Fragmentations of protonated benzaldehydes via intermediate ion/molecule complexes

✍ Scribed by U. Filges; Hans-Fr. Grützmacher

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 981 KB
• Volume: 21
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210211012

✦ Synopsis

Ions a, and a, corresponding to protonated pand m-methoxymethylbenzaldehydes have been generated in a mass spectrometer by electron impact fragmentation of the correspondingly substituted l-phenylethanols (1 and 2). Metastable ions a, and urn (2nd FFR of a VG-ZAB-2F mass spectrometer) react by elimination of CH,OH, loss of HCOOCH3, formation of ions CHp=OCH3 and to a small extent by loss of CH,O and CH30CH,, respectively. The mechanisms of these reactions have been studied by extensive D-labelling, and it is shown that these fragmentations are initiated hy a transfer of the proton located originally at the carbonyl group onto the aromatic ring. The formation of ions CHp=6CH3 and the loss of CH30H occurs via n-and a-complexes. The elimination of HCOOCH, from ions up and a, corresponds to a functional group interaction between distal side chains and occurs via intermediate ion/molecule complexes formed by a protolytic cleavage of the formyl group. The loss of CHzO and CH,OCH, proceeds also by intermediate ion/molecule complexes which are generated by a protolytic cleavage of the methoxymethyl side chain in ions a, and a , .