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An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines.
J Mass Spectrom. 2006 Sep; 41(9):1195-204.JM

Abstract

The collision-induced dissociation (CID) mass spectra of several protonated benzylamines are described and mechanistically rationalized. Under collision-induced decomposition conditions, protonated dibenzylamine, for example, loses ammonia, thereby forming an ion of m/z 181. Deuterium labeling experiments confirmed that the additional proton transferred to the nitrogen atom during this loss of ammonia comes from the ortho positions of the phenyl rings and not from the benzylic methylene groups. A mechanism based on an initial elongation of a C--N bond at the charge center that eventually cleaves the C--N bond to form an ion/neutral complex of benzyl cation and benzylamine is proposed to rationalize the results. The complex then proceeds to dissociate in several different ways: (1) a direct dissociation to yield a benzyl cation observed at m/z 91; (2) an electrophilic attack by the benzyl cation within the complex on the phenyl ring of the benzylamine to remove a pair of electrons from the aromatic sextet to form an arenium ion, which either donates a ring proton (or deuteron when present) to the amino group forming a protonated amine, which undergoes a charge-driven heterolytic cleavage to eliminate ammonia (or benzylamine) forming a benzylbenzyl cation observed at m/z 181, or undergoes a charge-driven heterolytic cleavage to eliminate diphenylmethane and an immonium ion; and (3) a hydride abstraction from a methylene group of the neutral benzylamine to the benzylic cation to eliminate toluene and form a substituted immonium ion. Corresponding benzylamine and dibenzylamine losses observed in the spectra of protonated tribenzylamine and tetrabenzyl ammonium ion, respectively, indicate that the postulated mechanism can be widely applied. The postulated mechanisms enabled proper prediction of mass spectral fragments expected from protonated butenafine, an antifungal drug.

Authors+Show Affiliations

Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16924596

Citation

Bialecki, Jason, et al. "An Unprecedented Rearrangement in Collision-induced Mass Spectrometric Fragmentation of Protonated Benzylamines." Journal of Mass Spectrometry : JMS, vol. 41, no. 9, 2006, pp. 1195-204.
Bialecki J, Ruzicka J, Attygalle AB. An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines. J Mass Spectrom. 2006;41(9):1195-204.
Bialecki, J., Ruzicka, J., & Attygalle, A. B. (2006). An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines. Journal of Mass Spectrometry : JMS, 41(9), 1195-204.
Bialecki J, Ruzicka J, Attygalle AB. An Unprecedented Rearrangement in Collision-induced Mass Spectrometric Fragmentation of Protonated Benzylamines. J Mass Spectrom. 2006;41(9):1195-204. PubMed PMID: 16924596.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines. AU - Bialecki,Jason, AU - Ruzicka,Josef, AU - Attygalle,Athula B, PY - 2006/8/23/pubmed PY - 2007/8/19/medline PY - 2006/8/23/entrez SP - 1195 EP - 204 JF - Journal of mass spectrometry : JMS JO - J Mass Spectrom VL - 41 IS - 9 N2 - The collision-induced dissociation (CID) mass spectra of several protonated benzylamines are described and mechanistically rationalized. Under collision-induced decomposition conditions, protonated dibenzylamine, for example, loses ammonia, thereby forming an ion of m/z 181. Deuterium labeling experiments confirmed that the additional proton transferred to the nitrogen atom during this loss of ammonia comes from the ortho positions of the phenyl rings and not from the benzylic methylene groups. A mechanism based on an initial elongation of a C--N bond at the charge center that eventually cleaves the C--N bond to form an ion/neutral complex of benzyl cation and benzylamine is proposed to rationalize the results. The complex then proceeds to dissociate in several different ways: (1) a direct dissociation to yield a benzyl cation observed at m/z 91; (2) an electrophilic attack by the benzyl cation within the complex on the phenyl ring of the benzylamine to remove a pair of electrons from the aromatic sextet to form an arenium ion, which either donates a ring proton (or deuteron when present) to the amino group forming a protonated amine, which undergoes a charge-driven heterolytic cleavage to eliminate ammonia (or benzylamine) forming a benzylbenzyl cation observed at m/z 181, or undergoes a charge-driven heterolytic cleavage to eliminate diphenylmethane and an immonium ion; and (3) a hydride abstraction from a methylene group of the neutral benzylamine to the benzylic cation to eliminate toluene and form a substituted immonium ion. Corresponding benzylamine and dibenzylamine losses observed in the spectra of protonated tribenzylamine and tetrabenzyl ammonium ion, respectively, indicate that the postulated mechanism can be widely applied. The postulated mechanisms enabled proper prediction of mass spectral fragments expected from protonated butenafine, an antifungal drug. SN - 1076-5174 UR - https://www.unboundmedicine.com/medline/citation/16924596/An_unprecedented_rearrangement_in_collision_induced_mass_spectrometric_fragmentation_of_protonated_benzylamines_ L2 - https://doi.org/10.1002/jms.1089 DB - PRIME DP - Unbound Medicine ER -