硼化合物研究 Ⅹ.四氢硼酸单苄基季铵盐的脱苄热解法制取叔胺合甲硼烷

硼化合物研究 Ⅹ.四氢硼酸单苄基季铵盐的脱苄热解法制取叔胺合甲硼烷 STUDIES ON BORON COMPOUNDS X. Synthesis of Tertiaryamine Borane From Quaternary Monobenzylammonium Tetrahydroborate by Pyrolytic Debenzylation 张国敏 Zhang Guomin and yuan Guozheng first-author 袁国正 < 正 > 1967年四氢硼酸四乙基季铵盐的热解研究导致了合成闭多面体硼氢阴离子B 10 H 10 2- 新法的发现[1],这一反应在机理上被认为是由季铵阳离子Et 4 N + 和四氢硼酸根阴离子BH 4 - 之间的首步氧化还原作用,经由多面体碎片离子的生成,最后导致闭多面体阴离子的生成[2]。季铵阳离子的结构对这一反应过程有重要影响。但考查四氢硼酸单苄基季铵盐的热解则主要表现为四氢硼酸阴离子和季铵阳离子间的氧化还原作用,即从季铵阳离子上消去苄基,生成甲苯和叔胺合甲硼烷,得不到闭多面体硼氢阴离子。反应过程如下式所示: Quaternary monobenzylammonium tetrahydroborate （1-） on thermolysis readily eliminates a benzyl group according to the general equation: R 1 R 2 R 3 N+CH 2 PhBH 4 - →R 1 R 2 R 3 N·BH 3 +PhCH 3 and forms tertiaryamine borane, no evidence was obtained for B 10 H 10 2- or B 12 H 12 2- . The process of debenyylation may be conveniently employed for the prepa-ation of triethylamine borane、tri-n-propylamine borane、tri-n-butylamine borane、N, N-diethyl-n-butylamine borane、N,N-diethyl-n-hexylamine borane、N,N-dimethyl aniline borane and N-ethylpiperidine borane, in yield of 85%、75%、92%、63%、64%、80% and 61% respectively. Seven corresponding quaternary monobenzylammonium tetrahydroborate （1-） were conveniently prepared by metathesis in 5N NaOH/CH 2 Cl 2 according to the general equation: R 1 R 2 R 3 N + CH 2 PhCl - +KBH 4 →R 1 R 2 R 3 N + CH 2 PhBH 4 - +KCl 1984-04-01 2021-04-01 4