R·BH 3中B-H键与酚类物质的反应研究  

The reactivity of B-H bond in R·BH_3 towards phenol

作　　者：李慧珍[1] 王瑞瑞 夏庆春 杨秋雨 王芃远 魏昌庚 麻娜娜[1] 陈学年[1] LI Huizhen;WANG Ruirui;XIA Qingchun;YANG Qiuyu;WANG Pengyuan;WEI Changgeng;MA Nana;CHEN Xuenian(Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials,School of Chemistry and Chemical Engineering,Henan Normal University,Xinxiang 453007,Henan,China)

机构地区：[1]河南省硼化学与先进能源材料重点实验室,河南师范大学化学化工学院,河南新乡453007

出　　处：《化学研究》2018年第2期118-124,共7页Chemical Research

基　　金：国家自然科学基金(21601051,21371051);中国博士后科学基金第60批面上项目(2016M602246);河南省省级项目(162300410018,2015079)

摘　　要：硼烷化合物既能表现路易斯酸性,因分子B-H键中的氢带负电荷,又可表现出路易斯碱性.本文系统研究了R·BH_3(R=THF,DMA,NH_3)与酚类物质在常温常压无催化剂条件下的反应,发现R·BH_3(R=THF,DMA)硼烷中与B相连的负电性氢能够全部与酚中与氧相连的正电性氢发生反应,生成含BO_3的硼酸酯和氢气,但NH_3·BH_3却不与酚发生反应.DMA·BH_3与间苯二酚反应生成聚合物.根据实验结果,我们推测随着与硼配位的路易斯碱的配位能力/碱性减弱(NH_3>DMA>THF),B-H活性增强,即R·BH_3与酚类物质的反应程度按照NH_3·BH_3<DMA·BH_3<THF·BH_3顺序依次增强.结合实验和理论计算发现,硼烷与酚的反应是分四步进行的,反应第一步的主要影响因素是与硼配位的配体离去的难易,而B-Hδ-…δ+H-O双氢键在第二步到第四步反应中发挥了重要作用.配体的性质及B-Hδ-…δ+H-O双氢键在反应中发挥着重要作用.Understanding the reactivity of borane is a challenging task since the complex R·BH 3 can behave as both Lewis acid and Lewis base.The deficiency in valence electrons in B always makes such type compounds act as Lewis acid.On the other hand,the electronegativity of boron(2.0)is less than that of hydrogen(2.1),thus the hydrogen of B is hydridic,which can act as Lewis base.The reactivity of B-H bond in R·BH 3(R=THF,DMA,NH 3)towards phenols has been studied systematically.The experiment results have shown that all hydridic hydrogens in B-H of R·BH 3(R=THF,DMA)can react with the protic hydrogens in O-H of phenol(ROH)to produce H 2 and B(OR)3 borate.With the base strength decreased,NH 3>DMA>THF,the relative reactivity of hydridic hydrogen of B-H increased in the sequence of NH 3·BH 3<DMA·BH 3<THF·BH 3.According to the experiment results and the DFT calculation,we proposed a four-step mechanism for the reaction of R·BH 3 and phenols.The characteristics of the ligands(THF,NH 3,DMA)of borane and the B-Hδ-…δ+H-O dihydrogen bonds play important roles in the reactions.

关 键 词：硼烷 酚 硼酸酯 正电性氢 负电性氢 双氢键 

分 类 号：O611.4[理学—无机化学]