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Platinum nitriles

Hydrogenation Catalysts. The key to catalytic hydrogenation is the catalyst, which promotes a reaction which otherwise would occur too slowly to be useful. Catalysts for the hydrogenation of nitro compounds and nitriles are generally based on one or more of the group VIII metals. The metals most commonly used are cobalt, nickel, palladium, platinum, rhodium, and mthenium, but others, including copper (16), iron (17), and tellurium... [Pg.258]

Platinum, palladium, and rhodium will function well under milder conditions and are especially useful when other reducible functions are present. Freifelder (23) considers rhodium-ammonia the system of choice when reducing -amino nitriles and certain )5-cyano ethers, compounds that undergo extensive hydrogenolysis under conditions necessary for base-metal catalysis. [Pg.97]

Catalysts show remarkable product variation in hydrogenation of simple nitriles. Propionitrile, in neutral, nonreactive media, gives on hydrogenation over rhodium-on-carbon high yields of dipropylamine, whereas high yields of tripropylamine arise from palladium or platinum-catalyzed reductions (71). Parallel results were later found for butyronitrile (2S) and valeronitrile (74) but not for long-chain nitriles. Good yields of primary aliphatic amines can be obtained by use of cobalt, nickel, nickel boride, rhodium, or ruthenium in the presence of ammonia (4J 1,67,68,69). [Pg.97]

Reductions of nitronitriles situated to favor interaction are apt to involve both functions (S4,93). Hydrogenation of o-nitrobenzonitrile over either palladium or platinum gave o-aminobenzamide (78), with the amide oxygen transferred from the nitro group (66). On the other hand, l-amino-2-cyanonaphthalene gave the amino amide on reduction over Pt02, but the amino nitrile over palladium (82). [Pg.110]

Hydrogenation of 3 over 10% Pd-on-C led to the expected cyanoamine (4), the amide (5), the lactam (7), as well as 6, in which the nitrile carbon is lost (5. ). The nitrile function is lost before formation of the amine, for 4 resists reduction. A somewhat different distribution is obtained over Pt02, as expected, and accords with the tendency of platinum to produce more intermediate hydroxylamine (82). [Pg.110]

By selection of conditions and catalyst, the intermediate hydroxyimine (11) can be directed to either (he hydroxy ketone (10) or amino alcohol (12), Over platinum oxide in methanol-acetic acid-water the amino alcohol forms, whereas over alkali-free Ra-Ni in methanol-water or over 10% Pd-on-C in methanol-water containing boric acid, the hydroxy ketones form in excellent yield. Nitrile oxide cycloadditions have been applied to five-membered ring syntheses (.50). [Pg.142]

In a study of the hydrolysis of platinum(II)-nitrile complexes to afford the corresponding amides, the first well-characterized examples of platinum(II) complexes that dimerize spontaneously to form weakly bonded Pt-Pt dimers with an unsupported intermetallic bond have been described.166 For example, treatment of cw-[PtCl2(NCBut)2] with excess KOH affords the amide species cw-[PtCl2 HN=C(OH)But 2], which exists as a dimer (49) both in solution and in the solid state, with a Pt-Pt bond length of 3.165(1) A, as determined by X-ray crystallography. Four... [Pg.695]

Numerous examples of nucleophilic attack on coordinated nitrile ligands are found in the literature, particularly when the transition metal is platinum(II).224 The nucleophilic attack of two equivalents of CIO I2CII20 on the electrophilic nitrile carbon atoms of both nitrile ligands in cis-or /r<7H.v-[PtC12(RCN)2] (R = Et, Prn, Pr1, Bu p-CF3C6H4, p- and o-MeC6H4) affords the corresponding A2-l,3-oxazoline complexes ((76) and (77), respectively), in which the heterocycle acts as a... [Pg.701]

The palladium-catalyzed C-Se bond formation79-81 and the platinum-catalyzed carboselenation of alkynes with selenoesters have been reported in analogy with the thiolate chemistry. An electron-withdrawing or electron-donating group on the aromatic residue leads to the formation of the desired carboselenation product with acceptable yields. Functionalities like benzyl, hydroxyl, or nitrile group are tolerant with the reaction conditions. This method provides a new access to the functionalized vinylselenide 60,82 molecules of interest as key intermediate (Scheme 19) 85... [Pg.308]

