Abstract: A phenylacetone or its derivative having the general formula (I): ##STR1## wherein X, Y, and Z are independently a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, an amino group, a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, or a benzyloxy group and any two substituents of X, Y, and Z may form, together with the benzene ring, a heterocycling ring having 5 to 7 members including 1 or 2 oxygen atoms is produced at a high yield and a high selectivity by reacting a 3-phenylpropylene or its derivative having the general formula (II): ##STR2## wherein X, Y, and Z are as defined above, with an alkyl nitrite having the general formula (III):RONO (III)wherein R is an aliphatic, aromatic, or alicyclic saturated or unsaturated hydrocarbon group in the presence of (a) water, (b) an alcohol, (c) a palladium catalyst, and (d) an optional amine or copper compound, or by reacting the above-mentioned 3-phenylpropylene or its derivative with the above-mentioned

Abstract: A process for preparing protocatechualdehyde or a 3-alkoxy-4-hydroxybenzaldehyde which comprises subjecting catechol or a 2-alkoxyphenol to reaction with glyoxylic acid in a basic aqueous medium in the presence of a catalyst containing one or more compounds selected from aluminium oxide, silicon oxide and hydrated aluminium oxide in an amount of not less than 0.01 g per 1 g of the starting catechol or 2-alkoxyphenol at a temperature of 0.degree. to 50.degree. C., and then oxidizing the thus obtained reaction mixture in a basic medium.