The Foundations of Chemistry

Some carboxylic acid molecules contain more than one XCOOH group (Table 27-12).

These acids are nearly always called by their common names. For example, oxalic acid,

found in rhubarb, spinach, and tomatoes, is a dicarboxylic acid; citric acid, found in citrus

fruits, is a tricarboxylic acid.

Aromatic acids are called by their common names or named as derivatives of benzoic

acid, which is considered the “parent” aromatic acid.

Although many carboxylic acids occur in the free state in nature, many occur as amides

or esters (Section 27-14). -Amino acids are substituted carboxylic acids with the general

structure

OH

C

O OH

C

Cl CH 3

CH 3

O OH

C

O

benzoic acid p-chlorobenzoic acid 2,4-dimethylbenzoic acid
These two derivatives of acetic acids
act as herbicides (weed killers) by
overstimulating the plant’s growth
system.

107 8CHAPTER 27: Organic Chemistry I: Formulas, Names, and Properties

TABLE 27-12 Some Naturally Occurring Organic Acids

Name Source

acetic acid CH 3 XCOOH vinegar

citric acid citrus fruits

lactic acid sour milk

malic acid apples, watermelons,

grape juice, wine

oxalic acid HOOCXCOOH rhubarb, spinach, tomatoes

quinic acid cranberries

tartaric acid grape juice, wine

OH

COOH

HOOC CH 2 C CH 2 COOH

OH

CH 3 CH COOH

OH

HOOC CH 2 CH COOH

C

C C

CH 2 COOH

HO CCH 2 OH

H

H OH

H OH

OH

CH

OH

HOOC CH COOH

CH 2

Cl

Cl O C OH

O

CH 2

CH 3

Cl O C OH

O