VERFAHREN ZUR HERSTELLUNG VON UNGESÄTTIGTEN KETONEN

摘要

Unsaturated ketones, comprising optionally substituted but-3-enyl and/or buta-2.3-dienyl methyl ketones, are prepared by: (a) reacting allyl alcohols and/or propargyl alcohols with isopropenyl ethers, with formation of ketals as by-product; (b) preparing isopropenyl ethers by catalytic gas phase reaction of ketals with propyne and/or allene; and (c) feeding the ketal from stage (a) into stage (b). The but-3-enyl methyl ketones of formula (Ia) and but-2,3-dienyl methyl ketones of formula (Ib) formed, allyl alcohols of formula (IIa) and/or propargyl alcohols of formula (IIb) and isopropenyl ethers (III) used as starting materials are ketals (IV). R1, R2, R3, R4, R5 = H or (cyclo)alkyl, (cyclo)alkenyl or ar(alk)yl (optionally containing O); or R1R2 = 5-6-membered ring; and R6 = 1-4C alkyl. (III) are prepared by the gas phase reaction of (IV) and propyne or allene at elevated temperature in the presence of a heterogeneous catalyst containing Zn or Cd plus Si and O.