Amines - Class 12 JEE Revision Notes

Vocabulary flashcards covering classification, nomenclature, preparations, basicity, physical properties, and named reactions of amines for Class 12 JEE revision.

Amines

Organic derivatives of ammonia ($\text{NH}_3$) in which one or more hydrogen atoms are replaced by alkyl or aryl groups.

Primary Amines ($1^\circ$)

Amines with the general structure $\text{R-NH}_2$, where nitrogen is directly attached to one carbon group.

Secondary Amines ($2^\circ$)

Amines with the general structure $\text{R}_2\text{NH}$, where nitrogen is directly attached to two carbon groups.

Tertiary Amines ($3^\circ$)

Amines with the general structure $\text{R}_3\text{N}$, where nitrogen is directly attached to three carbon groups.

Quaternary Ammonium Salt

Organic salts with the general structure $\text{[R}_4\text{N]}^+ \text{X}^-$, containing four carbon groups attached to nitrogen.

Aliphatic Amines

Amines in which nitrogen is directly attached only to alkyl groups, such as methylamine ($\text{CH}_3\text{NH}_2$).

Aromatic Amines

Amines in which nitrogen is directly attached to an aromatic ring, such as aniline ($\text{C}_6\text{H}_5\text{NH}_2$).

Pyramidal Inversion

A process that ordinary amines rapidly undergo at room temperature due to their approximately $sp^3$ hybridised nitrogen and pyramidal geometry.

Ammonolysis

The nucleophilic substitution reaction of alkyl halides with ammonia ($\text{R-X} + \text{NH}_3 \rightarrow \text{R-NH}_2$) yielding a mixture of $1^\circ$, $2^\circ$, and $3^\circ$ amines along with quaternary ammonium salts.

Gabriel Phthalimide Synthesis

A reaction converting phthalimide, $\text{KOH}$, and an alkyl halide ($\text{R-X}$) followed by hydrolysis into pure primary aliphatic amines.

Hofmann Bromamide Degradation

The reaction of an amide with $\text{Br}_2$ and $\text{NaOH}$ ($\text{RCONH}_2 + \text{Br}_2 + 4\text{NaOH} \rightarrow \text{RNH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O}$) yielding a primary amine with one fewer carbon atom.

Carbylamine Reaction

A diagnostic test where primary amines react with chloroform ($\text{CHCl}_3$) and alcoholic $\text{KOH}$ to form an isocyanide ($\text{RNC}$) with an extremely unpleasant smell.

Hinsberg Reagent

Benzenesulphonyl chloride ($\text{C}_6\text{H}_5\text{SO}_2\text{Cl}$), used to distinguish $1^\circ$, $2^\circ$, and $3^\circ$ amines based on sulphonamide formation and solubility in alkali.

Diazotisation

The reaction of a primary aromatic amine like aniline with $\text{NaNO}_2$ and $\text{HCl}$ at $0\text{--}5\,^\circ\text{C}$ to produce an aryl diazonium salt.

Sandmeyer Reaction

The replacement of a diazonium group in aryl diazonium salts by $\text{Cl}$, $\text{Br}$, or $\text{CN}$ using copper(I) salts ($\text{CuCl}$, $\text{CuBr}$, or $\text{CuCN}$).

Gattermann Reaction

The replacement of an aryl diazonium group by $\text{Cl}$ or $\text{Br}$ using copper powder in the presence of $\text{HCl}$ or $\text{HBr}$.

Balz-Schiemann Reaction

The thermal decomposition of aryl diazonium tetrafluoroborate ($\text{ArN}_2^+\text{BF}_4^-$) upon heating to produce an aryl fluoride ($\text{ArF}$), $\text{BF}_3$, and $\text{N}_2$.

Azo Coupling

An electrophilic substitution reaction where diazonium salts react with activated aromatic compounds like phenols or anilines to form brightly colored azo dyes containing the $-\text{N}=\text{N}-$ group.

2,4,6-Tribromoaniline

The white precipitate formed when aniline reacts readily with excess bromine water ($\text{Br}_2$ water) without requiring a Lewis acid catalyst.

Acetylation of Aniline

The protection of aniline's amino group by reaction with acetyl chloride ($\text{CH}_3\text{COCl}$) to form acetanilide, which temporarily reduces its activating power for controlled electrophilic substitution.