Carlqvist P, Eklund R, Brinck T
Physical Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
J Org Chem. 2001 Feb 23;66(4):1193-9. doi: 10.1021/jo001278c.
The mechanisms for the uncatalyzed and boron trifluoride (BF3) assisted Baeyer-Villiger reactions between acetone and hydrogen peroxide have been investigated using high level ab initio [MP2 and CCSD(T)] and density functional theory (B3LYP) methods. Both steps in the uncatalyzed reaction are found to have very high transition state energies. It is clear that detectable amounts of the Crieege intermediate or the products cannot be formed without the aid of a catalyst. The main function of BF3 in both the addition step and the rearrangement (migration) step is to facilitate proton transfer. In the addition step the complexation of hydrogen peroxide with BF3 leads to an increased acidity of the attacking OH group, while in the rearrangement step BF3 takes active part in the proton-transfer process. This latter step is found to be rate determining with an activation free energy of 17.7 kcal/mol in organic solution. The products of the reaction are BF2OH, hydrogen fluoride, and methyl acetate. Thus, BF3 is not directly regenerated from the reaction.
采用高水平从头算方法（MP2和CCSD(T)）以及密度泛函理论（B3LYP），研究了丙酮与过氧化氢之间未催化的以及三氟化硼（BF₃）辅助的拜耳-维利格反应机理。发现未催化反应的两个步骤都具有非常高的过渡态能量。显然，在没有催化剂的情况下，无法形成可检测量的克里格中间体或产物。BF₃在加成步骤和重排（迁移）步骤中的主要作用是促进质子转移。在加成步骤中，过氧化氢与BF₃的络合导致进攻性OH基团的酸度增加，而在重排步骤中，BF₃积极参与质子转移过程。发现后一步是速率决定步骤，在有机溶液中的活化自由能为17.7千卡/摩尔。反应产物是BF₂OH、氟化氢和乙酸甲酯。因此，BF₃不会直接从反应中再生。
