Diazonium salts industrial applications

Potassium nitrite is an antidote to cyanide poisoning. It also is a vasodilator. An important application is in the dye industry to prepare diazonium salts and azo dyes. Another use is in curing certain meat products where the salt imparts an appetizing pink color to cured meats and retards microbial growth on the meat. The commerical product is usually a nitrite-nitrate mixture, containing 85% KNO2 and 15% KNO3... 

The patent literature discloses a large variety of other initiators including different Lewis acids, stable carbenium, oxonium or diazonium salts, and derivatives (esters or anhydrides) of strong protonic acids. However, BF3 seems to maintain its superior position in industrial applications. 

Two industrially relevant azo coupling processes are carried out. The two azo coupling steps are successfully carried out in a laboratory-scale microreactor at flow rates of up to 80 mL min . Whereas in the first example a diazonium salt solution is applied, the second diazonium salt is fed as suspended starting material into the microchannels. The microfiuidic-derived pigments show improvements in application properties such as color strength compared with batch-derived standards. One reason for the improvements of color properties is the significant reduction in mean particle size from 600 to 90 nm. (Figure 16.4). 

Belmont, J. A., C. Bureau, M. M. Chehimi, S. Gam-Derouich, and J. Pinson. Patents and industrial applications of aryl diazonium salts and other coupling reagents, in Aryl Diazonium Salts. New Coupling Agents in Polymer and Surface Science. M. M. Chehimi (Ed.), Wiley-VCH, Weinheim, 2012. Chapter 14. 

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