| Gas-phase acid-base properties of melamine and cyanuric acid. | |
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MedLine Citation:
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PMID: 20621504 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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The thermochemical properties of melamine and cyanuric acid were characterized using mass spectrometry measurements along with computational studies. A triple-quadrupole mass spectrometer was employed with the application of the extended Cooks kinetic method. The proton affinity (PA), gas-phase basicity (GB), and protonation entropy (Δ(p)S) of melamine were determined to be 226.2 ± 2.0 kcal/mol, 218.4 ± 2.0 kcal/mol, and 26.2 ± 2.0 cal/mol K, respectively. The deprotonation enthalpy (Δ(acid)H), gas-phase acidity (Δ(acid)G), and deprotonation entropy (Δ(acid)S) of cyanuric acid were determined to be 330.7 ± 2.0 kcal/mol, 322.9 ± 2.0 kcal/mol, and 26.1 ± 2.0 cal/mol K, respectively. The geometries and energetics of melamine, cyanuric acid, and related ionic species were calculated at the B3LYP/6-31+G(d) level of theory. The computationally predicted proton affinity of melamine (225.9 kcal/mol) and gas-phase deprotonation enthalpy of cyanuric acid (328.4 kcal/mol) agree well with the experimental results. Melamine is best represented as the imide-like triazine-triamine form and the triazine nitrogen is more basic than the amino group nitrogen. Cyanuric acid is best represented as the keto-like tautomer and the N-H group is the most probable proton donor. |
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Authors:
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Sumit Mukherjee; Jianhua Ren |
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Publication Detail:
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Type: Journal Article Date: 2010-06-11 |
Journal Detail:
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Title: Journal of the American Society for Mass Spectrometry Volume: 21 ISSN: 1879-1123 ISO Abbreviation: J. Am. Soc. Mass Spectrom. Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-09-24 Completed Date: 2010-12-30 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9010412 Medline TA: J Am Soc Mass Spectrom Country: United States |
Other Details:
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Languages: eng Pagination: 1720-9 Citation Subset: - |
Copyright Information:
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Copyright © 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved. |
Affiliation:
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Department of Chemistry, University of the Pacific, Stockton, California 95211, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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