Basicity of Phosphanes and Diphosphanes in Acetonitrile
Basicity of Phosphanes and Diphosphanes in Acetonitrile
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DOI：
10.1002/ejoc.201200009
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发表时间：
2012-04-01
影响因子：
2.8
通讯作者：
Leito, Ivo
中科院分区：
文献类型：
--
作者：
Haav, Kristjan;Saame, Jaan;Leito, Ivo
膦在有机化学中有着广泛的应用。它们的碱性在决定它们在不同酸度的溶液中的行为方面很重要。我们报告了乙腈中各种单和二膦的碱性研究，其中一些具有重要的实际意义（BINAP，BIPHEP）。所研究的膦在乙腈中的碱度在pK（a）4-16的范围内。根据实验结果，分析了膦配体的结构与碱性之间的关系，并与类似结构的胺类化合物进行了比较。当烷基被芳基取代时，与膦相比，可以在胺中观察到显着更强的碱性变化。这主要是由芳基和碱性中心的孤对电子之间的共振引起的，该共振在氮原子的情况下是强的，而在磷原子的情况下是弱的。通过对二膦的碱性测定，得出了两个初步结论：（1）具有烷基主链的质子化二膦不存在分子内氢键;（2）具有芳香族主链的质子化二膦可能存在较弱的分子内氢键。
Phosphanes are widely used in organic chemistry. Their basicity is important in determining their behavior in solutions of different acidity. We report a study of the basicities of various mono-and diphosphanes in acetonitrile, some of them of significant practical interest (BINAP, BIPHEP). The basicities of the studied phosphanes in acetonitrile are in the pK(a) range of 4-16. From the results, the relationship between the structure and basicity of the phosphanes has been analyzed and compared with that of amines of similar structure. A remarkably stronger change in basicity can be observed in the amines in comparison with the phosphanes when alkyl groups are replaced by aryl groups. This is mainly caused by resonance between the aryl group and the lone pair of the basicity center, which is strong in the case of the nitrogen atom and weak in the case of the phosphorus atom. The results of the basicity measurements of the diphosphanes in this work has led to two tentative conclusions: (1) there is no intramolecular hydrogen bond in protonated diphosphanes with an alkyl backbone, and (2) there may be a weak intramolecular hydrogen bond in protonated diphosphanes with an aromatic backbone.