Process for the preparation of substituted trans-cinnamaldehyde, a natural yellow dye, from phenylpropane derivatives

The present invention relates to the preparation of substituted trans-cinnamaldehyde, a natural yellow dye from Phenylpropane derivatives having R2-R3-R4-R5-R6 substitution, wherein R2 to R6 equal or different, being hydrogen or hydroxy or acyl or halogen or alkyl or heterocyclic or aryl or dioxymethylene or alkoxy groups, etc., by oxidizing the said phenylpropane derivatives using a oxidising agent such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or p-chloranil or pyridinium chlorochromate (PCC) or tBuOOH or CrO3 with a catalytic amount of inorganic/organic acid or alumina, celite, and silica gel as a solid support for microwave irradiation and thus substituted trans-cinnamaldehydes, a natural yellow dye, are obtained in high yield ranging from 68-82%.