ORGANIC CHEMISTRY

Dr. SURENDRAN PARAMBADATH (M.Sc, M.Phil, M.Tech)

Formerly: Post Doctoral Research Associate,Nano-Information Materials Research Laboratory,

Pusan National University, Busan-South Korea

Currently: Assistant ProfessorGovt. Polytechnic College, Perinthalmanna

Organic Chemistry is the chemistry of hydrocarbon and their derivative.

Various sources of organic compounds

Plant: Sugar, Starch, Cellulose, AlkaloidsAnimals: Proteins, Fats, Urea, VitaminsCoal or Coal tar: Benzene, Toluene, XylenePetroleum: Petrol, Kerosene oil, Diesel, Naphtha………

Introduction

Organic Compound Inorganic Compound

1 Found in living organisms Found in non living matters-minerals

2 Besides carbon they are compounds of H, O, N, S and P

They are composed of one or more of any of the known elements.

3 They are covalent compounds They are electrovalent compounds

4 They are volatile and inflammable They are generally nonvolatile and non inflammable

5 Generally insoluble in water and soluble in non polar solvents, like benzene.

Soluble in water and insoluble in non polar solvents.

6 Reaction involving organic compounds are slow

Reaction is fast

7 They exhibit isomerism Only coordination compounds exhibit isomerism

8 They are non conductors of electricity Many of them conduct electricity in solution or fused form

9 Their number is very large Small in number

10 Generally, solids, liquids or gases Generally liquids or high melting solids.

The number of organic compounds is very large (~90%)

Because: 1.Catenation capacity2.Strength of C-C bond3.Tetra-covalency4.Capacity to combine with other non-

metals like, H, O, N, S, P, Cl, Br, I etc.5.Possibility of multiple bonds and6.Isomerism

Uniqueness of Carbon

Catenation CapacityThe tendency of an element to form chain of identical atoms is called catenation. Due to catenation, carbon atoms can form straight chains, branched chains or closed chain compounds.

CCC

CCCCC

CCCCC

CC

CCCCC

CCC

CC

CCCC

CC

Strength of C-C bond

Compared to Si-Si, S-S, N-N or O-O bond C-C bond is stronger and requires higher energy for breaking. Hence chains with C-C bonds are stable.

Tetra-covalency

Carbon atoms has four electrons in its valence shell and can form four covalent bonds. This tetra-covalency or quadri covalency of carbon gives rise to various possibilities for formation of variety of structures.

CC

CC

IsomerismIsomerism is the phenomenon in which one and the same molecular formula represents more than one compound with different properties. Due to directional character of covalent bonds different spacial arrangements and isomers are possible for compounds with the same structural formula.

CH3

CH3 H3C CH3

Trans-2-butene cis-2-butene

Saturated and Unsaturated Compounds

Organic compounds with only single covalent bonds between the carbon atoms are called saturated compounds.

In saturated compounds there will be no double or triple bond between carbon atoms.In unsaturated compound, double or triple bond between carbon atoms.

CH3-CH2-CH2-CH2-CH3

CH3-CH=CH-CH2-CH3

Test for saturated or unsaturated compounds

1. Unsaturated compounds decolorizes yellow colored bromine water.

2. Baeyrs test: Unsaturated compounds decolorize alkaline potassium permanganate solution.

Saturated Unsaturated

Contain only single covalent bonds between carbon atoms.

Contain at least one covalent double or triple bond between carbon atoms.

Less reactive More reactive

Does not decolorize bromine water Decolorize bromine water

General Classification of Organic compounds

Open Chain (Acyclic or aliphatic) Compounds

These compounds contain an open chain of carbon atoms which may be a straight or a branched chain. CH3-CH2-CH2-CH3

CH3-CH-CH3

CH3

Normal butane (n-butane)Straight chain

Isobutane (iso-butane)Branched chain

Closed Chain (Cyclic or ring) Compounds

These compounds contain one or more rings of carbon atoms.

If the ring contains only carbon atom, it is called homocyclic ring system.

If it contains carbon and oxygen, nitrogen or sulphur it is called heterocyclic ring system.

Homocyclic

Alicyclic

Aromatic

O

Cyclopropane

Naphthalene

Furan

Benzene

Cyclobutane

O

N

Oxazole

Organic Compound

Open Chain

Straight Chain

Branched Chain

Closed Chain

Heterocyclic

Homocyclic

Alicyclic Aromatic

Aromatic Compounds

Alicyclic

Heterocyclic

Classification of Organic Compounds based on Functional Groups

Class of Organic

Compound

Nature of the functional

group

Formula of the

functional group

Example

Alkenes Double bond C=C Ethene

Alkynes Triple bond -CC- Acetylene

Alcohols Hydroxy -O-H Methanol

Aldehydes Aldehydic Group

-CHO Acetaldehyde

Acids Carboxyl -COOH Acetic acid

Ethers Ether group -O- Diethyl ether

Ketones Ketonic group

-CO- Acetone

Amines Amino group -NH2Methyl amine

Esters Ester group -COO- Methyl acetate

IsomerismTwo or more compounds having the same molecular formula but different properties are called isomers and the phenomenon is called isomerism.

Structural: If the difference in properties of two isomers is due to difference in their structure, it is called structural isomerism.

Stereo: If the isomers have the same structure but different configuration it is called stereoisomerism.

CH3-CH2-CH2-CH3

CH3-CH-CH3

CH3

Normal butane (n-butane)

Isobutane (iso-butane)

Structural isomerism

Molecular Formula: C4H10

CH3-CH2-CH2-OH

CH3-CH-CH3

OH

Normal propyl alcohol

Isopropyl alcohol

Molecular Formula: C3H7-OH

Stereo isomerism

CH3

CH3 H3C CH3

Trans-2-butene cis-2-butene

Thanks