To bridge the gap between ab initio interaction energy information and macroscopic properties prediction, we constructed potential models for acetonitrile and methanol based on ab initio pair interaction energy data of Bukowski et al. [J. Phys. Chem. A 103, 7322 (1999)]. Lennard-Jones functions plus charge-charge interactions are used to model the ab initio interaction energies for several hundred dimer configurations. Gibbs ensemble Monte Carlo simulations were performed with these models for the pure components. The simulated phase diagrams are in reasonable agreement with experimental data; critical temperatures are predicted within six and twelve percent for acetonitrile and methanol, respectively. For comparison, simulations were also performed with a previously published potential for acetonitrile [J. Phys. Chem. A 101, 8327 (1997)].