Chapter 19.2, Problem 1LTS

Interpretation Introduction

Interpretation: The name of the given compounds has to be determined.

Concept introduction:

IUPAC naming for Alkane:

• Name the main chain: Find the longest carbon chain and name the chain according to the number of carbon atoms it contains; is also the suffix part of the name.
• Number the carbon atoms in the main chain: The carbons are numbered, in which the substituents must get lowest possible numbers.
• Identify the substituents, and number each: The number at where substituents are present has to be noted. The substituents written as prefix.
• Write the names as a single word: Use the hyphen to separate the numbers from the different prefix; commas to separate numbers. If two or more different substituents are present, arrange them in alphabetical order. If two or more identical substituents are present, use prefixes di-, tri-, tetra-, but this particular prefix should not be used for alphabetizing purpose.

According to IUPAC nomenclature, the naming of compound is determined by the priority of the functional group if more than one functional group is present. The carbon attached to the functional group having most priority should get the least number while naming the compound.

The order of priority is,

$\begin{array}{l}\text{carboxylic}\text{acid>esters>amides>aldehydes>ketones>}\text{alcolhols>thiols>}\text{amines}\text{>}\\ \text{ethers>alkenes>alkyl}\text{halides>alkanes}\end{array}$

R and S nomenclature: it is used to assign the molecule using CIP rules.

The CIP rules are as follows:

Select the chiral carbon and assign the numbers according to the decreasing atomic mass of atoms attached to it.

If the numbering follows clockwise direction then the molecule is termed as R and if it follows anti-clockwise direction then molecule is termed as S.

Ketone: Ketone is a group of organic compound where two aryl or alkyl groups are connected by a carbonyl group. It is represented as $RC\left(=O\right)R\text{'}$.

The IUPAC name for the ketone is written by replcing the ‘e’ of alkane to ‘one’