这是个误区,E1,E2和SN1,SN2之间没有一点关系。反例如下(图10): 图10 氯代叔丁烷既可以发生E1消除反应,也可以发生E2消除反应(取决于碱的强弱),但由于氯代叔丁烷ɑ-碳的周围有太多甲基造成位阻太大,所以只能发生SN1亲核取代反应。 E1cB机理 当离去基团先离去,碱夺质子很慢,反应机理为E1;当...
因此,如果亲核试剂亲核性很强(比如是个强碱),那可以优先考虑SN2和E2。注意,这并不代表有强碱就不能进行E1或者SN1--下一篇要讲的E1cb机理就是个特例。 至此,我们可以对以上三个反应做出初步判断--第一个只可能是SN2或者E2,第二个优先考虑SN2E2,第三个不可能是SN2 一般来讲,进行到这一步我们都会需要在SN1/E1...
Draw a stepwise mechanism for the reaction below. Draw a stepwise mechanism for the given reaction. Draw out a stepwise mechanism for the given reaction. Draw out a stepwise mechanism for the reaction below. Which mechanism, E1 or E2, will occur in the given reaction? Depict a ...
there are two major classes of elimination reactions (E1 and E2): E1 Reactions: In an E1 elimination reaction, only one molecule is involved in the step where the leaving group is lost (the rate- determining step): E2 Reactions: In an E2 elimination...
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