Technical diazotization procedures

Technical Observations. The procedure is different in large scale operations. As soon as the reaction is ended, the excess ammonia is blown out through a condensing system (water), and the autoclave contents, in which all of the nitroaniline remains dissolved at 150°, is put through a strong iron filter press. The nitroaniline is given no opportunity to crystallize out, but is poured directly into cold water, whereupon it crystallizes in finely divided form. This is highly desirable because it can then be diazotized smoothly in the cold. 

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