Question

Heat RCN in $ LiAl{{H}_{4}} $ and Dry ether.

Answer 1

Hint RCN is alkyl nitrile in which the functional group is cyanide. $ LiAl{{H}_{4}} $ is the lithium aluminium hydride and it is a very good reducing agent. So, the alkyl nitrile will be reduced which means there will be the addition of hydrogen to the compound.

Complete step by step answer:
RCN is an alkyl nitrile in which the functional group is cyanide having formula $ -CN $ , there is a triple bond between the carbon atom and hydrogen atoms.
 $ LiAl{{H}_{4}} $ is the lithium aluminium hydride and it is a very good reducing agent. It is an inorganic compound and it is a grey solid. In organic reaction, this is used as a reducing agent which is used for the addition of hydrogen atoms in the compound or removal of the oxygen atoms.
When the alkyl nitrile is treated with lithium aluminium hydride in the presence of dry ether, then there will be the addition of hydrogen atoms on the carbon atom of the cyanide group as well as to the nitrogen atom of the cyanide group. The reaction is given below:
 $ RCN+LiAl{{H}_{4}}\xrightarrow{dry\text{ }ether}R-C{{H}_{2}}-N{{H}_{2}} $
So, the alkyl nitrile will be converted into alkyl amine.
An example of this conversion can be, acetonitrile can be converted into ethylamine with lithium aluminium hydride with dry ether. The formula of acetonitrile is $ C{{H}_{3}}C\equiv N $ and the formula of ethylamine is $ C{{H}_{3}}-C{{H}_{2}}-N{{H}_{2}} $ . The reaction is given below:
 $ C{{H}_{3}}C\equiv N+LiAl{{H}_{4}}\xrightarrow{dry\text{ }ether}C{{H}_{3}}-C{{H}_{2}}-N{{H}_{2}} $

Therefore, the nitrile is converted into amine with lithium aluminium hydride with dry ether.

Note: There are many other reagents that can be used to convert nitrile to amine like hydrogen in the presence of Raney nickel, sodium amalgam in the presence of alcohol like ethanol, etc.