the most significant being the ability to form hydrogen bonds. The formation of
hydrogen bonds between amines, and between amines and water, accounts for their
higher boiling points (than alkanes) and their water solubility.
b. Reactions of Amines. Since amines are derivatives of ammonia, they are
bases as defined by the Bronsted-Lowry theory. The nitrogen of the amine can accept
a proton to form a substituted ammonium ion.
CH3 CH2 NH2 + H+ ---> CH3 CH2 NH3 +
Amines will thus react with inorganic acids to form salts. (Amines react with organic
acids to form amides, a class of organic compounds discussed later in this subcourse.)
CH3 NH2 + HCl ---> CH3 NH3 +Cl-
The reaction in the example above results in a hydrochloride salt of the amine and is a
very important reaction in pharmacy. Many drugs contain an amine functional group,
and if they contain many carbon atoms, they are not very soluble in water. The salts
formed from amines, however, are very soluble in water. Therefore, if we wish to use a
water solution of an amine drug that is insoluble, we can make it soluble by forming the
salt of the amine.
c. Use of Amines. As already stated, the amine functional group is contained
in many different drugs that have quite different actions in the body. Generally, these
drugs are very complex and you would never be expected to draw or know the structure
for these drugs. You should, however, recognize the -NH2 group of an amine and be
cognizant of its basic properties.
3-12. CARBOXYLIC ACIDS
Carboxylic acids are formed by the two-step oxidation of alcohols as stated
previously and have the general structural formula
or R COOH.
Some examples of carboxylic acids are:
CH3 C OH
O C OH
CH3 CH C OH