Hydrogenations with CO

As mentioned earlier, the slow step in WGSR is often the liberation of H2 and in the presence of a suitable reducible substrate the intermediate metal-(mono)hydrides may show fast reactions. Appropriate substrates can be the various nitro-compounds, which are reduced in one-electron steps, or the hydrogenolysis of C-Cl or C-OH bonds. Several papers describe the 

In a true biphasic system (i.e. with no PTC agent) with toluene as the organic phase, nitrobenzene and nitrotoluene were reduced with high efficiency with CO + H20 catalyzed by RhCl3.3H20, [Rh CO ] or [ RhCl(l,5-hexadiene) 2] (12 mol aniline/mol Rh.h, at room temperature and 1 bar CO) [364], Other nitroarenes reacted similarly, however, no or only negligible reaction took place with nitroaliphatics. Nitrobenzene is the standard substrate in such reactions, its reduction to aniline was also catalyzed by c/s-[Rh(CO)2(2-picoline)2]PF6 [365] and analogous cis-[Rh(CO)2(amine)2]PF6 complexes immobilized on poly(4-vinylpyridine) [366], 

Similarly selective hydrogenation of aromatic nitro groups was achieved [368] with [Ru3(CO)i2] as catalyst precursor in the presence of small amounts of certain amines (HN Pr2, HNBu2, NEt2 and piperidine). Other unsaturated groups such as C= 0, C=N, C=C and C=C were not effected at 

Comils, W. A. Herrmann, eds., Aqueous-Phase Organometallic Catalysis, Wiley-VCH, Weinheim, 1998 

Seidell, Solubilities of Inorganic and Metal-Organic Compounds, American Chemical Society, Washington, D.C., USA, 1958, Vol. I. p. 1075 

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Alkyl ketones can be prepared by the carbonylation of alkyl iodides in the presence of organoboranes. The carbonylation of iodocyclohexane with 9-octyl-9-BBN at 1 atm gives cyclohexyl octyl ketone in 65% yield[386]. This reaction is treated in Section 1.1.3.3. Methyl o-methylacetoacetate (919) is obtained by the reaction of the 2-bromopropionate 918, which has a /9-hydrogen, with CO and Me4Sn. PhjAs as a ligand gives better results than Ph3P[771]. 

The important reactions of atomic hydrogen with CO and H2CO are subject to a considerable activation barrier in the gas phase 1,000 K). It has been proposed... 

The water gas shift reaction and hydrogenations with CO-H2O mixtures... 

Hydrogenations with [Co(CN)5]3 as catalyst have been long thought to involve radical reactions. Hydrogen is activated prior to reaction with the alkene, the mechanism involving homolytic fission by two [Co(CN)5]3 ions (Scheme 3).54... 

Industrial Chemicals Co. on biphasic catalysis can be found in a 1962 edition of the Journal of the American Chemical Society describing hydrogenations with [Co(CN)5H]3 under aqueous-organic conditions.161 Although we are not yet aware of any publication prior to that, it is highly likely that biphasic catalysis has a longer history than thought until recently. Yet, it was the systematic studies of Joo and Manassen that really laid the foundations to the field. 

The reaction of hydrogen with CO forms the basis of an industrial process for making methanol carried out at high pressure over a mixed copper-zinc catalyst. Though CO is insoluble in, and unrcactive with, water at ordinary pressures, formic acid is produced at very high pressures. Under similar conditions CO and aqueous NaOH combine to give sodium formate. 

Morkel M, Rupprechter G, Freund H-J (2005) Finite size effects on supported Pd nanoparticles Interaction of hydrogen with CO and C H. Surf Sci Lett 588 L209... 

Atom-molecule reactions of hydrogen with COS, ° of carbon with CO, CS, and CS2, of argon with COS, and of barium with C02 have... 

PTC Reduction and Hydrogenation with CO and H2 Using Metal Carbonyls or Complexes... 

PT-catalyzed reductions and hydrogenations with CO and H2 in the presence of metal carbonyls or complexes and TAA salts are described in the next section. 

Phase-Transfer Catalyzed Reduction and Hydrogenation with CO and H2 Using Metal Carbonyls or Complexes. Reduction of organic compounds with metal carbonyls or with CO or H2 catalyzed with metal complexes— an important tool in organic synthesis—often proceeds more selectively, faster and under milder conditions when executed under PTC conditions (eqs. 198-200). 

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