Aerobic oxidation of alkylaromatic hydrocarbons to hydroperoxides catalysed by N-hydroxyimides in ionic liquids as solvents

Solvent‐Free Aerobic Oxidation of Ethylbenzene Promoted by NHPI/Co(II) Catalytic System: The Key Role of Ionic Liquids

“…Here, we report on the aerobic oxidation of EB with NHPI/ Co(II) system in the presence of catalytic amounts (0.25-1 %) of the imidazolium-based ILs previously investigated as solvents. [28] The full set of experiments here described point to a marked effect of alkylsulfate ILs in the solubilization of NHPI in EB, which in turn allowed to perform substrate oxidation under solvent free conditions, reaching conversion up to 35 % with selectivity higher than 82 % in AP. Detailed analysis of the outcome of oxidation reactions performed by varying IL species, Co(II) counterions, with and without NHPI, presents a complex scenario with multiple concomitant equilibria which should be taken into account and points to the presence of a specific interaction between IL and NHPI.…”

“…Here, we report on the aerobic oxidation of EB with NHPI/Co(II) system in the presence of catalytic amounts (0.25–1 %) of the imidazolium‐based ILs previously investigated as solvents . The full set of experiments here described point to a marked effect of alkylsulfate ILs in the solubilization of NHPI in EB, which in turn allowed to perform substrate oxidation under solvent free conditions, reaching conversion up to 35 % with selectivity higher than 82 % in AP.…”

“…[24][25][26][27] Recently, some of us reported the oxidation of cumene and other alkylaromatic hydrocarbons to hydroperoxides in the presence of various N-hydroxyimides, including NHPI, in a broad range of ILs composed of 1-alkyl-3-methylimidazolium cations and bis(trifluoromethylsulfonyl)imide ( OSO 3 ] anions. [28] However, the replacement of standard polar solvents, such as MeCN, with ILs might not be an improvement in terms of costs and process implementation. Interestingly, ILs have been also used as catalytic additives capable to promote oxidation reactions.…”

Selective oxidation of cumene into 2-phenyl-2-propanol and acetophenone over activated carbon supported Co1.5PW12O40 material

“…To prevent the decomposition of the hydroperoxde produced, alkaline solution was used to neutralize the acids formed (Hsu andCheng 1998, Suresh et al 2000) . Besides Low degrees of conversion equal to 20% and selectivity to hydroperoxide of 90%-95%, are achieved there are still some drawbacks such as poor safety (Wu et al 2008, Dobras andOrlińska 2018). This method, although selective produces large amounts of waste water alkaline or sulfur.…”

Efficient catalytic oxidation of methyl aromatic hydrocarbon withN-alkyl pyridinium salts

“…Encouraging progresses have been achieved on the metalfree organocatalysis such as the oxidation of alcohol to aldehyde/ketone catalyzed by 2,2,6,6-tetramethyl-piperidyl-1oxy (TEMPO), and selective oxidation of hydrocarbon by Nhydroxyphthalimide (NHPI) system, or the other organic molecules. [25][26][27][28][29] Besides these systems, it was found that simple nitrogen cation compounds were useful in facilitating the oxidation of hydrocarbon. For example, quaternary ammonium salts could catalyze the oxidation of different hydrocarbon such as cyclohexene, tetralin, and ethylbenzene.…”