Secondary phosphine oxides are known to be excellent ligands in palladium-catalyzed coupling reactions and platinum-catalyzed nitrile hydrolysis. A series of chiral enantiopure secondary phosphine oxides 49 and 50 has been prepared and studied in the iridium-catalyzed enantioselective hydrogenation of imines [48] and in the rhodium- and iridium-catalyzed hydrogenation functionalized olefins [86]. Especially in benzyl substituted imine-hydrogenation, 49a ranks among the best ligands available in terms of ex. [Pg.1011]

Isomorphic monomers, 19 762 Isoniazid, 25 798 Isonicotinic hydrazide, 21 103 Isonitrile complexes, platinum, 19 656 Isonitrile-nitrile rearrangement, 21 149 Isononanoic acid, physical properties, 5 35t Isononyl alcohol, properties of commercial, 2 12t... [Pg.496]

The functionalized dichlorosilane monomers are synthesized generally by radical addition of dichloro-methylsilane to an unsaturated carboxylic acid ester or an unsaturated nitrile. Catalysts used for this purpose are platinum/charcoal (Jl 0,J 1 ), or organic peroxides (T2), but for laboratory syntheses hexachloroplati-nic acid (13,14) proved to be most convenient (scheme 1 a). ... [Pg.343]

Selective reduction of the nitrile group in 87% yield without the reduction of the carbonyl was achieved by stannous chloride [1153]. Oximes of keto nitriles are reduced preferentially at the oximino group by catalytic hydrogenation in acetic anhydride over 5% platinum on carbon (yield 85%)... [Pg.175]

A combination of bromide ions and methyl octyl sulphide is able to oxidise secondary alcohols at the potential necessary to fonn bromine. Conversion of the alcohol to the ketone follows the Scheme 8.2 and uses an undivided cell with benzo-nitrile as the solvent containing 2,6-lutidine as base and tetraethylamnionium bromide. The reaction occurs using a platinum anode at 1.1 V vs-, see [28], Thio-anisole alone, in absence of bromide, will function as a catalyst for the oxidation of secondary alcohols but in these cases a more positive anode potential of 1.5 V vs. see is needed to oxidise the thioether [29]. [Pg.265]

Williams group observed low enantioselectivities for the Michael addition of a prochiral nucleophile, ethyl 2-cyanopropionate 623, to methyl vinyl ketone 624 catalyzed by chiral platinum complexes (Scheme 8.196)." The NMR analysis indicated that these cationic Pt complexes act as Lewis acids toward nitriles. The X-ray crystal structure as well NMR analysis showed that the solvent ligand that is readily displaced by an organic substrate is situated cis to the nitrogen donor in the Pt complex and, therefore, is in a chiral pocket created by the oxazoline ring. [Pg.504]

Asahi Chemical Industries KK have patented [25] a process for the fluorina-tion of benzene using a nitrile solvent, a base salt, typically (n-C4H9)4NF 3HF, at a rhodium anode, said to be superior to platinum in corrosion resistance and performance. [Pg.204]

DSM jointly with Du Pont de Nemours308 have patented platinum catalysts generated from the water soluble sulfonated ligand 30 (Table 2 m=0, n=0, m=l, n=2 m=l, n=l, Ar=nBu-S03Li) and used in the aqueous phase hydroformylation of internally unsaturated carboxylic acids, esters or nitriles to their corresponding formyl derivatives which are useful intermediates for the preparation of di-carboxylic acids (e.g. adipic acid). For example, TOFs up to 105 h-1 were achieved in the hydroformylation of 3-pentenoic acid catalysed by Pt/30 (m=0, n=0) at 100°C and 80 bar CO/H2 to give aldehydes with a selectivity of 83% (n/i=3.4), valeric acid (4.6%) and adipic acid (8.1%).308 The products were separated from the aqueous catalyst solution by extraction with ether. Five recycles of the aqueous catalyst solution showed that the Pt/30 (m=0, n=0) catalyst retains its activity. [Pg.152]


See other pages where Platinum nitriles is mentioned: [Pg.184]    [Pg.200]    [Pg.220]    [Pg.82]    [Pg.130]    [Pg.284]    [Pg.97]    [Pg.99]    [Pg.23]    [Pg.199]    [Pg.257]    [Pg.30]    [Pg.343]    [Pg.183]    [Pg.730]    [Pg.251]    [Pg.239]    [Pg.299]    [Pg.16]    [Pg.69]    [Pg.70]    [Pg.32]    [Pg.25]    [Pg.175]    [Pg.280]    [Pg.120]    [Pg.248]    [Pg.34]    [Pg.387]    [Pg.224]   
See also in sourсe #XX -- [ Pg.494 ]




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