Substitution Reactions of Alkanes

In this article, we will learn about substitution reactions of alkanes. We will discuss the substitution reactions of alkanes through examples.

What are alkanes?

Alkanes are saturated hydrocarbons. There are single covalent bonds between carbon atoms.

What is substitution reaction?

The substitution reaction is a reaction in which one atom or group of atoms is replaced by other atoms or atoms.

What is substitution reaction of alkanes?

Alkanes are inert in the presence of most of the reagents but chlorine in the presence of sunlight replaces hydrogen atoms of alkanes one by one. This is how substitution reaction takes place in alkanes.

Substitution reaction of alkanes examples

Methane does not react with chlorine in the dark but in the presence of sunlight, all hydrogen atoms are replaced by chlorine one by one.

Following are the reactions of substitution reactions of methane

Methane reacts with chlorine to produce chloromethane (Methyl chloride) in the presence of sunlight.

CH₄ +Cl₂ →CH₃Cl + HCl

Chloromethane reacts with chlorine to produce dichloromethane

CH₃Cl +Cl2 →CH₂Cl₂ + HCl

Dichloromethane reacts with chlorine to produce trichloromethane or chloroform.

CH₂Cl₂ + Cl₂ →CHCl₃ + HCl

Chloroform reacts with chlorine to produce carbon tetrachloride.

CHCl₃ + Cl₂ →CCl₄ + HCl

So we can easily understand through the reaction of methane with chlorine that all the hydrogen atoms are replaced by chlorine.

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FAQs

    1.  Why do alkanes only undergo substitution reactions?

Ans – Alkanes are saturated hydrocarbons with single covalent bonds between carbon atoms and these bonds are strong bonds.

In alkanes, carbon has no free valence electron to share with other atoms so alkanes do not undergo an addition reaction.

That’s why they only undergo substitution reactions.

   2.  Why are substitution reactions of alkanes not very practical?

Ans – Alkanes are relatively unreactive. They require specific conditions like heating or sunlight. That’s why substitution reactions of alkanes are not very practical.

   3.  What is the condition of the substitution reaction of methane with chlorine?

Ans- The substitution reaction of methane with chlorine occurs in the presence of sunlight or ultraviolet light.

   4.  Why is the reaction between methane and chlorine considered a substitution reaction?

Ans- Because in this reaction, all hydrogen atoms are replaced by chlorine atoms one by one in the presence of sunlight.

substitution reaction of alkanes with halogens