METHOD OF SYNTHESIS OF ISOPRENE FROM ISOBUTENE-CONTAINING HYDROCARBON MIXTURES AND FORMALDEHYDE Russian patent published in 2001 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method of synthesis of isoprene from isobutene-containing C₄-hydrocarbon mixtures and formaldehyde by chemical conversion in the presence of acid water-soluble and/or solid catalyst in at least three reaction zones. In the first zone isobutene is extracted from hydrocarbon mixture by hydration process; in the second zone formation of semiproducts is carried out that are able to decompose further to isoprene and in the third zone the decomposition of semiproducts is carried out followed by separation of reaction mixtures obtained in this zone and their recirculation of at least part of isobutene to be isolated into the zone of synthesis of semiproducts. Part of the parent formaldehyde is fed to the zone of isobutene extraction, reaction mass of indicated zone is stratified for an aqueous and organic flows. An aqueous flow containing at least tert.-butanol, 3-methylbutanediol-1,3 and 4,4-dimethyldioxane-1,3 and other part of the parent formaldehyde is fed to the zone of semiproducts synthesis. An aqueous and organic flows are removed from the zone of semiproducts synthesis that are fed to the decomposition zone, possibly passing their through the hydrolysis zone. Organic flow in isobutene extraction zone is fed to the distillation off unit of C₄-hydrocarbons and residue after distillation off of C₄-hydrocarbons containing at least tert.-butanol and 4,4-dimethyldioxane-1,3 is fed to the zone of synthesis of semiproducts and/or the zone of decomposition, and/or the zone of hydrolysis. Possible variant involves addition of nontertiary alcohol with carbon number atoms from 2 to 6 to the zone of isobutene extraction. EFFECT: optimal technological relationship between processes of isobutene extraction and isoprene synthesis, simplified method, improved efficiency. 8 cl, 2 tbl, 2 dwg, 2 ex