Platinum oxide vinyl halides

A very active elemental rhodium is obtained by reduction of rhodium chloride with sodium borohydride [27]. Supported rhodium catalysts, usually 5% on carbon or alumina, are especially suited for hydrogenation of aromatic systems [iTj. A mixture of rhodium oxide and platinum oxide was also used for this purpose and proved better than platinum oxide alone [i5, 39]. Unsaturated halides containing vinylic halogens are reduced at the double bond without hydrogenolysis of the halogen [40]. 

Earlier work on the reactions of vinyl halides with tertiary phosphine platinum(0) compounds showed that complexes such as [Pt( y -vinyl halide)(PPh3)2] are formed initially, and the kinetics and mechanism of the oxidative addition (isomerization) were examined. Corresponding work on halogenoalkynes has now been carried out. Thus when c/5 -[PtCl2(PPh3)2] is reduced with hydrazine in the presence of PhC=CX (X =Br or I") the product obtained is [PtX(C= CPhXPPhs). ]. However, with PhC = Cl the intermediate substitution product [Pt(jj -PhC CCl)(PPh3)2] could be isolated and its internal oxidative addition examined mechanistically [see equation (8)]. 

Irioxide, platinum, silver, potassium chlorate, potassium ferricyanide, potassium mercuric cyanide, silver chloride, stibine, tellurium halides, tellurium hydropentachloride, tetramethy-lammonium amide, trimethylammonium amide, trioxygen difluoride, vinyl acetate. Violent polymerization with ethylene oxide. Attacks some coatings, plastics, and rubber. Attacks copper, brass, bronze, aluminum, steel, and their alloys. 

The oxidative addition reactions of organic halides to platinum phosphine compounds easily proceed. For example, reactions are shown in eqs. (21.22) and (21.23) [26,34]. The vinyl bromide derivative obtained by the reaction shown in eq. (21.22) is liable and it gives PtBr2(PMePh2)2 and acetylene by elimination [34]. 

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