General

What are the relative reactivities of acyl compounds?

Figure 51.5: Relative reactivities of acyl compounds.

How are acyl chlorides named?

Acyl chlorides have the suffix ``-oyl'' plus the name of the halide.

1. The carbon of the acyl halide will always be positioned at the end of a carbon chain, i.e. at the ``1'' position. For this reason, the ``1" is omitted from naming.
2. The suffix ``-oyl" replaces the terminal ``-e'' of the alkane name. After this, the name of the halide is added.

Figure 51.6: Examples of acyl chlorides: (left) methanoyl chloride, (center) ethanoyl chloride, (right) 2-methylpropanoyl chloride.

How are anhydrides named?

Anhydrides have the suffix ``-oic anhydride", which denotes a $-OCOR$ group that replaces the $-OH$ of a carboxylic acid.

1. The $-OCOR$ will always be positioned at the end of a carbon chain, making a number designation unnecessary.
2. Most anhydrides are named by dropping the word ``acid'' from the carboxylic acid and replacing it with ``anhydride.''
3. If two alkane moieties (halves) exist, name both and arrange the shorter chain first
4. Cyclic anhydrides are named as alkanedioic anhydrides

Figure 51.7: Examples of anhydrides: (a) methanoic anhydride (formic anhydride), (b) ethanoic anhydride (acetic anhydride), (c) ethanoic propanoic anhydride, (d) pentanediic anhydride.

How are esters named?

1. To name the alkyl alkanoate (i.e. ester), identify the carbon chains that are separated by an ``ether'' oxygen
2. Naming the two halves:
   • Name the chain without the carbonyl group - this is the ``alkyl'' chain - with the suffix of ``-yl''
   • Name the chain with the carbonyl group - this is the ``alkanoate'' chain - with the suffix of ``-oate''

Note: the location of the carbonyl group determines which is the alkanoate chain.

Figure 51.8: Examples of esters: (left) ethyl methanoate and (right) but-2-yl 3-methylpentanoate.

How are amides named?

1. The ``amide'' suffix is added to the end of an alkane chain
2. When two amides exist at each end of an alkane, the ``diamide'' suffix is used. Because a consonant is used (``d''), the vowel is preserved in the alkane chain (see Figure 51.9(c) below for an example)
3. Cyclic amides are called lactams designated $\beta$-lactam (2 non-carbonyl carbons), $\gamma$-lactam (3 non-carbonyl carbons), and $\delta$-lactam (4 non-carbonyl carbons)

Note: Amines will be reviewed in another chapter.

Figure 51.9: Examples of amides: (a) methanamide, (b) ethanamide, (c) propanediamide, (d) $\beta$-lactam (penicillin G).