Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Amines are derivatives of ammonia () obtained by the replacement of one or more hydrogen atoms by alkyl or aryl groups.
Classification: Based on the number of hydrogen atoms replaced, amines are classified as primary (, ), secondary (, ), and tertiary (, ).
IUPAC Nomenclature: Amines are named as alkanamines. In the case of secondary and tertiary amines, the prefix '' is used to denote substituents attached to the nitrogen atom (e.g., -methylethanamine).
Reduction of Nitro Compounds: Nitro compounds are reduced to amines using , , or . Reduction with is preferred because formed gets hydrolyzed to release , requiring only a small amount of initiator acid.
Ammonolysis of Alkyl Halides: The process of cleavage of the bond by ammonia is called ammonolysis. It usually yields a mixture of amines and quaternary ammonium salts.
Reduction of Nitriles and Amides: Nitriles () and Amides () can be reduced to amines using or catalytic hydrogenation.
Gabriel Phthalimide Synthesis: This method is used specifically for the preparation of primary aliphatic amines. It involves the reaction of phthalimide with , followed by an alkyl halide () and subsequent alkaline hydrolysis. It cannot be used for aniline because aryl halides do not undergo nucleophilic substitution with the phthalimide anion.
Hoffmann Bromamide Degradation Reaction: An amide reacts with in an aqueous or ethanolic solution of to yield a primary amine with one carbon atom less than the starting amide.
📐Formulae
💡Examples
Problem 1:
Write the IUPAC name for .
Solution:
-methylpropan-2-amine
Explanation:
The longest carbon chain attached to nitrogen contains 3 carbon atoms (propane) with the amino group at the 2nd position. The smaller methyl group is treated as a substituent on the nitrogen atom.
Problem 2:
How will you convert Benzamide to Aniline?
Solution:
By Hoffmann Bromamide Degradation reaction:
Explanation:
Treating benzamide with bromine and sodium hydroxide results in the loss of the carbonyl carbon atom as carbonate, yielding aniline (a primary amine) with one less carbon.
Problem 3:
Why is Gabriel Phthalimide synthesis not preferred for the preparation of Aniline?
Solution:
Aryl halides do not undergo nucleophilic substitution with the phthalimide anion.
Explanation:
The reaction requires the nucleophilic attack of the phthalimide anion on an organic halide. Since aryl halides () are less reactive towards nucleophilic substitution due to partial double bond character of the bond and resonance, they do not react with potassium phthalimide.