A Novel Synthesis of Cyclohexanol Derivatives by the Catalytic Hydrogenation of Benzene with Acid Additives

Article abstract of DOI:10.1246/bcsj.67.2779

The hydrogenation of benzene over a platinum group metal in the presence of various strong acids was carried out.Cyclohexanol derivatives (C6H11X, X=OH, OAc, Cl, Br) were found to be produced by the catalytic hydrogenation of benzene with acid additives.The following two sequences of adsorption strength were observed between platinum metals (adsorbent) and additive reagents (adsorbate): Ru >> Rh > Pd > Ir > Pt (I) and HI, HCOOH >> HBr > HCl >> AcOH, H2O. (II).When a weak adsorbate, such as acetic acid or water, was used as an additive reagent, ruthenium, the strongest adsorbent, exhibited the best selectivity.When hydrogen chloride, a strong adsorbate in the sequence (II), was used an additive reagent, palladium or rhodium, moderately strong adsorbent, exhibited excellent selectivity.By the reaction of 2 ml of benzene, 5 ml of 35percent HCl and 0.2 g of 5percent Pd/SiO2, under 10 atm-G (P atm-G=1.013(P+1)*10⁵ Pa) hydrogen at 100 deg C for 20 h, 8,4percent of the yield of chlorocyclohexane was obtained at 64.2percent of the selectivity (13.1percent of the conversion of benzene).