EFFECTS OF PRESSURE AND TEMPERATURE ON THE DYNAMICS OF LIQUID TERT-BUTYL ALCOHOL

The solution structure of tert-butyl alcohol was investigated as a fun ction of pressure and temperature using high-resolution nuclear magnet ic resonance (NMR) spectroscopy. Simulations of the solution structure were undertaken using molecular dynamics and a simple phenomenologica l model describing clustering in liquid tert-butyl alcohol, Chemical s hifts, relaxation times (T-1), and line widths (fwhm) of the CH3 and O H groups were monitored over a pressure and temperature range up to si milar to 1.0 kbar and from 297 to 423 K, respectively. Simulations dem onstrated a cyclic tetramer as the dominant structure in the liquid, w ith pressure having negligible effects on the overall liquid structure . Temperature shifted the structural distribution and increased the mo le fraction of short linear chains in liquid tert-butyl alcohol. The r otational correlation time determined from the spin-lattice relaxation time, T-1, and its pressure dependence is consistent with a cyclic st ructure for liquid tert-butyl alcohol that is stable as a function of pressure. This is in contrast to earlier studies of methanol in which pressure was determined to decrease hydrogen bonding and linear chain structures were predominant in the liquid.