【摘要】 <正> 按照经典机理,由卤仿产生二卤卡宾是经过了一个简单的两步过程:虽然这一过程缺少可靠的全面验证,但该机理已被广泛接受,并推广到了许多类似反应,迄今尚未见有对其提出异议的报道。我们在研究溴仿和氯仿混合体系的反应中发现产物组成与预期结果不符。在烯烃存在下,反应同时给出三种偕二卤环丙烷。更多还原

【Abstract】 Based on chemical and physical evidences, a single electron transfer （SET）mechanism for the reaction of generating dihalocarbene from haloform and sodium hydroxide is suggested. It is proved that no equilibrium exists between the carbenoid-trihalocarbanion and dihalocarbene, and the halogen-exchange brought about by trihalomethyl and dihalomethyl radicals formed via the single electron transfer process occurs prior to the addition of carbene to carbon-carbon double bond. The primary electron donor in this reaction is CX₃^- and the main electron acceptor is the haloform present in excess.更多还原