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Fragmentation studies and electrospray ionization mass spectrometry of lapachol: protonated, deprotonated and cationized species
Author(s) -
Vessecchi Ricardo,
Emery Flavio S.,
Galembeck Sérgio E.,
Lopes Norberto P.
Publication year - 2010
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4625
Subject(s) - chemistry , fragmentation (computing) , deprotonation , protonation , dissociation (chemistry) , electrospray ionization , mass spectrometry , electron ionization , thermochemistry , computational chemistry , molecule , tandem mass spectrometry , photochemistry , ionization , analytical chemistry (journal) , ion , organic chemistry , chromatography , computer science , operating system
Electrospray ionization mass spectrometric analysis of lapachol (2‐hydroxy‐3‐(3‐methyl‐2‐butenyl)‐1,4‐naphthoquinone) was accomplished in order to elucidate the gas‐phase dissociation reactions of this important biologically active natural product. The occurrence of protonated and cationized species in the positive mode and of deprotonated species in the negative mode was explored by means of collision‐induced dissociation (CID) experiments. For the protonated molecule, the H 2 O and C 4 H 8 losses occur by two competitive channels. For the deprotonated molecule, the even‐electron rule is not conserved, and the radicalar species are eliminated by formation of distonic anions. The fragmentation mechanism for each ion was suggested on the basis of computational thermochemistry. Atomic charges, relative energies, and frontier orbitals were employed aiming at a better understanding of the gas‐phase reactivity of lapachol. Potential energy surfaces for fragmentation reactions were obtained by the B3LYP/6‐31+G(d,p) model. Copyright © 2010 John Wiley & Sons, Ltd.