Cyanates, CNO

Cyanides are dangerously toxic materials that can cause instantaneous death. They occur in a number of industrial situations but are commonly associated with plating operations, and sludges and baths from such sources. Cyanide is extremely soluble and many cyanide compounds, when mixed with acid, release deadly hydrogen cyanide gas. Cyanide is sometimes formed during the combustion of various nitrile, cyanohydrin, and methacrylate compounds. Cyanides (CN ) are commonly treated by chlorine oxidation to the less toxic cyanate (CNO ) form, then acid hydrolyzed to COj and N. Obviously, care should be taken that the cyanide oxidation is complete prior to acid hydrolysis of the cyanate. 

Distillation of sample is often necessary for the removal of interfering contaminants. The sample is buffered at pH 9.5 with borate buffer prior to distillation. This decreases hydrolysis of cyanates (CNO ) and organic nitrogen compounds. 

Results on the adsorption of azide (N3 ) and cyanate (CNO ) ions have been reported by Corrigan et al. [113,135]. For adsorbed azide ion on a silver electrode only one potential-dependent band has been reported between 2074 and 2083 cm . As discussed by Corrigan and Weaver [135], at low potentials a loss of azide ions in solution is observed (band at 2048 cm in Fig. 44) without a corresponding adsorbate gain. As the potential is made more positive a weak adsorbate band is developed (2074 cm ). The most probable interpretation, according to Corrigan and Weaver, is that at low potentials the linear N3 ion is flat-adsorbed. As the degree of... 

In the metal plating industry, cyanides are frequently eliminated from waste discharges by treatment with chlorine at high pH (alkaline chlorination process). Two steps are involved (1) the oxidation of cyanide, CN , to cyanate, CNO , and (2) oxidation of CNO to Nj and CO2. 

A minor route of metabolism is the oxidation of cyanide to cyanate (CNO-), which occurs via enzymatic and nonenzymatic pathways. The interaction of cystine and cyanide to form 2-amino thiazoline 4-carboxylic acid and its tautomer accounts for approximately 20% of cyanide metabolism. This increases with toxic doses of cyanide. However, the protection conferred by forming cyanate derivatives is limited because of the cell s inability to utilize oxygen during cyanide intoxication. 

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... 

A. Electrolysis in Figure 17-2 generates the powerful oxidant Fe(VI) as FeO , which can oxidize hazardous species in wastewater. For example, sulfide (S ) is converted to thiosulfate (8203 ), cyanide (CN ) is converted to cyanate (CNO ), and arsenite (ASO2) is converted to arsenate (AsOj ). 

Similar differences are found for organic azides (e.g. MeN3). In ionic azides (p. 417) the N3 ion is both linear and symmetrical (both N-N distances being 116 pm) as befits a 16-electron species isoelectronic with CO2 (cf. also the cyanamide ion NCN, the cyanate ion NCO, the fulminate ion CNO and the nitronium ion N02 ). 

C09-0108. Carbon, nitrogen, and oxygen form two different polyatomic ions cyanate ion, NCO, and isocyanate ion, CNO". Write Lewis stmctures for each anion, including near-equivalent resonance structures and indicating formal charges. 

Having the same atomic composition as cyanates but drastically different properties are the fulminates, which contain CNO-. Many organic compounds having the formula R-N-C-O are known (the isocyanates). Cyanides undergo an addition reaction with sulfur to produce thiocyanates. 

Now we will apply this formal-charge concept to the cyanate ion OCN We chose this example because many students incorrectly write the formula as CNO , and then try to use this as the atomic arrangement in the Lewis structure. Based on the number of electrons needed, the carbon should be the central atom. We will work this example using both the incorrect atom arrangement and the correct atom arrangement. Notice that in both structures all atoms have a complete octet. 

The structures of lithium and sodium cyanates and isocyanates and their related ion-pair 5n2 reactions have been examined by using quantum mechanics at the Hartree-Fock (HF)/6-31G V/HF/6-31G level. (The cyanate ion is NCO the isocyanate ion is CNO. ) The isocyanate ion pairs are the most stable monomeric forms the lowest energy dimers are planar eight-membered rings. For the ionic 5 n2 reaction of cyanate ion with MeF or MeCl, methyl isocyanate is the predicted major product. Predictions about the 5ivr2 reactions of the ion pairs were also made. 

Cyanates are salts of Cyanic Acid contg the monovalent radical -CNO. See under Cyanic Acid... 

Predict the bond angles at the central atom of the following triatomic molecules and ions (a) ozone, 03 (b) azide ion, N3 (c) cyanate ion, CNO ... 

Ba(CNO)2 (aq.). Lemoult1 measured the heats of decomposition of aqueous barium cyanate with aqueous sulfuric acid and with aqueous nitric acid. 

The formula of cyanate is CNO It is a univalent anion formed by partial oxidation of cyanide (CN-). 

In the above calculation for cyanate, the concentration of ammonia-nitrogen was multiplied by 3 because the formula weight of CNO- is (12 + 14 + 16) or 42, which is three times 14 (the atomic weight of N, as ammonia-N).]... 

In contrast, CNO- (fulminate) has only one structure that is at all plausible, and even it has flaws. Consequently, on the basis of structures, great differences would be predicted between the chemistry of cyanates and fulminates. In fact, cyanates are generally stable,... 

Complete and balance an equation for the reaction in which cyanate ion (CNO ) is oxidized to CO2 and N03 by Mn04, in which two elements in the same chemical species are oxidized. (Hint The carbon to nitrogen ratio is set by the formula of CNO. )... 

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