title: Mechanistic Insight into the Oxidation of Organic Phenylselenides by H2O2.
abstract: The oxidation of organic phenylselenides by H2O2is investigated in model compounds, namely, n-butyl phenyl selenide (PhSe(nBu)), bis(phenylselanyl)methane (PhSeMeSePh), diphenyl diselenide (PhSeSePh), and 1,2-bis(phenylselanyl)ethane (PhSeEtSePh). Through a combined experimental (1H and77Se NMR) and computational approach, we characterize the direct oxidation of monoselenide to selenoxide, the stepwise double oxidation of PhSeMeSePh that leads to different diastereomeric diselenoxides, the complete oxidation of the diphenyldiselenide that leads to selenium-selenium bond cleavage, and the subsequent formation of the phenylseleninic product. The oxidation of PhSeEtSePh also results in the formation of phenylseleninic acid along with 1-(vinylseleninyl)benzene, which is derived from a side elimination reaction. The evidence of a direct mechanism, in addition to an autocatalytic mechanism that emerges from kinetic studies, is discussed. By considering our observations of diselenides with chalcogen atoms that are separated by alkyl spacers of different length, a rationale for the advantage of diselenide versus monoselenide catalysts is presented.
authors.affiliation: Dipartimento di Scienze del Farmaco, Università degli Studi di Padova, Via Marzolo 5, 35131, Padova, Italy.
authors.forename: Giovanni
authors.identifier: http://orcid.org/0000-0003-3679-5530
authors.initials: G
authors.lastname: Ribaudo
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131, Padova, Italy.
authors.forename: Massimo
authors.identifier: http://orcid.org/0000-0002-8187-0264
authors.initials: M
authors.lastname: Bellanda
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131, Padova, Italy.
authors.forename: Ileana
authors.identifier: http://orcid.org/0000-0003-2677-3979
authors.initials: I
authors.lastname: Menegazzo
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131, Padova, Italy.
authors.forename: Lando P
authors.identifier: http://orcid.org/0000-0003-0052-0121
authors.initials: LP
authors.lastname: Wolters
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131, Padova, Italy.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0001-5506-6347
authors.initials: M
authors.lastname: Bortoli
authors.affiliation: Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la Repúbica, Igua 4225, Montevideo, Uruguay.
authors.forename: Gerardo
authors.identifier: http://orcid.org/0000-0002-8663-8480
authors.initials: G
authors.lastname: Ferrer-Sueta
authors.affiliation: Dipartimento di Scienze del Farmaco, Università degli Studi di Padova, Via Marzolo 5, 35131, Padova, Italy.
authors.forename: Giuseppe
authors.identifier: http://orcid.org/0000-0001-7053-4196
authors.initials: G
authors.lastname: Zagotto
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131, Padova, Italy.
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0002-1673-5111
authors.initials: L
authors.lastname: Orian
keywords: enzyme models; organocatalysis; oxidation; reaction mechanisms; selenium