Platinium catalyst

Methyldecamine (174) was synthesized from pelletierine and the alkali-insoluble amide 170 by Hanaoka et al. (81). Decamine (18) was synthesized by Lantos et al. by the kinetically controlled condensation of pelletierine with biphenyl aldehyde (169) which afforded the cfs-quinolizidone (173) in 50% yield. Reduction of the carbonyl group with Henbest catalyst followed by alkaline hydrolysis produced the undesirable trans-fused quinolizidols as a major product. However, hydrogenation with platinium catalyst in an alkaline solution afforded the less stable cis-fused axial carbinol, which on cyclization followed by a mild basic hydrolysis yielded decamine (18). 

Catalytic hydrosilylation of alkenes performed in the presence of a chiral catalyst results in the formation of chiral silanes. Initially platinium catalysts of the type L PtCl2, L = (/ )-benzyl-(methyl)phenylphosphine (BMPP) or (/ )-methyl(phenyl)propylphosphine and 1,1-disubstituted prostereogenic alkenes, such as a-methylstyrene, 2,3-dimethyl-l-butene and 2-methyl-l-butene, were used however, the stereoselectivity was low4,5. A slightly higher stereoselectivity is obtained when dichlorobis[(/ )-benzyl(methyl)phenylphosphine]nickel [Ni(BMPP)2Cl2] is used as the catalyst. Note that two chiral silanes are formed in this reaction, both of which are products of anti-Markovnikov addition. The major product is the expected dichlorosilane 3, while the byproduct is an anomalous chlorosilane 4 both products were separated by fractional distillation and the major product methylated to give the trimethylsilanes 56 7. 

The main processes for the manufacture of hydroxybenzaldehydes are based on phenol. The most widely used process is the saligenin process. Saligenin (2-hydroxybenzyl alcohol [90-01-7]) and 4-hydroxybenzyl alcohol [623-05-2] are produced from base-catalyzed reaction of formaldehyde with phenol (35). Air oxidation of saligenin over a suitable catalyst such as platinium or palladium produces sahcylaldehyde (62). 

Degussa Also called BMA. The process by which this large German company is best known is its version of the Andrussov process for making hydrogen cyanide. Methane and ammonia are reacted in the absence of air, at approximately 1,400°C, over a platinium metal catalyst ... 

The advantages of this catalyst are that it is cheaper and less delicate than platinium, fairly large quantities of organic substrate may be hydrogenated and the process is reasonably rapid. The following method gives a catalyst of moderate activity (W2 Raney nickel). 

Conversion of an alkene (or an alkyne) into an alkane is readily achieved by shaking it under hydrogen at room temperature and at atmospheric pressure in the presence of a platinium or palladium catalyst. With a Raney nickel catalyst somewhat higher temperatures and pressures are employed (see Section 2.17.1, P- 88). 

At last, Hamaide et al. described also shortly their attempts for performing directly the hydrosilylation without protective groups. In addition to incompatible solubilities, they observed up to 50% 0-silylation, instead of C-silylation with Karstedt s catalyst (Platinium divinyltetramethyldisiloxane complex) [21]. 

Stereoselective introduction of a silyl moiety may also be realized by intramolecular hydrosilylation, for example, using a silyl group anchored to a neighboring hydroxy group in the presence of a transition metal catalyst such as platinium or rhodium. This reaction has been used for the stereoselective synthesis of 1,3-diols 9—11Sc. 

Hydrogenation of nitroaromatic compounds was performed by W. Theilacker and Coll, in Anisole with platinium as catalyst (ref. 8). 

Catalysts which are in a different phase as the reactants (usually a solid catalyst speeding up reactants in a solution or gaseous mixture) are termed heten eneous catalysts. Industrially important heterogeneous catalysts include solid nickel, platinium and rhodium. These catalysts work by allowing reactant molecules to stick (adsorb) to the surface of the metal catalyst, so causing the bonds between atoms in the reactant molecules to weaken, making molecular rearrangement easier. 

Polymerization of Silanes with Platinium Metal Catalysts 555... 

Acres,G.J.K., A.J.Bird and P.J.DavTdson. Recent developments in platinium metal catalyst systems". Chem.Engr. (London) No 283 (1974) 145-158. 

The addition cure mechanism, known as hydrosilylation reaction cf. Figure 7.2 [38]), involves the transformation of silicon hydride (Si-H) groups to an unsaturated C-C bond (vinyl/alkenyl functionality) in presence of nobel metal catalyst (platinium, palladium, rhodium, etc.) [34, 38]. 

Supported metalloporphyrins have also been synthesized by electropolymerization leading to films of polymers. They were formed on the platinium working electrode during the oxidative electrosynthesis (Scheme 49) [98], Contrary to the preceding catalysts 102 and 103, these electropolymerized catalysts led to low enantioselectivities for the bench-mark reaction between styrene and EDA. Up to 53% ee at - 40°C was reached in the presence of 105 a. Moreover, at room temperature, the reactions proceeded efficiently (yields 80-90%). Seven recycling of polymer 105a were carried out without a significant decrease in enantioselectivity and activity. 

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