Iron(II) and copper(II) phthalocyanine-catalyzed synthesis of 2-nitro-4-methylsulfonylbenzoic acid under mild conditions

Oxidation of NMST to NMSBA catalyzed by Co/Mn/Br together with porous carbon made from coconut shell with acetic acid as an activator

In this paper, a heterogeneous catalytic system consisting of Co/Mn/Br/activated carbon is used to catalyze 2-nitro-4-methylsulfonyl benzoic acid (NMSBA) production from the oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) by oxygen. The activated carbon (AC) is made from coconut shell with acetic acid as an activator. The experiments indicate that the best AC is made by immersing coconut shell in 12 mol L−1 HAc solution at 50 °C for 32 h with a liquid/solid ratio (mL/g) of 5:1 and then being heated in nitrogen at 800 °C for 6 h. Compared with the Co/Mn/Br/H3PMo12O40@CAC (CAC, commercial activated carbon originated from coconut shell) catalytic system, the Co/Mn/Br/AC catalytic system is able to gain much higher NMSBA selectivity. In spite of holding smaller surface and less acidic groups, the AC owns much more carboxyl than CAC, which is the main reason for its better performance in the preparation of NMSBA.

Metallophthalocyanines as Catalysts in Aerobic Oxidation

The first remarkable property associated to metallophthalocyanines (MPcs) was their chemical “inertness”, which made and make them very attractive as stable and durable industrial dyes. Nevertheless, their rich redox chemistry was also explored in the last decades, making available a solid and detailed knowledge background for further studies on the suitability of MPcs as redox catalysts. An overlook of MPcs and their catalytic activity with dioxygen as oxidants will be discussed here with a special emphasis on the last decade. The mini-review begins with a short introduction to phthalocyanines, from their structure to their main features, going then through the redox chemistry of metallophthalocyanines and their catalytic activity in aerobic oxidation reactions. The most significant systems described in the literature comprise the oxidation of organosulfur compounds such as thiols and thiophenes, the functionalization of alkyl arenes, alcohols, olefins, among other substrates.

Effect of Competitive Adsorbates on the Catalytic Activity of H3PMo12O40@C in the Oxidation of NMST to NMSBA

The effect of competitive adsorption on the catalytic performance of H3PMo12O40@C catalyst for producing 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4- methylsulfonyltoluene (NMST) by oxygen in acetic acid has been investigated. Six kinds of acids were added into the impregnation solution as competitive adsorbates for phosphomolybdic acid in the preparation of H3PMo12O40@C catalyst. H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are beneficial to improving the catalytic activity of the H3PMo12O40@C catalyst. The corresponding optimum impregnation concentrations for H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are 0.4, 0.3, 0.3, 1.0 and 0.3 mol L−1, respectively. The addition of H3PO4 exerts a negative effect on the catalytic capability of H3PMo12O40@C catalyst. The results of TEM characterization show that good dispersion of H3PMo12O40 on the surface of the H3PMo12O40@C catalyst is beneficial to ameliorating the catalytic ability of H3PMo12O40@C catalyst in the production of NMSBA from NMST by oxygen in acetic acid. The results of NH3-TPD indicate that the acidity of the H3PMo12O40@C also favors the improvement of the catalytic capability of H3PMo12O40@C in the oxidation of NMST to NMSBA.

Production of NMSBA from NMST Catalyzed by Co/Mn/Br and HPW@C Modified with ZnCl2 Solution

2-nitro-4-methylsulfonylbenzoic acid (NMSBA) can be produced by oxidizing 2-nitro-4-methylsulfonyltoluene (NMST) with air catalyzed by Co/Mn/Br and phosphotungstic acid(HPW) loaded on activated carbon. This paper reports that the catalytic ability of the HPW@C catalyst in the oxidation of NMST to NMSBA can be improved by treating the activated carbon with ZnCl2solution. The best modification condition with ZnCl2solution is impregnating the carbon sample in 0.1 mol/L solution for 6 h followed by calcination at 600 °C for 4 h. The increase of the surface area and the acidic groups on the carbon surface enhances the catalytic ability of the HPW@C catalyst. The mesopores play an important role in the catalytic oxidation of NMST to NMSBA.