Sustainable process for adipic acid production from cyclohexene in microemulsion.

• adipic acid synthesis from cyclohexene and hydrogen peroxide in microemulsion is investigated. • stearyl dimethyl benzyl ammonium chloride is used as surfactant. • reaction carried out without organic ligand and without phase transfer catalyst. • non-polluting catalyst sodium tungstate, which contains no heavy metal, is used. • by recycling the catalyst and the surfactant, the process becomes truly green. Adipic acid appears as an intermediate compound for the synthesis of polyamides and preferentially for the production of nylon-6,6 polyamide. It can be synthesized by the oxidation of cyclohexene by hydrogen peroxide in microemulsion media which has the main advantage to lead a better contact between the two phases thus increasing the yield of the reaction. The microemulsion is generated by stearyl dimethyl benzyl ammonium chloride (C18) as a surfactant avoiding the use of harmful organic solvents and phase-transfer catalysts. The reaction is performed under mild conditions (85 °C, 8 h) with sodium tungstate, - a no heavy metal catalyst - leading to the production of adipic acid in high yield (>80%). By recycling the catalyst and the surfactant, the process becomes truly green. [ABSTRACT FROM AUTHOR]