The kinetics and mechanism of the reaction of trimethyl phosphate with benzylideneacetophenones
作者:Imre Petneházy、György Clementis、Zsuzsa M. Jászay、László Töke、C. Dennis Hall
DOI:10.1039/p29960002279
日期:——
The kinetics and mechanism of the equilibrium reaction of benzylideneacetophenones 4 with trimethyl phosphate (TMP) to yield, 2,2,2-trimethoxy-2,3-dihydro-1,2λ5-oxaphospholes 5 are reported. The secondorder rate constants for the formation of 5 were determined using a polarographic method and the rate constants for the decomposition reaction were calculated from the equilibrium constants. The linear
动力学和benzylideneacetophenones 4与磷酸三甲酯(TMP)的平衡反应的机制,以产生,2,2,2-三甲氧基-2,3-二氢- 1,2λ 5报道了-恶唑磷5。使用极谱法确定形成5的二阶速率常数,并根据平衡常数计算分解反应的速率常数。线性哈米特图在某些情况下是曲线图,在另一些情况下是曲线图,表明决定速率的步骤取决于4和5中环取代基的特性。正向反应的热力学研究表明,焓较小,负熵较大。与过渡态中存在强极化和/或拥挤结构的活化作用一致。拟议的机制,1闭环到氧杂膦酸酯I 2并扩环到氧杂膦烯5限速步骤中的羰基基团,然后快速将I 3闭环为氧杂磷腈5。