Platinum , synthesis

W. Bums, T. R. B. Mitchell, M. A. McKervey, J. J. Rooney, G. Ferguson, P. Roberts, Gas-Phase Reactions on Platinum. Synthesis and Crystal Structure of Anti-Tetramantane, a Large Diamondoid Fragment. J. Chem. Soc. Chem. Commun. 1976, 893-895. 

More recently, a commercial process has been introduced for the manufacture of methyl isocyanate (MIC) which involves the dehydrogenation of /V-m ethyl form am i de [123-39-7] in the presence of palladium, platinum [7440-06-4], or mthenium [7440-18-8], at temperatures between 50—300°C (31). Aprotic solvents, such as ben2ene [71-43-2], xylenes, or toluene [108-88-3], may optionally be used. A variation of this synthesis employs stoichiometric amounts of palladium chloride [7647-10-1], PdCl2. 

Another synthesis of pyrogaHol is hydrolysis of cyclohexane-l,2,3-trione-l,3-dioxime derived from cyclohexanone and sodium nitrite (16). The dehydrogenation of cyclohexane-1,2,3-triol over platinum-group metal catalysts has been reported (17) (see Platinum-GROUP metals). Other catalysts, such as nickel, rhenium, and silver, have also been claimed for this reaction (18). 

Hydroisoquinolines. In addition to the ring-closure reactions previously cited, a variety of reduction methods are available for the synthesis of these important ring systems. Lithium aluminum hydride or sodium in Hquid ammonia convert isoquinoline to 1,2-dihydroisoquinoline (175). Further reduction of this intermediate or reduction of isoquinoline with tin and hydrochloric acid, sodium and alcohol, or catalyticaHy using platinum produces... 

Hydrogenation of Acetylenes. Complete hydrogenation of acetylenes to the corresponding alkanes, which maybe requited to remove acetylenic species from a mixture, or as a part of a multistep synthesis, may be accompHshed using <5 wt % palladium or platinum on alumina in a nonreactive solvent under very mild conditions, ie, <100°C, <1 MPa (10 atm). Platinum is preferred in those cases where it is desired to avoid isomeri2ation of the intermediate olefin. Silver on alumina also can be used in this appHcation as can unsupported platinum metal. 

A.n log ue Synthesis. Two notable examples, in which analogues have greater therapeutic indexes than the parent dmgs, have been identified in Phase I trials. These are carboplatin (29) and ado2elesin (37) (35). Carboplatin s approval was based on its comparable efficacy to cis-platinum (28) and its more favorable toxicity profile, ie, reduced and delayed episodes of emesis, reduced ototoxicity, etc. On the other hand, ado2elesin, a totally synthetic analogue of natural product CC1065, has demonstrated a similar potency and antitumor activity profile as its natural prototype but is devoid of the delayed death UabiUty associated with the parent dmg in animals (36). 

Two synthesis processes account for most of the hydrogen cyanide produced. The dominant commercial process for direct production of hydrogen cyanide is based on classic technology (23—32) involving the reaction of ammonia, methane (natural gas), and air over a platinum catalyst it is called the Andmssow process. The second process involves the reaction of ammonia and methane and is called the BlausAure-Methan-Ammoniak (BMA) process (30,33—35) it was developed by Degussa in Germany. Hydrogen cyanide is also obtained as a by-product in the manufacture of acrylonitrile (qv) by the ammoxidation of propjiene (Sohio process). 

Platinacyclopent-2-ene-4,5-diones synthesis, 1, 669 Platinates, tetracyano-charge density waves in, 1, 352 Platinum... 

Acetoxy-21-nor-5a-cholestan-20-one (73a) as well as the free alcohol (73b) react with methylmagnesium iodide to give a mixture of epimeric diols (74). After treatment with acetic anhydride and subsequent hydrogenation over reduced platinum oxide this mixture alfords 3j5-acetoxy-5oc-cholestane (75) which is identical with the natural product. This synthesis has been used to prepare the 21- C compound (75) in a total yield of 18... 

Suitable starting materials for the Kolbe electrolytic synthesis are aliphatic carboxylic acids that are not branched in a-position. With aryl carboxylic acids the reaction is not successful. Many functional groups are tolerated. The generation of the desired radical species is favored by a high concentration of the carboxylate salt as well as a high current density. Product distribution is further dependend on the anodic material, platinum is often used, as well as the solvent, the temperature and the pH of the solution." ... 

Carboplatin (96) is significantly less toxic in the clinic than cisplatin. Most particularly, it is much less nephrotoxic. Use of a bidentate ligand also ensures formation of a ds complex. Its synthesis begins with cis-diammine platinum diiodide (94) which is reacted with silver sulfate to give cis-diaquodiam mine platinum sulfate (95). This is reacted with the barium salt of 1,1-cyclo-butanedicarboxylic acid to yield carboplatin [23],... 

The only prominent antitumor tetravalent platinum complex so far is iproplatin (102). In vitro it has been shown to cause interstrand DNA-breaking and cross linking. Free radical scavengers inhibit these effects. The complex is less neurotoxic and less nephrotoxic than cisplatin. Its synthesis begins with hydrogen peroxide oxidation of cis-dichlorobis(isopropvlamine) platinum (100) to the dimethylacetamide complex 101. The latter is heated in vacuum to liberate iproplatin [25]. 

Dicyclopentadiene can be hydrogenated conveniently over a platinum catalyst in a Parr apparatus. The tetrahydro product is used in the synthesis of adamantane (Chapter 15, Section I). 

Hardacre et al. have developed a procedure for the synthesis of deuterated imidazoles and imidazolium salts [65]. The procedure involves the platinum- or palladium-catalyzed deuterium exchange of 1-methyl-d -imidazole with D2O to give 1-methylimidazole-d , followed by treatment with a deuterated alkyl halide. 

The main use of rhodium is with platinum in catalysts for oxidation of automobile exhaust emissions. In the chemical industry, it is used in catalysts for the manufacture of ethanoic acid, in hydroformylation of alkenes and the synthesis of nitric acid from ammonia. Many applications of iridium rely on... 

The main uses of palladium [13] are in the electronics and electrical industries, in circuitry and in dental alloys. It finds many catalytic applications in industry, as well as in diffusion cells for the synthesis of hydrogen, and in automobile catalysts. Jewellery and three way auto-catalysts are the principal uses of platinum, which fulfils a wide range of roles in the chemical industry. 

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