The invention is concerned with a new process for preparing 7-hydroxy dihydrocitronellal. This process consists in causing citronellal to react with a secondary amine, in transforming the derivative obtained, by treatment in aqueous acid medium, into the immonium of the citronellal, which is hydrated, then in hydrolysing the immonium of the hydroxycitronellal thus formed into 7-hydroxy dihydrocitronellal, all these operations being effected in the liquid base.
7-Alkoxydihydrocitronellals (and their homologues) and their acetals useful as perfumes are prepared from citronellal (or homologues thereof) by reaction with ammonia or a primary or secondary amine, followed by treatment of the product with an alkanol in the presence of a strong acid and then neutralization of the reaction mixture.
A sterically hindered enamine (vinyl amine) is reacted with an alkylene oxide followed by hydrolysis of the reaction product to produce a monohydroxyl alkyl aldehyde wherein the hydroxyl group is on the third carbon atom from the carbonyl group, such as 4-hydroxybutanal. The monohydroxyl alkyl aldehyde may be further hydrogenated to produce the corresponding alkanediol, such as 1,4-butanediol.
A process as described for preparing hydroxycitronellal by isomerizing certain 7-hydroxygeranylamine compound or 7-hydroxynerylamine compounds using a catalyst comprising a divalent palladium compound and a phosphine compound.
