甲基三氢集团的研究

本文通过FT-IR,溶解热和从头计算分子轨道法,对含三氢集团的分子(丙酮、乙酸甲酯、二甲基亚砜等)分子间的相互作用做了研究。在所研究的体系中,计算表明在甲基3个氢原子的中心方向有一个正电势区。它导致负电集团红外吸收带频率位移,溶解热的数据进一步说明三氢集团的集体效应。

Investigation of Methyl Tri-Hydrogen Group

In this paper, compounds containing methyl trihydrogen group (acetone, methyl acetate, dimethyl sulfpxide) are investigated by FT-IR. When dilute them with,inert Solvents, the overtones of stretching model of CO and SO groupsshift to high frequency. At the same time, the C-H stretching model shifts to low frequency. It declares that CH3 interacts with O atom, but the interaction is different, from hydrogenbonding.For two model molecules of methyl 3H groups methanol and acetone are calculated by ab inintio method. The computation performed by ab inintio program MQAB-80 and electrostatic potential program EPS. It is exploded by the results, of ab inintio electrostatic potential calculations, at; the direction of the center of methyl trihydrogen atoms, there is. a positive electrppotential region. This points out the collective effect of methyl trihydrogen. and the cause to easily understand the larger interaction of it with negative atoms.The ratio of the heat of solution in squalane, PEG6000 and dioctyl decylate are determinated with gas chromatography for n-octane, it is non-polar, andn-prppyl acetate, 2-heptanone, they have CH3-C- grpup. The heat of solution reveals the effect of trihydrogen group and shows that C=O is adequate well in space with CH3, so that the interaction between them is much larger than that between -O- and CH3.The optimization for all of the geometric parameters by CNDO/2 of supermolecule which is composed of two acetones shows that, the configuration with O atom that oriented to the center of methyl of another molecule is lower in energy than that orient one of the H of methyl. Above results support the grpup adaptability model about selective intermolecular force suggested by Chinese chemist Jin Songshou.