Efforts at Denitrification

An attempt was made to reduce the amount of wastewater generated in the reactions for manufacture of DNBP at the source by controlling the molar ratios of OSBP and fuming sulfuric acid. Instead of using 2 mol of sulfuric add only 1 mol was used. This change resulted in the same yield (94 to 97%) and purity (97 to 98.5%) of the product. Since the sulfuric acid use was reduced by half, the volume of wastewater per pound of product fell from 0.63 gallon/pound of product to 0.45 gallon/pound of product This attempt to reduce 

The reaction must be safe and able to be controlled properly. 

The reaction rate must be adequate to meet the throughput requirements. 

Management support must be obtained to implement changes and new ideas, with emphasis on cost savings, safety, and ease of operation. 

Virtually all nitration reactions involve electrophillic attack by nitronium ions, NO2. Consequently, reactions can be regulated by controlling the concentration of nitronium ions in solution. The conditions required for the nitration reaction vary greatly with the reactivity of the aromatic substrate. The nitration mixture required for introduction of the second nitro group into benzene to prepare dinitrobenzene and concentrated nitric and sulfuric acids at 95°C is unsuitable for dinitration of alkylated phenol because it provides the conditions for an uncontrollable exothermic reaction. The DNBP process described above was based on controlling the nitration conditions and has the advantage of having very few side reactions because it is a two-phase system with nitration reactivity based on mass transfer between phases. 

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