a. Properties of Alcohols. The low-molecular-eight alcohols are volatile
liquids, and the high-molecular-weight alcohols (more than 13 carbons) are solids. The
first three alcohols (C1 to C3) are completely miscible (mix in any proportion) with water.
The water solubility decreases as the number of carbons increases, and the large-
molecular-eight alcohols are insoluble in water. Alcohols have higher boiling points and
melting points than alkanes with the same or similar molecular weights (MW). For
The water solubility and the high melting and boiling points of alcohols result from their
ability to form hydrogen bonds with water and to form hydrogen bonds intermolecularly
b. Reactions of Alcohols. Chemically, the alcohols can be considered to be
neutral (in terms of acids and bases) even though they can act as very weak acids or
bases as water does. They undergo several kinds of chemical reactions, the most
important of which is oxidation. Oxidation in organic chemistry is defined as the
elimination of hydrogen from or the addition of oxygen to a compound.
The oxidation of a primary alcohol can be expressed by the following
C=O and -C-OH are two more functional groups, indicating aldehydes
and carboxylic acids, respectively.
The first step in this oxidation is the removal of two hydrogen atoms from the alcohol to
form an aldehyde, and the second step is the addition of one oxygen atom to the
aldehyde to form a carboxylic acid.
(2) Secondary alcohols undergo only the first step. For example, a three-
carbon alcohol is oxidized to form CH3 C CH3 , which is an example of a new class of
compounds called ketones.
Tertiary alcohols are not oxidized.