Which is the stronger acid in each of the following pairs?(a) (b) (c) (d) Sample Solution...

Which is the stronger acid in each of the following pairs?

(a)

(b)

(c)

(d)

Sample Solution (a) Think of the two compounds as substituted derivatives of acetic acid. A tert-butyl group is slightly electron-releasing and has only a modest effect on acidity. The compound (CH3)3CCH2CO2H is expected to have an acid strength similar to that of acetic acid. A trimethylammonium substituent, on the other hand, is positively charged and is a powerful electron-withdrawing substituent. The compound (CH3)3NCH2CO2H is expected to be a much stronger acid than (CH3)3CCH2CO2H. The measured ionization constants, shown as follows, confirm this prediction.