Chapter 20, Problem 15A

Interpretation Introduction

Interpretation:

The order to name of a hydrocarbon with several substituentshave 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

Numbering of the parent chain is necessary to find the position of substituents in the longest chain of a hydrocarbon.

Answer to Problem 15A

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. When several substituents are present in the long chain hydrocarbon, the order is arranged by the name of the substituents in alphabetical order. As for example, the following compound contains three substituents such as chloro, ethyl and methyl. So, the substituent (-Cl) will be placed first in the order and methyl substituent will be the last one.

  

Explanation of Solution

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. When several substituents are present in the long chain hydrocarbon, the order is arranged by the name of the substituents in alphabetical order. As for example the following compound contains three substituents such as chloro, ethyl and methyl. So, the substituent (-Cl) will be placed first in the order and methyl substituent will be the last one.