylbenzylchloirides are prepared by chloromethylation of alkylbenzenes either with formaldehyde or with formaldehyde-releasing agents under the reaction conditions, for example formaldehyde polymer and hydrogen chloride and / or monochlorodimethyl ether. The reaction is determined by a liquid catalyst system consisting of a complex of zinc chloride and / or tin tetrachloride with an aliphatic monocarboxylic acid or fuco mixture of aliphatic monocarboxylic acids containing one to four carbon atoms in the molecule.

A liquid catalyst system is prepared by dissolving anhydrous ZnCl 2 and / or SnCl 4 in aliphatic acid or a mixture of aliphatic monocarboxylic acids at a temperature of at least 30 ° C, preferably at 50 to 80 ° C: An effective catalyst system is obtained when the anhydrous weight ratio ZnCl 2 and / or SnCl 4 to the aliphatic acid ranges from 18 to 60 parts of ZnCl 2 and / or SnCl 4 per 100 parts of aliphatic acid.

According to the present invention, chloromethylated alkylbenzenes prepared by alkylacetic benzene may be chloroalkanes, unbranched 1-alkenes, n-alkenes with a double bond found statistically separated by carbon chain lengths, alkene-derived oligomers for n-butenes, pentenes, hexenes and heptenes, codimerization propene, butenes, pentenes, heptenes with heptene, octene and nonenes, decenium undecenes. Alkylbenzenes can also be prepared by alkylation of benzene with chemical or other mixtures of said alkylating agents containing 10 to 18 carbon atoms per molecule.

During the chloromethylation of alkylbenzenes with formaldehyde and hydrogen chloride, water of reaction is formed. According to the present invention, it has been found that the water content of the reaction mixture is preferably kept at a maximum of 10% by weight, preferably at a maximum of 2.5% by weight. . The water content of the reaction mixture is regulated by its chemical bonding with an anhydride, preferably with an acid anhydride used to prepare the catalyst system.

Excess reaction water can also be coupled chemically by phosphorus pentoxide. The water content of the chloromethylation mixture can be adjusted by adsorption water binding using zeolite molecular sieves or amorphous anhydrous aluminosilicates.

The water content of the reaction mixture can be controlled by combining water-binding agents chemically, by combining water-binding agents with adsorption and by combining water-binding agents chemically and adsorptively.

Alkylbenzenes may be chloromethylated at 40 ° C to 140 ° C, preferably at 50 ° C to 80 ° C at atmospheric pressure or at a maximum pressure of 2.0 MPa. The chloromethylation of the alkyl benzenes is either formaldehyde or formaldehyde-forming in the reaction conditions and the hydrogen chloride is either manochlorodimethylether or any mixture of chloromethylating agents. In the case of chloromethylation of alkyl benzenes with paraformaldehyde and hydrogen chloride, it is advantageous to work with these weight components of the reaction mixture: 100 weight parts of alkylbenzene, at least 100 weight parts of liquid catalyst system, 15 to 40, preferably 25 weight parts of paraformaidehyde, Hydrogen chloride is fed to the reaction mixture gradually over the entire reaction time. When chloro-methylated alkylbenzenes are obtained to a chlorine content of 5% by weight and lower, it is preferable to return the mixture to chloromethylation using a fresh catalyst system.

The liquid catalyst system can be recycled in whole or partially to the chloromethylation reactor after separation of the reactants.

During the chloromethylation of monochlorodimethylether, the most suitable weight ratios of the reaction components were experimentally found: 100 parts by weight of alkylbenzenes, 100 to 250, preferably 175 to 230 parts by weight of liquid catalyst system, 40 to 100, preferably 60 to 80% by weight. parts of mono-chlorodimethyl ether. An advantage of the process for the preparation of the alkylbenzyl chlorides of the present invention is that high yields of sheet products as well as chlorinated alkylbenzenes are obtained. With chloromethylation of alkylbenzenes with paraformaldehyde and hydrogen chloride, 0.7: 6 with a molar ratio of ZnCl2 to acetic acid and alkylbenzene. : 1 achieves conversion of alkylbenzenes

Claims (4)

