Question

Choose the correct answer among the alternatives given:
Classify the following compounds as primary, secondary and tertiary halides.
(i) 1-Bromobut-2-ene
(ii) 4-Bromopent-2-ene
(iii) 2-Bromo-2-methylpropane

(A) (i)-secondary, (ii)-tertiary and (iii)-primary
(B) (i)-secondary, (ii)-primary and (iii)-tertiary
(C) (i)-primary, (ii)-tertiary and (iii)-secondary
(D) (i)-primary, (ii)-secondary and (iii)-tertiary

Answer 1

Hint: In primary halides, the halogen atom is bonded to a primary carbon atom. In secondary halides, the halogen atom is bonded to a secondary carbon atom while in tertiary halide; the halogen atom is bonded to a tertiary carbon atom.

Complete step by step answer:
In order to solve this question, we need to first understand the meaning of primary, secondary and tertiary halides.
Primary Halides: In primary halides, the carbon atom bonded to the halogen atom is bonded to only one carbon atom and the rest are hydrogen atoms or the carbon bonded to the halogen atom is only bonded to hydrogen atoms. More simply, we can say that the halogen atom is bonded to a primary carbon.
Example:

Secondary Halides: In secondary halides, the carbon atom bonded to the halogen atom is bonded to two carbon atoms and one hydrogen atom. More simply, we can say that the halogen atom is bonded to a secondary carbon.
Example:

Tertiary halides: In tertiary halides, the carbon atom bonded to the halogen atom is bonded to three carbon atoms. More simply we can say that the halogen atom is bonded to a tertiary carbon.
Example:

In order to solve this question, we need to draw the structures of the compounds given:

1-Bromobut-2-ene
    

Here Bromine is bonded to a primary carbon atom; therefore 1-Bromobut-2-ene is a primary halide.

 4-Bromopent-2-ene
                      

Here Bromine is bonded to a secondary carbon atom; therefore 4-Bromopent-2-ene is a secondary halide.

2-Bromo-2-methylpropane

Here Bromine is bonded to a tertiary carbon atom; therefore 2-Bromo-2-methylpropane is a tertiary halide. So, the correct answer is “Option D”.

Note: In this question all the names of the organic compound were given in accordance with the IUPAC (International Union of Pure and Applied Chemistry) nomenclature. Therefore in order to draw the structure of the compounds from their names, you should know the rules of the IUPAC nomenclature.