Diazo reactions, coupling reactions and condensation reactions commonly seen in chemical and dye processing are typical exothermic reactions, and the reaction heat should be removed in time. The ideal reaction conditions should be 0-10℃, if the temperature is too high, not only nitrite is easy to decompose, but also accelerate the decomposition of compounds. Many major chemical processing plants use ice to control the temperature of chemicals in the reaction, to add water to the process during cooling, or for rapid cooling to stop timed reactions.

For faster cooling, ice is preferred over traditional jacketed tanks or external heat exchanger. Adding ice to the solution gives it a much larger cooling surface area, lowering the temperature in less time and maintaining better control. Ice can be fed continuously or at specific times during the batch process.