Document Detail


Experimental and computational study on the molecular energetics of 2-pyrrolecarboxylic acid and 1-methyl-2-pyrrolecarboxylic acid.
MedLine Citation:
PMID:  19670901     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This paper reports a combined thermochemical experimental and computational study of 2-pyrrolecarboxylic acid and 1-methyl-2-pyrrolecarboxylic acid. Static bomb combustion calorimetry and Knudsen mass-loss effusion technique were used to determine the standard (p degrees = 0.1 MPa) molar enthalpies of combustion, Delta(c)H(m) degrees, and sublimation, Delta(cr)(g)H(m) degrees, respectively, from which the standard (p degrees = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, were derived. The values obtained were -(286.3 +/- 1.7) and -(291.6 +/- 1.7) kJ x mol for 2-pyrrolecarboxylic acid and 1-methyl-2-pyrrolecarboxylic acid, respectively. For comparison purposes, the gas-phase enthalpies of formation of these two compounds were estimated by G3(MP2)//B3LYP and MP2 approaches, using a set of gas-phase working reactions; the results are in excellent agreement with experimental data. G3(MP2)//B3LYP computations were also extended to the calculation of N-H bond dissociation enthalpies, gas-phase acidities and basicities, proton and electron affinities and adiabatic ionization enthalpies. Moreover, the results are also discussed in terms of the energetic effects of the addition of a carboxylic and of a methyl groups to the pyrrole ring and compared with structurally similar compounds.
Authors:
Ana Filipa L O M Santos; Manuel A V Ribeiro da Silva
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  113     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2009 Sep 
Date Detail:
Created Date:  2009-08-27     Completed Date:  2009-12-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9741-50     Citation Subset:  IM    
Affiliation:
Centro de Investigação em Química, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto, Portugal.
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MeSH Terms
Descriptor/Qualifier:
Calorimetry
Carboxylic Acids / chemistry*
Computer Simulation
Gases / chemistry
Models, Molecular*
Molecular Conformation
Phase Transition
Proline / analogs & derivatives*,  chemistry
Pyrroles / chemistry*
Thermodynamics
Chemical
Reg. No./Substance:
0/1-methyl-2-pyrrolecarboxylic acid; 0/Carboxylic Acids; 0/Gases; 0/Pyrroles; 147-85-3/Proline; 634-97-9/2-pyrrolecarboxylic acid

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