Vibrational Circular Dichroism study of chiral food additives: c-valero- and c-caprolactone

Abstract

c-valerolactone and c-caprolactone are commonly used as flavor additives in the food industry. In the present work we fully explore the molecular structure and conformational distribution of enantiopure c-valerolactone and c-caprolactone in solution state by using Vibrational Circular Dichroism (VCD) spectroscopy assisted by quantum chemical calculations. In order to establish the most accurate DFT method for this type of samples a set of methods and basis sets have been implemented and their performances have been compared. Subsequently, we have performed a complete vibrational assignment, which allowed to detect certain key vibrational features related to specific solution-state conformational speciation. In spite of the rigidity of the samples being studied, our results point to the incidence of conformational mixture in CCl4 solution in both samples.