Selective Aerobic Oxidation of Toluene in the Presence of Co²⁺ and Task-Specific Organic Salts, Including Ionic Liquids

Abstract

This paper presents research on the catalytic activity of systems composed of transition-metal compounds and organic bromide salts, [X][Br] or [X][Br 3 ], in the oxidation of toluene and its derivatives with oxygen using acetic acid as a solvent. Salts containing imidazolium, tetraalkylammonium, bromoalkylammonium, phenylalkylammonium, or benzylalkylammonium cations in combination with Co 2+ compounds were used. It was found that the [X][Br] and [X][Br 3 ] systems with Co 2+ compounds enabled the oxidation of toluene and its derivatives to the corresponding carboxylic acids with high selectivities and reaction rates. Moreover, long-term corrosion studies on three selected stainless steels showed that the organic salts that contained nitrogen atoms had an inhibitory effect on the corrosion caused by the Br − ions present in the reaction system. For the first time, the possibility of replacing inorganic bromides, used on an industrial scale in the Amoco process, by organic bromide salts, including ionic liquids, with corrosion-inhibiting properties was demonstrated.

Oxidation of Picoline with Oxygen to Nicotinic Acid against Co2+, NHPI, and Phosphonium or Ammonium Bromides

“…As org bromides, bromide quaternary ammonium salts, phosphonium salts, and 1-butyl-3thylimidazolium bromide were used. As our previous studies [44] have shown, qua nary ammonium salts exhibit corrosion-inhibiting properties, which are a significant vantage when using organic bromides as catalysts in the oxidation of alkyl aromatic drocarbons. The composition of 3-picoline oxidation products was compared to a num of organic bromides, and the influence of basic parameters (temperature, time, press type of oxidizing agent) was examined for those selected.…”

Methods to Produce Nicotinic Acid with Potential Industrial Applications

“…The use of air as an oxidizing agent and the high yields and conversions are the advantages of this method. However, the high corrosivity of the Co/Mn/Br catalytic system and resulting need to use an appropriate construction material or corrosion inhibitors should be taken into account [88].…”

A Metal‐Organic Complex Constructed from Co(II), Azo‐amide‐pyridyl and Benzenetricarboxylate Mixed Ligands: Efficient Catalysis for Selective Oxidation of Benzyl Alcohols to Benzyl Acids

“…At present, benzoic acid is mainly prepared by liquid-phase air oxidation of toluene in industry, which generally uses transition metal salts (such as Co, Mn) as catalysts under a temperature of 150-170 °C and pressure of 8-10 MPa. [4] This method shows a high product yield for 80 %-90 %. However, the harsh reaction conditions lead to excessive energy consumption.…”

“…The demand for benzoic acid in the world is increasing every year, and the synthesis method of benzoic acid has attracted extensive attention of researchers. At present, benzoic acid is mainly prepared by liquid‐phase air oxidation of toluene in industry, which generally uses transition metal salts (such as Co, Mn) as catalysts under a temperature of 150–170 °C and pressure of 8–10 MPa [4] . This method shows a high product yield for 80 %–90 %.…”