RU2214389C2 - Method for preparing 1-phenyl-1-(alkyl)phenyl- acetones - Google Patents

Abstract

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method for preparing 1-phenyl-1-(alkyl)phenylacetones of the general formula: R_nC₆H_5-nCH(C₆H₅)COCH₃ wherein R means alkyl; n = 1-3. Method involves preparing firstly the complex 1-chloro-1- phenylacetone with aluminum chloride in methylene chloride or chloroform, or carbon tetrachloride at temperature 30 C, not above, followed by its interaction with alkylbenzene at temperature 30-50 C. Method provides elimination of disproportionation reaction of alkylbenzenes. EFFECT: improved preparing method, enhanced quality and yield of end product. 1 tbl, 1 ex

Description

The invention relates to a method for producing 1-phenyl-1- (alkyl) phenylacetone of the general formula R _n C ₆ H _5-n CH (C ₆ H ₅ ) COCH ₃ , where R = alkyl; n = 1-3, which are intermediates for the production of α, α-diaryl-substituted 2-acetylindanedione-1,3, used as rodenticides.

 A known method of producing 1-phenyl-1- (alkyl) phenylacetone, in particular 1-phenyl-1-tolylacetone, based on the interaction of 1-bromo-1-phenylacetone with alkylbenzenes, in particular with toluene in the presence of anhydrous aluminum chloride (Auth. USSR 145417).

A known method for producing 1-phenyl-1- (alkyl) phenylacetone, in particular 1-phenyl-1- (ethyl) phenylacetone, in which anhydrous aluminum chloride and ethylbenzene is first charged to the reactor, then after heating the mixture to 60-70 ^{° C.} at while stirring, 1-chloro-1-phenylacetone is added dropwise to it, after which the reaction mass is maintained at 60-65 ^{° C.} for 1 hour (ed. St. USSR 1037441). Since aluminum chloride, especially when heated, causes isomerization of alkylbenzenes, including dealkylation and transalkylation, the process is accompanied by the formation of a number of by-products, in particular up to 8% α, α-diphenylacetone and up to 40% other impurities.

A known method for producing 1-phenyl-1- (alkyl) phenylacetone is taken as a prototype, according to which alkylbenzene and 1-chloro-1-phenylacetone are first charged to the reactor, then anhydrous aluminum chloride is added in portions so that the temperature of the reaction mass does not exceeded 50 ^o C (US Pat. RF 2151138). After loading the entire amount of aluminum chloride (used in excess with respect to 1-chloro-1-phenylacetone), the reaction mass is kept under stirring at a temperature of 50-60 ^o C for 1.0-1.5 hours. This sequence of loading reagents can reduce the occurrence of side reactions, including the reaction of disproportionation of alkylbenzene, but does not completely exclude them. The mass fraction of the main substance in the preparation of 1-phenyl-1- (alkyl) -phenylacetone reaches 80-85%, impurities from 15 to 20%. In addition, the gradual loading of anhydrous aluminum chloride during the process itself under production conditions is very difficult, and the violation of the uniformity of this load in practice leads to an increase in the formation of by-products.

 The purpose of the invention is to improve the quality of the target product and its yield by eliminating the occurrence of adverse reactions, in particular the disproportionation of alkylbenzenes, and simplifying the technology.

The goal is achieved through the use of a method for producing 1-phenyl-1- (alkyl) phenylacetone by the interaction of 1-chloro-1-phenylacetone with alkylbenzenes in the presence of anhydrous aluminum chloride, followed by exposure of the reaction mixture and isolation of the target product in a known manner. First, a complex of 1-chloro-1-phenylacetone with aluminum chloride in methylene chloride or chloroform or carbon tetrachloride is obtained at a temperature of 20-30 ^o С, and then it is reacted with alkylbenzene at a temperature of 30-50 ^o С.

An example implementation of the method
The method consists in the interaction of 1-chloro-1-phenylacetone with alkylbenzenes in the presence of an equimolar amount of anhydrous aluminum chloride in a medium of methylene chloride. In this case, the solvent and anhydrous aluminum chloride are first charged to the reactor (in one go), 1-chloro-1-phenylacetone in the same solvent is gradually added to the resulting suspension with cooling and stirring. The mixture is stirred at 20-30 ^o C to obtain a homogeneous solution of the complex. To this solution, an excess of alkylbenzene is gradually added with stirring and heating. The reaction mass is stirred at a temperature of 30-50 ^o With at least 3 hours. Then carry out the usual processing of the reaction mass and the selection of the target product. After distillation of the solvents, 1-phenyl-1- (alkyl) phenylacetones are obtained with a mass fraction of the basic substance of 90-95% (according to GLC).

