08 Amines and Nitrogen-Containing Functional Groups Free Online FlashCards

How are primary, secondary, and tertiary amines classified?

A primary amine has one carbon group attached to nitrogen; a secondary amine has two, and a tertiary amine has three. The labels count carbon groups, not hydrogen atoms.

Why are amides less basic than amines?

In amines, the nitrogen lone pair is available; in amides, it is delocalized into the carbonyl. Amides are therefore much less basic and nucleophilic than amines.

What two roles does an amine nitrogen lone pair enable?

The nitrogen lone pair lets an amine accept a proton as a Brønsted–Lowry base and donate an electron pair as a nucleophile.

How does conjugate-acid $pK_a$ generally relate to amine basicity?

A higher $pK_a$ for an amine’s conjugate acid generally indicates a stronger amine base.

How can acid–base extraction separate an amine from a mixture?

Extract the mixture with aqueous acid to transfer the amine into water as an ammonium salt. Separate that layer, then add base to regenerate the neutral amine.

What does reductive amination do?

Reductive amination converts a carbonyl compound and ammonia or an amine through an imine or iminium intermediate, then reduces it. Ammonia gives a primary amine; primary and secondary amines give secondary and tertiary amines, respectively.

What is a key limitation of direct amine alkylation?

Direct alkylation can form a new carbon–nitrogen bond, but further alkylation may produce mixtures. Use it cautiously when a single substitution level is needed.

What transformation occurs when a primary or secondary amine is acylated?

Primary and secondary amines react with acid chlorides or acid anhydrides by nucleophilic acyl substitution to form amides. The amide is less nucleophilic because its nitrogen lone pair is delocalized into the carbonyl.

What is the synthetic use of an arenediazonium salt?

Cold acidic nitrous acid converts a primary aromatic amine such as aniline into an arenediazonium salt. Its diazonium group can then be replaced by groups such as $\mathrm{Cl}$, $\mathrm{Br}$, $\mathrm{I}$, $\mathrm{CN}$, $\mathrm{OH}$, or $\mathrm{H}$.

What defines a quaternary ammonium ion?

A quaternary ammonium ion has four carbon groups bonded to nitrogen and carries a permanent positive charge: $\mathrm{R_4N^+}$.

Why is aniline less basic than a typical alkylamine?

Aniline is less basic than a typical alkylamine because its nitrogen lone pair can delocalize into the aromatic ring, making it less available to accept a proton.

What is the main advantage of the Gabriel synthesis?

The Gabriel synthesis alkylates phthalimide with a suitable alkyl halide, then cleaves the imide to give a primary amine. It helps avoid mixtures from repeated alkylation of ammonia.