Espinosa Ferao Arturo
Departmento de Química Orgánica, Universidad de Murcia , Campus de Espinardo, 30071 Murcia, Spain.
J Phys Chem A. 2017 Aug 31;121(34):6517-6522. doi: 10.1021/acs.jpca.7b06262. Epub 2017 Aug 18.
Two competitive mechanistic pathways for the reaction between trimethyl phosphite and chloroacetone are analyzed by high-level calculations. FMO analysis and HSAB-derived descriptors point to a preferential initial interaction of the nucleophile with the carbonyl group as electrophile. The Perkow reaction starts by chelotropic addition of the P atom to the carbonyl C-O bond, which is the rate-determining step in THF or CHCl solution, yielding an oxaphosphirane intermediate. The oxaphosphirane undergoes sequential P-C bond cleavage with elimination of chloride ion and O-demethylation. The alternative Michaelis-Arbuzov reaction involves nucleophilic displacement of chloride by the P atom and subsequent O-demethylation. The Perkow path is kinetically and thermodynamically favored with respect to the Michaelis-Arbuzov path in the gas phase, but it is only kinetically preferred in polar (THF or CHCl) solvents.
通过高水平计算分析了亚磷酸三甲酯与氯丙酮反应的两种竞争机理途径。前线分子轨道（FMO）分析和基于硬软酸碱（HSAB）理论得出的描述符表明，亲核试剂优先与作为亲电试剂的羰基发生初始相互作用。佩尔科夫反应始于磷原子向羰基碳 - 氧键的螯合加成，这是在四氢呋喃（THF）或氯仿（CHCl）溶液中的速率决定步骤，生成氧杂磷杂环丙烷中间体。该氧杂磷杂环丙烷依次发生磷 - 碳键断裂并消除氯离子以及氧去甲基化反应。另一种迈克尔is - 阿尔布佐夫反应涉及磷原子对氯离子的亲核取代以及随后的氧去甲基化反应。在气相中，相对于迈克尔is - 阿尔布佐夫途径，佩尔科夫途径在动力学和热力学上更有利，但在极性（THF或CHCl）溶剂中仅在动力学上更占优势。
