Competitive Binding of Methanol and Propane for Water Via Matrix-Isolation Spectroscopy: Implications for Inhibition of Clathrate Nucleation

Methanol is a well-known thermodynamic inhibitor of clathrate hydrate formation. The interactions responsible for the inhibition, however, are not well-identified. Propane is a relatively simple hydrocarbon that forms a clathrate hydrate under mild conditions. This paper reports data about the interaction of methanol with water−propane complex. Methanol, water, and propane are isolated in carbon tetrachloride, and the interaction is probed with infrared spectroscopy. Water is known to interact with propane via the oxygen lone pairs and the propane methylene hydrogens. Experimental evidence indicates that methanol hydrogen bonds to water via donation of the hydroxyl hydrogen (K = 4.4 × 102). Methanol does not have a direct interaction with propane. These results are consistent with an inhibitory mechanism in which methanol competes with propane for the oxygen atom of water.