Organic acids
Organic acids typically contain the ˆCOOH group called the carboxyl group. and is commonly written ˆCOOH. Acids with one carboxyl group are known as monocarboxylic acids, and those with more than one are polycarboxylic acids.
A wide variety of saturated monocarboxylic acids occur in nature as constituents of fats, oils, and waxes. Unsaturated acids are also found in these materials, and, as a result, both types are commonly known as fatty acids. The majority of the fatty acids derived from natural products have an even number of carbon atoms and usu-ally have a straight-chain or normal structure.
Acrylic Acid (CH2¨CHCOOH) Acrylic acid is used extensively because of its ability to polymerize, a characteristic of many compounds with unsaturated linkages. Derivatives of the acid are used to form colorless plastics such as Lucite and Plexiglas.
Oleic Acid [CH3(CH2)7CH¨CH(CH2)7COOH]
Dicarboxylic acids
Name Formula
Oxalic (COOH)2
Malonic CH2(COOH)2
Succinic (CH2)2(COOH)2
Glutaric (CH2)3(COOH)2
Adipic (CH2)4(COOH)2
Pimelic (CH2)5(COOH)2
Suberic (CH2)6(COOH)2
Linoleic Acid [CH3(CH2)4CH¨CHCH2CH¨CH(CH2)7COOH]
Linolenic Acid [CH3(CH2CH¨CH)3CH2(CH2)6COOH]
Oleic, linoleic, and linolenic acids are normal constituents of the glycerides of most fats and oils.
A glyceride is the ester formed by combining glycerol with these acids.
Oleic acid is considered to be an essential acid in the diet of humans and animals.
Linoleic and linolenic acids as glycerides are important constituents of linseed and other drying oils.
Hydroxy Acids
Hydroxy acids have OH groups attached to the molecule other than in the carboxyl group. Thus, they act chemically as acids and as alcohols. A number of the hydroxy acids have special names. Some examples are
HOCH2COOH Hydroxyacetic acid, glycolic acid
CH3CHOHCOOH - Hydroxy-propionic acid, lactic acid
HOCH2CH2COOH - Hydroxy-propionic acid, hydracrylic acid
HOCH2CH2CH2COOH - Hydroxybutyric acid
Lactic acid - hydroxypropionic acid, is of special interest since it is formed during bacterial fermentation of milk and therefore is a normal constituent of industrial wastes from the dairy industry
Hydroxy Polycarboxylic Acids
There are several hydroxy polycarboxylic acids.
Citric acid L-(+)-Tartaric acid
Tartaric acid occurs in many fruits, especially grapes, and is present in canning and winery wastes. Citric acid is the major acid of all citrus fruits: oranges, lemons, limes, and grapefruit