Question

How are ${\text{propan - 1 - amine}}$ and ${\text{propan - 2 - amine}}$ prepared from oxime?

Answer 1

Hint : Note that the number of carbons of carbons in the oxime and the number of carbon atoms in the resulting amine will be the same. The formula of oxime is ${\text{R1R2NOH}}$ . We have to choose the alkyl groups ${\text{R1}}$ and ${\text{R2}}$ according to the product required.

Complete Step By Step Answer:
${\text{Propan - 1 - amine}}$ and ${\text{propan - 2 - amine}}$ can be prepared from oxime when oxime is reacted by ammonium salt of carboxylic acid in the presence of active metals like magnesium. The reactions are basic in nature. The formula of oxime is ${\text{R1R2NOH}}$ where ${\text{R1}}$ and ${\text{R2}}$ are alkyl groups. The number of carbon atoms present in ${\text{R1}}$ and ${\text{R2}}$ determines the number of carbons in the amine formed. ${\text{R1}}$ and ${\text{R2}}$ also determine the type of amine formed that is whether the amine is primary or secondary. If ${\text{R1}}$ is hydrogen then the amine formed will be primary and if ${\text{R1}}$ and ${\text{R2}}$ are both alkyl groups then the amine formed will be a secondary amine.
For the formation of ${\text{propan - 1 - amine}}$ :
Consider ${\text{R1 = H}}$ and ${\text{R2 = C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}$ , the oxime ${\text{H(C}}{{\text{H}}_2}{\text{C}}{{\text{H}}_3}){\text{NOH}}$ reacts with ammonium salt of carboxylic acid in the presence of magnesium. The reaction will be:
${\text{H(C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}){\text{NOH + HCHOON}}{{\text{H}}_4}{\text{ + Mg}} \to {\text{propan - 1 - amine}}$
For the formation of ${\text{propan - 2 - amine}}$ :
Consider ${\text{R1 = C}}{{\text{H}}_3}$ and ${\text{R2 = C}}{{\text{H}}_3}$ , the oxime ${\text{C}}{{\text{H}}_3}{\text{(C}}{{\text{H}}_3}){\text{NOH}}$ reacts with ammonium salt of carboxylic acid in the presence of magnesium. The reaction will be:
${\text{C}}{{\text{H}}_3}{\text{(C}}{{\text{H}}_3}){\text{NOH + HCHOON}}{{\text{H}}_4}{\text{ + Mg}} \to {\text{propan - 2 - amine}}$ .

Note :
Remember that the alkyl groups ${\text{R1}}$ and ${\text{R2}}$ play a major role in determining the number of carbon atoms in the resulting amine and also help in determining the type of amine formed i.e. whether the amines formed are primary, secondary or tertiary.