Contribution of ring strain and the stereoelectronic effect to the hydrolysis of cyclic five-membered ring phosphorus esters
作者:Ji-Charng Yang、David G. Gorenstein
DOI:10.1016/s0040-4020(01)89980-4
日期:1987.1
estimate of the magnitude of ring strain in these cyclic esters. In contrast, cyclic ester hydrolyzes 1.5 × 106 times faster than its acyclic analog , corresponding to an activation free energy difference of 8.4 . This later energy difference is thought to be derived from both a ring strain effect (~ 5.2 ) and a stereoelectronic effect (~3.2 ).
环状五元环2-氧代-2-苯基-1,2-氧杂磷杂环戊酸酯,1和2-氧代-2-苯基-1,3,2-二氧杂磷杂环戊烷及其无环类似物的碱催化水解速率测量了乙基苯基膦酸乙酯和苯基膦酸二乙酯。环状酯的水解速度比3快6.2×10 3倍,相当于5.2的活化自由能差。这很好地估计了这些环状酯中环应变的大小。相比之下,环状酯的水解速度是无环类似物的1.5×10 6倍,对应的活化自由能差为8.4。后来的能量差异被认为是由环应变效应(〜5.2)和立体电子效应(〜3.2 )引起的。