Patent ID: 7154008

Claim:
A method of producing an alkylbenzaldehyde from a starting alkylbenzene (A), comprising: (I) a step of preparing a solution of complex of said starting alkylbenzene (A) and a hydrogen fluoride-boron trifluoride catalyst (B); (II) a step of formylation by bringing the solution of complex into contact with carbon monoxide; and (III) a step of decomposition of the produced alkylbenzaldehyde/hydrogen fluoride-boron trifluoride complex to the products of alkylbenzaldehyde and hydrogen fluoride-boron trifluoride catalyst (B), wherein: (i) the starting alkylbenzene (A) has at least one primary alkyl group having at least two carbon atoms on the benzene ring; (ii) the solution of complex was prepared in the presence of a disproportionation inhibitor (C) comprising aliphatic or alicyclic saturated hydrocarbon having 6 to 10 carbon atoms which contains at least one tertiary carbon atom but contains no quaternary carbon atom; (iii) the hydrogen fluoride-boron trifluoride catalyst (B) comprises an amount of hydrogen fluoride of 5 mole or more and an amount of boron trifluoride of 1.1 to 2.0 mol per one mole of the starting alkylbenzene (A); (iv) the amount of the disproportionation inhibitor (C) is 0.1 to 2.0 mol % based on the starting alkylbenzene (A); and (v) the temperature of a tank for preparing a solution of the complex of the starting alkylbenzene (A) and the hydrogen fluoride-boron trifluoride catalyst (B) in step (I) is controlled so as to maintain an inner pressure of the preparation tank higher than a vapor pressure of the complex in step (II) and lower than a decomposition pressure in step (III) of the produced alkylbenzaldehyde/hydrogen fluoride-boron trifluoride complex.