ISOPRENE PRODUCTION PROCESS Russian patent published in 1999 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: process consists in liquid-phase interaction of formaldehyde with isobutylene and/or trimethylcarbinol in presence of aqueous acid catalyst solution at elevated temperature and pressure in two consecutive contact steps withdrawing, in the second step, liquid stream containing aqueous catalyst solution and gaseous stream containing at least unreacted isobutylene and isoprene product, after which gaseous stream is condensed and recycle isobutylene and isoprene are isolated from condensate, the former being returned into the first step. According to invention the second contact step comprises several reaction zones provided with mass-exchange and/or distributive means. External heat is supplied at least into the first of these zones and each following zone has temperature lower than temperature of preceding zone. Reaction products from the first contact step before or after stratification into aqueous and hydrocarbon layers are introduced into the first and/or any of the subsequent reaction zones. Gaseous stream from each preceding reaction zone is transferred into the following zone and discharged from top part of the last reaction zone. Liquid stream from each preceding reaction zone is transferred into the following zone and discharged from the first and optionally from an intermediate reaction zone in the form of stream containing aqueous catalyst solution, which is divided into two streams, the first one being returned into the first contact step and the other being optionally fed into one or several zones of the second contact step. EFFECT: reduced isoprene cost price due to reduced raw material, power, and investment expenses, simplified equipment, and increased yield of product. 6 ex