Platinum uptake

S. Rauch and G. M. Morrison, Platinum uptake by the freshwater isopod Asellus aquaticus in urban rivers, Sci. Total Environ., 235 (1999), 261D268. 

G. Rosner, H. P. Konig, W. Koch, H. Kock, R. F. Hertel, H. Windt, Engine test experiments to assessing platinum uptake by plants, Angew. Botanik, 65 (1991), 127D132. 

Decreased platinum uptake indeed in many cispladn-resistant cell lines reduced accumulation was indeed observed... 

Precious metal catalysts have shown to be effective for the desulfurization of the steri-cally hindered compounds. One example is given with a commercial catalyst using both, palladium and platinum [23]. The high activity of these metals towards hydrogenation would result in aromatic saturation reactions, and consequently an increase in operating costs (not only for the catalyst cost but also for the increase in hydrogen uptake). 

Hodge et al. [689] have described a method for the determination of platinum and iridium at picogram levels in marine samples, based upon an isolation of anionic forms of these elements using appropriate resins, with subsequent purification by uptake on a single ion-exchange bead. All steps are followed by radiotracers, and yields vary between 35 and 90%. Graphite furnace AAS was employed as the determinative step. 

In the above mentioned reaction, platinum oxide and palladium on barium sulfate showed no perceptible change in the rate of hydrogen uptake. On the other hand, platinum oxide was selective in the hydrogenation of cyclohexa-2,4-diene-l,2-dicarboxylic acid to 1,4,5,6-tetrahydrophthalic acid140. A similar result may be the favored reduction of a symmetrical disubstituted double bond over a more hindered trisubstituted bond. The retarding effect of additional substitution is demonstrated in the hydrogenation of a trisubstituted double bond in the presence of a tetrasubstituted double bond (equation 53)141. 

Liu, Q. Qu,Y Van Antwerpen, R. Farrell, N. Interaction of Polynuclear Platinum Anticancer Agents. Implications for Gellular Uptake. Biochemistry 2006, 45, 4248-4256. 

Fig.6 The organo-platinum(II) complex containing N,C,N tridentate ligands reversibly binds gaseous SO2 in the solid state. The reversible reaction occurs at the Pt(ll) complex by Pt-S bond formation and cleavage. Uptake and release of SO2 does not destroy the crystalline ordering... 

A soln of the Ser[PO(OC6H4-2-tBu)2]-peptide H-Leu-Arg-Arg-Ala-Ser[PO(OC6H4-2-tBu)2]-Leu-Gly-OH 3 TFA (5.8 mg, 0.004 mmol) and Pt02 (30.0 mg) in TFA (4 mL) was charged with H2 and stirred rapidly until the cessation of H2 uptake. The platinum was removed by gravity filtration and the solvent removed under reduced pressure. The peptide was precipitated by the addition of Et20 (10 mL) and the solid triturated with Et20 (2 x 10 mL). The crude peptide was dissolved in H20, filtered (20-prn pore)... 

Oxidation of Elaidic Acid Ozonization Products. Aliquots of the unseparated ozonization products from elaidic acid were autoxidized at 95 °C. uncatalyzed and in acetone over reduced platinum oxide as before. Total yields of acids and esters were determined by titration and were found to be 74.6 and 19.2%, respectively, in the catalyzed reaction with uptake of 63% of the theoretical volume of oxygen. Time required for uptake of half this volume was 4 hours at 21 °C. Uncatalyzed oxidation at 95°C. of the other fraction gave 27.4% yield of esters and 74.5% yield of acids, calculated on the assumption that one original olefinic linkage can produce one ester function or two acid functions. When elaidic acid was ozonized in methyl acetate and the catalyzed oxidation performed in the same solvent, acid yield was 80.8%, and ester yield was 7.3% with a half-uptake time of 5.6 hours and 88% of the theoretical quantity of... 

Catalytic oxidation of ozonides over platinum appears to be accompanied by the same ester by-product disadvantage found in the thermal process. Chain degradation by other reactions is less serious, however, and transesterification does not occur. The method can therefore be used to prepare a half-ester of a dicarboxylic acid from an ester of a suitable unsaturated acid. If ozonide autoxidation occurs by the route, ozonide — aldehyde — peracid, with the latter acting as precursor of both acid and ester products (20-24), it is interesting to compare reaction rates observed in the present study with the rate of uptake of oxygen by... 

Reductive alkylation is an efficient method to synthesize secondary amines from primary amines. The aim of this study is to optimize sulfur-promoted platinum catalysts for the reductive alkylation of p-aminodiphenylamine (ADPA) with methyl isobutyl ketone (MIBK) to improve the productivity of N-(l,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (6-PPD). In this study, we focus on Pt loading, the amount of sulfur, and the pH as the variables. The reaction was conducted in the liquid phase under kinetically limited conditions in a continuously stirred tank reactor at a constant hydrogen pressure. Use of the two-factorial design minimized the number of experiments needed to arrive at the optimal solution. The activity and selectivity of the reaction was followed using the hydrogen-uptake and chromatographic analysis of products. The most optimal catalyst was identified to be l%Pt-0.1%S/C prepared at a pH of 6. 

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