Aplicação de fotocatálise homogênea e heterogênea na oxidação de ligações C(sp³)-H

Abstract

The functionalization of C(sp³)-H bonds represents a central challenge for the contemporany chemical industry. Both homogeneous and heterogeneous catalytic processes are widely employed to modulate the activation energy of these reactions, aiming to obtain high-value-added derivatives. Among the transformation routes, oxidation stands out for generating products such as alcohols, ketones, and carboxylic acids. To make such processes viable, photocatalytic strategies have been developed to reduce costs and operate under mild conditions, seeking high conversion and selectivity rates. In this context, carbon nitrides have gained prominence due to their significant photocatalytic potential. In the present work, highly crystalline ionic carbon nitrides in the form of poly(heptazine imide) (PHI) were synthesized and subjected to specific structural modifications: the stabilization of metallic single-atoms via cation exchange and the protonation of negative sites using HCl. These materials were applied in the photo-oxidation of cyclohexane, resulting in the formation of KA oil (a mixture of cyclohexanone and cyclohexanol) under mild conditions with good conversion and selectivity. Furthermore, homogeneous photocatalysis was explored for the selective conversion of methane to formic acid, utilizing iron (III) chloride, a simple, inexpensive, and abundant compound, as a photocatalyst. This reaction approach operated under visible light irradiation and at room temperature, consolidating a simple and effective system.