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Participation of halogen atoms in hydrogen transfer between remote positions in gas‐phase ionized isomeric haloresorcinols
Author(s) -
Weisz Adrian,
Andrzejewski Denis,
Mandelbaum Asher
Publication year - 1992
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210270808
Subject(s) - halogen , chemistry , dissociation (chemistry) , hydrogen atom , ion , hydrogen , ionization , atom (system on chip) , electron transfer , photochemistry , medicinal chemistry , organic chemistry , group (periodic table) , alkyl , computer science , embedded system
Mono, di‐ and trihaloresorcinols substituted by a halogen atom at position 2 exhibit a highly specific elimination of H 2 O on electron impact ionization and under conditions of collisionally induced dissociation (CID). The high isomer specificity suggests the intermediacy of a hydrogen transfer from one of the hydroxy groups to the adjacent halogen atom. A subsequent hydrogen migration to the other hydroxy group readily explains the facile elimination of H 2 O from the M +· ions of these particular isomers. An analogous three‐step hydrogen transfer has not been observed in 2,3‐dihalo‐l,4‐hydroquinones. 4‐Bromo‐ and 4‐icdoresorcinol undergo elimination of the halogen atom followed by a very fast loss of CO under CID conditions, affording [M − Hal] + ions of low abundance and highly abundant[M − Hal − CO] + ions. The elimination of CO is suppressed in the isomeric 5‐haloresorcinols, resulting in very highly abundant [M − Hal] + ions. This behavior suggests that a ‘hidden hydrogen transfer’ accompanies the elimination of the halogen atom from the molecular ions of 4‐haloresorcinols.