CNCl CYANOGEN CHLORIDE

CNCl CYANOGEN CHLORIDE 21.270 1.1915E-01 -1.6822E-04 1.1457E-07 -2.9210E-11 100 1500 gas... 

CNCl Cyanogen chloride, 2 90, 93 (CN)2Ni Nickel cyanide, 2 228 CN2Ag2 Silver cyanamide, 1 98... 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

The formation of cyanogen chloride (CNCl) in Eq. (11) is essentially instantaneous. The second reaction in Eq. (12), the formation of cyanate, is accomplished most rapidly and completely at a pH of 10 or higher. A detention time of 30 min to 2 h is usually allowed. The cyanates can be further decomposed into nitrogen and carbon dioxide by excess chlorination, or superchlorination ... 

In the benzidine-pyridine method [14,15], chlorine reacts with cyanide ions to form cyanogen chloride (CNCl). The product of the reaction of CNCl with pyridine (glutaconaldehyde) is condensed with primary amines to form polymethine dyes. 

Cyanogen chloride (CNCl) was discovered by Wurtz and first prepared by Berthollet in 1802. It is a colorless gas with an irritating odor that immediately attacks the oral-nasal passages. 

Cyanogen ohlorids. — Ttvo polymeric chlorids are known. Gaseous cyanogen chlorid—CNCl—is formed by the action of Cl upon anhydrous hydrocyanic acid or upon mercuric cyanid in the dark. It is a colorless gas, intensely irritating and poisonous. Solid cyanogen chlorid—CsNsCls—is formed, as a crystalline solid, when anhydrous hydrocyanic acid is acted upon by Cl in... 

Cyanuric Acid, (CNOH)3, is obtained by the action of water on cyanuric chloride, C3N3CI3, which results from the polymerization of cyanogen chloride, CNCl. It is also obtained when urea is heated to a high temperature —... 

Cyanide can be a colorless gas, such as hydrogen cyanide (HCN) or cyanogen chloride (CNCl), or a crystal form such as sodium cyanide (NaCN) or potassium cyanide (KCN). 

Bleaching powder destroys tabun, but it gives rise to cyanogen chloride, CNCl, which is also toxic. 

Alkaline chlorination of wastewaters is one of the more widely used methods of treating cyanide wastes. In this process, cyanogen chloride (CNCl) is formed, which is hydrolyzed to the cyanate (CNO ) at alkaline pH. If free chlorine is present, CNO can be further oxidized. The use of sulfur dioxide in a high dissolved oxygen environment with a copper catalyst reportedly reduces total cyanide... 

Cyanogen chloride is volatile and almost as toxic as cyanide, so the reaction should be carried out in a closed vessel and the temperature optimized at 20°C. The second reaction involving the hydrolysis of the CNCl is rather slow and is the rate determining step. 

The cyanide (CN ) is converted to cyanogen chloride (CNCl) at pH < 8, without hydrolyzing to the cyanate, by reaction with the Chloramine-T which acts as a source of hypochlorous acid (HOCl). After the reaction is complete, the CNCl forms a blue dye (pyrazole blue) on the addition of the pyridine-pyrazalone reagent. 

FIGURE 27.3 A typical calibration curve for cyanogen chloride (CNCl) at pH 7.0 (+0.1) and 25°C. Experimental data are represented by gray circles, and the black line is the hnear fit with Equation 27.8. Adapted fromNa and Olson [17] with the permission of the American Chemical Society. 

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