关键词: 吡啶 P, 高速液体色谱, 量子化学, 分子轨道理论, 一元腈, 格氏试剂

3-cyanopyridine with alkylmagnesium halides, but an unexpected product, 4-benzyl-3-cyanopyridine was formed in the reaction with benzylmagnesium chloride. In order to study the unusual result, the EHMO calculation on 3-cyanopyridine, butylmagnesium bromide and benzylmagnesium chloride was performed. The results indicated that there were two terms of competitive forces, the Coulombic force and the frontier orbital interaction, existing in these reactions. The cyano carbon atom in 3-cyanopyridine carried more net pos. charge and the C4 in the pyridine ring possessed higher AO coefficient The carbon atom adjacent to the magnesium atom in butylmagnesium bromide carried more net neg. charge, hence in the reaction with 3-cyanopyridine the Coulombic force was dominant and the reaction would occur at the cyano group to form 3-valerylpyridine. The carbon atom adjacent to the magnesium atom in the benzylmagnesium chloride possessed less net neg. charge, and in the reaction with 3-cyanopyridine, due to the presence of steric hindrance of the benzyl group to the cyano addition reaction, the frontier orbital interaction is the chief factor and the reaction would occur at the C4 of the pyridine ring to give 4-benzyl-3-cyanopyridine as the main product.

Key words: PYRIDINE P, HIGH SPEED LIQUID CHROMATOGRAPHY, QUANTUM CHEMISTRY, MOLECULAR ORBITAL THEORY, MONONITRILE, GRIGNARD REAGENT