Defination and types of haloalkanes.

Organic note.

Haloalkanes and Haloarenes.

Organic halogen compound is the hydrocarbon derivatives obtained by replacing one or more atoms by the corresponding number of halogen atom. Halogen compounds can be classified as mono, di, tri, tetra derivatives and so on depending on the number of halogen atom present in the molecules.

Organic halogen compounds are of two types as described below.

1. Aliphatic halogen compound.
2. Aromatic halogen compound.

Aliphatic halogen compound.

The halogen compound obtained by the replacement of one or more hydrogen atom of aliphatic hydrocarbon are known as aliphatic halogen compound. For example.

Aromatic halogen compound.

The halogen compound obtained by the replacement of one or more hydrogen atoms of aromatic hydrocarbon are known as aromatic halogen compound. They may be divided as.

1. Nuclear substation reaction.
2. Side chain substituted derivatives.

Nuclear substituted derivatives.

Nuclear substation derivatives in which the halogen atom is directly attached to the benzene nucleus. For example.

chlorobenzene

Side chain substituted derivatives.

Side chain substituted derivatives in which the halogen is linked to a carbon of the side chain For example.

Haloalkanes.

Haloalkanes are the organic compound formed by replacing a hydrogen atom by a halogen atom. They have general structure formula R-X, where R is an alkyl group and X is halogen (Cl, Br, and I). In homologous series, haloalkane is represented by CnH2n+1.X.

$$CH_3I=Iodomethane.$$

$$CH_3CH_2CH_2Br=1-Bromopropane$$

Classification of haloalkane.

They are classified into two groups on the basis of a number of halogen atoms and on the basis of the number of carbon atoms bonded with halogen carrying carbon.

1. On the basis of a number of halogen atoms.
2. On the basis of carbon atoms bonded with halogen carrying atom.

1. On the basis of halogen atom present in a haloalkane, they are of following types.

a. Monohaloalkane.

Haloalkane having only one halogen atom are called mono-haloalkane.

Example

$$CH_3Cl=Chloromethane$$

$$CH_3CH_2Br=Bromoethane$$

b. Dihaloalkane.

These haloalkanes possess two halogen atoms in the compound.

Example.

$$CH_2Br_2=(Dibromo\,methane)$$

$$C_2H_4I_2=(diiodo\, ethane)$$

c. Trihaloalkanes.

A halogen atom containing three halogen atom is called tri haloalkanes.

Example.

$$CHCl_3=(Chloroform)$$

$$CHI_3=(Iodoform)$$

d. Polyhaloalkanes.

A haloalkane containing more than three halogen atoms is called polyhaloalkane.

Example BHC, and DDT etc.

2. On the basis of carbon atoms bonded with halogen carrying atom.

On the basis, haloalkane is of three types.

1. Primary haloalkane.
2. Secondary haloalkane.
3. Tertiary haloalkane.

Primary haloalkane.

If the carbon containing halogen atom is linked with non or one carbon atom, the haloalkane is called primary haloalkane (1⁰).

Example.

Secondary haloalkane.

If halogen-containing carbon is further linked to two other carbon atoms, the haloalkane is classified as secondary haloalkane.(2⁰).

Example

Tertiary haloalkane.

If halogen-containing carbon is further bonded to three other carbon atoms, the haloalkane is called tertiary haloalkane (3⁰).

Example.

Reference.

Bahl, B S, Bahl, and Arun. Advanced Organic chemistry. S. Chand and company Ltd., n.d.

Sthapit, M K, R R Pradhananga, and K B Bajracharya. Foundations of chemistry. Taleju Prakashan, n.d.

Tewari, K S, S N Mehrotra, and N K Vishnoi. A textbook of organic chemistry. Vikash publishing House Pvt. ltd., n.d.

Verma, N K and S K Khanna. Compressive chemistry. 8th edition. Laxmi publications P. Ltd., 1999.