An Overview On Nomenclature

Chemical nomenclature is a system of identifying and naming chemical compounds in a standardised manner. Having a nomenclature ensures that each specific compound is named in a scientific way and has a distinct name. It also allows one to determine a structural formula of the compound. The two most widely used systems of nomenclature in organic chemistry are – 

1. Trivial Nomenclature
2. IUPAC Nomenclature 

Different Systems Of Nomenclature

Trivial Nomenclature 

This is the most traditional method of naming chemical compounds. The common name was derived from the source, a property, or some other factor. The names chosen were typical of Greek or Latin origin. As stated previously,

1. Acetic acid gets its name from the fact that it is the main component of vinegar (Latin: acetum = vinegar).
2. Formic acid gets its name from the fact that it’s made by red ants. Formicus is the Greek name for red ants.
3. The botanical sources for the names oxalic acid (oxalus), malic acid (pyrus malus), and citric acid (citrus) are indicated in parenthesis.
4. Both urea and uric acid get their names from the presence of both in urine.

The trivial nomenclature allows the names of compounds to be short and simple, making them easier to remember. They are also being used for a longer time than the IUPAC Nomenclature, and hence scientists across the world still identify different compounds through their trivial names over IUPAC names.

Drawbacks of Trivial Nomenclature

1. A single compound may have many different names and will be called differently in different states or countries. For example, phenol is also known as carbolic acid in some areas.
2. The trivial system of nomenclature does not name all the chemicals in each family. For example, in the carbolic acid family, the first two members are formic acid and acetic acid. However, as the number of carbons in the chain increases and the compound becomes more complicated, a trivial name is not assigned to those compounds.

IUPAC Nomenclature 

It is critical that organic compounds are named correctly and unambiguously so that there is no uncertainty regarding what chemicals are being reported or described. There have been numerous conventions for naming organic compounds, some of which have limited scope or have gotten embedded in general language, and others, which have endured over time. The International Union of Pure and Applied Chemistry (I.U.P.A.C.) analyses naming practices on a regular basis in order to standardise nomenclature. The following organic nomenclature guidelines are based on the I.U.P.A.C. definitive regulations (the International Union of Pure and Applied Chemistry). Knowing these guidelines and being provided a structural formula, one should be able to write a distinct name for each compound. Similarly, given an IUPAC name, a structural formula should be able to be written. An IUPAC name will, in general, contain three characteristics:

A root or base in a chemical structure denotes a large chain or ring of carbon atoms.

A suffix or other element(s) indicates the presence of functional groups in the compound.

Other than hydrogen, these are the names of substituent groups that complete the molecular structure.

IUPAC Guidelines

1. Determination of the hydrocarbon chain’s parent
2. The parent functional group, if any, should be identified in the highest order of precedence.
3. Recognize the side-chains. The carbon chains that are not part of the parent chain but have branched off from it are known as side chains.
4. If there are any remaining functional groups, identify them and name them using their ion names.
5. Double/triple bonds must be identified.
6. The chain’s numbering. This is accomplished by first numbering the chain in both directions (left to right and right to left), and then selecting a numbering scheme that adheres to the following rules, in order of precedence: 

• For the suffix functional group, it has the lowest-numbered locant (or locants).
• For multiple bonds, it has the lowest-numbered locants (The locant of multiple bonds is the number of the adjacent carbon with a lower number). 
• Has the smallest number of double bond locants. 
• Has the smallest number of prefix locants.

7. The locants of the various substituents and bonds are numbered. If there are many substituents/double bonds of the same kind, the prefix (di-, tri-, etc.) is appended.

8. Prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or “ane”) + primary functional group suffix with numbers + group of side chains and secondary functional groups with numbers made in step 3 Wherever it reads “with numbers,” it is believed that the prefix(di-, tri-) is used between the word and the numbers.

9. Punctuation between the names of multiple chemicals and their numbers is added.

Conclusion

The need for a systematic system to name compounds was recognized as early as the 1700s. This need gave rise to the two nomenclature systems we use today – 1. Trivial system of nomenclature 2. IUPAC system of nomenclature. Although IUPAC Nomenclature is the appropriate system for naming compounds, the trivial system is still prevalent, and many compounds are identified by their trivial names over their scientific names. Through this system of nomenclature, each scientist now has a set of guidelines that they can follow to name each individual compound.