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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >Role of the gauche effect and local 1,3-dipole-dipole interactions in stabilizing an unusual conformation of tartarodinitriles
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Role of the gauche effect and local 1,3-dipole-dipole interactions in stabilizing an unusual conformation of tartarodinitriles

机译:gauche效应和局部1,3-偶极-偶极相互作用在稳定酒石腈的异常构象中的作用

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摘要

This paper reports the synthesis, X-ray and NMR investigations of chiral and meso dinitriles of tartaric acid (tartarodinitriles) and their O, O'-diacetyl and O, O'-dibenzoyl derivatives. While in chiral tartaric acid its esters and NH amides the four-atom carbon chain is overwhelmingly trans, it is gauche in chiral tartarodinitriles. Conversely, meso-tartaric acid, its esters and amides display a tendency for the gauche conformation, but meso-tartarodinitriles usually have the trans conformation. The NMR studies of tartarodinitriles reveal the presence of a conformational equilibrium in solution with a preference for those conformers found in crystals. The gauche conformation of meso-tartarodinitriles seems to be stabilized by local dipolar interactions, intramolecular C-H center dot center dot center dot O hydrogen bonds and by a tendency for maximization of the gauche effect, the latter effect also operating in chiral tartarodinitriles. Stabilization of the trans conformers of tartarodinitriles in the crystals seems to originate from specific intermolecular interactions.
机译:本文报道了酒石酸(酒石二腈)及其O,O'-二乙酰基和O,O'-二苯甲酰基衍生物的手性和内消旋二腈的合成,X射线和NMR研究。在手性酒石酸中,其酯和NH酰胺中的四原子碳链绝大多数都是反式的,而在手性酒石腈中则是纯净的。相反,中酒石酸,其酯和酰胺显示出薄纱构象的趋势,但是中酒石腈通常具有反式构象。酒石腈的NMR研究表明,溶液中存在构象平衡,优选晶体中存在的构象平衡。中齿酒石腈腈的薄纱构象似乎可以通过局部偶极相互作用,分子内C-H中心点中心点中心点O氢键以及通过最大的薄纱效应趋势来稳定,后者的作用也在手性酒石腈中起作用。酒石腈中反式构象异构体的稳定似乎源自特定的分子间相互作用。

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