Summary

This chapter followed four nitrogen-containing organic families in the order set by

WBCHSE's own Unit 6 syllabus. Nitro compounds ($\text{R}-\text{NO}_2$) are made from

a haloalkane and $\text{AgNO}_2$, and their central importance is as a controllable

route to a primary amine -- the SAME nitro compound gives aniline with

$\text{Fe}/\text{Sn}/\text{HCl}$ or catalytic hydrogenation, but stops at

phenylhydroxylamine with the milder $\text{Zn}/\text{NH}_4\text{Cl}$.

Amines are classified $1^\circ/2^\circ/3^\circ$ purely by substitution at their

pyramidal, $sp^3$ nitrogen, and are prepared by reduction (of a nitro compound, nitrile

or amide), by ammonolysis (prone to over-alkylation), by the Gabriel phthalimide

synthesis (the cleanest route to a pure aliphatic primary amine, but never an aromatic

one), or by the Hoffmann bromamide degradation (the one method that SHORTENS the chain

by a carbon). Their basicity is governed by a balance of inductive electron-donation

(raising it) against resonance delocalisation into an aromatic ring and steric/solvation

effects (both lowering it), and the three classes are distinguished experimentally

either by their reaction with nitrous acid (diazonium salt / $N$-nitrosamine /

ring-nitrosation, depending on class) or, most reliably, by the Hinsberg test's

solubility-in-alkali criterion.

Cyanides and isocyanides, though constitutional isomers of one another differing

only in whether $\text{R}$ is bonded to carbon or to nitrogen, diverge sharply in every

downstream reaction: $\text{KCN}$ gives the cyanide while $\text{AgCN}$ gives the

isocyanide from the same haloalkane; hydrolysis of a cyanide gives a carboxylic acid

plus ammonia while hydrolysis of an isocyanide gives a primary amine plus formic acid;

reduction of a cyanide gives a primary amine while reduction of an isocyanide gives a

secondary amine.

Diazonium salts, formed only from an aromatic primary amine at $0$–$5^\circ \text{C}$, are the most versatile intermediate of the chapter: they either lose

nitrogen (Sandmeyer, Gattermann, Balz-Schiemann, hydrolysis to phenol, or reductive

deamination -- installing a new substituent at the original ring position) or retain it …