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卡宾(英:carbene;俄:德:carben)是次甲基(CH_2)及其衍生物的总称。卡宾一词与次甲基的关系,正如卡宾醇(carbinol)与甲醇(methanol)之间的关系。假如说,经典有机化学是四价碳化物的化学,则自由基化学可称为三价碳化物的化学,它自本世纪初开始,已有飞速发展。与前二者相比,则二价碳化物的化学——卡宾化学,是很年轻的,但它也已表现了强大的生命力。卡宾存在的可能(例如作为反应中间体)虽早经担出,但皆无真实的证据。直到1950年,才第一次出现了有力的论证:哈英(Hine)根据动力学的分析,指出氯仿碱性水解反应,是通过二氯卡宾(:CCl_2)而进行的,机理如下:
Carbene (English: carbene; Russian: German: carben) is a common name for methine (CH 2) and its derivatives. The term carbin is related to methine as the relationship between carbinol and methanol. If we say that classical organic chemistry is the chemistry of tetravalent carbides, then free radical chemistry may be called chemistry of trivalent carbides and has been rapidly developed since the turn of the century. Compared with the former two, the chemical-carbene chemistry of bivalent carbides is very young, but it has also shown great vitality. The possibility that carbenes exist (for example, as reaction intermediates) has long been assumed, but there is no real evidence. It was not until 1950 that the first strong argument was made: According to the kinetic analysis, Hine pointed out that the basic hydrolysis of chloroform is carried out by dichlorocarbene (: CCl 2) with the following mechanism: