Patent ID: 7064221

Claim:
A process for producing a pyran, which comprises reacting an aldehyde represented by the formula (I) (hereinafter, referred to as aldehyde (I)): R 1 —CHO (I) wherein R 1 represents a hydrogen atom, an alkyl or alkenyl group having 1 to 12 carbon atoms, an optionally alkyl-substituted cycloalkyl group having 3 to 12 carbon atoms in total or an optionally alkyl- or alkoxy-substituted aryl group having 6 to 12 carbon atoms in total, with isoprenol to produce a pyran represented by the formula (II): wherein R 1 has the same meaning as defined above, and is a single or double bond, wherein water in a reactor is maintained in an amount of 0.25 wt % or less while the conversion of that which has the lower charged total number of moles between aldehyde (I) and isoprenol is less than 50%.