Why is protonated pyrimidine (pK_a = 1.0) more acidic than protonated pyridine (pKa = 5.2)?

Rank the compounds in each of the following groups from strongest acid to weakest acid:

a.

Explain why the $\alpha$-hydrogen of an N,N-disubstituted amide is less acidic (pK_a = 30) than the $\alpha$-hydrogen of an ester (pK_a = 25).

Rank the compounds in each of the following groups from strongest acid to weakest acid:

c.

The pK_a values of a few ortho-, meta-, and para-substituted benzoic acids are shown below:

The relative pK_a values depend on the substituent. For chloro-substituted benzoic acids, the ortho isomer is the most acidic and the para isomer is the least acidic; for nitro-substituted benzoic acids, the ortho isomer is the most acidic and the meta isomer is the least acidic; and for amino-substituted benzoic acids, the meta isomer is the most acidic and the ortho isomer is the least acidic.

Explain these relative acidities.

a. Cl: ortho > meta > para

Why is the conjugate acid of morpholine more acidic than the conjugate acid of piperidine?

Explain why pyrrole (pK_a ~ 17) is a much stronger acid than ammonia (pK_a = 36).

Predict the products (if any) of the following acid–base reactions.

(d) α-bromopropionic acid + sodium propionate

(e) benzoic acid + sodium phenoxide

Rank the compounds in each set in order of increasing acid strength.

(c)