Chromium cyanates

The final solution should be checked for absence of free cyanide. The hypochlorite or CI2 + NaOH method is by far the most widely used commercially (45). However, other methods are oxidation to cyanate using hydrogen peroxide, o2one, permanganate, or chlorite electrolysis to CO2, NH, and cyanate hydrolysis at elevated temperatures to NH and salts of formic acid air or steam stripping at low pH biological decomposition to CO2 and N2 chromium... 

NO, Nitrosyls, molybdenum and tungsten, 26 132, 133 NOC, Cyanate tungsten complex, 26 42 NOC4H7, 3-Butenamide nickel complex, 26 206 NOC4H , 2-Propenamide, 2-methyl-nickel complex, 26 205 NOC H, Benzoyl isocyanide chromium complex, 26 32, 34, 35 N04ReC16H, Perrhenate, tetrabutylam-monium, 26 391... 

The scope of this chapter is based on the analogous one by Naso and Marchese published in 19831. Since the time of their review, the focus of work in this area has shifted somewhat, and sections have been added or omitted to reflect that focus. New sections covering chromium(II)-mediated reactions of halides and covering cobalt-mediated radical reactions of halides have been added. In view of the relatively mature nature of the areas, sections dealing with 7c-allylnickel complexes, iron oxyallyl cations and cyanation reactions have been omitted. 

The formation of cyclic structures and polymerization of aryl cyanates was followed from the changes in signal intensities of the reaction products. All intermediate spectra consist of two well separated signals arising from cyanate and triazine groups, respectively. Since a chromium acetylacetonate is added in order to eliminate the Nuclear Overhauser Effect and reduce the spin-lattice... 

Cyanation. 1-Aza-1,3-dienes are cyanated at C-2 by treatment with Me SiCN and chromium(VI) oxide. ... 

The pretreatment miit operations for various types of treatment facilities are shown in Table 24. The pretreatment processes generally involve separate treatment of cyanide wastes and other acid wastes containing metal ions. The cyanide wastes can be treated with ferrous sulfate and lime to convert highly toxic cyanides to less toxic cyanates or cyanide complexes, or can be oxidized to COj and Nj with chlorine under alkaline conditions. The acid waste streams are treated first to reduce hexavalent chromium to trivalent chromium, using ferrous sulfate, scrap iron, or sulfur dioxide, and then precipitating the metal ions (Cr +) as metal hydroxides. 

Interest continues in the effects of micellar agents on rates of inorganic reactions. Aquation of oxalato-cobalt(m) and -chromium(iii) complexes is mentioned in a review of reversed micellar systems predicted and actual rates have been compared for a variety of reactions, including the mercury(n)-catalysed aquation of [CoX(NH3)g] + cations. Micellar effects on uncatalysed aquation of cis- and of tra j -[CoCl2(en)2]+ are small (as expected) but real. Other reactions for which the kinetic consequences of micelle or polyelectrolyte addition have been d cribed include complex formation from nickel(ii), the conversion of ammonium cyanate into urea, and the hydrolysis of pyrophosphate. ... 

Linkage isomerism has been the subject of several reviews. - Much recent work has dealt with nitro-nitrite isomerizationlO and thiocyanate-isothiocyanate isomerization.11 12 Examples of linkage isomerism involving cyanate, methanesulfinate, terpyridyl, alizarin, dihydroxybenzoate, and acetone complexes have been reported also. Some additional examples are discussed in paragraphs that follow. Thus, the rate of M-CN/M-NC linkage isomerization at chromium has been studied, Eq. 11.1. 

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