VINYLMERCURY HYDRIDES

Vacuum distillation residues, 408 Vacuum ovens, 408 Vacuum pumps, 409 Vanadocenes, 409 Vapour cloud explosions, 409 Vapour explosions, 410 Vegetable oils, 411 Vent lines, 411 Vinylmercury hydrides, 411 Vinylsiloxanes, 411... 

In the reaction with halides of the less electropositive metals such as mercury,79 arsenic,80- 81 antimony,82 and indium,83 a stannane provides nucleophilic hydrogen and gives the new metal hydride (equation 15-27). Free radical inhibitors may be added to repress radical reaction of vinyl reactants. The preparation of vinylmercury hydride by this route involves the unusual use of tributyltin chloride as a solvent (equation 15-28).79 On the other hand, in the reactions of tributyltin hydride with Grignard reagents, RMgX, the hydrogen behaves as an electrophile towards R, and the Sn-Mg bonded compounds are formed.84... 

In the absence of base, vinylmercury reagents and lithium tetrachloropalladate(II) react with alkenes to form ir-allylpalladium complexes arising from addition of the vinylpalladium chloride to the alkene followed by palladium hydride elimination, a reverse readdition and rr-allyl formation (equation 10).31... 

In the case when the aromatic is supplied as arylmercury, there seems little doubt that the first mechanism is operative. First, the reaction is much faster than when the nonmercurated aromatic is used. This would not be expected if the formation of vinylmercurial is rate determining. Second, if olefins are not present, coupled products are formed by reaction of phenylpalladiums with each other (275). Third, the phenyl-palladium can be trapped by reaction with CO to give acids ( 15). Finally, products are formed that can only be explained by movement of Pd(II) around the ring after addition of the aryl group (89). This movement almost certainly occurs by a series of Pd(II)-hydride additions and eliminations. 

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