Gas-phase basicities of the isomeric dihydroxybenzoic acids and gas-phase acidities of their radical cations
UNSPECIFIED (2000) Gas-phase basicities of the isomeric dihydroxybenzoic acids and gas-phase acidities of their radical cations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY, 11 (6). pp. 544-552. ISSN 1044-0305Full text not available from this repository.
The thermochemical acid/base properties of the six dihydroxybenzoic acids (x,y-DHB) as prototypical matrices used in matrix-assisted laser desorption/ionization (MALDI) have been investigated. The ground-state gas-phase basicities (GB) of the six DHB isomers and the gas-phase acidities (Delta G(acid)) of the corresponding radical cations ([x,y-DHB](.+)) have been determined by Fourier-transform ion cyclotron resonance mass spectrometry employing the thermokinetic method. The gas-phase basicities vary from 814 kJ mol(-1) for the least basic isomer, 3,5-DHB, to 831 kJ mol(-1) for the most basic isomer, 2,4-DHB. The obtained gas-phase acidities of the corresponding radical cations vary from 815 kJ mol-l for the most acidic species, 3,4-DHB to 858 kJ mol(-1) for the least acidic one, 2,5-DHB. The results indicate that ground-state proton transfer from the matrix radical cations to the analyte may play a role in the ionization process of MALDI, whereas proton transfer from protonated matrix molecules can be excluded. (J Am Soc Mass Spectrom 2000, 11, 544-552) (C) 2000 American Society for Mass Spectrometry.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry
Q Science > QC Physics
|Journal or Publication Title:||JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY|
|Publisher:||ELSEVIER SCIENCE INC|
|Number of Pages:||9|
|Page Range:||pp. 544-552|
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