Experimental Basicities of Superbasic Phosphonium Ylides and Phosphazenes
作者:Jaan Saame、Toomas Rodima、Sofja Tshepelevitsh、Agnes Kütt、Ivari Kaljurand、Tõiv Haljasorg、Ilmar A. Koppel、Ivo Leito
DOI:10.1021/acs.joc.6b00872
日期:2016.9.2
spanning more than 30 pKa units, has been compiled. Basicities of 47 compounds (around half of which are newly synthesized) are included. The solution basicity of the well-known t-Bu-N═P4(dma)9 phosphazene superbase is now rigorously linked to the scale. The compiled scale is a useful tool for further basicity studies in THF as well as in other solvents, in particular, in acetonitrile. A good correlation
的一些曾经测量(鏻叶立德)最强的超强碱的实验碱度被报告,并通过采用这些化合物,在THF超强碱的实验自洽碱度规模,达到AP ķ α(对的估计ķ一个的35)和跨过超过30 p K a单位,已被编译。包括47种化合物的碱性(其中大约一半是新合成的)。公知的溶液碱度吨-Bu-N = P 4(DMA)9磷腈超强碱现已与规模紧密相关。编制的量表是在THF以及其他溶剂(尤其是乙腈)中进一步进行碱度研究的有用工具。THF和乙腈中的碱度之间的良好相关性跨越了25个数量级,从而可以得到实验支持的乙腈中非常高的碱度(p K a > 40),而无法直接测量。提出了结构-基本趋势的分析。
Stable Singlet Carbenes as Organic Superbases
作者:François Vermersch、Sima Yazdani、Glen P. Junor、Douglas B. Grotjahn、Rodolphe Jazzar、Guy Bertrand
DOI:10.1002/anie.202111588
日期:2021.12.20
Pyrazol-4-ylidenes, a type of mesoionic carbenes, also named cyclic-bentallenes (CBA), can be more basic than Verkade proazaphosphatrane and even Schwesinger phosphazene P4(tBu). With these results it is demonstrated that carbenes should not be overlooked as neutral purely organic superbases.
Pyrazol-4-ylidenes 是一种中离子卡宾,也称为环 Bentallenes (CBA),比 Verkade proazaphosphatrane 甚至 Schwesinger phosphazene P 4 ( t Bu) 的碱性更强。这些结果表明,作为中性纯有机超强碱不应忽视卡宾。
Method for preparing polyorganosiloxanes (pos) by polycondensation/redistribution of oligosiloxanes in the presence of a strong base and strong bases used
申请人:Baceiredo Antoire
公开号:US20050080215A1
公开(公告)日:2005-04-14
The invention concerns the synthesis of silicone by anionic polymerisation of cyclic organosiloxane oligomers in the presence of a slightly nucleophilic strong base. The invention aims at providing novel strong base catalysts, more efficient in terms of solubility in the silicones, with hydrolysis stability strength and polymerising capacity. To achieve this, the invention provides for the use of ylides derived from aminophosphonium such as for example that of formula: [Me3N)3P—CHMe2]+, MeO or derived from phosphoranylidenes such as that of formula: [Me3P—HC=Pme3]+, t-BuO. The invention also concerns strong base catalysts as novel products.
Free and Supported Phosphorus Ylides as Strong Neutral Brønsted Bases
作者:Stéphanie Goumri-Magnet、Olivier Guerret、Heinz Gornitzka、Jean Bernard Cazaux、Dennis Bigg、Francisco Palacios、Guy Bertrand
DOI:10.1021/jo9822030
日期:1999.5.1
Heteroorganic betaines
作者:I. V. Borisova、N. N. Zemlyanskii、A. K. Shestakova、Yu. A. Ustynyuk、E. A. Chernyshev
DOI:10.1007/bf02494719
日期:2000.5
A method for the synthesis of a new class of betaines,viz., R31P+CR2R3SiR4R5S−, was developed. The experimental evidence for the intermediate formation of betaines R31P+−CR2R3−CR4R5−S− in the Wittigreaction for a series of thiocarbonyl compounds was obtained. A comparative analysis of the NMR spectra of betaines containing the+P−C−Si−S− and+P−C−C−S− fragments was performed.