Hydrogenation of nitrobenzene to p-aminophenol in a four-phase reactor: reaction kinetics and mass transfer effects

A green and effective method is reported for the reduction of p-nitrophenol to p-aminophenol using a nano-sized nickel catalyst supported on silica-alumina in the presence of hydrazine hydrate as an alternative source of hydrogen. It was found that nickel loaded on a silica-alumina support is a very effective catalyst in the hydrogenation of p-nitrophenol to p-aminophenol. Thus it attained 100% conversion in only 69 seconds instead of 260 seconds for commercial Raney nickel. In addition, the possibility to reuse it more than one time with great efficiency gives it another advantage over commercial Rainey nickel which cannot be used more than once. This economical and environmentally friendly method provides a potentially new approach for the synthesis of the intermediate product of paracetamol in industry, which overcomes the drawbacks of the known reduction methods. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electron spin resonance (ESR) tehniques.

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An Environmentally Benign, Highly Efficient Catalytic Reduction of p‐Nitrophenol using a Nano‐Sized Nickel Catalyst Supported on Silica‐Alumina

p-Aminophenol was prepared by hydrogenation of p-nitro phenol over nano-sized nickel catalysts supported on two different supports, SiO2 and Al2O3 Hydrazine hydrate was used as hydrogen source in this reaction Several loadings of nano-sized Ni were used, thus 20, 5, and 25 wt% were prepared X-ray diffraction (XRD) and electron spin resonance (ESR) were employed to investigate the prepared catalysts The Ni/Al2O3 was found to be more effective and give high durability The catalytic activity of the reaction was found to be influenced by both the crystallinity of the nickel and the strain among nano-sized nickel particles The prepared catalysts showed higher catalytic activity, especially at lower loading During the reaction, a detectable change of the color was observed from yellow to green and finally to colorless, which enable us to suppose a mechanism of this reaction

The use of nano supported nickel catalyst in reduction of p-nitrophenol using hydrazine as hydrogen donor

The Effect of Titania Structure on Ni/TiO2 Catalysts for p-Nitrophenol Hydrogenation

A process for preparing unsubstituted and alkyl substituted p-aminophenols. A charge mixture is prepared comprising an unsubstituted or alkyl substituted nitrobenzene, a highly dissociated acid, a catalyst containing platinum and a divalent sulfur compound in which sulfur is bonded to two other moieties, the sulfur compound being present in a proportion of between about 0.1 and about 100 moles per gram-atom of platinum. The mixture comprises an organic phase containing the substrate and an aqueous phase containing the acid. Hydrogen is introduced into the mixture at a pressure of 0-50 psig while the mixture is agitated at a temperature of 70° C. to 100° C., thereby causing the substrate to be reduced to phenylhydroxylamine or an alkyl substituted phenylhydroxylamine. The hydroxylamine is rearranged in the presence of acid to the substituted or unsubstituted p-aminophenol, which is recovered from the aqueous phase.

Process for preparing p-aminophenol and alkyl substituted p-aminophenol

The preparation of p-aminophenol by the catalytic hydrogenation of nitrobenzene in an acid reaction medium containing an aqueous isopropyl alcohol solution of trimethyldodecylammonium chloride leads to the formation of chloro- and isopropoxyaniline impurities These end up in the by-product aniline The substitution of dimethyldodecylamine sulfate for the quaternary salt eliminates these impurities without significant adverse effect on the yield, production rate or purity of the p-aminophenol

Sathe Sharad S

Papers

Process for preparing p-aminophenol in the presence of dimethyldodecylamine sulfate

Verfahren zur herstellung von p-aminophenol.