Alcohol is an aliphatic hydrocarbon with a hydroxyl (OH) group substituting for one or more hydrogens as illustrated in Figure 15.

The -OH functional group does not behave in an ionic manner in the case of alcohols. The alcohols are molecular, not ionic, in nature. Alcohols are versatile compounds which are often used to make nearly every other kind of aliphatic compound.

Figure 15 Alcohol

Aldehydes

Aldehydes are one of the oxidation products of the alcohols. Each of these compounds contain a carbonyl group (a carbon atom double bonded to an oxygen atom) as illustrated in Figure 16.

The term "aldehyde" is a contraction of the term "alcohol dehydrogenation" indicating that two hydrogen atoms are removed from an end carbon when aldehydes are prepared from primary alcohols. The functional group (-C=0) is always at the end of the carbon chain.

Figure 16 Aldehyde