Chapter 20, Problem 14A

Interpretation Introduction

Interpretation:

The root to findthe position of substituents in the longest chain of a hydrocarbonhave to be described.

Concept Introduction:

Alkanes are the saturated hydrocarbons which contain only C-H and C-C single bonds. The general formula of alkane is C_nH_2n+2. The simplest alkane among all alkanes is methane CH₄.

Alkanes can be classified as-

1. Straight-chain alkanes
2. Branched-chain alkanes

Answer to Problem 14A

Numbering of the parent chain is necessary to find the position of substituents in the longest chain of a hydrocarbon. When a substituent is attached to a carbon chain, numbering of the carbon chain will start from that end which is closest to the substituent.

Explanation of Solution

A small chain of carbon atoms which is attached to a longer chain of carbon atoms are called substituents.Numbering of the parent chain is necessary to find the position of substituents in the longest chain of a hydrocarbon. When a substituent is attached to a carbon chain, numbering of the carbon chain will start from that end which is closest to thesubstituent.Substituents are added to the name of the alkanes as prefixes to the longest chain.

In the structure of 2-methylhexane, the parent chain is hexane i.e, it contains 6 carbon atoms and methyl group is attached in 2^nd carbon of the parent chain.