Method for producing 2- (alkyl) cycloalkenone

A method for producing 2-(alkyl) cycloalkenone (hereinafter referred to as Compound (2)) represented by the formula (2) as shown below, by using as a raw material 2-(1-hydroxyalkyl) cycloalkanone (hereinafter referred to as Compound (1)) represented by the following formula (1):

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• (wherein n represents an integer of 1 or 2, R1 and R2 each represent a hydrogen atom or a straight or branched-chain alkyl group having 1 to 8 carbon(s), or R1 and R2 may form together with adjacent carbon atoms a cyclopentane ring or a cyclohexane ring),
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• (wherein n, R1 and R2 represent the meanings as defined above), the method comprising a dehydration step and a subsequent isomerization step as follows:
• Dehydration step:
• using an acid catalyst, the reaction is allowed to proceed until a conversion ratio of hydration reaction based on Compound (1) reaches to 20 to 90%, to obtain a mixture containing Compound (1) and 2-(alkylidene) cycloalkanone (hereinafter referred to as Compound (3)) represented by the formula (3):
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• (wherein n, R1 and R2 represent the meanings as defined above);
• Isomerization step:
• Compound (3) is allowed to isomerize while allowing dehydration reaction of remaining Compound (1).