The two Lewis acid sites assumed to catalyze the Meerwein-Ponndorf-Verley (MPV) reaction are identified by IR bands at 3782 and 3660-3680 cm(-1). Different combinations of heat-treatment protocols were used and the results indicated that the final temperature, ramp rate, and gas environment make a difference in the relative intensities of the 3782 and 3665 cm(-1) bands. Combining different heat-treatment procedures, samples were produced where the 3782 and 3665 cm(-1) band intensities moved in opposite directions (i.e., one increasing and the other decreasing). The MPV reduction of 4-tert-butylcyclohexan one with 2-propanol in the gas phase was studied at 100 degreesC in a nitrogen atmosphere. The increasing trend of the relative intensity of the 3665 cm(-1) band showed a correlation in favor of the formation of cis-4-tert-butylcyclohexanol (cis-4-TBCHL). This suggests that the species associated with the 3665 cm(-1) band are likely responsible for cis-4-TBCHL selectivity. (C) 2003 Elsevier Inc. All rights reserved.