REACTIONS OF CARBODIIMIDES .I. MECHANISMS OF REACTIONS OF ACETIC ACID WITH DICYCLOHEXYLCARBODIIMIDE
REACTIONS OF CARBODIIMIDES .I. MECHANISMS OF REACTIONS OF ACETIC ACID WITH DICYCLOHEXYLCARBODIIMIDE
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DOI：
10.1021/ja00957a027
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发表时间：
1966-01-01
影响因子：
15
通讯作者：
SILVERST.R
中科院分区：
文献类型：
--
作者：
DETAR, DF;SILVERST.R
本文研究了二环己基碳二亚胺（DCC）和二异丙基碳二亚胺与乙酸在乙腈和四氯化碳中的反应机理。之前报道的醋酸与DCC反应的产物是醋酐、二环己基脲和乙酰基二环己基脲，现在已证明这些产物可以定量地解释反应物。此外，已经发现，产物产率与乙酸和DCC的初始浓度之间的关系可以由式1-3准确地预测，其中kijkz比为约60摩尔-11。乙腈和四氯化碳中约400。这些比率可以被视为经验参数。已经研究了酰脲可能部分来自乙酸酐与碳二亚胺的反应或来自脲的酰化的可能性，但这两种情况都被排除在外。在乙腈中，该反应在碳二亚胺中为一级反应，在乙酸中略高于一级反应。反应在四氯化碳中比在乙腈中快约30倍。这种不寻常的结果，相对于乙酸的顺序，和几个趋势的产品收率可以占的基础上，乙酸二聚体反应更迅速地与碳二亚胺比单体。基于方程1-5的机理预测与30 ℃下乙腈中k = 0.013 mol-11的产物数据定量雅阁。sec-1，kJ kj = 60 mole-1，Ki= 0.5摩尔-11.，Ars/Ati= 10。已发现乙酸在乙腈中的单体-二聚体平衡常数为0.5摩尔-11。
Themechanisms of the reactions of dicyclohexylcarbodiimide (DCC) and of diisopropylcarbodiimide with acetic acid in acetonitrile and in carbon tetrachloride have been studied. Previously reported products for the reaction of acetic acid with DCC are acetic anhydride, dicyclohexylurea, and acetyldicyclohexylurea, and these have now been shown to account quantitatively for reactants. Furthermore, it has been found that the relationship between product yields and initial concentrations of acetic acid and of DCC can be predicted accurately from eq 1-3 with a kijkz ratio of about 60 mole-11. in acetonitrile and about 400 in carbon tetrachloride. The ratios may be regarded as empirical parameters. The possibility has been investigated that the acylurea might arise in part from re-action of acetic anhydride with carbodiimide or from acylation of urea, but both of these have been excluded. In acetonitrile the reaction is first order in carbodiimide and somewhat higher thanfirst order in acetic acid. The reaction is about 30 times faster in carbon tetrachloride than in acetonitrile. This unusual result, the orderwith respect to acetic acid, and several trends of product yields can be accounted for on the basis that acetic acid dimer reacts more rapidly with carbodiimide than does the monomer. Predictions based on a mechanism consisting of eq 1-5 are quantitatively in accord with product data in acetonitrile at 30 with k¡= 0.013 mole-11. sec-1, kJkí= 60 mole-1\., Ki= 0.5 mole-11., Ars/Ati= 10. The monomer-dimer equilibrium constant for acetic acid in acetonitrile has been found to be 0.5 mole-11.