Document Detail

Comparison of the orders of gas-phase basicities and ammonium ion affinities of polyethers by the kinetic method and ligand exchange technique.
MedLine Citation:
PMID:  24225997     Owner:  NLM     Status:  In-Data-Review    
The orders of relative gas-phase basicities and ammonium ion affinities of a series of polyethers obtained by application of the kinetic method and ligand exchange technique are compared to evaluate the discrepancies of results between the two techniques. The order of gas-phase basicities determined by the ligand exchange technique in a quadrupole ion trap agrees with the order established previously by Kebarle using equilibrium methods in a high-pressure mass spectrometer. The order obtained by the kinetic method in a triple quadrupole mass spectrometer varies for the ranking of one polyether (12-crown-4), and this discrepancy is attributed to a difference in the rates of the competing dissociation pathways from the triethylene glycol dimethyl ether/12-crown4 proton-bound adduct, owing to a substantial variation in the flexibilities of these two ethers. For the order of gas-phase ammonium ion affinities, the kinetic method results agree overall with the ligand exchange results; however, the order of ammonium ion affinities for tetraethylene glycol dimethyl ether and 15-crown-5 could not be differentiated by the ligand exchange method because of the rapidity of ammonium ion transfer between the two polyethers in both directions.
H F Wu; J S Brodbelt
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of the American Society for Mass Spectrometry     Volume:  4     ISSN:  1044-0305     ISO Abbreviation:  J. Am. Soc. Mass Spectrom.     Publication Date:  1993 Sep 
Date Detail:
Created Date:  2013-11-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9010412     Medline TA:  J Am Soc Mass Spectrom     Country:  United States    
Other Details:
Languages:  eng     Pagination:  718-22     Citation Subset:  -    
Department of Chemistry and Biochemistry, University of Texas, 78712-1167, Austin, TX.
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