Benzenediazonium chloride and aq. sodium chloride is produced from a reaction of aniline (i.e. phenylamine or aminobenzene) and nitrous acid (produced in situ from 2 mol Hydrochloric acid and sodium nitrate). In the second step, phenol is coupled (at the para position) to the diazonium sal t with the loss of hydrochloric acid, to form a yellow- orange azo dye. draw a reaction scheme.