Method for preparing α,β-unsaturated aldehyde

A method for preparing an α,β-unsaturated aldehyde, comprising:

• reacting a compound of formula (I) with a compound of formula (II) to provide an α,β-unsaturated aldehyde of formula (III)
• in the presence of an alkali metal hydroxide and an alkanol having 1 to 4 carbon atoms,
• wherein an amount of the alkali metal hydroxide is 8 mol % or more and 12 mol % or less with respect to an amount of the compound of formula (I), and
• a total amount of water contained in materials that are used in the reaction is 10 mol % or more and 50 mol % or less with respect to the amount of the compound of formula (I),
• where R1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,
• R2 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,
• R3 represents a hydrogen atom, or
• R2 and R3 form 1,3-dioxolane together with carbon atoms to which R2 and R3 are bound, and
• R4, R5, and R6 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.