When irradiated in protic solvents such as water and primary alcohols, pyrazolinone derivatives undergo photocleavage between the two nitrogen atoms. Substituting the C-4 atom with an electronegative group stabilizes the open chain which is obtained but a thermal transposition takes place from the linear intermediate when C-4 carries a hydrogen atom or a methyl group. The abinitio scheme was used to
当在质子传递溶剂(例如
水和伯醇)中辐照时,
吡唑啉酮衍
生物会在两个氮原子之间发生光裂解。用负电性基团取代C-4原子可稳定获得的开链,但当C-4带有氢原子或甲基时,线性中间体会发生热易位。该AB从头方案被用来研究在光切割和C-4取代基的影响,给出其涉及π的三重激发态的机制的证据,σ *类型。