Kratko priopćenje

A Convenient Preparation of Organofluorosilanes. A Possible Involvement of Tetracoordinated Siliconium Ion Pairs

Yitzhak Apeloig ; Department of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
Osnat Merin-Aharoni ; Department of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel

Sažetak

Organofluorosilanes and their complexes with weakly coordinating fluorine con- taining salts are frequently used in mechanistic studies of organosilicon compounds.1 Examples include studies of nucleophilic attack at silicon2 and attempts to generate silicenium ions of type R3Si+.3’4 Silyl fluorides are also used in key steps in the synthesis of sterically hindered tetraalkylsilanes5’6 or of highly congested trialkylsilyl halides (chlorides, bromides and iodides).6’7
In view of these important applications, it is surprising that until very recently the available synthetic methods for preparing silyl fluorides were limited and used quite inconvenient chemicals, procedures and reaction conditions. Thus, organofluorosilanes were prepared by the treatment of the corresponding silyl halides with anhydrous hydrofluoric acid,8 antimony trifluoride,9 or zinc fluoride.7,10 Only one report in the older literature indicated that triphenylfluorosilane can be prepared under much milder conditions, i.e., by the reaction of the corresponding chloride with sodium fluoroborate in acetone at room temperature.11 The lack of simple straightforward methods for preparing silyl fluorides is especially intriguing in view of the fact that the Si-F bond is the strongest known bond to silicon, and consequently fluorosilanes are expected to exhibit high thermodynamic stability.12
Progress towards a more simple synthesis of fluorosilanes was made in recent years. Bassindale and Stout noted that the reaction of Me3SiCl with silver tetrafluoroborate yields trimethylfluorosilane138 (not trimethylsilyl tetrafluoroborate as previously suggested).136 Della and Tsanaktidis reported in 1988 that silyl triflates react at 25-70 °C with potassium fluoride in DMF in the presence of 18-crown-6 to produce the corresponding silyl fluorides.14

Ključne riječi

Hrčak ID:

137133

URI

https://hrcak.srce.hr/137133

Datum izdavanja:

15.10.1992.

Posjeta: 1.498 *