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z一和E-β-溴苯乙烯与镁在THF中反应生成构型保持的格氏试剂和部分异构化的格氏试剂。副产物有苯乙烯、苯乙炔和E,E-1,4-二苯基丁二烯-1,3。用~1Hnmr检测反应过程时,发现Z-β-溴苯乙烯与镁在THF-d_8中反应的产物Z-β-苯乙烯基溴化镁、E-β-苯乙烯-d和E,E-1,4-二苯基丁二烯-1,3出现CIDNP效应。根据这两个格氏试剂与二氧化碳反应所得产物和CIDNP效应,本文提出反应是通过镁转移单电子给β-溴苯乙烯的自由基机理进行的。研究题目格氏试剂与三苯基氯甲烷的反应,进一步证实了由单电子转移生成的烯基格氏试剂自由基正离子可以发生β-氢转移。由自由基二聚和交叉结合的速率的不同,文中解释了苯基取代氯甲烷与烯基格氏试剂反应时所得的AA,AB和BB型产物的分布。
The reaction of z-E-beta-bromostyrene with magnesium in THF results in the maintenance of the Grignard reagent and the partially isomerized Grignard reagent. By-products are styrene, phenylacetylene and E, E-1,4-diphenylbutadiene-1,3. When the reaction was detected with ~ 1H nmr, it was found that Z-β-styryl magnesium bromide, E-β-styrene-d and E, E- 1,4-diphenylbutadiene-1,3 CIDNP effect. According to the products of the two Grignard reagents reacted with carbon dioxide and the CIDNP effect, the present paper suggests that the reaction is carried out by the free radical mechanism of β-bromostyrene by the transfer of magnesium by magnesium. The reaction of Grignard reagent with triphenylmethyl chloride further confirmed that β-hydrogen transfer can occur in the free radical cations of alkenyl Grignard reagents generated by single electron transfer. Due to the difference in the rate of free radical dimerization and cross-coupling, the distribution of the products of AA, AB and BB resulting from the reaction of phenyl-substituted methyl chlorides with alkenyl Grignard reagents is explained herein.