Patent ID: 7777081

Claim:
A process for producing a 4-(4-alkylcyclohexyl)-benzaldehyde or 4-(cyclohexyl)benzaldehyde having a purity of 98% or more, comprising formylating a benzene derivative represented by the following formula (1a) with carbon monoxide in the presence of hydrogen fluoride and boron trifluoride to obtain a 4-(4-alkylcyclohexyl)benzaldehyde represented by the following formula (2) or 4-(cyclohexyl)benzaldehyde, wherein R 1 represents an alkyl group having 1 to 10 carbon atoms, or a hydrogen atom, wherein R 1 represents an alkyl group having 1 to 10 carbon atoms, or a hydrogen atom, wherein the hydrogen fluoride is used in an amount of not less than 2 moles but not more than 20 moles per 1 mole of the benzene derivative represented by the formula (1a), wherein the boron trifluoride is used in an amount of not less than 1.1 mole but not more than 5 moles per 1 mole of the benzene derivative represented by the formula (1a), and wherein the formylation is carried out at a temperature of from −50° C. to 30° C.