The sodium salts of pent-2-ynoic (I), penta-2,3-dienoic (II), and pent-3-ynoic (III) acids are interconverted on heating in aqueous sodium hydroxide. The reaction was followed by g.c. analysis of the methyl esters after methylation of the acid mixtures with diazomethane at –70°. Rate and equilibrium constants for the individual steps were obtained, allowance being made for a competing hydration reaction
在加热的
氢氧化钠水溶液中,将戊-2-炔酸(I),戊-2,3-二烯酸(II)和
戊-3-炔酸(III)的钠盐相互转化。在反应之后,在–70°下用
重氮甲烷将酸混合物甲基化后,对甲酯进行gc分析。获得各个步骤的速率和平衡常数,为竞争
水合反应留出余地。溶剂同位素效应k(D 2 O)/ k(H 2O)可以将(I)转化为(II)1·4,将(II)转化为(III)1·6,并被解释为碳负离子中间体的证据。核磁共振也研究了氧化
氘中的异构化,并且观察到戊-3-
戊酸酯在C-2处的
氘化速度快于其异构化成(II)的现象,这与该异构化的碳负离子机理是一致的。