Infrared and Dielectric Studies of Chloroform as Proton Donor in Hydrogen-Bond Formation

Infrared absorption bands of free and associated species of deuterochloroform were observed in binary solutions (with triethylamine). Temperature-dependent spectra were used to calculate the equilibrium constants at various temperatures and the heat of formation of the complex molecule. A value of 0.133±3% liter mole−1 was obtained for the equilibrium constant at 25°C. The heat of formation of the deuterochloroform—triethylamine complex was determined to be 4.0 kcal mole−1. The dielectric constant shows a substantial increase over the value predicted by Onsager's theory. This indicated that the associated complex possesses a large dipole moment. In conjunction with the infrared data, the dipole moment of the associated molecule was evaluated as 3.15×10−18±10% cgs units. Similar infrared and dielectric measurements were carried out on deuterochloroform—acetonitrile mixtures. No strong hydrogen bonding was detected by either method.