α,β-不饱和醛或酮与单取代肼反应生成Δ~2-吡唑啉的反应机理,一般认为是通过1,2加成脱水生成腙,然后闭环而得.分离得到的中间体腙在酸性溶液中加热亦可得到Δ~2-吡唑啉.等人曾报道烯键上无取代基的α,β-不饱和酮与单取代肼反应是经过1,4加成所生成的β-肼基取代的酮闭环而得Δ~2-吡唑啉.我们在研究苯丙烯酰苯和甲肼的反应中,发现用略微过量的甲肼与苯丙烯酰苯(摩尔比 The reaction mechanism of α, β-unsaturated aldehydes or ketones with mono-substituted hydrazines to generate Δ ~ 2-pyrazolines is generally believed to be obtained by the dehydration of 1,2-addition to generate hydrazones and then ring-closure. The isolated intermediate hydrazone A ~ 2-pyrazoline can also be obtained by heating in acidic solution.It has been reported that the reaction of α, β-unsaturated ketone with no substituent on the ethylenic bond with mono-substituted hydrazine is formed by 1,4 addition - hydrazino-substituted ketones ring closed to give Δ 2-pyrazoline we studied the reaction of phenyl acrylonitrile and methyl hydrazine, it was found with a slight excess of methyl hydrazine and phenyl acrylonitrile (molar ratio