process for the production of one or several ungesaettigten aldehydes or their acetalen, acylalen, oximen, hydrazonen, semicarbazonen or schiffschen bases

摘要

Mono- or poly-unsaturated aldehydes or their functional derivatives are prepared by reacting an acetal, hemiacetal, mercaptal, aminal, acylal, oxime, hydrazone, semicarbazone or Schiff's base derivative prepared from phosphonium salts having the formula FORM:1078858/C2/1 in which Ar denotes an aryl radical optionally substituted by alkyl or alkoxy groups, X is an anion, and n is an integer from 0 to 6, with a proton acceptor to convert the compounds into their ylids which are simultaneously or subsequently reacted with aldehydes or ketones by a Wittig reaction. The aldehyde derivatives so obtained may be hydrolysed to the corresponding aldehydes. Examples of phosphonium salts of Formula III mentioned are triphenylformylmethyl phosphonium chloride, triphenyl-b -formylcrotyl phosphonium chloride, triphenyl-b -formylcrotyl phosphonium bromide, triphenyl-a - formylcrotyl phosphonium chloride, triphenyl - 5 - formyl - 5 - methylpentadiene - (2,4)-yl phosphonium chloride, and triphenyl-7-formyl - 3,7 - dimethylheptatriene(2,4,6)-yl phosphonium chloride. Suitable proton acceptors are, for example, sodium alcoholates, ammonia, amines and aqueous alkali solutions such as caustic soda or potash solution. Suitable aldehydes or ketones to be reacted with the ylids are, for example, b -ionone, a -ionone, C14- aldehyde, b -ionylidene acetaldehyde, retinene, the apocarotenals and carotene dialdehydes. Examples are given of the preparation of (a) the tetraethyl acetal of crocetin dialdehyde, (b) b -apo-121-carotenal; (c) b -apo-81-carotenal; (d) b - apo - 121 - carotenal - dinitrophenylhydrazone; (e) b - apo - 121 - carotenal - semicarbazone and (f) b -apo-121-carotenal-oxime.