Patent ID: 6518464
Filing Date: 2003-02-11
Classification: C07C

Abstract:
A process for the preparation of unsaturated acetals of the formula I in whichR1 to R7 independently of one another are hydrogen, a straight-chain or branched, optionally substituted C1-C6-alkyl radical and R8 is hydrogen, a saturated or a mono- or polyunsaturated, straight-chain or branched, optionally substituted C1-C12-alkyl radical or an optionally substituted 3- to 12-membered saturated or a mono- or polyunsaturated carbocycle, by reacting one mole of an aldehyde of the formula II in which R1 to R3 are as defined above, with at least 1 mol of an alcohol of the formula III in which R5 to R8 are as defined above, in the presence of catalytic amounts of acid and with removal of the water formed during the reaction, the improvement comprising only partially reacting the reactants in a reaction column, concentrating the resulting acetal in at least two successive evaporation stages, and returning the recovered reactants to the reaction column.