Aspirin. An Ab Initio Quantum-Mechanical Study of Conformational Preferences and of Neighboring Group Interactions.

Rainer Glaser

Department of Chemistry
University of Missouri-Columbia
Columbia, Missouri, 65211 (USA)

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Figure 1. Crystal structure of aspirin: A, B, C & D.

Figure 2. Structures of benzoic acid isomers.
The structures of s-trans BA & s-cis BA determined at RHF/6-31G*.
The structures of s-trans BA & s-cis BA determined at B3LYP/6-31G*.

Figure 3. Structures of phenyl acetate isomers.
The structures of s-trans PA & s-cis PA determined at RHF/6-31G*.
The structures of s-trans PA & s-cis PA determined at B3LYP/6-31G*.

Figure 4. Isomers of aspirin with ester C-O s-trans conformation (a-structures) and with ester C-O s-cis conformations (b-structures).
The a-structures determined at RHF/6-31G*: 1a, 2a, 3a, 4a, 5a.
The a-structures determined at B3LYP/6-31G*: 1a, 2a, 3a, 4a, 5a.
The b-structures determined at RHF/6-31G*: 1b, 2b, 3b, 4b.
The b-structures determined at B3LYP/6-31G*: 1b, 2b, 3b, 4b.