| 摘要 |
PURPOSE: To obtain cyclopentadiene which is useful as a an intermediate in chemical industry from inexpensive raw materials through simple reactions by subjecting a ketone or aldehyde as a raw material to reaction in the presence of a catalyst followed by vapor-phase dehydrative cyclization of the product. CONSTITUTION: A ketone and another ketone, an aldehyde and another aldehyde or a ketone and an aldehyde are allowed to react with each other in the presence of an acidic or basic catalyst at 0-200 deg.C. Then, the reaction product is subjected to dehydrative cyclization in the presence of a solid acid catalyst such as silica/alumina at 120-600 deg.C under a pressure of 10kg/cm<2> to give a cyclopentadiene. When a weak basic catalyst is used in the reaction of ketones or aldehydes, β-hydroxycarbonyl is mainly obtained, while the use of a strong acid or strong base catalyst gives an α, β-unsaturated carbonyl compound. In some cases, the α, β-unsaturated carbonyl compound isomerizes to a β, γ-unsaturated carbonyl compound. |
