The functional group in nitriles and amides is on the same oxidation level as carboxylic acids and their other derivatives such as acid chlorides and esters.
All of these functional groups have three bonds at carbon to more electronegative atoms.
Each of these compounds
The primary amide and nitrile functional groups are both converted on reaction with LiAlH4 to –CH2NH2.
Therefore primary amides and nitriles with the same number of carbons are converted to the same primary amine.
It should also be noted that this reaction of nitriles is limited to preparation of amines where the NH2 group is also bonded to a CH2 group.
Secondary and tertiary amides are converted to secondary and tertiary amines.
All of these functional groups have three bonds at carbon to more electronegative atoms.
 |  | CH3C≡N |
Each of these compounds
has a polar multiple bond with carbon bonded to oxygen or to nitrogen.
reacts at the multiply-bonded carbon with LiAlH4, a compound which is a source of H:–.
reacts at the multiply-bonded carbon with LiAlH4, a compound which is a source of H:–.
The primary amide and nitrile functional groups are both converted on reaction with LiAlH4 to –CH2NH2.
Therefore primary amides and nitriles with the same number of carbons are converted to the same primary amine.
Reaction 1:  | LiAlH4 | CH3CH2CH2NH2 |
Reaction 2: CH3CH2C≡N |
It should also be noted that this reaction of nitriles is limited to preparation of amines where the NH2 group is also bonded to a CH2 group.
The limitation is that amines that can be prepared by this method MUST have a CH2 group bonded to the nitrogen. These CH2 groups are highlighted in the amine products below.
Reaction 3:  | LiAlH4 | CH3CH2NHCH2CH3 |
Reaction 4:  | LiAlH4 | CH3CH2N(CH3)2 |