Nitriles are organic compounds that have the general formula RCN (RC≡N).
Nitriles can be prepared by a substitution reaction using KCN.
The –:C≡N: ion is a good carbon nucleophile, and this substitution results in extension of the carbon chain.
This means that nitriles and carboxylic acid derivatives can be inter-converted by addition or removal of water.
An alternate preparation of nitriles is by reaction of primary amides with the dehydrating agent P4O10. The co-product of the reaction is phosphoric acid (H3PO4)
Note that because two hydrogens must come from the nitrogen, the amide must be a primary one.
Secondary amides have only one H at nitrogen, and tertiary ones do not have any H at nitrogen.
Similarly nitriles, like amides can be hydroysed to carboxylic acids and ammonium salts with aqueous acid.
Note that because two hydrogens must come from the nitrogen, the amide must be a primary one.
Secondary amides have only one H at nitrogen, and tertiary ones do not have any H at nitrogen.
Reactions 1 and 3 can be combined to convert a haloalkane to a carboxylic acid having an additional carbon atom.
Nitriles can be prepared by a substitution reaction using KCN.
The –:C≡N: ion is a good carbon nucleophile, and this substitution results in extension of the carbon chain.
Reaction 1: CH3Br + –:C≡N: 
CH3C≡N: + Br–
The nitrile functional group is on the same oxidation level as carboxylic acids and amides which also have three bonds from carbon to more electronegative atoms. CH3C≡N: + Br–This means that nitriles and carboxylic acid derivatives can be inter-converted by addition or removal of water.
An alternate preparation of nitriles is by reaction of primary amides with the dehydrating agent P4O10. The co-product of the reaction is phosphoric acid (H3PO4)
Reaction 2:  | P4O10  | CH3CH2C≡N |
Note that because two hydrogens must come from the nitrogen, the amide must be a primary one.
Secondary amides have only one H at nitrogen, and tertiary ones do not have any H at nitrogen.
Similarly nitriles, like amides can be hydroysed to carboxylic acids and ammonium salts with aqueous acid.
| Reaction 3: CH3CH2C≡N | H3O+ |  |
Note that because two hydrogens must come from the nitrogen, the amide must be a primary one.
Secondary amides have only one H at nitrogen, and tertiary ones do not have any H at nitrogen.
Reactions 1 and 3 can be combined to convert a haloalkane to a carboxylic acid having an additional carbon atom.