Production of alkoxymandelic acids, e.g. intermediates for alkoxyaromatic aldehydes, comprises reacting alkoxyaromatic compound with glyoxylic acid in presence of strong protonic acid

Process (A) for producing alkoxymandelic acids comprises reacting alkoxyaromatic compound with glyoxylic acid in the presence of a strong protonic acid. Process (A) for producing alkoxymandelic acids comprises reacting alkoxyaromatic compound of formula (I) with glyoxylic acid in the presence of a strong protonic acid. x = 0-4; R1 = 1-12C hydrocarbon group, a mono- or heterocyclic aromatic or cycloaliphatic group or an aliphatic group with a cyclic substituent; R = H, 1-6C, preferably 1-4C, alkyl group, 2-6C, preferably 2-4C, alkenyl group, an 1-6C, preferably 1-4C, alkoxy group, an alkenyloxy group preferably phenoxy group, cyclohexyl, phenyl, benzyl, 2-6C acyl group, -R2OH, -R2COOR3, -R2OCOR3, -R2CHO, -R2NO2, -R2CN, -R2N(R3)2, -R2CON(R3)2, -R2X, -R2CF3 or two of the groups on adjacent groups link to give a benzene ring; R2 = is a link of 1-6C hydrocarbon group that is divalent preferably methylene, ethylene, propylene, isopropylene or isopropylidene; R3 = H or 1-6C alkyl; and X = halogen preferably Cl, Br or F. An Independent claim is included for a process for producing alkoxyaromatic aldehydes that comprises oxidizing compound produced by process (A). La présente invention a pour objet un procédé de préparation de composés mandéliques et plus particulièrement les composés alkoxymandéliques.Le procédé de préparation d'un composé alkoxymandélique et dérivé selon l'invention est caractérisé par le fait que l'on fait réagir un composé aromatique porteur d'au moins un groupe alkoxy et l'acide glyoxylique, en présence d'un acide protonique fort.L'invention vise également le procédé de préparation d'un aldéhyde alkoxyaromatique à partir dudit composé alkoxymandélique.