Cyclohexane nitro-, reduction

The aryl rings of acetophenone and methyl benzoate are preferentially hydrogenated, with only minor reduction of the substituents. In contrast, hydrogenation of nitrobenzene, under essentially the same conditions, produces aniline and nitro-cyclohexane in ca. 9 1 ratio, with an overall conversion of >79%. This observation has additional significance when compared with the hydrogenation of the nitro derivative of vinylbenzene (Table 11.25). In all cases, it is the C=C bond which is hydrogenated and, only after a prolonged reduction time, is 1-nitro-2-phenylethene completely reduced to the aminoethane [4],... 

Photolytic. The UV photolysis (7, = 300 nm) of bifenox in various solvents was studied by Ruzo et al. (1980). In water, 2,4-dichloro-3 -(carboxymethyl)-4 -hydroxydiphenyl ether and 2,4-di-chloro-3 -(carboxymethyl)-4 -aminodiphenyl ether were identifled. In cyclohexane, 2,4-dichloro-4 -nitrodiphenyl ether and methyl formate were the major products. In methanol, a dichloro-methoxy phenol was identified. Photodegradation occurred via reductive dechlorination, de-carboxymethylation, nitro group reduction, and cleavage of the ether linkage (Ruzo et al., 1980). 

The solubility of the catalyst salt is improved by the use of 3,5-bis(trifluoromethyl)phenylborate or triflate anions. Unsaturated fatty acids can be reduced in the same way.173 Hydrogenations in sc carbon dioxide can be more selective than in the gas phase while using 35 times less catalyst.174 Cyclohexene was reduced with hydrogen and a polysilox-ane-supported palladium catalyst in in a continuous-flow reactor in 95-98% yields. Epoxides, oximes, nitriles, aldehydes, ketones, and nitro compounds can also be reduced. By varying the temperature, the products from the reduction of nitrobenzene can be selected from aniline, cyclo-hexylamine, dicyclohexylamine, and cyclohexane. In the... 

Extensive work showed that this methodology can be applied to many hydrogenations alkenes or alkynes [33], substituted benzene —> substituted cyclohexane [33, 34], deuterium exchange [34], selective reduction of polycyclic aromatics [35, 36], selective double-bond reduction in the presence of nitro groups (e.g., PhCH=CHN02 —> PHCH2CH2N02) [37], and reduction of double bonds in a,[i-unsaturated esters and carbonyls [38, 39]. 

Besides reduction of C-C multiple bonds, metal NPs embedded into MOF have also been used for hydrogenation of other functional groups including aromatic rings, carbonyl groups, and nitro compounds. Thus, hydrogenation of benzene to cyclohexane has been... 

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