Hydrogen from cyclohexane

Assuming all alkoxy radicals abstract hydrogen from cyclohexane at the same rate, and that there is no interference by chlorine atom chains in the hypochlorite decompositions. See Reference c. 

It may be concluded that the role of the deutero-chloric acid in the ethylation reaction is that suggested by Equations 7 and 8. The deuterivun chloride acts as a chain transfer agent by terminating the cycle and yielding a chlorine atom which initiates a new cycle by abstracting hydrogen from cyclohexane ... 

Triplet diphenylcarbene, detected spectroscopically on excimer laser flash photolysis of diphenyldiazomethane, readily abstracts hydrogen from cyclohexane to give the CHPh2 radical.Analogous hydrogen abstraction also occurs from alcohols but at low temperatures and in a polycrystalline matrix in contrast to reaction in solution in which O-H bond insertion is preferred. In a similar fashion, irradiation of diphenyldiazomethane in polycrystalline (S)-butan-2-ol at — gave amongst other products an enantiomerically pure... 

The 0x0 species abstracts a hydrogen from cyclohexane to form Fe" -OH and c clohexyl radical which rebounds at rates as high as lO /sec to form cyclohexanol and Fe porphyrin is regenerated". Even though free radicals are involved, the oxidation is not a chain reaction and it does not involve alkyl peroxide radicals as in the commercial processes described earlier. 

Reduction of enones and bicyclic phenols. French chemists have reported transfer of hydrogen from cyclohexane to enones and phenols in this super acid. The products are the more stable isomers. This method has obvious advantages over Li-NHa for reduction of bicyclic phenols. 

The propagation step in this free radical polymerization has been demonstrated to involve radical attack on episulfide sulfur (as depicted above) by telomerization studies with cyclohexane. From the structures of the two major products, 20 and 21, cyclohexyl radical attacks at the sulfur atom by displacing fluoroalkyl radical. This new radical, a prototype of the growing polymer chain, then abstracts hydrogen from cyclohexane to form 20 or attacks another molecule of 6 (n = 1) at sulfur to give 21. 

Frcc-Radical Reactions. Eree-radical reactions of maleic anhydride are important in polymeri2ations and monomer synthesis. Nucleophilic radicals such as the one from cyclohexane [110-82-7] serve as hydrogen donors that add to maleic anhydride at the double bond to form cyclohexylsuccinic anhydride [5962-96-9] (20) (63). 

Caprolactam [105-60-2] (2-oxohexamethyleiiiiriiQe, liexaliydro-2J -a2epin-2-one) is one of the most widely used chemical intermediates. However, almost all of the aimual production of 3.0 x 10 t is consumed as the monomer for nylon-6 fibers and plastics (see Fibers survey Polyamides, plastics). Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation (see Cyclohexanoland cyclohexanone). Reaction with ammonia-derived hydroxjlamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring S-caprolactam. 

A route to phenol has been developed starting from cyclohexane, which is first oxidised to a mixture of cyclohexanol and cyclohexanone. In one process the oxidation is carried out in the liquid phase using cobalt naphthenate as catalyst. The cyclohexanone present may be converted to cyclohexanol, in this case the desired intermediate, by catalytic hydrogenation. The cyclohexanol is converted to phenol by a catalytic process using selenium or with palladium on charcoal. The hydrogen produced in this process may be used in the conversion of cyclohexanone to cyclohexanol. It also may be used in the conversion of benzene to cyclohexane in processes where benzene is used as the precursor of the cyclohexane. 

That material was hydrogenated in cyclohexane using a Raney nickel catalyst. The product after distillation was recrystallized from ethyl acetate affording 10.0 g of 6-ethyl-6-(m-meth-oxyphenyl)hexahydro-2H-azepin-2-one, MP87°C to 88°C. 

Sodium methoxide (1.2 g) in dimethylformamide (150 ml) was stirred with 3,5-dim ethoxy-4 reaction mixture was then treated with /3-morpholinoethyl chloride (3.4 g) and heated for 1 hour at 140°C, then evaporated to dryness, and treated with water to give a solid material. The mixture was filtered, washed and crystallized from cyclohexane to give 3,5-di-methoxv-4 -chloro-4-( morpholinoethoxy)-benzophenone (6.5 g), MP 91°C to 92°C. The product was then reacted at about 0°C with gaseous hydrogen chloride in ether to give, after crystallization from isopropanol, the corresponding hydrochloride which hada MPof 187.9°C. 

