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在相同反应条件下,进行一系列烯烃与丙二酸二乙酯的加成反应,求得产率与烯烃结构间的定量关系,即反S型曲线.根据此结构关系可以推定此加成反应是由丙二酸二乙酯形成的自由基[·CH(CO_2C_2H_5)_2]对烯烃的亲电子性自由基加成反应. 从产率曲线可以确定在一定的反应条件下I_(50)点的位置.根据I_(50)值讨论各类烯烃同系物在反应中的产率变化,及可得高产率的结构范围.例如,可以推定所有脂肪α-烯的产率均高,在氯烷基代烯中,氯原子与双键至少应隔两碳原子,而在羧代烷基烯中,羧基应隔三碳原子,始能得高产率.
Under the same reaction conditions, a series of addition reaction of olefins and diethyl malonate was carried out to obtain the quantitative relationship between the yield and the olefin structure, that is, the inverse S-curve. According to the structure relationship, it can be inferred that the addition reaction Is an electrophilic radical addition reaction of the free radical [· CH (CO_2C_2H_5) _2] formed by diethylmalonate.It can be determined from the yield curve that the I_ (50) point under certain reaction conditions Position.According to the value of I_ (50), we discussed the yield change of various alkene homologues in the reaction and the range of structure with high yield.For example, it can be inferred that the yields of all aliphatic α-olefins are high, In the alkene, the chlorine atom and the double bond should be separated by at least two carbon atoms. However, in the carboxyalkyl olefin, the carboxyl group should be separated by three carbon atoms to obtain a high yield.