Amine tests, diazonium salts and azo dyes – Hinsberg, carbylamine and coupling

What it shows

Amines are classed by the number of carbon groups on nitrogen. In the Hinsberg test, primary amines give a sulfonamide that dissolves in alkali because it still has an acidic N–H; secondary amines give an insoluble one; tertiary amines do not react. Only primary amines give the foul isocyanide in the carbylamine test. Aniline with nitrous acid forms benzenediazonium chloride, which decomposes to phenol and nitrogen faster as it warms, so it is made and used at 0–5 °C. It couples with phenols and aromatic amines to give coloured azo dyes.

How to use

In Amine tests, choose a Sample, press Hinsberg test, then Add dilute HCl, and also press Carbylamine test; use the unknowns A, B and C for the task. In Diazotisation, set the Bath temperature and Total time, then press Add NaNO₂ and read the nitrogen volume. In Azo dyes, choose the Coupling partner and press Couple; the dye is weighed. Each result goes into the table.

Parameters you can change

• Screen Amine tests, Diazotisation, Azo dyes
• Sample Butan-1-amine, Phenylamine (aniline), Diethylamine, N-methylaniline, Triethylamine, N,N-dimethylaniline, Unknown A, Unknown B, Unknown C
• Bath temperature 0–50 °C
• Total time 10–60 min
• Coupling partner Phenol, 2-naphthol, Aniline

Questions to explore

1. Which observations in the Hinsberg test separate a primary amine from a secondary amine?
2. How much nitrogen is given off in 30 min at 5 °C, and at 30 °C?
3. How does keeping the diazonium solution warm change the mass of dye you obtain?