Each of these compounds can react as a nucleophile. In each case, use curved arrows to show how the nucleophile would react with the strong electrophile BF₃.
(e) CH₃CH₂OH

The pK_a of ascorbic acid (vitamin C, page 55) is 4.17, showing that it is slightly more acidic than acetic acid (CH₃COOH, pK_a 4.74).

a. Show the four different conjugate bases that would be formed by deprotonation of the four different OH groups in ascorbic acid.

b. Compare the stabilities of these four conjugate bases, and predict which OH group of ascorbic acid is the most acidic.

The pK_a of ascorbic acid (vitamin C, page 55) is 4.17, showing that it is slightly more acidic than acetic acid (CH₃COOH, pK_a 4.74).

c. Compare the most stable conjugate base of ascorbic acid with the conjugate base of acetic acid, and suggest why these two compounds have similar acidities, even though ascorbic acid lacks the carboxylic acid (COOH) group.

Each of these compounds can react as an electrophile. In each case, use curved arrows to show how the electrophile would react with the strong nucleophile sodium ethoxide, Na^{+ −}OCH₂CH₃.

a.

b. NH₄⁺

Each of these compounds can react as an electrophile. In each case, use curved arrows to show how the electrophile would react with the strong nucleophile sodium ethoxide, Na^{+ −}OCH₂CH₃.

(c) CH₃CH₂Br

(d) BH₃

Each of these compounds can react as a nucleophile. In each case, use curved arrows to show how the nucleophile would react with the strong electrophile BF₃.

(f) (CH₃)₂S

Each of these compounds can react as a nucleophile. In each case, use curved arrows to show how the nucleophile would react with the strong electrophile BF₃.

(a)

(b)