METHOD OF SYNTHESIS OF ISOPRENE Russian patent published in 1997 - IPC

FIELD: chemical technology. SUBSTANCE: isoprene is synthesized by liquid-phase interaction of formaldehyde with isobutylene and/or trimethylcarbinol in the presence of an acid catalyst aqueous solution. Process is carried out under increased temperature and pressure in two successive contacting steps the second of that involves a zone of heat supply, separation zone and circulation contour for liquid phase. After the first contacting step reaction mass is separated for hydrocarbon and an aqueous flows. Hydrocarbon flow is fed to circulation contour of liquid phase at the second contacting step before and/or after heat supply zone; an aqueous flow is fed to contour before hydrocarbon flow feeding or to separation zone at the second contacting zone. From the separation zone of the second contacting step reaction products were removed and isoprene is isolated from their. Hydrocarbon flow is fed to circulation contour of liquid phase at the second contacting step before or after heat supply zone at ratio = (3:1)-(1:3), respectively. Before feeding to the second contacting step an aqueous flow is heated to temperature not exceeding temperature in circulation contour of liquid phase at this step by above 20 C. Before feeding to the second contacting step hydrocarbon flow can be heated to temperature not above that in circulation contour of liquid phase at the second step. EFFECT: improved method of synthesis. 4 cl, 1 tbl