18 Questions
Which compound has the highest boiling point between Propanamine and N,N-dimethylmethanamine?
Propanamine
What chemical test can be used to differentiate between CH3NH2 and (CH3)2NH?
Reaction with HNO2 to form a stable diazonium salt
Why does aniline not undergo Friedel-Crafts reaction?
Lacks a hydrogen atom on the benzene ring
Why are diazonium salts of aromatic amines more stable than those of aliphatic amines?
Presence of resonance stabilization in aromatic compounds
Which compound has the highest pK value among Aniline, p-nitroaniline, and p-toluidine?
p-toluidine
In gaseous state, which compound is the strongest base among C2H5NH2, (C2H5)NH, and (C2H5)3N?
(C2H5)3N
Which compound will have the highest basic character among the following?
C6H5NH(CH3)2
What is the foul-smelling compound 'C' produced when compound 'B' reacts with CHCl3 and alcoholic KOH?
Phenyl isocyanide
Why is Gabriel phthalimide synthesis not preferred for preparing aromatic primary amines?
The method is not suitable for generating aromatic compounds.
What product is obtained when N-phenylethanamide is converted to p-bromoaniline?
p-bromoacetanilide
What is the main product formed in the Hoffmann bromamide degradation reaction?
Secondary amine
In the reaction of benzene sulphonyl chloride with a primary amine, why does a product soluble in alkali form?
Formation of sulfonamide linkage
Why is aniline considered a weaker base compared to ethanamine?
Aniline has a higher pKa value than ethanamine.
Why does aniline not undergo Friedel-Crafts reaction?
Friedel-Crafts reagents cannot react with aniline due to steric hindrance.
Why can only aliphatic primary amines be prepared by Gabriel Phthalimide synthesis?
The reagents in the synthesis cannot react with secondary or tertiary amines.
Why does NH2 group in aniline give good yield of m-nitroaniline on nitration?
Stabilization of the intermediate by resonance
Why is (CH3)NH more basic than (CH3)3N in an aqueous solution?
(CH3)NH can form stronger hydrogen bonds with water molecules.
Why is ammonolysis of alkyl halides not a good method to prepare pure primary amines?
Ammonolysis forms a mixture of primary, secondary, and tertiary amines.
Study Notes
Amines
Distinguishing between compounds
- Aniline and Ethanamine: Aniline gives a foul smell on heating with CHCl₃ and alcoholic KOH, whereas Ethanamine does not.
- Aniline and N-methylaniline: Aniline gives a positive carbylamine test, whereas N-methylaniline does not.
Boiling points
- Butanol > Butanamine > Butane (in decreasing order of boiling points)
Properties of Aniline
- Aniline is a weaker base compared to ethanamine due to resonance stabilization of the amino group.
- Aniline does not undergo Friedel-Crafts reaction because the amino group deactivates the benzene ring.
Gabriel Phthalimide Synthesis
- Only aliphatic primary amines can be prepared by Gabriel Phthalimide synthesis.
Basicity of Amines
- (CH₃)NH is more basic than (CH₃)₃N in an aqueous solution due to steric hindrance.
- Propanamine has a higher boiling point than N,N-dimethylmethanamine because of stronger intermolecular hydrogen bonding.
Diazonium Salts
- Diazonium salts of aromatic amines are more stable than those of aliphatic amines.
- Diazonium salts react with HNO₂ at low temperatures to form stable diazonium salts.
Chemical Tests
- Aniline can be distinguished from Ethanamine by reacting with HNO₂ at a low temperature to form a stable diazonium salt.
- Aniline can be distinguished from CH₃NH₂ by reacting with ferric chloride to precipitate hydrated ferric oxide.
pKb Values
- p-toluidine > aniline > p-nitroaniline (in decreasing order of pKb values)
- C₂H₅NH₂ > (C₂H₅)₂NH > (C₂H₅)₃N (in decreasing order of pKb values)
Reactions
- Aniline reacts with CHCl₃ and alcoholic KOH to form a foul-smelling compound.
- Benzene diazonium chloride reacts with water to form phenol.
- Benzoic acid reacts with Sn/HCl to form aniline.
Synthesis of Amines
- Aniline can be converted to p-bromoaniline by reacting with Br₂ and KOH.
- Benzene diazonium chloride can be converted to nitrobenzene by reacting with water.
- Benzoic acid can be converted to aniline by reacting with Sn/HCl.
Hoffmann Bromamide Degradation Reaction
- The Hoffmann bromamide degradation reaction involves the reaction of an amide with bromine in the presence of sodium hydroxide, resulting in the formation of an amine with one fewer carbon atoms.
Test your knowledge on distinguishing between organic compounds and arranging them based on boiling points in this quiz. Also, explore concepts like the reactivity of different compounds and specific reactions they undergo.
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