Ethyl acetate: X-ray, solvent and computed structures.

Ethyl acetate (ethyl ethanoate) was crystallized in situ and the crystal structure was determined. In the solid, the molecule is flat with trans conformation. The geometric details of ethyl acetate as a solvate are analyzed statistically using the Cambridge Structural Database, uncovering a high degree of hidden disorder. Despite the disorder, they exhibit a preference of the trans over the gauche isomer, with a negligible contribution of the cis isomer. These results are compared to ab initio calculations on both solid-state and molecular level. For the molecular structures, the computed energy differences of the isomers match the statistics found as a solvent. Several DFT-D2 methods used to calculate the solid state yield results that differ significantly from the experiment.