苯氧基在二苯醚亲电取代反应中的定位效应

Phenoxyl's Location Effect in the Diphenyl ether Electrophilicity Replace Reaction

本文从理论上研究了二苯醚的电子结构,结果表明,二苯醚的苯氧基在空间的位置对二苯醚的原子电荷分布和体系能量影响较大,从而影响二苯醚的亲电取代反应.二苯醚的O—Ph键旋转,形成不同构象之间的最大与最小体系能量值之差[ΔE=5.258 03a.u.(3 299.466 4 kcal.mol-1)]很大,O23-C1单键不可自由旋转.当C1-O23-C7与苯环垂直时,体系能量[E(90)=E(270)=-534.885 08a.u]最低,为最稳定的优势构象.二苯醚中苯氧基表现为吸电基,它的作用使邻、间位碳原子的负电荷比苯环碳原子少,使对位碳原子的负电荷比苯环碳原子多,对位反应的途径最有利,苯氧基主要表现为对位定位基.

From theory, the paper discusses the electronic structure of dipheny! ether. The result shows that phenoxyl of diphenyl ether in space position has great influence upon diphenyl ether＇s atomic electronic charge distribution and system energy, which influence the diphenyl ether＇s eleetrophilicity substituting reaction. The turning of diphcnyl ether＇ s O-Ph bond can form the great difference [△E=5.25803a.u.（3299.4664kcal·mol^-1） between maximum and minimum system energy value. Single linkage 023 - C1 can＇t circle freely. When C1 - O23 - C7 is vertical with benzene ring, the system energy [E（90）=E（270）=-534.88508a.u] is the lowest and the most stable superior conformation. Phenoxyl in diphenyl ether makes the adjacent and metaposition carbon atom＇ s negative charge less than benzene ring carbon atom, and makes the contraposition＇ negative charge more than benzene ring carbon atom. The contraposition reaction＇s way is the most favorable, and phenoxyl mainly acts as contraposition location radix.