Chapter 23, Problem 8PS

Interpretation Introduction

Interpretation: The number of noncyclic structural and geometrical isomers has to be determined for the given hydrocarbon ${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}$. Any chiral isomer among all the isomers has to be identified.

Concept introduction:

Alkenes are the hydrocarbons which have a genral molecular formula ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$. Alkenes are consist of double bond (one pi bond) due to which they are known as unsaturated hydrocarbons. Alkenes can show two type of isomerism,(1) Geometrical Isomerism (2) Structural Isomerism.

(1) Geometrical Isomerism: This type of isomerism in case of alkenes is known as cis-trans isomerism. When two same group or have similar priority present opposite side of double bond then isomer is known as trans isomer, and if both are present same side of the double bond then isomer is called as cis isomer.

(2) Structural Isomerism: Structural Isomers are the structure of a molecule with same molecular formula but have different arrangements of bonds and atoms and position of double bond also changes from more substituted to less substituted or vice-versa.

A chiral carbon is the carbon atom which is substituted to four different groups. Due to presence of chiral carbon a molecule become chiral and it gives optical isomers also that is $R\text{ and }S$ isomers. For example,

  

All the substituents are different hence is is a chiral carbon and so molecule.