When it comes to the common naming of esters, we're going to follow the same rules as IUPAC, except now the parent chain consists of common name prefixes with an -ate ending. So the naming convention will be substituent, prefix, and then modifier. Let's take a look at this example. It asks us to provide a common name for the following ester:
- Identify the alkyl group connected to the oxygen atom. Looking at the structure, the alkyl group is a 3-carbon chain named propyl, which we name as a substituent. Remember, substituents are named at the beginning of the name. Here, no numerical location for the alkyl group is needed because it is attached directly to an oxygen, not a carbon.
- Identify and name the carbon chain including the carbonyl group. We figure out the length of the carbon chain starting from the carbonyl group, which as carbon number 1 is implied. In this case, there are 5 carbons. For common names, a 5-carbon chain uses the prefix valer-, and since it is an ester, we use the ending -ate, resulting in valerate.
- Assign numbers to the locations of each substituent on the carbon chain with the carbonyl group. When more than one identical substituent is attached, use prefixes such as di- for 2, tri- for 3, and tetra- for 4. Name all substituents in alphabetical order, noting that prefixes do not count.
Now, valerate is the name of the carbon chain including the carbonyl group. Attached to carbon number 2, there is an isopropyl group. Thus, this substituent makes it '2-isopropyl valerate'.
Finally, commas are used to separate numbers from numbers, and dashes are used to separate letters from numbers. Letters are not separated from letters. Remember to write the alkyl group name with spaces.
So, bringing it all together, the alkyl group attached to the oxygen was propyl, placed at the beginning of the name. The complete name of the ester is 'propyl 2-isopropyl valerate'. This indicates that this propyl portion is connected to the oxygen of the ester, and the rest, highlighted in red, is part of the main chain that contains a carbonyl group. This is the approach we take when naming esters using a common naming system.