METHOD OF PREPARATION OF ISOPRENE Russian patent published in 1998 - IPC

FIELD: chemical industry. SUBSTANCE: present invention describes method of preparing isoprene from isopentane. Said method comprises oxidizing isopentane with the resulting tert- amyl hydroperoxide, epoxidizing 2-methyl-2-butene, thermocatalytically decomposing the resulting 2-methyl-2- butene oxide to produce isoprene and methyl isopropyl ketone and dehydrating the resulting tert-amyl and secisoamyl alcohols, separating tert-amylenes by rectification, isomerizing 2-methyl-2-butyl and the latter is epoxidized. Unreacted isopentane is recycled for oxidation. Methylisopropyl ketone is removed from system or thermocatalytically decomposed to obtain additional amount of isoprene. Alternatively, isomerization is combined with isomerization of 2-methyl- 1-butene-3-ol impurity in isoamyl alcohols and/or with dehydration of isoamyl alcohols. Decomposition of methylisopropyl ketone is combined with decomposition of 2-methyl-2-butene oxide. Prior to epoxidation, isopentane is removed from oxidate with optional addition of 2-methyl-2-butene, and mixture of carbonyl compounds and C₁-C₃-alcohols is separated from said 2-methyl-2-butene by aqueous extraction. Acetic acid is separated from oxidate by extraction with water followed by reextraction of tert-amylhydroperoxide with 2-methyl-2-butene or, after epoxidation stage, acetic acid is separated from mixture containing isoamyl alcohols by azeotropic rectification with water. EFFECT: more efficient preparation method. 6 cl, 5 dwg, 5 tbl