THE UNUSUAL EFFECTS OF ORTHO-CARBOXYL AND CARBOMETHOXY SUBSTITUENTS ON THE STABILITY OF IODOBENZENE DICHLORIDE
THE UNUSUAL EFFECTS OF ORTHO-CARBOXYL AND CARBOMETHOXY SUBSTITUENTS ON THE STABILITY OF IODOBENZENE DICHLORIDE
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DOI：
10.1021/ja01525a025
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发表时间：
1959-01-01
影响因子：
15
通讯作者：
KEEFER, RM
中科院分区：
文献类型：
--
作者：
ANDREWS, LJ;KEEFER, RM
邻碘苯甲酸二氯脱氯化氢的产物与均四甲苯在乙酸乙酯中反应生成氯化均三甲苯和邻碘苯甲酸。在没有微量氯化氢的情况下，该反应不发生，其速率被邻碘苯甲酸减慢。提出的动力学证据表明，邻碘苯甲酸二氯化物是反应中间体，与已研究过的其他取代二氯碘苯不同，它必须与游离碘化合物和氯迅速平衡。游离氯是均四甲苯的有效氯化试剂。邻碘苯甲酸甲酯二氯化物与其组分在醋酸中的平衡也很快，但它的^-异构体和间、F-碘苯甲酸二氯化物在该介质中的解离速度很慢。提出邻位基团邻位COOH和邻位COOCH3参与，解释了这些取代基对二氯甲烷解离速率的极端影响。在冰醋酸中，二氯碘苯与碘苯和氯发生缓慢平衡。1芳环上取代基的电子性质不同，平衡速率和平衡常数也不同，但一些邻位取代二氯化物的反应活性与其m-和？-异构体的反应活性极为相似。2显然，邻位取代基对该反应的空间效应很小，因为氯-i-氯基团位于苯环平面上，而不是平行于苯环平面。这些二氯化物是有效的试剂。
The product of dehydrochlorination of o-iodobenzoic acid dichloride reacts with durene in acetic acidto form chlorodurene and o-iodobenzoic acid. The reaction does not occur in the absence of traces of hydrogen chloride, and its rate is retarded by o-iodobenzoic acid. Kinetic evidence is presented which indicates that o-iodobenzoic acid dichloride is a reaction intermediate and that it, unlike other-substituted iodobenzene dichlorides which have been studied, must equilibrate rapidly with the free iodo compound and chlorine. Free chlorine is the effective chlorinating agent for durene. Methyl o-iodoben-zoate dichloride also equilibrates rapidly with its components in acetic acid, although its^-isomer and m-and F-iodobenzoic acid dichlorides dissociate very slowly in this medium. A neighboring group type participation of o-COOH and 0-COOCH3 is suggested to explain the extreme influences of these substituents on the dichloride dissociation rate.In acetic acid iodobenzene dichloride undergoes slow equilibration with iodobenzene and chlorine. 1 The equilibration rate and the equilibrium constant vary with the electronic natures of substituents on the aromatic ring, but the reactivities of a number of o-substituted dichlorides are strikingly similar to those of their m- and¿>-isomers. 2 Apparently steric effects of o-substituents are minimal for this reaction because the Cl-I-Cl grouping lies perpen-dicular rather than parallel to the plane of the ben-zene ring. These dichlorides are effective agents