Cyclohexene hydrogenolysis

The tungsten carbides on FSM-16 were prepared in carburizing of WO3/FSM-I6 with 20% CH4/H2 and characterized using nitrogen adsorption, XRD, TEM, and NMR. The relationship between the surface properties and the catalytic activity of tungsten carbides on FSM-16 in cyclohexene hydrogenolysis at 250°C was discussed. 

PdO, cyclohexene, methanol, 30 min for a primary ROH, 90-95% yield. Secondary alcohols require longer times. The primary TBDPS and TIPS groups are cleaved much more slowly (18-21 h). Benzylic TBDMS ethers are cleaved without hydrogenolysis. ... 

Transfer hydrogenolysis using Pd/C and cyclohexene has been used for de-N-benzylation in peptide synthesis. This process, however, is not suitable... 

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... 

In 2004 Caporali investigated the hydroformylation of 1-hexene and cyclohexene using HRh(CO)(PPh3)3 [61]. The collected data indicated that the rate-determining step in the hydroformylation cycle depends upon the structure of the olefin. With an alpha-olefin like 1-hexene, the slowest step seems to be the hydrogenolysis of the acyl rhodium complex. In the presence of cyclohexene as a model for an internal olefin, the rate-determining step is the reaction of the olefin with the rhodium hydride complex (intermediate II in Fig. 6). 

AUylic ethers were reduced by treatment with lithium in ethylamine to alkenes [636]. Benzyl ethers are hydrogenolyzed easily, even more readily than benzyl alcohols [637], 3,5-Bis(benzyloxy)benzyl alcohol gave 3,5-dihydroxy-benzyl alcohol on hydrogenation over palladium on carbon at room temperature and atmospheric pressure in quantitative yield [638. Hydrogenolysis of benzylic ethers can also be achieved by refluxing the ether with cyclohexene (as a source of hydrogen) in the presence of 10% palladium on carbon in the presence of aluminum chloride [639]. 

Vinylamines (enamines) are reduced by alane, mono- and dichloroalane to saturated amines, and hydrogenolyzed to amines and alkenes [710]. Reduction is favored by dichloroalane while hydrogenolysis is favored by alane. Alane, chloroalane and dichloroalane gave the following results with -N-pyrrolidinylcyclohexene V-pyrrolidinylcyclohexane in 13, 15 and 22% yield, and pyrrolidine and cyclohexene in 80, 75 and 75% yields, respectively [710]. Saturated amines were also obtained by treatment of enamines with sodium borohydride [711], with sodium cyanoborohydride [103, 712] (Procedure 22, p. 210) and by heating for 1-2 hours at 50-70° with 87% or 9S% formic acid (yields 37-89%) [320]. 

The hydrogenolysis of EtaSiH over silica-supported Pd and Pt catalysts resulted in significant poisoning, specifically, the loss of activity in the hydrogenation of cyclohexene.375 Oxidation, however, fully restored the activity of catalysts with small metal particles (>50% dispersion) as a result of surface reconstruction. 

Similarly to alkyl fluorides, fluorocyclohexane is resistant toward catalytic hydrogenolysis. Hydrides and metals appear to be more efficient in the hydrodefluorination of alicyclic fluorine-containing compounds. Butyllithium in refluxing hexane defluorinates fluorocyclohexane to cyclohexane.20 The complete defluorination of fluorocyclohexane (11) is accomplished by activated magnesium in propan-2-ol, but the reaction leads to the predominant formation of cyclohexene.21... 

Even though n-hexane is a minority hydrogenolysis product, it is a reliable measure of the degree of hydrogenolysis because of its ease of mass spectro-metric detection and it is not formed in a background reaction with the walls of the reaction chamber. Besides the saturated hydrogenolysis products and benzene, we found the olefinic products cyclohexene, ethylene, and propylene. Cyclohexene is an intermediate in the dehydrogenation to benzene and its various reactions will be discussed separately in the next section. The olefinic product distribution of ethylene propylene cyclohexene benzene is 10 1 0.5 1. 

C. Dehydrogenation and Hydrogenolysis of Cyclohexene on Platinum Crystal Surfaces at Low Pressures (35)... 

In a series of studies, the dehydrogenation and hydrogenolysis of cyclohexane was studied on both the stepped and low Miller index (111) crystal faces of platinum at a surface temperature of 300°C and a hydrogen to cyclohexane ratio of 20 1. While the rates on the stepped and low Miller index surfaces were not very different for the formation of benzene and hexane, the formation of cyclohexene was very structure sensitive, its rate being 100 times greater on the stepped surface than on the (111) crystal face. In Table III mrnnare the initial turnover numbers for the various reactions at low... 

Hydrogenolysis of the benzyl group of 9-benzyloxy-4//-pyrido[ 1,2-a]pyrimidin-4-ones 336 in ethanol over 10% palladium-on-charcoal under pressure of hydrogen (3 atm), or in the presence of cyclohexene and 10% palladium hydroxide, afforded 9-hydroxy derivatives 337 in 25-30% and 78% yield, respectively (89TL1529 91JHC1287). 

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