ISOPRENE PRODUCTION METHOD Russian patent published in 1997 - IPC

FIELD: industrial organic syntheses. SUBSTANCE: invention concerns method of producing isoprene by way of interaction of isobutylene-containing C₄-fraction with water in presence of acid catalyst followed by isolation of stream chiefly containing tert-butanol, interaction of the latter with formaldehyde in presence of acid catalyst at elevated temperature and pressure, separation of reaction mixture into aqueous and oil layers, and isolation of isoprene from oil layer via rectification and washing followed by cleaning isoprene from oxygen-containing compounds via rectification involving preliminarily produced tert-butanol as selective solvent, after which oxygen-containing compounds are desorbed from saturated solvent and desorbed solvent is reused for interaction with formaldehyde. According to invention, desorption with degree 30-95% is more advantageous that full desorption and isolated isoprene being directed into cleaning stage may contain 2.0 to 20 wt % tert-butanol. In one of embodiments of invention, tert-butanol with up to 15 wt % water is brought in contact with liquid stream of isoprene withdrawn as top fraction or as side stream from the upper part of extractive rectification column, whereupon lower layer containing mainly water is separated and upper layer containing predominantly isoprene and tert-butanol is returned into upper part of extractive rectification column. EFFECT: enhanced efficiency of process. 4 cl, 5 tbl