دانلود رایگان مقاله اثر حلال بر اکسیداسیون آلیلیک کاتالیز سیکلوهگزین با نانولوله کربنی نیتروژن

Abstract

A wide spectrum of, up to 22, organic solvents, including aprotic/protic aliphatics/aromatics, was studied to achieve a comprehensive understanding to the solvent effect on the cyclohexene oxidation. It was found that the catalytic activity was significantly influenced by the viscosity, polarity and basicity of solvents in this reaction. Among these solvents, the polar aprotic aliphatic solvents displayed higher catalytic reactivities than other types of solvents. A volcano curve was found describing the dependence of activity on solvent basicity because of the suitable stability of intermediates. Among the solvents investigated, acetonitrile afforded the highest activity and selectivity of 2-cyclohexen-1-one, because of a good compromise between strong polarity and moderate basicity.

4. Conclusions

In conclusion, the solvent effects on the selective oxidation of cyclohexene with NCNTs as catalyst have been revealed by analyzing the reactivity and selectivity across a solvent library containing up to 22 organic solvents. The higher polarity is beneficial for the activity in protic and aprotic aliphatics, because of the improved desorption of oxide products. A modest solvent basicity is required for high reactivity, implying that a suitable stability of intermediates is needed. On the aspect of selectivity, the increase of solvent polarity results in a slight increase of –one selectivity and decrease of -ol selectivity, thus a higher ketone/alcohol ratio. In addition, the selectivity of oxygenated products strongly depends on the functionality of solvent. The comprehensive phenomenological survey may guide a more rational design of the liquid-phase oxidation reactions catalyzed by nanocarbons, the emerging metal-free catalysts.