Process for preparing fluorine-containing benzaldehydes

A process for preparing fluorine-containing benzaldehydes of the formula

• 3
• wherein
• n represents 1 or 2, and
• R1, R2, and R3 each represent, independently of one another, hydrogen, fluorine, chlorine, bromine, C1-C6-alkyl, C1-C6-fluoroalkyl, C1-C6-fluoroalkoxy, or C1-C6-fluoroalkylthio, where at least one of the radicals R1 to R3 represents fluorine or a fluorine-containing radical and not more than two of the radicals R1 to R3 represents bromine, C1-C6-fluoroalkoxy, and/or C1-C6-fluoroalkylthio,
• comprising reacting an aromatic acid chloride of the formula
• 4
• where R1, R2, R3, and n are as defined for formula (I), with hydrogen in the presence of a supported palladium catalyst and a catalyst moderator.