Polarimetry study of the intrinsic rotation of (1R,4R)-(+)-camphor in organic solvents

Abstract

Optical activity, or the ability of a chiral molecule to rotate the plane of linearly polarized light, varies with the solvent for chiral molecules in solution. In an attempt to derive relationships between solvent properties and solute optical activity, the intrinsic rotations of (+)-camphor were measured in organic solvents at ambient temperature using a laser-based polarimeter with a wavelength of 532 nm. The intrinsic rotation values were analyzed using various solvent properties as independent parameters. Our results suggest that solvent dipolarity, solvent acidity, and solvent relative permittivity are weakly correlated with (+)-camphor intrinsic rotation, while solvent polarizability, solvent basicity, and (+)-camphor solubility show no significant correlation with the optical activity. A clear chemical underpinning of the solvent effect on optical activity remains elusive.