(3) Amide formation, as illustrated by the reaction below, is the reaction of
a carboxylic acid with an amine to yield a new class called an amide.
+ CH3 CH2 NH2
------> CH3 CNHCH2 CH3 + H2O
c. Uses of Carboxylic Acids. Many acids, such as acetic, salicylic, and lactic,
are used topically to treat local conditions. Others are used systemically. Still others,
like citric acid, which is found naturally in lemons, are used to flavor syrups for
administration of other drugs. They are also used in many analytical procedures in the
Aldehydes result from the first oxidation of alcohols and have the general
structural formula R-C-H. Since aldehydes cannot form hydrogen bonds between
themselves, they have lower boiling points than corresponding alcohols or acids.
Again, as with the other classes or organic compounds in table 3-3, the lower-
molecular-weight aldehydes (up to five carbons) are soluble in water. Aldehydes are
neutral in pH and undergo both oxidation and reduction reactions. They are easily
oxidized to acids and reduced to alcohols. Some aldehydes, such as vanillin and
benzaldehyde, are frequently used in the pharmacy as flavoring agents.
Ketones result from the oxidation of a secondary alcohol and have the general
O where R and R' can be the same or different
a. Ketones are similar to aldehydes in their boiling points, which are lower than
those of corresponding alcohols and carboxylic acids.
b. Ketones are neutral compounds, being neither acids nor bases. They
undergo the process of reduction, by which they are converted to secondary alcohols.