The first step in producing caprolactam from benzoic acid is its hydrogenation to cyclohexane carboxylic acid at approximately 170°C and 16 atmospheres over a palladium catalyst ... 

The production of alcohols by the catalytic hydrogenation of carboxylic acids in gas-liquid-particle operation has been described. The process may be based on fixed-bed or on slurry-bed operation. It may be used, for example, for the production of hexane-1,6-diol by the reduction of an aqueous solution of adipic acid, and for the production of a mixture of hexane-1,6-diol, pentane-1,5-diol, and butane-1,4-diol by the reduction of a reaction mixture resulting from cyclohexane oxidation (CIO). 

Type 66 nylon is a polyamide first commercialized by DuPont just prior to World War II. At that time, the needed hexamethylenediamine was made from adipic acid by reaction with ammonia to adiponitrile followed by reaction with hydrogen. The adipic acid then, like now, was made from cyclohexane. The cyclohexane, however, was derived from benzene obtained from coal. The ammonia was made from nitrogen in the air by reaction with hydrogen from water obtained in the water-gas shift reaction with carbon monoxide from the coal. So, in the 1950s, nylon was honestly advertised by DuPont as being based on coal, air, and water. 

Hexamethylenediamine (HMDA), a monomer for the synthesis of polyamide-6,6, is produced by catalytic hydrogenation of adiponitrile. Three processes, each based on a different reactant, produce the latter coimnercially. The original Du Pont process, still used in a few plants, starts with adipic acid made from cyclohexane adipic acid then reacts with ammonia to yield the dinitrile. This process has been replaced in many plants by the catalytic hydrocyanation of butadiene. A third route to adiponitrile is the electrolytic dimerization of acrylonitrile, the latter produced by the ammoxidation of propene. 

Source Based on Saito, Y., Hodoshima, S., Shono, A., and Otake, K., Hydrogen production from cyclohexane and hydrogen production. Proceedings of 9th Asian Hydrogen Energy Conference, Tokyo, 2007. 

Because large quantities of unsaturated organic compounds are obtained by removing hydrogen from saturated hydrocarbons, these processes are also important in production of hydrogen commercially. In one of these processes, hexane is converted to cyclohexane by the reaction... 

BenSat [Benzene saturation] A process for removing benzene from C5 to C6 petroleum fractions by selective hydrogenation to cyclohexane. Developed by UOP, based on its HB Unibon process, and first offered for license in 1991. 

PNC [Photonitrosation of cyclohexane] A photochemical process for making caprolactam (a precursor for nylon) from cyclohexane, nitrosyl chloride, and hydrogen chloride. The first photochemical product is cyclohexanone oxime ... 

RADIATION-RESISTANT GROUPS. Aromatic groups have long been known to give significant radiation resistance to organic molecules. There was early work on the hydrogen yields from cyclohexane (G=5) and benzene (G=0.04) in the liquid phase, and of their mixtures, which showed a pronounced protective effect. 

Many of the quantitative rate data on radical reactions which are to be found in the scientific literature have been obtained by comparison of reaction rates rather than by direct measurement of absolute rate constants (Ingold, 1973). For example, it is a straightforward matter to compare the rate of chlorine abstraction from CC14 by phenyl radicals with the rate of hydrogen abstraction from cyclohexane by the same species, simply by comparing the PhCl/PhH product ratio from a suitable competition experiment (Bridger and Russell, 1963). In contrast, direct measurements of the absolute rates of these reactions have yet to be carried out (although indirect estimates are available). 

An example of radical coupling foUowing hydrogen abstraction by excited nitro-ethane from cyclohexane or diethyl ether in solution has also been reported Formation of -methyl-N-arylnitrones is observed during photoreduction (via electron transfer) of sterically hindered nitrobenzenes in triethylamine 39) ... 

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