We explore the effects of different molecular surroundings on the equilibrium conversion of ethanol and acetic acid to ethyl acetate and water. While the equilibrium conversion of this reaction is limited from 66% to 68% in the liquid phase, experimental measurements have found that the reaction yield can be enhanced within a supercritical carbon dioxide solvent and within microporous carbons. The reactive Monte Carlo simulations presented mirror these experimental findings, and provide the molecular-level information needed to explain the experimental observations. The simulations demonstrate that selectivity is the driving force for the enhanced conversion in carbon slit-pores and in the supercritical carbon dioxide solvent. Ethyl acetate tends to be selectively adsorbed within carbon slit-pores in the range of 1.0 to 2.0 nm in width, and is selectively solubilized within carbon dioxide clusters near the critical point of the fluid. (C) 2003 American Institute of Physics.