Health & Environmental Research Online (HERO)


Print Feedback Export to File
8330230 
Journal Article 
Effect of the ion stability on the fate of intermediate ion/neutral complexes 
Grã¼Tzmacher, HF; Thielking, G; Wittneben, D; Eikenberg, D 
1990 
98 
3 
259-268 
English 
Carbonyl protonated aromatic ketones a-i [R-C(OH+)-C6H4CH2OCH3] containing a 4-methoxymethylphenyl group and R = H, CH3, C2H5, n-C3H7, C6H5, 4-CH3OC6H4, 4-CF3C6H4, and CF3, respectively, are generated in the ion source by 70eV electron impact induced dissociation of the benzylic alcohols 1-10. The ions a-i may dissociate to yiled acylium ions of different stability. The spontaneous fragmentations of metastable a-i have been studied by mass-analysed ion kinetic energy spectrometry and the reactions observed generally agree with the mechanisms suggested before for similar protonated aromatic ketones. In particular, these ions form intermediate ion/neutral complexes consisting of an acylium ion RCO+ and a benzyl methyl ether molecule, and fragment by an internal ion/molecule reaction generating C7H+7 and RCOOCH3 as well as by a direct dissociation releasing RCO+. By varying R it is shown that the competition between these fragmentations of metastable ions depends strongly on the stability of RCO+. In the case of carbonyl protonated benzophenones the proton migrates predominantly to the more basic (substituted) phenyl group. Labelling experiments show that a proton transfer between the two phenyl groups of the protonated benzophenones does not occur. © 1990.