2,7-Dimethyl-octa-2,4,6-trienedial is prepared by double enolether condensation of a butenedial-bisacetal, hydrolysis, dialdehyde conversion and crystallization with all steps effected in an organic solvent

摘要

All steps for production of 2,7-dimethyl-octa-2,4,6-trienedial (I) are in presence of an inert, water-immiscible organic solvent, the process involving (A) Lewis acid-catalyzed double enolether condensation of a butenedial-bisacetal with an enol ether; (B) hydrolysis of the acetal group of the product by aqueous acid addition; (C) conversion of the resulting dialdehyde to (I) using an aqueous base; and (D) crystallization of (I) from the mixture. All of the steps (a) - (d) in the following process for production of 2,7-dimethyl-octa-2,4,6-trienedial of formula (I) are effected in presence of an inert, water-immiscible organic solvent : (A) double enolether condensation of a butenedial-bisacetal of formula (II) with an enol ether of formula (III) in presence of a Lewis acid catalyst; (B) hydrolysis of the acetal group of the resulting condensation product of formula (IV) by adding an aqueous acid to form a dialdehyde of formula (V); (C) conversion of (V) to (I) by reaction with an aqueous base; and (D) crystallization of (I) from the mixture. R 1 and R 21-6C alkyl. [Image].