Patent ID: 6566557
Filing Date: 2003-05-20
Classification: C07C,C09B

Abstract:
A process for the preparation of substituted trans-cinnamaldehyde, a class of natural yellow dye represented by formula (I): wherein R1=CH&boxH;CHâ€”CHO with at least one hydrogen atom selected from substituents represented by R2, R3, R4, R5 and R6, and a methylenedioxy group formed by the combination of at least two of these adjacent substituents represented by R2, R3, R4, R5 or R6, together with other substituents selected from the group consisting of hydroxyl protected hydroxyl acyl, hydroxyl protected hydroxyl benzyl, alkoxy, alkyl and aryl group, the process comprising steps of:a) oxidizing substituted phenyl propane derivatives in a solvent in presence of a catalyst and an oxidizing agent at temperature between âˆ’15Â° to +210Â° C. for a period of 0.5 to 48 hours, b) cooling a reaction mixture of step (a) and filtering an unwanted solid and separating a clear mother liquor, c) removing a solvent from the clear mother liquor of step (b) under reduced pressure to yield a residue, d) providing a solution of the residue of step (c) in an organic solvent, optionally washing with aqueous alkali solution, followed by brine solution and separating an organic layer and discarding an aqueous layer, e) drying the organic layer of step (d) over anhydrous sodium sulphate, filtering; and evaporating to the organic layer to obtain a second residue, and f) purifying the second residue of step (e) by column chromatography over silica gel to obtain compounds of formula (I) in a yield ranging between 68-72%.