Historical introduction of organic compounds
(i) Catenation : The property of atoms of an element to link with one another forming chains of
identical atoms is called catenation
If we look at the vast number of organic compounds, two things will strike our mind –the skeleton is either open or
closed. Based on this, organic compounds are classified as acyclic (open–chain) or cyclic (closed–chain)
Organic compounds and functional groups
These are open–chain aliphatic saturated compounds which have no functional groups. These are also called
paraffins
Alkyl groups
Alkenes
Alkenyl groups
Unsaturated aliphatic hydrocarbons containing a carbon–carbon triple bond are called alkynes.
Alkynyl groups
The characteristic group of atom which decided the physical and chemical properties of an organic molecule is
called functional group
Functional group and residue 02
Some common names of hydrocarbon alkyl groups
Iso alkyl group
Neo alkyl group
Types of carbon and hydrogen atoms in alkanes
The basic criteria for naming a structure by IUPAC system is choice of a parent name or the basic carbon
skeleton
It is the basic unit of the name. It denotes the number of carbon atoms present in the principal chain (the longest
possible continuous chain of carbon atoms including the functional group and based upon the common names
of alkanes) of the organic molecules
A primary suffix is always added to the word root to indicate whether the carbon chain is saturated or unsaturated.
The three basic primary suffixes are given below
A secondary suffix is then added to the primary suffix to indicate the nature of the functional group present in the
organic compounds. Secondary suffix of important functional groups are given below in their decreasing order of
seniority
A primary prefix is used simply to distinguish cyclic from acyclic compounds
In IUPAC system of nomenclature, certain groups are not considred as functional groups but are treated as
substituents
IUPAC nomenclature of branched / complex alkanes
(1) Select the longest chain containing carbon–carbon double bond. This need not be the longest chain in the
compound as a whole. Parent name will be alkene corresponding to number of carbon atoms in the longest
chain.