 The proposed sequence of the process almost completely eliminates the occurrence of side processes, including the reaction of the disproportionation of alkylbenzenes. Due to the greater reactivity of 1-chloro-1-phenylacetone as compared to simple halogen alkyls, alkylbenzene alkylation products, for example, methylene chloride, are not formed under experimental conditions. Unlike a number of known methods, anhydrous aluminum chloride is used in an equimolar amount with respect to 1-chloro-1-phenylacetone, and the alkylation process itself proceeds in a homogeneous medium, which positively affects the yield of the target product.

 Thus, improving the quality of the target product and increasing its yield is achieved by changing the sequence of loading of the reagents and the process through the stage of obtaining the specified complex. The use of anhydrous aluminum chloride without excess significantly reduces the amount of production waste, and loading it in one go at room temperature simplifies the technology. The binding of aluminum chloride in the first stage of the process to a complex with 1-chloro-1-phenylacetone, dissolved in methylene chloride (chloroform, carbon tetrachloride), makes it easy to control the next stage of alkylbenzene alkylation. It should be noted that this second stage of the process proceeds without a noticeable thermal effect. Obtained by the proposed method 1-phenyl-1- (alkyl) -phenylacetone can be used to obtain 2- (diarylacetyl) -indanedione-1,3 without further purification and, in particular, without vacuum distillation.

 Example 1. Obtaining 1-phenyl-1- (ethyl) phenylacetone.

30 ml of methylene chloride and 14.3 g (0.107 mol) of anhydrous aluminum chloride are placed in a 100 ml glass reactor equipped with a mechanical stirrer, reflux condenser, thermometer and dropping funnel. A mixture of 18 g (0.1 mol in terms of 100%) of 1-chloro-1-phenylacetone and 20 ml of methylene chloride is added from a dropping funnel while cooling (in a cold water bath) and stirring, at a rate such that the reaction temperature the mass was not higher than 30 ^o C. The mixture was stirred at this temperature for 1 hour. In this case, aluminum chloride completely passes into the solution. To the resulting dark cherry solution of the complex of 1-chloro-1-phenylacetone with aluminum chloride in methylene chloride, 40 ml of ethylbenzene are gradually added with stirring at a temperature of 30-50 ^{° C.} The reaction mass is stirred at this temperature for 4 hours. After cooling, it is poured into a glass with a mixture of ice and concentrated hydrochloric acid, stirred for several minutes and transferred back to the reactor. Methylene chloride is distilled off with stirring. The residue is cooled, the lower aqueous layer is separated, extracted twice with ethylbenzene (in 20 ml portions). The extracts are combined with the main organic layer and washed twice with water. Ethylbenzene is distilled off in a vacuum of a water-jet pump. VAT residue - a brown oily liquid is analyzed by GLC. According to the analysis, a product is obtained with a mass fraction of 1-phenyl-1- (p-ethyl- and o-ethyl) phenylacetone of about 95% (32.4% of the o-isomer and 62.8% of the p-isomer). Distillation of a technical product in vacuo gives 20.4 g (85.7%) of a yellow oil liquid with a boiling point. 158-163 ^o C / 1 mm, n $\genfrac{}{}{0ex}{}{\text{20}}{\text{D}}$ 1.5662. Similar results are obtained when carrying out the reaction in a medium of chloroform or carbon tetrachloride.

Example 2. Obtaining 1-phenyl-1- (methyl) phenylacetone
By the method described in example 1, from 18 g of 1-chloro-1-phenylacetone, 40 ml of toluene and 14.3 g of aluminum chloride in 50 ml of methylene chloride, 1-phenyl-1- (methyl) phenylacetone was obtained with a basic substance content of 97, 7% (30.8% of the o-isomer and 66.9% of the p-isomer).

 Other 1-phenyl-1- (alkyl) phenylacetones are similarly prepared.

 The results of the experiments, see the table.

Claims (1)

The method of producing 1-phenyl-1- (alkyl) phenylacetone by the interaction of 1-chloro-1-phenylacetone with alkylbenzenes in the presence of anhydrous aluminum chloride, followed by exposure of the reaction mixture and isolation of the target product in a known manner, characterized in that the 1-chloro-complex is first obtained 1-phenylacetone with aluminum chloride in methylene chloride, or chloroform, or carbon tetrachloride at a temperature of no higher than 30 ^o C, and then enter it into interaction with alkylbenzene at 30-50 ^o C.

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