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Ab initio studies of structural features not easily amenable to experiment. 38. Structural and conformational investigations of propanoic, 2-methylpropanoic, and butanoic acid

✍ Scribed by K. Siam; V. J. Klimkowski; J. D. Ewbank; Lothar Schäfer; C. Van Alsenoy

Publisher
John Wiley and Sons
Year
1984
Tongue
English
Weight
412 KB
Volume
5
Category
Article
ISSN
0192-8651

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✦ Synopsis

The structures and conformational energies of several conformations of propanoic acid, 2-methylpropanoic acid, and butanoic acid were determined by geometrically unconstrained ab initio gradient geometry refinement on the 4-21G level. The O=C-C-C torsional potentials of propanoic acid and butanoic acid are found to be practically identical. There are energy minima a t 0" and 120", and maxima in the 60" region and at 180". In 2-methylpropanoic acid there are energy minima at H-C-C=O dihedral angles of 0" and 120", and maxima at 60" and 180". The exact positions of the maxima and minima of the H-C-C=O torsional potential of 2-methylpropanoic acid are found t o be predictable from propanoic acid rotationalpotential parameters. Some conformationally dependent, local geometry trends are discussed.

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