Methyl cyclohexene, hydrogenation

In contrast to 1,2-dimethylcyclohexene, methyl cyclohexene-1,2-dicarboxylate was reported to yield only the cis saturated product in the hydrogenation over platinum oxide in acetic acid at 26-27°C, independently of the pressure of hydrogen (0.1-20 MPa) and the concentration of the substrate (0.05-1,0M).140 Hydrogenation of methyl cyclohexene-1,6-dicarboxylate also gave the same result at about 1 atm H2, but some of the trans isomer (6+2%) was formed at a pressure of 13 MPa H2. 

The partial hydrogenation of benzene and of toluene over ruthenium catalysts - the effect of salt addition on the selectivity to (methyl-)cyclohexenes... 

A study has been made of the batch-wise partial hydrogenation of benzene and of toluene to cyclohexene and the methyl-cyclohexenes, respectively, over ruthenium as a catalyst in the presence of an aqueous zinc sulphate solution. The reaction has been performed in a stirred autoclave at 423 K and at a total pressure of 5.0 MPa. Both the hydrogenation rates of benzene and of toluene are governed by diffusion processes, which can be shown by applying the Carberry and Wheeler-Weisz criteria. The high selectivities and yields of cyclohexene and methylcyclohexenes are mainly explained by mass transfer limitation of hydrogen and cyclic alkenes towards the active catalyst surface. The lower toluene hydrogenation rate can be explained from the lower solubility of toluene in water as compared to benzene. 

The initial selectivities to (methyl-)cyclohexenes in the hydrogenation of benzene and toluene. = initial selectivities in the competitive hydrogenation as shown in Fig.3. 

M. Soede, E.J.A.X. van de Sandt, J. Struijk, M. Makkee and J.J.F. Scholten, "The partial hydrogenation of benzene and of toluene to (methyl-)cyclohexenes over modifled ruthenium catalysts" in M.P.C. Weijnen and A.A.H. Drinkenbuig (eds.). Precision Process Technology , Kluwer Acadamic, Dordrecht, 219-224. 

The reaction of cyclohexene over differently dealuminated H-Y samples at 370 K (isomerization to methylcyclopentene and hydroisomerization to methyl-cyclopentane, hydrogen transfer resulting in benzene and cyclohexane, cracking and coke formation) was monitored by Joly et al. [904] via in-situ IR spectroscopy in an IR flow-reactor cell coupled with a gas chromatograph. A good correlation was reported between the activity of the Bronsted acid sites and their strength... 

Basic metal oxides are active in diene hydrogenation to mono-olefins. MgO prepared from Mg(0H)2 by calcination at 1373K is highly selective in butadiene hydrogenation to cis-2-butene. A-isopropenyl-methyl-cyclohexene in the... 

In this process, cyclohexene is mixed with aqueous 30% hydrogen peroxide, and sodium tungstate and methyl-trioctylammonium hydrogen sulfate are added to the resulting two-phase system. (Cyclohexene is insoluble in water.) Under these conditions, cyclohexene is oxidized to adipic acid in approximately 90% yield. 

Catalytic activity tests for cyclohexene hydrogenation were carried out for 3 hours at 60 °C in a Parr reactor (40 mL), magnetically stirred (1100 rpm), using about 30 mg of the hybrid catalyst, 10 mL of a 5 vol.% of a cyclohexene methanol solution and 10 bar H2. In the case of the homogeneous test, 0.8 mg (2 pmol) of the Rh(NN)Si complex was used. Product analysis was performed by Gas Chromatography (HP6890 Series II, capillary column HP-1 Methyl Siloxane, 30 m x 250 pm x 0.25 pm, FID detector) after each catalytic run. 

Among the cases in which this type of kinetics have been observed are the addition of hydrogen chloride to 2-methyl-1-butene, 2-methyl-2-butene, 1-mefliylcyclopentene, and cyclohexene. The addition of hydrogen bromide to cyclopentene also follows a third-order rate expression. The transition state associated with the third-order rate expression involves proton transfer to the alkene from one hydrogen halide molecule and capture of the halide ion from the second ... 

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]. 

If the hydroxy-acid is heated with hydrobromic acid, it is converted into l-methyl-l-bromocyclohexane-4-carboxylic acid, and this is decomposed by boiling with sodium carbonate with loss of hydrogen bromide and with formation of 1-methyl-A cyclohexene-4-carboxyhc acid—... 

The rate of transfer hydrogenation also varies markedly with donor structure. For cyclohexene, 1 -methylcyclohexene, l-methyl-4-isopropyl-cyclohexene,and l-methyl-4-f-butyIcycIohexene as donor in the above hydrogenations, after 1 min the reduction was 11, 78, 99, and 99% complete, respectively (97). 

We have shown that a number of aliphatic ethers, containing steric-ally accessible p-hydrogen atoms, are cleaved in good yield when the tetrahalogenoanthranilic acids are diazotised in ethers 128,59). Diethyl ether is cleaved to the tetrahalogenophenetole (90) and methyl-cyclohexyl ether affords the tetrahalogenoanisole. In this latter reaction we were able to detect cyclohexene and therefore a plausible, but as yet unproved, mechanism is as shown. 

Tetrahydrobenzyl alcohol (( )3-cyclohexenene-l-methanol) and 30% aqueous hydrogen peroxide were purchased from Fluka, AG. 3-Cyclohexene-1-carboxylic acid and cis-4-cyclohexene-l,2-dicarboxylic acid were used as purchased from Lancaster Chemical Co. Methyl iodide, acetic anhydride, Oxone (potassium peroxymonosulfate), Aliquot 336 (methyl tri-n-octylammonium chloride), sodium tungstate dihydrate and N,N-dimethylaminopyridine (DMAP) were purchased from Aldrich Chemical Co. and used as received. 3,4-Epoxycyclohexylmethyl 3, 4 -epoxycyclohexane carboxylate (ERL 4221) and 4-vinylcyclohexene dioxide were used as purchased from the Union Carbide Corp. (4-n-Octyloxyphenyl)phenyliodonium hexafluoroantimonate used as a photoinitiator was prepared by a procedure described previously (4). 

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