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US 4,361,712 AGranted
Cyanide reduction in nitroaromatic process
AssigneeAir Products and Chemicals, Inc.
InventorsFrederick L. Herman, John E. Sawicki
Life of this patent
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Abstract
The invention relates to a method of eliminating or substantially reducing the amount of cyanide formed in a polynitroaromatic, e.g. dinitrotoluene process. The invention comprises removing the nitrophenolic material from the mononitroaromatic formed in a first stage nitration of toluene prior to feeding the mononitroaromatic to the subsequent nitration zones.
Claims6
In a process for producing a polynitroaromatic compound from a mononucleararomatic compound which comprises:
- nitrating the mononucleararomatic compound in a first stage nitration zone with an aqueous mixture of sulfuric and nitric acid to form an organic phase containing mononitroaromatic and by-product nitrophenolic material and an aqueous phase containing spent acid;
- separating the organic phase from the aqueous phase containing spent acid;
- nitrating the mononitroaromatic contained in the organic phase in a second stage nitration zone using an aqueous mixture of sulfuric and nitric acid to form an organic phase containing a polynitroaromatic compound and an aqueous acid phase;
- and
- separating the organic phase from the aqueous phase;
- and
- recovering the polynitroaromatic compound from the organic phase;
- the improvement for reducing cyanide and nitrous acid formation during the process for producing polynitroaromatic compound which comprises:
- reducing the by-product nitrophenolic material present in the organic phase from the first stage nitration zone prior to nitrating the mononitroaromatic in the second stage nitration zone.
6 more elements
Dependencies are inferred from the claim text.