METHOD OF PREPARING ISOPRENE Russian patent published in 1999 - IPC

FIELD: manufacture of synthetic rubber. SUBSTANCE: isoprene is prepared by liquid phase reaction of isobutylene and/or tert-butanol with formaldehyde solution in the presence of acid catalysts in at least two reaction zones in which isoprene precursors are synthesized and decomposed into isoprene. Unvaporized organic stream enriched with isoprene synthesis by-products is withdrawn from decomposition zone. Isoprene is subjected to further conversion in the presence of acid catalyst at temperature higher than that in decomposition zone. Organic solvent or some condensate from rectification stage are introduced into decomposition zone. Hydrocarbons containing four carbon atoms are distilled off from stream being directed to decomposition zone. After decomposition zone or after further conversion zone, some unvaporized aqueous stream is contacted, after removing excessive amount of water, with isobutylene- containing hydrocarbon fraction in the presence of acid catalyst to prepare tert-butanol being directed as stock to isoprene precursor synthesis zone. EFFECT: improved technology and reduced energy consumption. 7 cl, 3 dwg, 1 tbl