作者:Cris E. Johnson、Kristin A. Sannes、John I. Brauman
DOI:10.1021/jp953249p
日期:1996.1.1
independent measurement of the kinetic isotope effect, allowed the kinetic effect of the alkyl environment on the relative proton transfer rates to be determined. The primary and secondary isotope effects are also estimated from the enolate ion product ratios. By examining the magnitude of the kinetic alkyl effect, the primary isotope effect, and the secondary isotope effect, we learn about the transition
考察了不同程度的烷基取代对气相中几个不对称酮中两个不同位点的去质子化相对速率的影响。适当地氘标记的醇盐离子的红外多光子活化产生了离子分子复合物,用于烷基阴离子和不对称酮之间的双分子质子转移过程的半反应,其中一个去质子位被选择性地氘化。所得产物是通过去除氘核或质子而产生的烯醇酸根离子,因此可以通过质量区分。烯醇盐离子产物比率的测量,以及动力学同位素效应的独立测量,使得可以确定烷基环境对相对质子转移速率的动力学效应。初级和次级同位素效应也可以从烯醇盐离子产物比率估算出来。通过研究动力学烷基效应,初级同位素效应和次级同位素效应的大小,我们了解了质子转移的过渡态。