CONFORMATIONAL-CHANGES OF BUTANEDIOIC ACID AS A FUNCTION OF PH AS DETERMINED FROM CHANGES IN VICINAL PROTON-PROTON NMR COUPLINGS

被引：35

作者：

LIT, ES ^{[1
]}

MALLON, FK ^{[1
]}

TSAI, HY ^{[1
]}

ROBERTS, JD ^{[1
]}

机构：

[1] CALTECH,GATES & CRELLIN LABS,PASADENA,CA 91125

来源：

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 1993年 / 115卷 / 21期

关键词：

D O I：

10.1021/ja00074a022

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Vicinal proton-proton NMR couplings have been used to estimate the changes in conformational equilibria for butanedioic acid in the progression of its diprotic to monoprotic to di-ionized forms as a function of pH, concentration, and nature of the counterion. The results support earlier conclusions that the K1/K2 ratio for butanedioic acid is little, if at all, affected by internal hydrogen bonding in the monoanion. Perhaps surprisingly, the conformational preferences are weak, despite the possibility of steric hindrance and strong stabilizations by hydrogen-bonding, induction, and/or electrostatic effects.

引用

页码：9563 / 9567

页数：5

共 45 条

[1] ROTATIONAL ISOMERISM .7. EFFECT OF SUBSTITUENT ON VICINAL COUPLING CONSTANTS IN XCH2.CH2Y FRAGMENTS [J].