Organic Chemistry

Introductory to organic chemistry:

Organic chemistry is the study of carbon and hydrogen containing compounds excluding the very simple compounds like Carbon dioxide, Carbon monoxide, Carbonates etc. The main source of organic compounds are living things : Human, Plants and animals. The study includes preparations, properties and uses of organic chemicals.

Organic Compound:                    

The hydrocarbons and their derivatives are organic compounds. They have molecules containing C-C or C-H,  C-Y  (where Y is the functional group)  bonds.

There are vast numbers of Organic compounds around us . To make things easier, chemists arranged them into different families of chemicals called Homologous series.

Homologous series:

It is the series of organic compounds which have :

1)      Same functional group

2)      Same general formula

3)      Similar chemical properties

4)      Differing physical properties

5)      General Trend in chemical and physical properties

6)      Each successive member of the groups differs by CH₂ OR  M_r by 14.

For example: Alkanes, Alkenes, Alcohol etc. 

Three different homologous series are shown above.

Functional group:

• It is an atom or group of atoms which is present in a homologous series and it determines the chemical properties of that homologous series.

• Functional group gives the chemical characteristics of each Homologous series.

• Homologous series have same functional group and hence have same chemical behavior.

• Functional group is responsible for many chemical reactions of a homologous series.

For example: Alkenes have C=C as functional group, Alcohols have –OH as functional group etc.

Alkenes have C=C bonds as functional groups and Alcohols have -OH as functional groups.                                                 But alkanes have no functional  group.

Hydrocarbons:

The compounds which consist of only carbon and hydrogen. They have only C=C, C-C and C-H bonds.

Derivatives of Hydrocarbons:-

These are the compounds where one or more hydrogens get substituted by equivalent no. of another atoms or groups of atoms.

For example:-

Carbon:

 Carbon can form many compounds than any other elements. 

Carbon has 4 valence electrons which can form stable covalent bonds like C-H , C-C ,C=C , C=O , C-Cl etc.

This is because :

    1. Carbon can form long chains , branched chains and rings of varying sizes. 
    

    2. Carbon can form these different arrangement because C-C, C-H bonds are strong, inert and  

        stable in the molecules.

    3. Carbon has 4 valence electrons. When carbon forms chains by forming covalent bonds with   

        another carbon, this leaves that carbon 2 other valence electrons  not bonded. 

        Then those valence electrons can form C-H, C-O,C-I,C-F,C-Cl , C-Br etc bonds by sharing 

        electrons with other atoms.

 

The carbon which is already forms covalent bonded with another carbon atoms can form stable covalent bonds with hydrogen , oxygen and halogens atoms.

        
  1)  Organic compounds can be classified according to the arrangement of carbon atoms:

        a) Aliphatic Molecules have branched chain and long chain molecules. 

        b) Alicyclic Molecules have carbon attached altogether in a ring.

2) Organic compounds are also classified according to the bonds arrangement around carbon atoms:

  a) Saturated Organic compounds: Compounds which have only single covalent bonds within the

            molecules.

 

   b) Unsaturated Organic compounds: Compounds which have double or triple bonds beside  

       single bonds within the molecules.