A specific gas phase substitution reaction between enol radical cations and t-butyl nitrite

Eur. J. Mass Spectrom. 10, 889–898 (2004)
DOI: 10.1255/ejms.686

A specific gas phase substitution reaction between enol radical cations and t-butyl nitrite

Pascal Gerbaux,^a* Pascale Wantier,^a* Pham Can Nam^b, Minh Tho Nguyen^b, Guy Bouchoux^c and Robert Flammang^a
^aOrganic Chemistry Laboratory, University of Mons-Hainaut, 19 Avenue Maistriau, B-7000 Mons, Belgium
^bDepartment of Chemistry, University of Leuven, Celestijnenlaan 200 F, B-3001 Leuven, Belgium
^cLaboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau Cedex, France

ABSTRACT:

Ion–molecule reactions between ionized carbonyl compounds or ionized enols with t-butyl nitrite allow a clear-cut distinction to be made between both these isomeric structures. The most relevant difference between the observed reactions is the formal substitution of a hydrogen atom by nitric oxide in the enol ions. Collisional activation experiments on the product ions are interpreted in terms of α- nitroso carbonyl structures. However, a quantum chemical investigation at the B3LYP/6-311++G(d,p) level of theory shows that ionized α-nitroso carbonyl and vinyl nitrite structures may isomerize provided they contain ca 60 kJ mol^–1 of internal energy. It is therefore possible that both structures are generated in the substitution reaction.

Keywords: mass spectrometry, ion-molecule reaction, substitution, t-butyl nitrite, enol-carbonyl isomerization, collisional activation

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