Hydrogen bonding, dielectric effects, and steric effects are all factors which determine the carbonyl stretching frequency, <i>v</i>C=O, of ketones in solution. The <i>v</i>C=O frequency for ketones shifts continuously at constant concentration in solutions of CHCl<sub>3</sub>/CCl<sub>4</sub> with change in the mole ratio of the two solvents. The <i>v</i>C=O frequency is also affected by change in concentration in either CCl<sub>4</sub> or CHCl<sub>3</sub> solution.
R. A. Nyquist, C. L. Putzig, and L. Yurga, "Solvent and Concentration Effects on Carbonyl Stretching Frequencies: Ketones," Appl. Spectrosc. 43, 983-991 (1989)