METHOD OF PRODUCING DIPHENOL A Russian patent published in 2012 - IPC C07C39/16 C07C37/20 

FIELD: chemistry.

SUBSTANCE: invention relates to production of diphenol A (DPA) making initial stock for production of plastic materials, particularly, polycarbonates. Proposed consists in catalytic condensation of phenol and acetone in presence of promoted sulphonated ion-exchange resins using fractionation crystallisation for extraction of "п,п'"-DPA-isomer wherein condensation of phenol and acetone is conducted in multistage reaction system with inter-stage temperature regulation and acetone cocentration and with water concentration regulation before final crystallisation stage of reaction system by recycling portion of postcrystallisation solutions from crystallisation from solution into flow directed into final reactor, continuous dispensing into reactor system containing catalyst of reaction mix containing acetone, water and phenol. At the next stage, water, acetone and portion of phenol are evaporated from reaction mix to be mixed with solution coming from fractionation crystallisation dissolved in isomerisate enriched in o,"п"-isomer-diphenol A obtained by method of isomerisation of portion of flow of concentrated solutions after crystallization from solvent. Note here that isomerisation is performed using macroporous sulphonated ion-exchange resin in hydrogen format with pore diameter making at least 20 nm as catalyst. Obtained flow of phenol is crystallized from solvent to produce adduct of DPA A and phenol and postcrystallisation solutions. Then, solutions are divided into two parts: flow recirculated to final stage of reaction system and flow directed to concentration by distillation. Then, one portion of concentrated postcrystallisation solutions are subjected to isomerisation while remaining portion is rectified with simultaneous decomposition of phenol derivatives. DPA A and phenol derivatives are thermally decomposed to produce mix of isomers of DPA A, phenol and byproducts wherein content of isomer of "п,п'"-diphenol A makes at least 90 cg/g, while mix is directed to fractionation crystallisation to produce pure diphenol A while phenol extracted from concentrated portion of flow of postcrystallisation solutions and from thermal decomposition of diphenol A/phenol adduct, and from rectification is recycled into multistage reaction system.

EFFECT: liquid target product with clean and stable colour, good selectivity and efficiency.

8 tbl, 1 ex