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AssigneeDeutsche Gold- und Silber-Scheideanstalt vormals Roessler
InventorsWerner Heimberger, Gerd Schreyer
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Cyanogen chloride or cyanogen bromide is prepared by reaction of hydrogen cyanide with hydrogen chloride or hydrochloric acid (or hydrogen bromide or hydrobromic acid) and hydrogen peroxide in aqueous medium in the presence of cupric and ferric ions under superatmospheric pressure, preferably between 1.5 and 16 bar, and the cyanogen chloride (or cyanogen bromide) recovered separated from oxygen and nitrogen. In a preferred form of the invention, the hydrogen chloride or hydrochloric acid is either partially or entirely formed directly in the recycling catalyst solution of cupric and ferric ions by reaction of chlorine and hydrogen cyanide, either with or without pressure.
In a process for the production of cyanogen chloride or cyanogen bromide by reaction of (1) hydrogen cyanide with (2) hydrogen chloride or hydrogen bromide, and (3) hydrogen peroxide, in aqueous medium, in the presence of cupric ions and ferric ions as catalysts, the improvement comprising carrying out the reaction at a pressure of 1.5 to 16 bar and recovering the cyanogen chloride or cyanogen bromide free from oxygen and nitrogen.
Dependencies are inferred from the claim text.
Cyanogen; Compounds thereof: halogenides of cyanogen
Improvements relating to the production of bulk chemicals: recycling of catalysts
Ammonia
Low-carbon manufacturing
Term ended 6 Sep 1994 (estimated)
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It is known to react hydrogen cyanide and hydrogen chloride with hydrogen peroxide in the presence of an aqueous solution of cupric ions and ferric ions as catalysts to form cyanogen chloride, see Heilos German Pat. No. 2,027,957 and Heilos German Pat. No. 2,131,383 and Heilos U.S. Pat. No. 3,840,648, which is related to the two German patents. The entire disclosure of the Heilos United States patent is hereby incorporated by reference and relied upon.
The reaction takes place in a yield of about 90-92% based on the hydrogen cyanide, thereby the always-trifling decomposition of the hydrogen peroxide and the oxidation of the hydrogen cyanide causes a part up to 5 weight % each of oxygen and carbon dioxide in the cyanogen chloride gas.
In the trimerization of cyanogen chloride to cyanuric chloride there appears an increased consumption of the activated carbon through the oxygen content, whereby the continuous production of cyanuric chloride is made difficult through the frequent interruption of the operation to add activated carbon.
In the continuously-operating apparatus shown in FIG. 1, there were recirculated 40 liters of an aqueous solution containing 13.0 grams CuCl.sub.2.2H.sub.2 O/l and 3.35 grams FeCl.sub.3.6H.sub.2 O/l through a reactor 20, let-down vessel 22, washer 24, volatile stripper 26 and pressure washer 28.
1.6 kg/h of gaseous hydrogen cyanide were added via line 1 into the reaction solution found in line 10, which solution was conveyed through pump 30 into the reactor 20. There were closed into reactor 20, via line 3, 4.301 kg/h of 50 weight % aqueous hydrogen peroxide (which is 10% excess over the stoichiometric amount) and over line 2, 21.6 kg/h of 10 weight % aqueous hydrochloric acid with the help of pumps 32 and 34.
In continuous operation, by regulation of the addition of hydrochloric acid, the pH was held exactly between 0.25 and 0.35. Through the cyanogen chloride released, there was built up in reactor 20 and pressure washer 28 a pressure up to 4 bar which was held constant via the pressure check valve 36 at the top of the pressure washer. There were collected at the top of the reactor 20 the oxygen released by the decomposition of the hydrogen peroxide and the carbon dioxide and nitrogen formed by oxidation and subsequent reactions.