Question

Give the structures of the following compounds:
(A) 3- bromo-2- methyl pentane
(B) 2- Bromo-3- ethyl-2- methyl hexane
(C) 1- chlorobutane

Answer 1

Hint: To answer this question, you must recall the rules given by IUPAC for the nomenclature of organic compounds. IUPAC or The International union of Pure and Applied Chemistry has set rules for nomenclature of organic compounds in such a way that the name of each compound is unique. The longest chain is the parent chain and the substituents are numbered according to the carbon they are attached to.

Complete step by step solution
(i) We have 3- bromo- 2- methyl pentane.
From the IUPAC name of the compound we can first figure out the longest carbon chain using the word root. Pent- represents a five carbon parent chain and – ane represents an alkane, i.e. the bonds between the carbon atoms of the principal chain are singly bonded. The prefixes signify the substituent groups attached to the chain. On the third carbon, we have a bromo group and on the second carbon, we have a methyl group. The structure of the compound is:

(ii) We have 2- Bromo- 3- ethyl- 2- methyl hexane
The word root is hexane. Hex- represents a six carbon parent chain and – ane represents an alkane, i.e. the bonds between the carbon atoms of the principal chain are singly bonded. On the second carbon atom, we have a bromo group and a methyl group, on the third carbon, we have an ethyl group. The structure of the compound is:

(iii) We have 1- chloro butane.
The word root is butane. But- represents a four carbon parent chain and – ane represents an alkane, i.e. the bonds between the carbon atoms of the principal chain are singly bonded on the first carbon atom a chloro group is attached. The structure of the compound is:

Note
The position of each substituent group is represented by the number of the carbon atom it is attached to. They are assigned such that each substituent gets the lowest number possible.