Chapter 23, Problem 14PS

Interpretation Introduction

Interpretation: The structure of structural isomer of the isooctane, 2,2,4-trimethylpentane which has molecular formula ${\text{C}}_8{\text{H}}_{18}$ has to be drawn. Another two structural isomers of ${\text{C}}_8{\text{H}}_{18}$ which has longest five carbon chain has to be drawn and thier systematic name has to be written .

Concept introduction:

Systematic Name: It is a standardized name given for a chemical compound in systematic manner. Any organic molecule can be named by using IUPAC (International Union for Pure and applied chemistry) rules. IUPAC name consists of three parts in major namely Prefix suffix and root word.

Prefix represents the substituent present in the molecule. It can be any alkyl group and carboxy, amino, cyano etc…

Suffix represents the substituent present in the molecule. It can be any alkene, alkyne, alcohol, carboxylic acid...

Root word represents the longest continuous carbon skeleton present in the organic molecule.

When a molecule consists of cyclic structure, the root word of the molecule is prefixed with cyclo.

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.

Isomersim: Compounds having same molecular formula but exhibit different structures called isomers.This phenomenon is known as isomersim

Structural Isomers are the possible structures of a molecule with same molecular formula but have different arrangements of bonds and atoms. For a single molecular formula of alkanes higher than propane different arrangements of atoms can give a different structure.