iit jee Organic Chemistry notes pdf
organic chemistry notes for jee mains pdf
Organic Chemistry Some Basic Principles and Techniques Chemistry Chapter 12
• Organic Chemistry
Organic chemistry is the branch of chemistry that deals with the study of hydrocarbons and their derivatives.
The Shapes of Carbon Compounds:
In organic or carbon compounds, s and p orbitals are involved in hybridisation. This leads to y three types of hybridisation which are sp3(in alkanes) – Tetrahedral in shape sp2(in alkenes) – Planar structure sp(in alkynes) – Linear molecule
Functional Group: The functional group are atom or group of atoms joined in a specific manner which determines the chemical properties of the organic compound. The examples are hydroxyl group (—OH), aldehyde group (—CHO) and carboxylic acid group (—COOH) etc.
• Homologous Series
A homologous series may be defined as a family of organic compounds having the same functional group, similar chemical properties and the successive members differ from each other in molecular formula by —CH2 units.
The members of a homologous series can be represented by same general molecular formula.
• Nomenclature of Organic Compounds
Common name (Common system): Before the IUPAC system of nomenclature, organic compounds were named after the sources of origin, for example, urea was so named because it was obtained from the urine of mammals. Formic acid was so named since it was extracted from red ants called formica.
• I UP AC (International Union of Pure and Applied Chemistry) System
According to IUPAC system, the name of an organic compound contains three parts: (i) word root, (ii) suffix, (iii) prefix.
(i) Word root: Word root represents the number of carbon atoms present in the principal chain, which is the longest possible chain of carbon atoms.
(ii) Suffix: Suffix are of two types, primary suffix, secondary suffix.
(a) Primary Suffix: It indicates the type of bond in the carbon atoms.
(b) Secondary Suffix: Secondary suffix is used to represent the functional group.
(iii) Prefix: Prefix is a part of IUPAC name which appears before the word root. Prefix
are of two types:
(a) Primary prefix: For example, primary prefix cyclo is used to differentiate cyclic compounds.
(b) Secondary prefix: Some functional groups are considered as substituents and denoted by secondary prefixes.
For example:
Substituted Group Secondary prefix.
— F Flupro
— Cl Chloro
— Br Bromo
— NO Nitroso
— NO2 Nitro
— CH3 Methyl
— OCH3 Methoxy
Naming of Compounds Containing Functional Groups: The longest chain of carbon atoms containing the functional group is numbered in such a manner that the functional group is attached at the carbon atoms possessing lowest possible number in the chain.
In case of polyfunctional compounds, one of the functional group is selected as principal functional group and the compound is named on that basis. The choice of principal functional group is made on the basis of order of preference.
The order of decreasing priority for the functional group is
• Isomerism
When there are two or more compounds possessing the same molecular formula but different structural formula and different physical and chemical properties, the phenomenon is called isomerism. Such compounds are called isomers.
It is of two types:
(1) Structural Isomerism
(2) Stereoisomerism
(1) Structural Isomerism: Structural isomerism is shown by compounds having the same molecular formula but different structural formulae differing in the arrangement of atoms.
(2) Stereoisomerism: When isomerism is caused by the different arrangements of atoms or groups in space, the phenomenon is called stereoisomerism. The steroeoisomers have same structural formula but differ in arrangement of atoms in space. Stereoisomerism is of two types:
(i) Geometrical or Cis-Trans Isomerism
(ii) Optical Isomerism
• Fundamental Concepts in Organic Reaction Mechanism
Fission of a covalent bond: A covalent bond can undergo Fission in two ways:
(i) By Homolytic Fission or Homolysis
(ii) By Heterolytic Fission or Heterolysis
Homolytic Fission: In this process each of the atoms acquires one of the bonding electrons.
Heterolytic Fission: In this process one of atoms aquires both of the bonding electrons when the bond is broken.
If B is more electronegative than A which thereby aquires both the bonding electrons and becomes negatively charged.
The products of heterolytic fission are ions.
Reaction Intermediates: Heterolytic and homolytic bond fission results in the formation of short-lived fragments called reaction intermediates. Among the important reaction intermediates are carbonium ions, carbanions, carbon free radicals and carbenes. Carbonium Ions (carbocations): Organic ions which contain a positively charged carbon atom are called carbonium ions or carbocations. They are formed by heterolytic bond fission.
where Z is more electronegative than carbon.
Tertiary carbonium ion is more stable than a secondary, which in turn is more stable than a primary because of +1 effect associated with alkyl group.
organic chemistry notes for jee mains pdf
