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The pK, of an acyclic aliphatic heptaol ((HOCH2CH2CH(OH)CH2)3COH) was measured in DMSO, and its gas-phase acidity is reported as well. This tertiary alcohol was found to be 1O~ times more acidic than tert.butyl alcohol in DMSO and an order of magnitude more acidic than acetic acid (i.e., plC2 = 11.4 vs 12.3). This can be attributed to a 21.9 kcal mol' stabilization of the charged oxygen center in the conjugate base by three hydrogen bonds and another 6.3 kcal mol-1 stabilization resulting from an additional three hydrogen bonds between the uncharged I primary and secondary hydroxyl groups. Charge delocalization by both the first and second solvation shells may be used to facilitate enzymatic reactions. Acidity constants of a series of polyols were also computed, and the combination of hydrogen-bonding and electron-withdrawing substituents was found to afford acids that are predicted to be extremely acidic in DMSO (i.e., pK2< 0). These hydrogen bond enhanced acids represent an attractive class of Bronsted acid catalysts. [ABSTRACT FROM AUTHOR]