Chloride compounds halide hydrogenolysis

The air-sensitive Cp-substituted hydridovanadium complex is obtained by hydrogenolysis of the corresponding methyl derivative. The corresponding anionic compound is obtained by reduction of CpV(CO)4 with sodium and protonation with water (Scheme 64). Thus obtained [CpVH(CO)3] (106) is a useful one-electron reductant to reduce bromo- and iodoalkanes, bromoalkenes, and arylbromides in THF. Furthermore, acid chlorides are reduced to the aldehydes. A similar reduction with (106) is performed by using phase-transfer conditions in the presence of tetrabutylammonium hydrogen sulfate. Nitro compounds and organic halides are reduced under these conditions. 

An alternative solution is to use organotin reagents supported on an insoluble, but porous, polymer at the end of the reaction, the polymer can be filtered off, and the catalyst can be regenerated.72 Most of the work in this field has involved polymer-bound tin hydrides (for hydrogenolysis of halides, thiocarbonyl compounds, or hydrostannation of ketones),73-76 but also tin chlorides (for use as Lewis acids),77 allylstannanes (for allyla-... 

A unique application comprises a facile hydrodehalogenation (hydrogenolysis) of aromatic compounds in 15% KOH with a heterogeneous Pd/C catalyst and Ali-quat 336 as PT catalyst [42], The latter results in a marked rate enhancement in many cases. The ease of halide removal falls from iodide through chloride to fluoride. It is believed that the lipophilic Q+ promotes the transport of the halide ion produced, from the Pd site to the alkaline aqueous phase. 

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