Fragmentation reactions of phenoxide anions: deprotonated Dinoterb and related structures

✍ Scribed by Ahmad Rifai; Sophie Bourcier; Delphine Arquier; Yannick Charvet; Farouk Jaber; Guy Bouchoux

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 771 KB
• Volume: 46
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1991

✦ Synopsis

Dinoterb (6‐t‐butyl‐2,4‐dinitrophenol), 1, Dinoseb (6‐secbutyl‐2,4‐dinitrophenol), 2, TBP (2‐t‐butylphenol), 3, and DNP (2,4‐dinitrophenol), 4, have been analyzed by electrospray ionization in the negative mode (ESI‐N) ‐ tandem mass spectrometry. Nominal laboratory collision energy was varied from zero to 60 eV during the experiments. Apparent fragmentation energies were estimated from a parametric fitting of the collision efficiency curves. In parallel, fragmentation mechanisms of the deprotonated molecules [M‐H]^−^ were explored using quantum chemistry modeling at the B3LYP/6‐31 + G(d,p) level. A major fragmentation of the [M‐H]^−^ ions of Dinoterb and Dinoseb is elimination of an alcohol molecule. This reaction is shown to involve one oxygen atom originating from a nitro group rather than the phenoxide moiety. Eliminations of NO, CH~4~ and CH~2~ = C(CH~3~)~2~, i.e. reactions involving significant rearrangements, constitute the major part of the other fragmentation pathways observed from [3‐H]^−^ and [4‐H]^−^ ions. Copyright © 2011 John Wiley & Sons, Ltd.