Estudo comparativo de métodos de oxidação de álcoois utilizando energia de microondas e reações sob suporte sólido

Abstract

In this work, a comparative study is presented of the oxidation of secondary alcohols to form ketones by different routes: (I) potassium permanganate adsorbed on copper sulfate as a solid support without solvent, (Ia) using microwave irradiation, or (Ib) using conventional heating; (II) potassium permanganate adsorbed on montmorillonite, K-10 at room temperature. The alcohols used in this study have structures based on alkyl chains (1a), cyclopentyl rings (1d), cyclohexyl rings with different substituents (1c, 1e, 1f, 1h), allylic alcohol (1f), benzylic alcohols (1g and 1i) and a hydroxyketone (1b). This structural diverse collection of alcohols was used to valid the oxidative protocols as a general method of oxidation. Since the principal line of research in our group is the formation of heterocyclic systems, we used benzil 2b, obtained from the oxidation of alcohol 1b, for the cyclization reaction with the 1,4 N- dinucleophiles such as semicarbazide hydrochloride and thiosemicarbazide to give the heterocycles 5,6-diphenyl-2,3-dihydro-1,2,4-triazin-3-one 4 and 5,6-diphenyl-2,3-dihydro- 1,2,4-triazin-3-thione 6, respectively. Different methodologies, reactions with microwave irradiation or in refluxing ethanol were also evaluated. The investigation of possible biological activity of the heterocyclic compounds 4 and 6 obtained was carried out using Bioautography method with different microorganisms.