Identify the reaction

This question from compounds containing nitrogen typically refers to the diazotisation of an aromatic amine followed by coupling reaction to form an azo dye.

The general sequence is: $\text{ArNH}_2 \xrightarrow[0-5^\circ C]{\text{NaNO}_2/\text{HCl}} \text{ArN}_2^+\text{Cl}^-$ followed by coupling with an activated aromatic ring such as phenol or aniline: $\text{ArN}_2^+\text{Cl}^- + \text{activated aromatic compound} \rightarrow \text{azo compound}$

Nature of the product

The product contains the azo group: $-\mathrm{N=N}-$ Such compounds are highly conjugated and are generally deeply coloured dyes.

Typical colour

The azo dye formed in such coupling reactions is commonly orange to red in colour. Among the given options, the correct matching colour is: $\boxed{\text{Red}}$

Check options

• A: White — incorrect, azo dyes are coloured.
• B: Yellow — possible for some azo compounds, but the standard expected answer here is not yellow.
• C: Red — correct.
• D: Blue — incorrect for the usual diazo coupling product.

Final answer

The product is red in colour.