Classes Of Functional Groups
Organic Chemistry deals mostly with carbon and hydrogens, also called hydrocarbons, but those groups which replace hydrogen and bonds with carbon to give a characteristic nature, unique of their own, to the hydrocarbon they are attached to, are called functional groups. All the compounds belonging to a functional group undergo reactions in a similar pattern and are known to have similar physical and chemical properties.
Characteristics Of Functional Groups
In organic chemistry, we encounter a number of special substituent groups which are attached to the hydrocarbon backbone. These groups impart certain characteristics to the molecule of which it is a part of and thus, become the highlight of that particular molecule.
IUPAC Nomenclature
In Chemistry, IUPAC stands for International Union of Pure and Applied Chemistry which suggested a systematic naming approach for the organic and inorganic compounds, as in the beginning stage of nomenclature one single chemical compound was named in many ways by which lead to confusion. The need for this approach aroused as the number of chemical compounds newly discovered were increasing (approximately 32 million compounds) and the basic concept of nomenclature i.e. the trivial nomenclature and the derived system of nomenclature failed to overcome the challenge. It is an important task to name a chemical compound systematically and unambiguously which reduces lots of confusion about the newly reported compounds.
According to IUPAC nomenclature :
- substituted aromatic compounds, the name of the substituent is placed as a prefix to the name of aromatic compounds.
- When different substituted groups are attached to the aromatic compounds, the substituent of the base compound is assigned number one and the next substituent gets the lowest number.
- Substituents are named in alphabetical order.
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When an organic compound contains two or more different functional groups, one of the functional groups is selected as the principal functional group while all other groups (also called the secondary functional groups) are treated as substituents. The choice of the principal functional is made on the basis of the following order of preference :
Amine salts > Carboxylic acids > sulphonic acids > anhydrides > esters > acid chlorides > acid amides > nitriles> isocyanides> aldehydes > ketones > alcohols > phenols > thiols > amines.
- When a substituent is such which when taken together with the benzene ring gives a special name to the molecule, then it is named as a derivative of that molecule with the substituent at position 1.
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