Each day many new compounds are identified and this can lead to confusion on how to classify, name and describe them in a systematic manner. A proper nomenclature can ascertain on the prefix, suffix or any other criteria to be allotted.
The IUPAC system for the nomenclature
A sensible nomenclature system should ensure 2 important aspects. Firstly, it must indicate how the carbon atoms of a given compound are bonded together resulting in the formation of the lattice of chains and rings. Secondly, the system should identify and locate the functional groups found within the compound. Since hydrogen is such a common component of organic compounds, its amount and locations can be assumed from the tetravalency of carbon, and need not be specified in most cases. The IUPAC nomenclature system help in avoiding the complexities arose out the arbitrary nomenclature. Knowing the IUPAC rules and given a structural formula, one should be able to write a unique name for every distinct compound. Similarly, one should be able to draw the structural formula based on the IUPAC name. 3 major elements of an IUPAC system are :
A root or base indicating a major chain or ring of carbon atoms found in the molecular structure.
A suffix or other element(s) designating functional groups that may be present in the compound.
Names of substituent groups, other than hydrogen, that complete the molecular structure.
Steps of carbon compound nomenclature with an example
In the carbon chain mentioned above, identify the functional group (If you look at the structure mentioned above, the compound is a hydrocarbon having a single bond between the carbon atoms. It is an alkane hence it will be indicated by the suffix “ANE”.
Find the longest carbon chain (There are four carbon atoms in the longest chain), the prefix of the compound will be “BUT”.
Now, number the carbon atoms in the longest chain as mentioned above and look for any branched group, name them and give their position on the carbon chain (In this case there are no branched groups).
Finally, combine different elements (from the above steps) of the name into a single word, in this case, the name of the compound is butane.
How to indicate a functional group
It is indicated either by prefix or suffix. For example, alkene has a suffix “ene” and alkyne has suffix “yne”, alcohol has a suffix “ol”, aldehyde has a suffix “al”, ketone has a suffix “one” etc. One of the suffix-ane and how to use this is given in the form of the table below.
Heteroatom and Functional Groups
In a chain of hydrocarbons, one or more hydrogen atoms can be replaced by other atoms based on their valencies, the element that replaces hydrogen is known as heteroatom. The heteroatoms and the group containing such elements will impart chemical properties to that compound therefore they are called functional groups. One such example is Pyridine, it is a heterocyclic compound having nitrogen as a heteroatom.