Organic Nomenclature

The naming of compounds containing mainly carbon and hydrogen (organic compounds) is called organic nomenclature.In order to have a universal way to name organic compounds around the world, the International Union of Pure and Applied Chemists (IUPAC) wrote a set of rules and guidelines followed by all organic chemist.There are a lot of terms to know like, functional groups, suffixes of names and basis names of parent chain. There are a total of six relevant steps to follow when naming an organic compound. A functional group is a group of organic compounds having the same physical and chemical characteristics.

The parent chain on an organic compound is the longest carbon chain and the chain containing the highest number of substituents highest number of substituents or functional groups. To detect the longest chain, one needs to just count the number of carbons. Also, making sure that the chosen chain has the greatest number of substituents and functional groups. The basis for the names of the longest chain is shown above in figure 2. The longest chain in the example above wold be a six carbon chain.

The are three main types of substituents: alkane substituents, common hydrocarbon substituents and halogen substituents. Figure 3 above summarizes the alkane substituents. As you can see above, the substituents also use the prefix like all other functional groups except they end with the suffix -yl instead of -an. Figure 4 gives the halogen substituents and their corresponding name. Using our example in figure 2, the two substituents were ethyl and methyl.

There are 18 main functional groups. Figure 5 gives the list of functional groups in order of decreasing priority. The longest chain will always be the chain with the functional group with the highest priority and the most substituents. The functional group in our example was an alkane

Depending on the prioritized functional group present, the name or the suffix of the organic compound will be different. Here is a list of functional groups and their suffixes.

When naming your compound, sometimes you might find two of the same substituent or two different substituents on the same carbon. In this case, locate the position of the substituent in your name by the number of that carbon twice. an example is shown in the figure above. if you have two of the same substituent, use di as a prefix. If you have three, use tri, if you have four, tetra, and so on. Also, always name your substituent in alphabetical order. The name of the compound above (example from figure 2) is 4-ethyl-2-methylhexane.

There should be no space between letters in your names. Words should be separated from letters using hyphens. Here are three examples you can try by yourself. The next page has the answers to the example.

Here is a table with the answers to the examples.