Platinum hexachloroplatinic acid

Hexachloroplatinic acid decomposes completely when ignited, leaving a residue of spongy platinum. Hexachloroplatinic acid on heating at 300°C in chlorine forms platinum tetrachloride ... 

The platinum hexachloroplatinic acid was used as precursor (Aldrich), usually employed in the preparation of supported catalysts. The aqueous solution was prepared shortly before impregnation and kept in dark bottle due to the instability of the platinum solution when exposed to light. Figure 7.14 shows the platinum particles of the Pt/Al2 O3 catalyst observed by TEM [12] and particle sizes as shown in Table 7.2. 

For transition-metal catalyzed hydroxylation of alkane C-H bonds, the reactions of alkanes with platinum(II) complexes were the most successful. In an aqueous solution of hexachloroplatinic acid and Na2PtCl4, alkanes were converted into a mixture of isomeric alkyl chlorides, alcohols, and ketones, and the platinum(IV) is reduced to platinum(II).7 The kinetics of the reaction with methane as the alkane have been described in detail.8... 

The NH4-Y (CBV712, ao = 24.35 A), H-Beta (CP811E-75), NH4-Beta (CP814E) zeolites were obtained from Zeolyst International. The NH4-Y and Beta zeolites were transformed to proton forms through step calcination procedure in a muffle oven. Zeolites containing 1 wt-% platinum were prepared by wet-impregnation method using hexachloroplatinic acid as the Pt-source. 

G.S. Attard, P.N. Bartlett, N.R.B. Coleman, J.M. Elliott, and J.R. Owen, Lyotropic liquid crystalline properties of nonionic surfactant/H20/hexachloroplatinic acid ternary mixtures used for the production of nanostructured platinum. Langmuir 14, 7340-7342 (1998). 

Hexachloroplatinic acid is obtained in an intermediate step during extraction of platinum from minerals. The compound is formed when platinum is dissolved in aqua regia containing a higher proportion of HCl and subsequently is evaporated repeatedly with hydrochloric acid, preferably in a chlorine atmosphere. Alternatively, hexachloroplatinic acid may be obtained by dissolving platinum tetrachloride, PtCh, in water. 

Pure hexachloroplatinic acid may be prepared by dissolving platinum sponge in hydrochloric acid under chlorine. 

It also may be obtained by thermal decomposition of platinum tetrachloride, PtCh, or hexachloroplatinic acid ... 

If platinum/carbon or hexachloroplatinic acid is taken as catalyst the trans products 3a, b are obtained stereospecifically via cis addition whereas peroxide catalysis leads to the cis-products 4a, b under trans addition with equal selectivity. 

Hydrosilylation is by far the most important route for obtaining monomers and other precursors to fluorinated polysiloxanes. Hydrosylilation80 is the addition of silicon hydride moiety across an unsaturated linkage using transition metal complexes of platinum or rhodium such as Speier s catalyst, hexachloroplatinic acid in isopro-... 

Historically, hexachloroplatinic acid in alcohol, so-called Speier s catalyst, was the first homogeneous catalyst and remained the most used for a long time. This platinum (IV) complex has been replaced by other (II) or (0) species, some of which are presented in Scheme 1. Their advantages are a reactivity that can be tuned by the choice of solvent or inhibitor and the absence of hydrochloride formation. Moreover, they are now commercially available as homogeneous solutions, which ensures a perfect dissolution of the complex, and some of them are colorless. 

The steamed sample (HPst) was treated with a O.IM hydrochloric acid solution at reflux for two hours in order to remove most of the EFAL generated (sample HPs ac). All the samples were then impregnated with 0.3 wt% platinum, using a solution of hexachloroplatinic acid in a 0.2M hydrochloric acid, by complete evaporation in a rotatory evaporator, and calcined at 773 K for three hours. 

Most research and industrial syntheses are carried out in the presence of platinum complexes, with H2PtCl6 commonly used as the initial precursor. A solution of this catalyst in isopropanol (1-10%) is referred to as Speier s catalyst [11]. In addition to isopropanol other solvents (alcohols, ketones, aldehydes, ethers, esters, THF, hydrocarbons) have also been used in the preparation of active catalysts from chloroplatinic acid. Since 1957 hundreds of catalysts based on chloroplatinic acid and other d -Pt and d °-Pt° complexes have been reported [1-5]. The Karstedt s type of catalyst obtained by treating hexachloroplatinic acid with divi-nyldisiloxane was discovered in 1973 [33] and has predominated in recent years. This catalyst has the empirical formula Pt2(CH2=CHMe2SiOSiMe2CH=CH2)3. Its structure was reported [34, 35]. 

Cyclopropane reacted with hexachloroplatinic acid to give 1,1-dichloroplatinacyclobutane which usually forms polymers. Another route to these organoplatinum compounds was the reaction of cyclopropane derivatives with dichloro(ethene)platinum dimer. Treat-... 

Platinum catalysts deposited on the supports modified with transition metal oxide monolayers exhibited high activity and satisfactory selectivity in the hydrogenation of unsaturated aldehydes to the corresponding unsaturated alcohols. Platinum acetylacetonate was a more suitable catalyst precursor than hexachloroplatinic acid in the preparation of the transition metal-O-Pt catalytic system for the hydrogenation of cinnamaldehyde and... 

Hexachloroplatinic acid hydrate (H2PtCle, chloroplatinic acid, platinum IV chloride soution) [16941-12-1] M 409.8 + H2O, m 60° (deliquescent solid). If it is to be purified, or... 

Stereochemistry of Hydrosilane Addition to Alkynes Platinum and Rhodium Catalysts. Hydrosilylation of hex-1-yne with trichlorosilane in the presence of hexachloroplatinic acid gave a mixture of two vinylsilanes (eq. [39]) (190). 

Hexachloroplatinic acid in isopropanol (Speier s catalyst) is the most commonly used hydrosilylation catalyst because of its broad applicability and effectiveness at very low concentrations. A generally accepted mechanism for homogeneous platinum catalysed hydrosilylation involves reduction of Pt(IV) to Pt(II) by the silane, ligand substitution by the alkene, oxidative addition of SiH to the metal, rearrangement to a a-bonded complex and finally reductive elimination of the product and recycle of the catalyst 206 208. The basic mechanism is summarised in Scheme 2. 

Hexachloroplatinic acid (SEMPSA, Spain) was used as the platinum inorganic precursor. An active phase loading of 0.2 wt. % was used in all the catalysts. 

The reaction between the PtCh ion and alkanes can be induced by irradiation [26]. When a solution of hexachloroplatinic acid and n-hexane in acetic acid is irradiated by light (A > 300 nm) [26a,c,d] or y-quanta [26b], a 7t-coinplex of hex-1-ene with platinum(II) is formed in addition to isomeric chlorohexanes. This complex has been isolated in the form of the pyridine adduct, (hex-l-cne)PtCl2Py. The yield of the it-complex in the y-induced reaction reaches 17% based on Pt. The photochemical reaction is of first order with respect to hexane. It is interesting that the photochemical reaction with hex-2-ene affords the n-complex ofhex-l-ene (Scheme VII.5). This complex can be also prepared by the reaction ofhex-l-ene with PtCL, " under irradiation. It should be noted that the photoinduced reaction of PtCl6 or PtCU with olefins is a convenient method for the synthesis of various n-o efin complexes of platinum(II) [27]. The photostimulated reaction of PtCU with stilbene does not occur, possibly due to steric restrictions. 

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