Evaluation and optimisation of the reagent addition sequence during the synthesis of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) using reaction calorimetry

The sequence of reagent addition and associated heats of reaction during the synthesis of the important herbicide atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) from cyanuric chloride, isopropylamine, and ethylamine have been investigated by means of calorimetric and analytical methods. Sodium hydroxide was used as proton scavenger in this procedure. The best addition sequence found was the concurrent addition of amine and NaOH, keeping the amine in slight excess at all times. Using this feed sequence, the reaction becomes feed-controlled, and provided that a proper level of mixing can be maintained in the reactor, a high degree of control over reaction selectivity is obtained.