Epimerization of benzylpenicilloic acid in alkaline media.

5R,6R-Benzylpenicilloic acid was found to epimerize slowly in alkaline media to 5S,6R-benzylpenicilloic acid until equilibrium was established. Epimerization proceeded via the imine tautomer of penamaldic acid rather than the enamine form and was found to favor the 5S,6R-epimer at equilibrium. The conversion process was monitored using both reverse-phase high-performance liquid chromatography and NMR spectroscopy.

The desolvation and oxidation of crystals of dialuric acid monohydrate.

Examination of the influence of the solvent of crystallization on the solid-state oxidation of dialuric acid (I) monohydrate to alloxantin (II) is reported. This reaction was investigated at low and high humidities using photomicrography, X-ray crystallography, and IR and mass spectrometry. Crystals of dialuric acid desolvated somewhat anisotropically; this behavior was consistent with crystal packing.