Reactions of Amines – Vocabulary Review

Vocabulary flashcards covering major reactions, intermediates, tests, and terms related to amines as discussed in the lecture notes.

Gabriel Phthalimide Reaction

A method for synthesizing pure aliphatic primary amines by treating potassium phthalimide with an alkyl halide followed by hydrolysis with aqueous NaOH.

Hinsberg Test

Qualitative test using benzene-sulfonyl chloride to distinguish 1°, 2°, and 3° amines; the sulfonamide from a 1° amine dissolves in alkali, the 2° product is insoluble, and 3° amines do not react.

Diazo Coupling Reaction

Reaction of an aromatic diazonium salt with activated rings (phenols or aryl amines) to form brightly colored azo dyes.

Schotten–Baumann Reaction

Base-catalyzed acylation of amines with acid chlorides (e.g., benzoyl chloride) to give amides; 3° amines do not undergo this acylation.

Hofmann Bromamide Degradation

Conversion of an amide to a primary amine with one carbon fewer using Br₂ and aqueous NaOH; proceeds through an isocyanate intermediate.

Alkyl/Aryl Migration in Hofmann Mechanism

Step in the Hofmann degradation where the alkyl or aryl group shifts from the carbonyl carbon to nitrogen during isocyanate formation.

Isocyanate Intermediate

R–N=C=O species formed in the Hofmann degradation before hydrolysis to the amine and CO₂.

Mendius Reaction

Reduction of an alkyl cyanide (nitrile) with sodium in ethanol to give a primary amine containing one additional carbon atom.

Carbylamine Reaction

Test in which a primary amine reacts with CHCl₃ and alcoholic KOH to produce a foul-smelling isocyanide; distinguishes 1° amines from 2° and 3°.

Dichlorocarbene (:CCl₂)

Reactive intermediate generated from CHCl₃ + KOH in the carbylamine test; inserts into the N–H bond of the amine.

Hofmann Mustard Oil Reaction

Formation of an isothiocyanate (R–N=C=S) with pungent mustard-oil odor when a primary amine reacts with CS₂ followed by HgCl₂.

Isothiocyanate

Compound with the functional group –N=C=S produced in the Hofmann mustard-oil test.

Primary Amine (1°)

Amine with one carbon attached to nitrogen (R–NH₂); gives positive Gabriel, Hinsberg (soluble product), carbylamine, and mustard-oil tests.

Secondary Amine (2°)

Amine with two carbons attached to nitrogen (R₂NH); forms insoluble sulfonamide in Hinsberg but gives negative carbylamine and mustard-oil tests.

Tertiary Amine (3°)

Amine with three carbons attached to nitrogen (R₃N); generally unreactive in Hinsberg, acylation, carbylamine, and mustard-oil tests.

Azo Dye

Colored compound containing the –N=N– linkage formed via diazo coupling (e.g., orange dye from p-naphthol).

Malachite Green

A triphenylmethane dye produced by coupling benzaldehyde with dimethyl-aniline; cited as an example of an azo dye product.