Process for preparing aromatic aldehyde compound

A process for preparing an aromatic aldehyde compound represented by the formula (2);

• wherein R represents a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkyloxy group having 1 to 12 carbon atoms, a phenyloxy group, a naphthyloxy group, a benzyloxy group or a phenethyloxy group, each group of which may have a substituent(s);
• n is an integer of 0 to 5;
• and when n is 2 or more, Rs may form a ring by combining with each other,
• which comprises reacting an aromatic methyl alcohol compound represented by the formula (1);
• wherein R and n have the same meanings as defined above,
• and a peroxide while maintaining a pH value of a reaction solution to a pH of 3 or higher and less than 8 in the presence of at least one metallic compound of a tungsten compound, and at least one salt selected from a quaternary ammonium salt and an organic phosphonium salt, wherein the aromatic aldehyde compound of the formula (2) is at least one selected from the group consisting of the following formulae (4) to (7):
• wherein R1 and R2 each represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, a phenyl group, a naphthyl group, a benzyl group or a phenethyl group, each group of which may have a substituent(s), and m is 1 or 2,
• wherein the quaternary ammonium salt is at least one selected from the group consisting of tetrabutyl ammonium hydrogen sulfate, tetra-n-hexyl ammonium hydrogen sulfate, tetrabutyl ammonium chloride and tetrabutyl ammonium bromide, and
• wherein the organic phosphonium salt is at least one selected from the group consisting of tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tetraphenylphosphonium chloride and tetraphenylphosphonium bromide.