The Foundations of Chemistry

In the Brønsted–Lowry description, an

acidis a proton donorand a baseis a

proton acceptor.Review the terminology

of conjugate acid–base pairs in Section

10-4.

28-4 Reactions of Brønsted–Lowry Acids and Bases 1115

REACTIONS OF BRØNSTED–LOWRY ACIDS AND BASES

Many organic compounds can act as weak Brønsted–Lowry acids or bases. Their reac-

tions involve the transfer of Hions, or protons(Section 10-4). Like similar reactions of

inorganic compounds, these acid–base reactions of organic acids and bases are usually fast

and reversible. Consequently, we can discuss the acidic or basic properties of organic

compounds in terms of equilibrium constants (Section 18-4).

Some Organic Acids

O

B

The most important organic acids contain carboxyl groups, XCXOXH. They are called

carboxylic acids (Section 27-13). They ionize slightly when dissolved in water, as illus-

trated with acetic acid.

28-4

CH 3 COOHH 2 OHCH 3 COO 3 O Ka 1.8 10^5

[CH 3 COO][H 3 O]

[CH 3 COOH]

acid 1 base 2 base 1 acid 2

Figure 28-9 The two conformations of cyclohexane. (a) Chair, (b) stereoview of the chair
conformation, (c) twist boat and (d) stereoview of the twist boat conformation.

(a)

(c)

(b)

(d)