Continuous method for production of cinnamaldehyde and dihydrocinnamaldehyde derivatives

A process for the

• (a) continuous preparation of a cinnamaldehyde compound of formula I
• in which
• R1, R2, R3, R4, R5 and R6, independently of one another, are hydrogen, C1- to C9-alkyl groups or C1-C9-alkoxy groups, by reacting a benzaldehyde compound of formula II
• with an alkanal of formula III
• in the presence of a base, which comprises
• reacting the reactants continuously in a plant consisting of a plurality of reactors in a cascade system,
• and introducing fractions of the alkanal of formula (III) into more than one of the reactors of the cascade system, and
• (b) optionally subsequent continuous hydrogenation in a circulation reactor in the presence of a suspension catalyst and hydrogen to give a dihydrocinnamaldehyde compound of formula IV,
• where R1 to R6 have the meanings given above.