METHOD FOR PRODUING 3,3'-DICHLORO-4,4'-DIAMINODIPHENYLMETHANE Russian patent published in 2017 - IPC C07C211/52 C07C209/78 

FIELD: chemistry.

SUBSTANCE: produced compound can be used to vulcanize and cure high-temperature epoxy compositions in the production of high-strength heat-resistant structural products from polymer composite materials, as well as in the production of dyes. The method consists in reacting o-chloroaniline with formalin in a water-toluene mixture in the presence of hydrochloric acid at the temperature of 75-80°C. The produced reaction mass is neutralized with 20% alkali. A special feature of the method is the use of a 10-20% excess of o-chloroaniline with respect to formaldehyde, wherein the produced 3,3'-dichloro-4,4'-diaminodiphenylmethane is isolated and purified by crystallization from toluene after partial distillation of the latter in vacuo, washed with toluene and dried in vacuo, the additional product being produced in a similar manner after evaporation with 2/3 of the mother liquor volume, and distilled toluene and excess o-chloroaniline are returned to the process for reuse. Preferably, the process is conducted using 10% excess of o-chloroaniline with respect to formalin.

EFFECT: producing the desired product with high yield and high purity of the product, increasing the productivity of equipment and reducing the amount of toxic waste by reducing the excess of o-chloroaniline and increasing the removal of target diphenylmethane.

2 cl, 5 ex