Final answer:
To make brown hair dye, two dyes are mixed: a diamine compound (1,4-diaminobenzene or 2,5-diaminotoluene) and a coupler compound. The diamine compound is oxidized to a quinone state, which reacts with the coupler compound to create the brown dye.
Step-by-step explanation:
The two dyes that are mixed to make brown hair dye are 1,4-diaminobenzene or 2,5-diaminotoluene (a diamine compound) and a coupler compound. The diamine compound undergoes oxidation to form a quinone state, which then reacts with the coupler compound to produce the final brown dye.