FTIR and Ab Initio Investigations of the MTBE−Water Complex

The infrared spectrum of methyl tert-butyl ether (MTBE) in liquid water has been studied using both FTIR absorption and FTIR-ATR spectroscopy in conjunction with ab initio calculations. Compared to the liquid MTBE IR spectrum, the C-O and C-C stretching vibrational frequencies of MTBE in water are found to shift to the red and blue by up to 26 and 9 cm (-1), respectively. Ab initio calculations suggest that these shifts are caused by complexation of the MTBE molecule with water molecules through hydrogen bonding. Our observation of the vibrational frequency shifts in the IR spectrum of MTBE in water provides the IR spectroscopic evidence of organics-water complexes in the diluted aqueous solution. The implication of the effect of the hydrogen bond in organics-water complexation on solvation and reactivity of the organic compound in aqueous chemical processes is discussed.