OH acidity
In chemistry, OH acidity is the tendency of molecules with a hydroxyl function to dissociate on this and to form anions with a negative charge on oxygen. The split-off proton creates an acidic reaction through the formation of an oxonium ion . Aliphatic alcohols generally exhibit only a low propensity to deprotonate, wherein methanol (pK s = 16) only slightly less acidic than water and thus is has a much higher acidity than higher-substituted alcohols such as t-butanol . Peroxides , enols and phenols , which increase the acid strength due to their mesomeric effect, are significantly more acidic . Picric acid is a by -I - and -M-effects of the three nitro groups very electron poor phenol, so that the hydroxyl group with a pK s value of 0.3 reacts strongly acidic. Other electron-withdrawing groups such as carbonyls and sulfones polarize an adjacent OH bond so strongly that the proton in these carboxylic acids or sulfonic acids can be split off very easily, which results in the typically acidic reaction of these substances. Thiols, on the other hand, are significantly more acidic than corresponding alcohols due to the longer SH bond, see SH acidity .
