NEET Chemistry Notes Some Basic Principles and Techniques – Representation of Different Formula
Representation of Different Formula
Representation of Different Formulae
An organic compound can be represented by the following ways:
Structural Formula
In this, all the bonds present between any two atoms are shown clearly.
Condensed Formula
In this type of chemical formula, all the bonds are not shown clearly.
Bond Line Formula
In this every fold and free terminal represents a carbon and lines represent the bond.
IUPAC System
In 1957, the International Union of Pure and Applied Chemistry evolved a scheme for giving systematic name to organic compounds on the basis of their structure. This is known as the IUPAC system of nomenclature. This system has set of rules for naming organic molecules from their structure.
After knowing the IUPAC names it is possible to draw the structures of organic compounds also. Remember IUPAC amends these rules from time to time and in this book we are following the 1993 (most recent) recommendations of IUPAC nomenclature.
IUPAC Nomenclature of Organic Compounds
Rules for IUPAC Nomenclature
- First of all, the longest carbon chain in the molecules is identified.
- Numbering is started from the terminal carbon from where branching is nearest.
- If the two substituents are found in equivalent positions, the numbering is done alphabetically.
- If there are two chains of equal size then that chain is to be selected which contains more number of side chains.
- The longest chain of carbon atoms containing the functional group is numbered in such a way that the functional group is attached at the carbon atom possessing lowest possible number in the chain.
- In polyfunctional compounds, one of the functional group is chosen (prioritywise) as the principal functional group and the
- compound is then named on that basis.
Some functional groups are always indicated by the prefixes instead of secondary suffixes. They are tabulated with their IUPAC names as
Secondary suffix is used to indicate the functional group in the organic compounds.
