SU391129A1 - - Google Patents

Description

METHOD OF OBTAINING SUBSTITUTED DIMETHOXIBENENES

one

The invention relates to methods for producing substituted dimethoxybenzenes, which can be used in agriculture, photography, polymer chemistry and the perfume industry.

A known method for producing substituted dimethoxybenzenes, for example 2-benzyl-1,4-dimethoxybenzene, by reacting 1,4-dimethoxybenzene with benzyl chloride at 130-140 ° C in (Presence of titanium powder as a catalyst. The desired product is isolated by known techniques. target product 70%.

In order to increase the yield of the final products, a method is proposed for the preparation of substituted dimethoxybenzenes of the general formula

DOS

where RI is benzyl;

R2 is hydrogen, benzyl,

lead in the presence of Fe2 (S04) s-9H20 as a catalyst. The process is carried out at 130-135 ° C for 15-20 minutes. Change the ratio of reagents in this

in the process, one can obtain either mono- or dibenzyl-1,4-dimethoxybenzenes.

According to the proposed method, substituted dimethoxybenzenes are obtained in a yield of up to 98%. The method allows the reaction to be carried out directly in a distillation flask-reactor with a reflux condenser and to use a catalyst that is relatively readily available and non-hygroscopic, repeatedly.

Example 1. Synthesis of 2-benzyl-1,4-dimethoxybenzene.

A mixture of 34.5 g (0.3 mol) of 1,4-dimethoxybenzene, 6.3 g (0.025 mol) of benzyl chloride and 0.0179 g (0.003 mol of powdered Pe2 (8O4) H-9H2O is placed in a distillation flask equipped with two thermometers and a capillary tube. The system is connected to a Tishchenko flask (with water) to absorb the released HC1.

The reaction mixture is heated to 135 ° C for 5 minutes. At the same time see the rapid release of hydrogen chloride. Subsequently, the reaction proceeds through self-heating and ends in time.

Then from the flask is first distilled off an excess of

1,4-dimethoxybenzene (1 fraction with m.p. 80-82 ° C / 5 mmHg), then 2-benzyl-1,4-dimethoxybenzene (II fraction with m.p. 165-166 ° C (5 mm Hg; up to 1.5770;).

According to gas chromatography data, fraction II contains 99.7% of 2-benzyl-1,4-dimethoxybenzene. The yield of fraction II is 10.6 g, which is 93% of the theoretical.

Example 2. Synthesis of 2,5-dibenzyl-1,4-dimethoxybenzene a.

The reaction is carried out under the same conditions. A mixture of 6.9 g (0.05 mol} 1,4-dimethoxybenzene, 12.65 g (0.1 mol of benzyl chloride and 0.008 g (0.00014 mol heated to 135 ° C for 20 minutes. At the end of the reaction temperature raise to 140 ° C. Distillation yields: I fraction — starting ester — 1,4-dimethoxybenzene (0.1 g), II fraction — 2,5-dibenzyl-1,4-dimethoxybenzene, bp 215-217 ° C / 5 mmHg, the yield is 13.7 g, which corresponds to 98% of the theoretical.

When recrystallized from methanol, 2,5-dibenzyl-1, 4-dimethoxybenwal melts at 98.5-99.0 ° C.

Paydeno,%: C 83.18; H 6.87.

C22H22O2.

Calculated,%: C 83.02; H 6.92.

Subject invention

The method of obtaining substituted dimethoxybenzenes of the general formula

OSSN

where RI is benzyl;

Ra is hydrogen, benzyl,

by reacting 1,4-dimethoxybenzene with benzyl chloride at 130-140 ° C in the presence of a catalyst with isolation of the target product by known methods, characterized in that, in order to increase the yield of the final product, Fe2 (5O4) H-9H2O is used as a catalyst.