TY - JOUR
T1 - Charge-remote fragmentation and the two-step elimination of alkanols from fast atom bombardment-desorbed (M + H)+, (M + Cat)+, and (M - H)- ions of aromatic β-hydroxyoximes
AU - Santana-Marques, M. G.O.
AU - Ferrer-Correia, A. J.V.
AU - Caldwell, K. A.
AU - Gross, M. L.
N1 - Funding Information:
Thea uthors are indebted to INIC (Institute National de Investi-gasso Cientifica) for a scholarship given to M. G. S.-M. and to FLAD (Fund+=@ Luso-Americana para o Desenvolvimento) for a travel grant to A. J. F.-C. They also thank Drs. K. B. Tamer (NIEHS, Research Triangle Park, NC) for early four sector data. P. O’Brien (Queen Mary College, London) and J. M. R. Carvalho (IST, Lisbon) for some of the Phydroxyoxime samples. This work was supported in part by the Midwest Center for Mass Spectrometry, a National Science Foundation Facility (Grant No. CHE 9017262).
PY - 1993/10
Y1 - 1993/10
N2 - Aromatic β-hydroxyoximes undergo unusual fragmentation reactions as protonated or cationized species, as radical cations, or as (M - H)- ions, As protonated species, they expel OH ' from the oxime functionality in violation of the even electron rule. Parallel eliminations of alkyl radicals follow OH' loss when the aromatic ring is substituted with an alkyl chain. Alkyl radical losses appear to be characteristic of radical cations that can isomerize to ions in which the alkyl chain bears a radical site and the charged site is the conjugate acid of a basic functionality (e.g., oxime or imine). Evidence for the mechanisms was found in the ion chemistry of oxime and imine radical cations. The imine reference compounds were conveniently generated by fast atom bombardment-induced reduction of oximes, removing the requirement for using conventional chemical synthesis. Protonated imines and the (M - H)- ions of oximes fragment extensively via charge-remote processes to eliminate the elements of alkanes. This chemistry is not shared by the protonated oximes.
AB - Aromatic β-hydroxyoximes undergo unusual fragmentation reactions as protonated or cationized species, as radical cations, or as (M - H)- ions, As protonated species, they expel OH ' from the oxime functionality in violation of the even electron rule. Parallel eliminations of alkyl radicals follow OH' loss when the aromatic ring is substituted with an alkyl chain. Alkyl radical losses appear to be characteristic of radical cations that can isomerize to ions in which the alkyl chain bears a radical site and the charged site is the conjugate acid of a basic functionality (e.g., oxime or imine). Evidence for the mechanisms was found in the ion chemistry of oxime and imine radical cations. The imine reference compounds were conveniently generated by fast atom bombardment-induced reduction of oximes, removing the requirement for using conventional chemical synthesis. Protonated imines and the (M - H)- ions of oximes fragment extensively via charge-remote processes to eliminate the elements of alkanes. This chemistry is not shared by the protonated oximes.
UR - http://www.scopus.com/inward/record.url?scp=9744277411&partnerID=8YFLogxK
U2 - 10.1016/1044-0305(93)80040-6
DO - 10.1016/1044-0305(93)80040-6
M3 - Article
AN - SCOPUS:9744277411
SN - 1044-0305
VL - 4
SP - 819
EP - 827
JO - Journal of the American Society for Mass Spectrometry
JF - Journal of the American Society for Mass Spectrometry
IS - 10
ER -