Document Detail

Rotational barriers in monomeric CH2=CX-COOH and CH2=CX-CONH2 (X is H or CH3) and vibrational analysis of methacrylic acid and methacrylamide.
MedLine Citation:
PMID:  17329157     Owner:  NLM     Status:  MEDLINE    
The internal rotations in acrylic and methacrylic acids CH2=CX-COOH and their amides CH2=CX-CONH2 (X is H or CH3) were investigated by DFT-B3LYP calculations with 6-311+G** basis set. The potential energy curves were consistent with two minima that correspond to planar cis and trans conformation in the case of the acids (or cis and near-trans forms in the case of the amides). Acrylic acid and acrylamide were predicted to have the cis form as the low and predominant conformation of the molecules. In the case of the methacrylic acid and methacrylamide, the conformational relative stability was predicted to reverse as going from the acrylic to the metha compounds. The trans conformer in methacrylic acid or the near-trans in methacrylamide were predicted to be thermodynamically low energy structures of the molecules. The CCCO rotational barrier was calculated to vary from 4 to 6kcal/mol in the four molecules. The OCOH and OCNH torsional barriers were calculated to be about 13 and 22kcal/mol in the acids and the amides, respectively. The vibrational frequencies of methacrylic acid and methacrylamide were computed at the DFT-B3LYP/6-311+G** level and reliable vibrational assignments were made on the basis of normal coordinate analyses and comparison with experimental data of both molecules in their low energy conformations.
H M Badawi; M A A Al-Khaldi; S S A Al-Abbad; Z H A Al-Sunaidi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-12-15
Journal Detail:
Title:  Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy     Volume:  68     ISSN:  1386-1425     ISO Abbreviation:  Spectrochim Acta A Mol Biomol Spectrosc     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-10-08     Completed Date:  2008-02-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9602533     Medline TA:  Spectrochim Acta A Mol Biomol Spectrosc     Country:  England    
Other Details:
Languages:  eng     Pagination:  432-42     Citation Subset:  IM    
Department of Chemistry, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia.
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MeSH Terms
Acrylamides / chemistry*
Methacrylates / chemistry*
Models, Chemical
Molecular Conformation
Spectrophotometry, Infrared
Spectrum Analysis, Raman
Torsion, Mechanical
Reg. No./Substance:
0/Acrylamides; 0/Methacrylates; 79-39-0/methacrylamide; 79-41-4/methacrylic acid

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