Catalytic hydrogenation cyclohexene

Other methods for the preparation of cyclohexanecarboxaldehyde include the catalytic hydrogenation of 3-cyclohexene-1-carboxaldehyde, available from the Diels-Alder reaction of butadiene and acrolein, the reduction of cyclohexanecarbonyl chloride by lithium tri-tcrt-butoxy-aluminum hydride,the reduction of iV,A -dimethylcyclohexane-carboxamide with lithium diethoxyaluminum hydride, and the oxidation of the methane-sulfonate of cyclohexylmethanol with dimethyl sulfoxide. The hydrolysis, with simultaneous decarboxylation and rearrangement, of glycidic esters derived from cyclohexanone gives cyclohexanecarboxaldehyde. 

Treatment of the piperidine 74, obtainable from an aminonitrile such as 73, under N-methylation conditions leads to the dimethylamino derivative 75. The carbobenzoxy protecting group is then removed by catalytic hydrogenation. Reaction of the resulting secondary amine 76 with cyclohexene oxide leads to the alkylated trans aminoalcohol. There is thus obtained the anti-arrhythmic agent transcainide (77) [18]. 

Assume that you are in a laboratory carrying out the catalytic hydrogenation of cyclohexene to cyclohexane. How could you use a mass spectrometer to determine when the reaction is finished ... 

The catalytic hydrogenation of alkenes by mixed NHC/phosphine complexes of rhodinm was also stndied. Initial resnlts of the hydrogenation of cyclohexene by /ranx-[RhCl(ICy)(L)2] (ICy = M/V -(dicyclohexyl)imidazol-2-ylidene, L = PPhj. 

Finke has reported remarkable catalytic lifetimes for the polyoxoanion- and tetrabutylammonium-stabi-lized transition metal nanoclusters [288-292]. For example in the catalytic hydrogenation of cyclohexene, a common test for structure insensitive reactions, the lr(0) nanocluster [296] showed up to 18,000 total turnovers with turnover frequencies of 3200 h [293]. As many as 190,000 turnovers were reported in the case of the Rh(0) analogue reported recently. Obviously, the polyoxoanion component prevents the precious metal nanoparticles from aggregating so that the active metals exhibit a high surface area [297]. 

Catalytic hydrogenation of azo compounds over Pt or Ra-Ni often leads to hydrogenolysis. 551 Catalytic transfer hydrogenolysis using cyclohexene and Pd is also used for the conversion of azobenzenes to anilines.552... 

Conversion of benzene to cyclohexene by partial catalytic hydrogenation is a very important industrial process, since it provides a new route to cyclohexanol, a precursor of nylon, when combined with hydration of cyclohexene. For example, Asahi Chemical Company of Japan developed a selective bilayer catalytic system including a Ru catalyst, Zr02 and ZnS04 under 50 atm of H2 pressure, a process affording the olefin with up to 60% selectivity after 90% conversion of benzene.72... 

The same authors also reported the dispersion of palladium nanoparticles in a water/AOT/n-hexane microemulsion by hydrogen gas reduction of PdClJ and its efficiency for hydrogenation of alkenes in organic solvents [79]. UV-visible spectroscopy and TEM analysis revealed the formation of Pd nanoparticles with diameters in the range of 4 to 10 nm. Three olefins (1-phenyl-l-cyclohexene, methyl trans-cinnamate, and trans-stilbene) were used as substrates for the catalytic hydrogenation experiments under 1 atm of H2 (Table 9.12). All of the Start-... 

Apart from the reaction of cyclohexanecarboxylic acid with methyllithium, cyclohexyl methyl ketone has been prepared by the reaction of cyclohexylmagnesium halides with acetyl chloride or acetic anhydride and by the reaction of methylmagnesium iodide with cyclohexanecarboxylic acid chloride. Other preparative methods include the aluminum chloride-catalyzed acetylation of cyclohexene in the presence of cyclohexane, the oxidation of cyclohexylmethylcarbinol, " the decarboxylation and rearrangement of the glycidic ester derived from cyclohexanone and M)utyl a-chloroj)ropionate, and the catalytic hydrogenation of 1-acetylcycIohexene. "... 

Pd- and Pt-nanoparticles protected by PS-b-PMAA were used to perform catalytic hydrogenations of cyclohexene in ethanol as solvent It could be shown that such colloids are catalytically active and thus interesting for the development of catalysts tailored for special reactions. 

Protons present in aqueous acid also act as reasonably efficient electron acceptors. If the reduced hydrogen atoms are formed on metallized suspensions, catalytic hydrogenation can result. For example, in contrast to the oxidative chemistry reported earlier for cyclohexene-4,5-bis-dicarboxylic acid (Eq. 28), if the reaction is conducted in the absence of oxygen in aqueous nitric acid, catalytic hydrogenation of the double bond becomes a major pathway, Eq. (34). ... 

Catalytic hydrogenation of benzene cannot be stopped at cyclohexene or cyclohexadiene it proceeds to cyclohexane. This is because the rate of the first addition step is much slower than of the subsequent steps ... 

Furthermore, one of the hitherto unknown two pseudo-sugars, pseudo-P-DL-ido-pyranose (77) was synthesized from readily accessible (l,2,4/3)-5-(hydroxymethyl)-5-cyclohexene-l,2,3,4-tetrol (75) [24], Catalytic hydrogenation of 75 in the presence of platinum catalyst gave pseudo-p-DL-idopyranose pentaacetate (76) after acetylation. 

Catalytic hydrogenation of benzene is the commercial method for producing cyclohexane and substituted cyclohexane derivatives. The reduction cannot be stopped at an intermediate stage (cyclohexene or cyclohexadiene) because these alkenes are reduced faster than benzene. 

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