58% by weight with a selectivity for alkylbenzyl chlorides of 94% by weight. In the chloromethylation with monochloroimethyl ether, at a molar ratio of zinc chloride to acetic acid and to 0.8: 8: 1 alkylbenzene, the alkylbenzene version reaches 50% by weight of the selectivity calculated to alkylbenzyl chlorides at least 90% by weight. A further advantage of the process for preparing the alkylbenzyl chlorides of the present invention is the possibility of returning the already used catalyst catalyst system to the reaction. The quaternary catalyst system is subjected to fractionation after the chloromethylation of the reaction mixture is complete, for example by sedimentation. Unreacted alkylbenzenes containing a maximum of 5% by weight of chlorine are collected as a separate fraction and returned to chloromethylation. Alkylbenzyl chlorides having from 10 to 18 carbon atoms in the alkyl chain are suitable, for example, for the production of nonionic and cationic surfactants. By way of illustration, examples are given but are not intended to limit the invention. EXAMPLE 1 125 parts by weight of a mixture of alkylbenzene boiling in the range of 130 DEG C. to 160 DEG C. at 266 DEG C. and 30 parts by weight of paraformaldehyde are introduced into a reactor equipped with a stirrer. The mixture is heated to 65 DEG C. and 233 parts by weight of liquid catalyst are added. a lysing system comprising 50 parts by weight of zinc chloride in acidic acetic acid with a minimum fraction of 95% by weight. The mixture is stirred vigorously and a total of 180 parts by weight of hydrochloric acid and 40 parts by weight of acetic anhydride are gradually added during the reaction time. After 6 hours of reaction at atmospheric pressure, 114.5 parts by weight of alkylhenzyl chlorides with a total chlorine content of 9.4% by weight are recovered after separation of the liquid catalyst system. EXAMPLE 2 CLAIMS 1. A process for the preparation of alkyl thenzyl chlorides containing from 10 to 18 carbon atoms in the alkyl chain in an elevated yield by reacting alkyl benzenes with formaldehyde or a substance which releases formaldehyde in the presence of the catalysts based on lusic and carboxylic acid complexes, characterized in that the water concentration in the reaction mixture is maintained at a maximum of 10% by weight, preferably at most 2.5% by weight, by chemical and / or adsorbed bonding. 2. Process according to claim 1, characterized in that the water of reaction is bound by a portion of water or by weight of alkylbenzenes boiling in the range of 110 DEG to 125 DEG C. at 266 Pa. After the stirrer has been put into operation, 270 parts by weight of a liquid catalyst system comprising 35 parts by weight of zinc chloride, 5 parts by weight of tin (II) chloride in anhydrous acetic acid are added to the alkylbenzene. At 70 ° C, 184 parts by weight of mono-chlorodimethyl ether were pumped into the reactor for 5 hours. The mixture was left to react under vigorous stirring for 1 hour. After separation of the liquid catalyst system, 79.3 parts by weight of alkylbenzyl chlorides were obtained with a total chlorine content of 6.9% by weight. EXAMPLE 3 Into a reactor equipped with a stirrer, 36 parts by weight of a part of the chloromethylated alkylbenzenes prepared in Example 2, but containing only 3% by weight of chlorine, were pumped. Thereafter, 91.0 parts by weight of the liquid catalyst system of Example 2 are metered into the reactor under vigorous stirring. The reactor is heated to 70 ° C and 130 parts by weight of monochloro-dimethylether are added with stirring for 5 hours. The mixture was allowed to stir for 1 hour with stirring. After separation of the liquid catalyst system, 28.6 parts by weight of alkylhenzyl chlorides were obtained with a total chlorine content of 8.6% by weight. Example 4 108 parts by weight of the alkylbenzenes specified in Example 2 are charged into a reactor equipped with a stirrer and then the liquid catalyst composition obtained by separating from the reaction mixture described in Example 2 is pumped. it gradually adds 230 parts by weight of monochlorodimethyl ether and 20 parts by weight of acetic anhydride. The mixture does not react for 6 hours. After separation of the catalyst layer, an alkylbenzyl chloride containing 4% by weight of chlorine is obtained. DISCLOSURE OF THE INVENTION By the in-process feeding of aliphatic acid anhydride or mixtures of aliphatic acids containing 2 to 4 carbon and thromes in the molecule and / or by adding anhydrous phosphorous oxide and / or an amorphous or crystalline alumina silicate adsorbent to the chloromethylation mixture. 3. A process according to claim 1, wherein said alkylbenzenes are chloromethylated to a chlorine content of at most 5% by weight. 4. The process of claim 1, wherein the liquid catalyst system is returned to the chloromethylation after the reactants have been separated.