The demand for azobenzenes has exponentially grown due to their wide range of applications in textile, medical, and dye industries. Here we report a procedure to synthesise azobenzenes by the dehydrogenative coupling of anilines in the presence of Co-II(TPP) (TPP=dianion of tetraphenyl porphyrin) catalyst and 4-nitrophenyl azide oxidant species. Differently substituted azobenzenes were obtained in yields up to 72 % together with 4-nitrophenyl amine, which is the stoichiometric by-product of the process. The procedure displayed a good sustainability due to the almost quantitative recovery of pure 4-nitrophenyl amine that can be transformed again into the desired azide to pave the way for an efficient circular process. Experimental data supported the occurrence of a radical mechanism mediated by putative nitrene radical cobalt intermediate.
Cobalt Porphyrin-Catalysed Synthesis of Azobenzenes by Dehydrogenative Coupling of Anilines / C. Damiano, M. Cavalleri, N. Panza, E. Gallo. - In: EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. - ISSN 1099-0690. - 2022:34(2022 Sep 13), pp. e202200791.1-e202200791.7. [10.1002/ejoc.202200791]
Cobalt Porphyrin-Catalysed Synthesis of Azobenzenes by Dehydrogenative Coupling of Anilines
C. Damiano
Primo
;M. CavalleriSecondo
;N. PanzaPenultimo
;E. Gallo
Ultimo
2022
Abstract
The demand for azobenzenes has exponentially grown due to their wide range of applications in textile, medical, and dye industries. Here we report a procedure to synthesise azobenzenes by the dehydrogenative coupling of anilines in the presence of Co-II(TPP) (TPP=dianion of tetraphenyl porphyrin) catalyst and 4-nitrophenyl azide oxidant species. Differently substituted azobenzenes were obtained in yields up to 72 % together with 4-nitrophenyl amine, which is the stoichiometric by-product of the process. The procedure displayed a good sustainability due to the almost quantitative recovery of pure 4-nitrophenyl amine that can be transformed again into the desired azide to pave the way for an efficient circular process. Experimental data supported the occurrence of a radical mechanism mediated by putative nitrene radical cobalt intermediate.File | Dimensione | Formato | |
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