ORGANIC CHEMISTRY
Chemistry of Carbon compounds:
exceptions CO,CO2,C3O2,Carbonates
So a better definition: Hydrocarbons and their derivatives: CCl4,
Catenation:
Importance of Organic chemistry and Organic compounds
History :Vital force theory: Berzelius, F.Wohler 1828, Urea, Acetic acid by Kolbe
(1845), Methane by Berthelot (1856)
Electronic theory of covalent bonding:
Hybridisations of Carbon : sp3,sp2 and sp:
Shapes of CH4,C2H6,C2H4,C2H2
Electronegativity and hybridisation:
Bond length, Bond angles:
pi -bonds: Free rotation impossible, More reactive
Structural Formulae: Lewis structure or electron dot structure, dash
structure,Complete, Condensed, Bond-line formula
(Empirical formula and molecular formula)
Three dimensional formula : 3-D representations,Wedge formula
Molecular Models:Framework models, Ball and stick models,Space filling
models
Classification of Organic compounds;
Acyclic or Open chain compounds
Cyclic or Closed chain compounds
(Aliphatic compounds):
(Ring compounds)
Alicyclic: Homocyclic or carbocyclic, Heterocyclic
(Non-aromatic)
Aromatic:
Benzenoid,Non-benzenoid,Heterocyclic(Aromatic)
(Give 2 examples for each)
Functional group: An atom or a group of atoms or a particular type of
bonding which characterises a homologous series of Organic compounds
eg.-X, -OH, -O-, -COOH, -CHO, -CO-, -COO-, -NH2, -NO2, -SH, (Can you write
Homologous series, Homology, Homologue:A series of closely related
organic compounds having five characteristics1.General formula
2.Consecutive members differ by -CH23.Common methods of preparation
4.Similar chemical properties since contain same functional group
5.Regular gradation in physical properties since increase in molecular weight
by -CH2Nomenclature of Organic compounds:
Common names and IUPAC names
Nomenclature of Alkanes: Straight chain alkanes and branched ones
Alkyl groups:
Rules for the IUPAC Nomenclature
1.
2.
3.
4.
5.
6.
7.
Longest Chain rule
Lowest Number rule
Lowest Sum rule
Highest Substituted Chain rule(More number of side chains)
Alphabetical Order rule
Lowest number and Alphabetical Order rule
Iso- and neo- are taken in the alphabetical order while sec- and tert- are
not considered in the alphabetical order.
Nomenclature of Organic compounds with other Functional groups
Order of decreasing priority of Functional groups:
-COOH, -SO3H ,-COOR,-COCl,-CONH2, -CN, -CHO, -CO- ,-OH, -NH2,
>C=C<, -C≡C-, -X, -NO2
-R, C6H5-,-X, -NO2 -OR etc are taken as prefixes.
Isomerism
Structural isomerism
Stereoisomerism
1.Chain or Nuclear
1.Geometrical isomerism or
2.Position or Substitution
Cis-Trans isomerism
3.Functional
2.Optical isomerism
4.Metamerism
5.Tautomerism
(Examples for each type of isomers)
Fundamental Concepts in Organic Reaction Mechanism
Reaction Intermediates
Heterolytic Cleavage or fission
Homolytic fission
Carbocations,Carbanions, Free radicals
Structure and order of stability
Substrate and Reagent
Nucleophiles and Electrophiles
Inductive effect
Resonance Structure, Resonance effect,
Electromeric effect
Hyperconjugation
Methods of Purification of Organic Compounds
Qualitative Analysis
Quantitative Analysis
HYDROCARBONS
LPG,CNG,LNG, Petrol,Diesel,Kerosene oil
Polythene,PP,PS
Classification
1.Saturated : Alkanes and Cycloalkanes
2.Unsaturated : With multiple bonds (With double bonds and
Triple bonds or both) Special type of cyclic compounds
3.Aromatic
ALKANES
Aliphatic (openchain) saturated hydrocarbons with C-C single
bonds and C-H bonds only.
CH4,C2H6,C3H8,.....
Paraffins- inert
CnH2n+2, Bond lengths(154 pm and 112 pm) Bond angles;
Nomenclature and Isomerism:
CH4,C2H6,C3H8
C4H10,C5H12,..... Boiling points:Butane (273 K),2-Methylpropane (261 K)
Pentanes (309,301,282.5 K)
Primary,Secondary,Tertiary and Quaternary Carbon atoms and Hydrogen
atoms
Alkyl groups: CnH2n+1CH3-, C2H5-, C3H7-, C4H9(Refer the examples and the exercises given in the text -book )
Methods of Preparation:
Natural sources: Petroleum and Natural gas
1. From unsaturated hydrocarbons
Hydrogenation- From Alkenes and Alkynes (Pt,Pd,Ni as catalyst)- Ni
requires higher temperatures. (Raney Ni )
1. From Alkyl halides
i. R-X (except Fluorides)- Reduction with Zn and dil.HCl
ii. Wurtz reaction- with even number of carbon atoms- ( mixed Wurtz
reaction)
1. From Carboxylic acids
i. Decarboxylation
ii. Kolbe’s electrolytic method
(Methane cannot be prepared by..)
Physical properties:
Non polar molecules-C1 to C4 Gases;C5 to C17 are liquids ,C18 onwards
waxy solids.Colourless and odourless. Solubility- like dissolves like.
Boiling point - Isomeric Pentanes
Chemical properties
1.Substitution reactions
2.Combustion
3.Controlled oxidation
4.Isomerisation
5.Aromatisation
6.Reaction with steam
7.Pyrolysis
Conformations
1.Sawhorse projections 2. Newman projections
ALKENES
Structure of the double bond
Olefins,Olefinic bond, Ethylenic bond, Pi- bond, bond lengths, Bond
energy,Electrophilic reagents
Nomenclature
Isomerism
Cis-Trans isomers
Preparations
1.From alkynes
2.From alkyl halides
3.From vicinal dihalides
4.From alcohols
Physical properties
Chemical properties
1.Addition of Hydrogen
2.Addition of Halogens
3.Addition of Hydrogen halides
Markovnikov Rule,Stability of carboca
Peroxide effect, Kharash effect
4.Addition of Sulphuric acid
5.Addition of Water
6.Oxidation
7.Ozonolysis
8.Polymerisation
ALKYNES
Structure of the triple bond
Nomenclature and Isomerism
Preparations
1.From Calcium carbide
2.From vicinal dihalides
Physical properties
Chemical properties
1.Acidic character of alkynes
2.Addition reactions
Addition of Hydrogen,Halogens,Hydrogen halides,Water
3.Polymerisation
Linear and cyclic polymerisations
AROMATIC HYDROCARBONS or ARENES
Benzenoids and non- benzenoids
Nomenclature and Isomerism
Structure of Benzene
Resonance
Aromaticity, Huckel’s rule
Preparations
1.From ethyne
2.Decarboxylation of benzoic acid
3.From phenol
Properties
1.Electrophilic substitution reactions
Nitration, Sulphonation, Friedel-Crafts reactions, Mechanisms
2.Addition reactions
3.Combustion
Directive Influence of Functional groups
Carcinogenic hydrocarbons