Functional Classes I, Structure and Naming - Organic Chemistry Concepts: An EFL Approach - page 34

2.8.3.1 NAMING
Acyl halides (RCO-Halogen) are given two-word functional class names. The
corresponding acyl group comes from the parent acid by replacing the termi-
nal -ic with -yl. Then this is written before the appropriate halide. For example,
CH 3 CH 2 CH 2 COBr is butanoyl bromide.
Esters (RCO-OR′) are given two-word names in a similar way to the naming
of salts. The R′ group becomes the first word, and the second word is formed
by changing the parent acid -ic to -ate. For example, CH 3 CH 2 CH 2 CO 2 CH 3 is
methyl butanoate.
Amides (RCO-NH 2 ) are named by replacing the name of the corresponding
acid by the systematic ending -amide. As with amines, the categories 1°, 2°, and
3° may exist for amides, and the naming is done in the same way. For example,
CH 3 CH 2 CH 2 CONH 2 is butanamide.
Acid anhydrides (RCO-O-COR′) are equal to two molecules of carboxylic acid
which have combined with the loss of a water molecule. Symmetrical examples
are named by replacing acid with anhydride in the parent carboxylic acid. For
example, CH 3 CH 2 CO-O-COCH 2 CH 3 is propionic anhydride.
2.8.3.2 NITRILES (CYANIDES)
Although nitriles do not have a carbonyl group, they are related chemically to
carboxylic acids. Chapter 7 discusses this chemistry in more detail. The nitrile
group (-C ^ N) has carbon as an sp -hybrid because of the triple bond to the het-
eroatom. Therefore, as is clear from Figure 2.14 , the carbon has the same formal
oxidation number of +3 as the other acyl derivatives.
FIGURE 2.14
Structure and naming of nitriles (cyano derivatives).
The molecular formula of the nitrile group clearly shows that it equals an amide
that has lost a water molecule. Simple members of the class are named by adding
the ending -nitrile to the parent chain name, and the nitrile carbon is numbered
as 1. More complex examples are named as derivatives of the corresponding
carboxylic acids by changing the -ic to -onitrile, or by replacing the -carboxylic
acid ending with -carbonitrile.