N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia.
Int J Mol Sci. 2023 Jun 27;24(13):10734. doi: 10.3390/ijms241310734.
Introduction of Cl and O atoms into C-vinyl carbocations was studied by X-ray diffraction analysis and IR spectroscopy. Chlorine atoms are weak electron acceptors in ordinary molecules but, within vinyl carbocations, manifest themselves as strong electron donors that accept a positive charge. The attachment of a Cl atom directly to a C=C bond leads to an increase in the e-density on it, exceeding that of the common double bond. The positive charge should be concentrated on the Cl atom, and weak δ may appear on the C=C bond. More distant attachment of the Cl atom, e.g., to a C atom adjacent to the C=C bond, has a weaker effect on it. If two Cl atoms are attached to the C atom of the vinyl cation, as in ClCCHCHCH, then the cation switches to the allyl type with two practically equivalent and almost uncharged CCC bonds. When such a strong nucleophile as the O atom is introduced into the carbocation, a protonated ester molecule with a C-O(H)-C group and a C=C bond forms. Nonetheless, in the future, there is still a possibility of obtaining carbocations with a non-protonated C-O-C group.
通过 X 射线衍射分析和红外光谱研究了 Cl 和 O 原子在 C-乙烯碳正离子中的引入。氯原子在普通分子中是弱电子受体，但在乙烯碳正离子中，它们表现为强电子供体，接受正电荷。Cl 原子直接连接到 C=C 键上会导致其上的 e 密度增加，超过普通双键的密度。正电荷应集中在 Cl 原子上，而 C=C 键上可能出现弱的 δ。Cl 原子的更远距离的连接，例如，连接到 C=C 键相邻的 C 原子，对其影响较弱。如果两个 Cl 原子连接到乙烯阳离子的 C 原子上，如 ClCCHCHCH，则阳离子会转变为具有两个几乎等效且几乎不带电荷的 CCC 键的烯丙型阳离子。当像 O 原子这样的强亲核试剂引入到碳正离子中时，会形成带有 C-O(H)-C 基团和 C=C 键的质子化酯分子。尽管如此，将来仍有可能获得带有非质子化 C-O-C 基团的碳正离子。
