CS209287B1 - Preparation method of 1,4-bis/2'-cyanostyryl/benzene - Google Patents

Description

The invention relates to a process for the preparation of 1,4-bis (2'-cyanstyryl) benzene of the formula

This substance is used for optical brightening of synthetic fibers and plastics. The compound can be prepared by the commonly used condensation of 2'-cyanobenzyldimethyl or diethylphosphite with terephthalaldehyde according to it. U.S. Pat. No. 1,108,219. The necessary phosphite compound is obtained by a conventional method by heating 2-cyanobenzyl chloride with trimethyl or triethylphosphite. Another possible way of preparing a phosphite compound, but not yet used in production, is by condensing the appropriately substituted benzyl chloride with the sodium salt; dialkylphosphite In an inactive organic solvent: solvent. The most suitable dialkyl phosphite is dibutyl phosphite, the sodium salt of which dissolves in organic solvents and the least suitable is dimethyl phosphite, since its sodium salt is very poorly reactive due to its low solubility (Crofts, Kosolapoff: J. Am. Sox. 73, 4040). / 1951).

It has now been found that a compound of the above composition can be prepared by a simple process by condensation of 2-cyanobenzyl chloride with dimethyl phosphite without the use of an additional organic solvent and without isolation of the resulting phosphite compound by reaction with terephthalaldehyde. The process for the preparation of 1,4-bis (2'-cyanstylyl) benzene by condensation of 2-cyanobenzyl chloride with dimethylphosphite and subsequent condensation of the resulting cyanobenzylphosphite with terephthalaldehyde in dimethylformamide medium with the addition of sodium methoxide or ethoxide or potassium hydroxide in methanol, by condensing 2-cyanobenzyl chloride with an equivalent or up to 10% increased amount of dimethyl phosphite by adding an equivalent or up to 10% increased amount of sodium methanolate or ethanolate at a temperature of 40-65 ° C, distilling off the volatiles and then directly forming the phosphite compound with terephthalaldehyde in an amount of 70 to 90 percent equivalent to the 2-cyanobenzyl chloride employed at 40 to 65 ° C. The precipitated product is isolated by suction after dilution with alcohol and washed with ethanol and water to give a very pure, about 70% of the theory for the 2-cyanobenzyl chloride used or 87% of the theory for the terephthalaldehyde used. At a different ratio of terephthalaldehyde in the reaction mixture than that mentioned above, the yield or the resulting product of the non-ethoxy-reactive side-beta-sime decreases.

According to the invention can be produced by simply> Chou path l, 4-bis / 2'-kyanstyryl / benzenkonden- pupils 2-cyanobenzylchloride the readily available dimethyl phosphite, bezpoužitíorganickýchrozpouŠtě- _(del, the next coupling is not necessary to isolate the obtained preform and still give very pure product, ready to be processed into optically brightening compositions.

. These examples sufficiently describe the process of the present invention; the parts indicated are by weight.

Example 1

To a mixture of 152 parts of 2-cyanobenzyl chloride and 150 parts of dimethyl phosphite, 420 parts of a suspension containing 85 parts of sodium ethanolate in anhydrous ethanol are added dropwise with stirring at a temperature not exceeding 65 ° C. Then, about 220 parts of volatiles were distilled off from the reaction mixture at the temperature of the water bath, the residue was cooled to 20 ° C and 200 ml.

Claims (1)

í SUBJECT A process for the preparation of 1,4-bis (2'-cyanstylyl) benzene of the formula by condensation of 2-cyanobenzyl chloride with dimethyl phosphite followed by condensation of the resulting cyanobenzyl phosphite with terephthalaldehyde in the environment of dimethyl parts of dimethylformamide. 55.3 parts are then entered of terephthalaldehyde, and at a temperature not exceeding 65 ° C, 420 parts of a suspension containing 85 parts of sodium ethanolate in anhydrous ethanol were added dropwise. After stirring briefly, the reaction mixture is diluted with 500 parts of ethanol, the crystalline product is filtered off with suction, washed into a colorless effluent with ethanol and water. After drying I, the yield was 117 parts, mp 226-227 ° C. Example 2) The procedure was as in Example 1 except that 265 dfl of a 30% sodium methoxide solution was used in place of sodium ethanolate in the first condensation, and sodium ethanolate was used in the second condensation with terephthalaldehyde; a solution of 83.7% potassium hydroxide in 198 parts of methanol. Methanol is used instead of ethanol to dilute the reaction mixture and wash the product. The yield of produtet was 113 parts, the melting point was 226-227 ° C. and OF THE INVENTION for the addition of sodium methanolate or ethanolate: sodium or potassium hydroxide solution in methanol, characterized in that the 2-cyanobenzyl chloride is condensed with an equivalent or up to 10% increased amount of dimethyl phosphite by adding equivalent or up to 10% increased amount of sodium methanolate or ethanolate at 40 to 65 ° C, volatiles are distilled off, whereupon the resulting phosphite compound is condensed directly with terephthalaldehyde in an amount of 70 to 90 percent: equivalent to 2-cyanobenzyl chloride used | at a temperature of 40 to 65 ° C. and