Patent ID: RE41008

Claim:
A process for the preparation of a 5-arylnicotinaldehyde of formula I in which A is a phenyl radical or naphthyl radical, each of which is unsubstituted, monosubstituted or polysubstituted by R, F, Cl, Br, I, —CN, —NO 2 , —CF 3 , —OCF 3 , —OCHF 2 , —OCF 2 CF 3 or —OH and in which one or more CH groups is optionally replaced by N, and R is H, a straight-chain or branched alkyl radical having 1 to 15 carbon atoms which is monosubstituted by —CF 3 or at least monosubstituted by fluorine, where, in addition, one more CH 2 groups is optionally independently replaced by —S—, —O—, —O—CO—, —CO—O— or —CH═CH— in such a way that heteroatoms are not directly adjacent, said process comprising reduction of a corresponding 5-arylnicotinic acid by catalytic hydrogenation in the presence of carboxylic anhydrides and a palladium/ligand complex, wherein molar ratio between palladium and ligand is from 1:5 to 1:15 in the case of monodentate ligands and from 1:2.5 to 1:7.5 in the case of bidentate ligands.