Collision-induced loss of AgH from Ag+ adducts of alkylamines, aminocarboxylic acids and alkyl benzyl ethers leads exclusively to thermodynamically favored product ions.
The loss of AgH from [M+Ag]+ precursor ions of tertiary amines, aminocarboxylic acids and aryl alkyl ethers is examined by deuterium labeling combined with collision activation (CA) dissociation experiments. It was possible to demonstrate that the AgH loss process is highly selective toward the hydride abstraction. For tertiary amines and aminocarboxylic acids, hydrogen originates from the alpha-methylene group carrying the nitrogen function (formation of an immonium ion). In all cases examined, the most stable, i.e. the thermodynamically favored product ion is formed. In the AgH loss process, a large isotope effect operates discriminating against the loss of D. The [M+Ag]+ ion of benzyl methyl ether loses a hydride ion exclusively from the benzylic methylene group supporting the experimental finding that the AgH loss reaction selectively cleaves the weakest C-H bond available.
Schäfer
Mathias
M
Institute for Organic Chemistry, University Cologne; Greinstr.4, 50939 Cologne, Germany. mathias.schaefer@uni-koeln.de
Dreiocker
Frank
F
Budzikiewicz
Herbert
H
D000588:Amines / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry; D004987:Ethers / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D013816:Thermodynamics
D000588:Amines; D002264:Carboxylic Acids; D004987:Ethers; D007477:Ions; D012834:Silver; D006859:Hydrogen; D003903:Deuterium