Chapter 23.2, Problem 15LC

Interpretation Introduction

Interpretation : To compare substitution reaction and addition reaction.

Concept Introduction : A addition reaction is used in organic chemistry to combine two or more molecules to form a new compound. On the other hand, a substitution reaction is used to replace an atom or group from the reactants.

Answer to Problem 15LC

An addition reaction is generally used to convert unsaturated carbon into saturated carbon forming large products. Whereas substitution reaction is used to replace a group or an atom with another group or atom.

Explanation of Solution

Addition reaction:

  ${\text{CH}}_{\text{2}}{\text{=CH}}_{\text{2}}{\text{+H}}_{\text{2}}\text{O}\to {\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH}$

In the above reaction, ${\text{H}}_{\text{2}}\text{O}$ is added with Ethene to form Ethanol by breaking the double bond of ethene.

  ${\text{CH}}_{\text{2}}{\text{=CH}}_{\text{2}}{\text{ + Cl}}_{\text{2}}\to {\text{ CH}}_{\text{2}}{\text{Cl-CH}}_{\text{2}}\text{Cl}$

In the above reaction, Ethene is reacted with chlorine to form a new molecule dichloroethane. Chlorine is added when the double bond between the carbon and carbon of ethene is disrupted.

Substitution reaction:

  ${\text{CH}}_{\text{4}}{\text{+Cl}}_{\text{2}}\to {\text{CH}}_{\text{3}}\text{Cl+HCl}$

In the above equation, one hydrogen is substituted with chlorine to form ${\text{CH}}_{\text{3}}\text{Cl}$ and HCl.

  ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH + HI }\to {\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{I + H}}_{\text{2}}\text{O}$

In the above example, the hydroxide group is substituted with Iodine to form Ethyl Iodide.

Conclusion

Addition reactions and substation reactions are used for different purposes in organic chemistry. Both reactions are important for synthesis in organic chemistry.