Patent ID: 6175044
Filing Date: 2001-01-16
Classification: C07C

Abstract:
A process for continuously preparing 3,7-dimethyl-2,6-octadien-1-al of formula I by: ##STR12##thermally cleaving, in the presence or absence of an acid catalyst, 3-methyl-2-buten-1-al diprenyl acetal of formula II: ##STR13##thereby eliminating 3-methyl-2-buten-1-ol of formula III and yielding cis/trans-prenyl 3-methylbutadienyl ether of formula IV: ##STR14##thermally rearranging the resultant butadienyl ether of formula IV thereby yielding 2,4,4-trimethyl-3-formyl-1,5-hexadiene of formula V: ##STR15##subsequently rearranging intermediate (V) thereby yielding citral product of formula I, which comprises:as the reaction proceeds, continuously distilling the reaction mixture thereby continuously removing prenol, which is formed by degradation of acetal II, and the intermediates of formula IV and V and any citral product which is formed during the reaction; andthermally rearranging said intermediates of formula IV and V at a temperature of 100-200.degree. C. in the absence or presence of said prenol to form citral product.