Cyanide method

Cuprous cyanide. Method 1 (Barber, 1943). This is based essentially upon the reaction ... 

Cyanide Method of Dissolving Gold. Put 0.01 g of gold foil into a test tube, add the calculated amount of a 0.03% sodium cyanide solution (in a fume cupboard ), and, while shaking the contents of... 

For impure dilute solutions of formaldehyde, especially those containing other aldehydes, the cyanide method should be used. The iodine... 

Formation of Ni(CO)4 or Co(CO)4- by the cyanide method depends upon the stepwise substitution of the anion of the cyano complex by the iso-electronic carbon monoxide molecule. By treating Co2(CO)8 with potassium cyanide we obtained cyanocarbonyls of cobalt of low oxidation number (83). In reactions of the nitrosyl carbonyls of iron and cobalt, Behrens (86) substituted all the CO groups with CN to give K3[Co(NO)(CN)3] or... 

Very recently Geus and co-workers [44, 45] have applied another method based on chemical complexes. This is the complex cyanide method to prepare both monocomponent (Fe or Co) and multicomponent Fischer-Tropsch catalysts. A large range of insoluble complex cyanides are known in which many metals can be combined, e.g. iron(n) hexacyanide and iron(m) hexacyanide can be combined with iron ions, but also with nickel, cobalt, copper, and zinc ions. Soluble complex ions of molybdenum(iv) which can produce insoluble complexes with metal cations are also known. Deposition precipitation (Section A.2.2.1.5) can be performed by injection of a solution of a soluble cyanide complex of one of the desired metals into a suspension of a suitable support in a solution of a simple salt of the other desired metal. By adjusting the cation composition of the simple salt solution, with a same cyanide, it is possible to adjust the composition of the precursor from a monometallic oxide (the case when the metallic cation is identical to that contained in the complex) to oxides containing one or several foreign elements. 

Complex metal cyanides decompose at fairly high temperatures. Decomposition in an oxidizing atmosphere (up to 600 K) results in the corresponding oxides, that in an inert or in a reducing atmosphere (up to 900 K) results in the metals or alloys. In either case, reaction of the oxides or of the metals/alloy with the support is minimized. The complex cyanide method can thus establish homogeneity of the constituent ions on a molecular scale and also prevent undcsircd reactions of the active precursors with the support. 

Gravimetric Methods.—The main difficulty is to obtain the cobalt in the form of one of its compounds entirely free from nickel or other metal. This may be accomplished by the cyanide method described under Wet Tests above. The solution, after separation of the nickel, is evaporated with dilute sulphuric acid until white fumes are evolved. On addition of water a solution of cobalt sulphate results, and the cobalt may be precipitated in a variety of ways, for example as oxide with hypobromites or persulphates,2 as sulphide, as cobalti-nitroso p-naphthol, or as basic carbonate.3 In each case the precipitate is ignited and reduced to metallic cobalt in a current of pure hydrogen. 

This cyanide method is particularly useful Because palladium is unique amongst the platinum metals in yielding a precipitate of cyanide on addition of mercuric cyanide hence palladium admits of separation from its allies in this manner, and from most of the commoner metals too, notable exceptions being lead and copper. 

The cyanide method is presently the only method for the determination of ketone groups in the polymers and was highly instrumental in the chemical characterization of degraded and oxidized celluloses. The use of this method enabled the development of the first two systems for the preparation of keto-cellulose, namely by mild oxidation with aqueous bromine at low pH values at room temperature [441,442] and by mild oxidation with hydrogen peroxide at pH 10 and 80°C [420,443]. 

Until the advent of the methylene chloride-water solvent system the less reactive acid chlorides could be used in the aqueous method but the more reactive acid chlorides required the anhydrous hydrogen cyanide method. This latter method is still sometimes used - and in fact has been used with quinoline and the 2- and 3-carboxylic acid chlorides of methylcyclopentadienyl manganese tricarbonyl."... 

The chemistry of the eleven-vertex nido tricarbaboranes (tricarbollides) is, in contrast to that of the dicarbollides1 one of the youngest areas of carborane chemistry. It was as late as in 1995 when the first representatives of this family were reported.2 Essentially, there are two synthetic routes leading to tricarbollide compounds cyanide and isonitrile methods.3 The cyanide method is based on a room-temperature reaction between the dicarbaborane... 

Cyanide (method 388), sulfone, " or nitro compound," " The vinyl group in the alpha or gamma positions on the pyridine nucleus also "ndergoes this type of addition. " The activity of the labilizing group is trans- mitted to the terminal double bond of a vinylogous system. Thus, methyl vinylacrylate reacts with malonic ester as follows ... 

Studies have been made on the influence of various groups on the rate of hydrogenation of the double bond. Reductions of olefinic alcohols (method 85), olefinic aldehydes (method 161), olefinic ketones (method 196), olefinic acids (method 267), olefinic esters (method 303), olefinic Cyanides (method 394), and olefinic amines (method 460) are treated separately. 

In a variation of the Michael condensation, nitroparaffins having active methylene groups add to reactive olefinic compounds including ot,/3-unsaturated esters (method 301), a.,y6-unsaturated cyanides (method 388), and a-nitro olefins. Interaction of primary or secondary aliphatic nitro compounds with the unsaturated nitro compounds in the presence of sodium ethoxide in alcohol yields 1,3-dinitroparaffins. The reaction is general, but the yields vary, depending on the degree of polymerization that the nitro olefin undergoes and the amount of addition of alcohol to it as well as on the reactivity of the product toward further condensation. 

Hydrocyaaation. Nagata ei have published in detail their results on hydro-cyanation with diethylaluminum cyanide (method B) and with a trialkylaluminum and hydrogen cyanide (R,A1-HCN, method A). The main difference between the two methods is that method A hydrocyanation is irreversible and thus controlled kinetically, whereas method B is reversible and therefore can be controlled both kinetically and thermodynamically that is, the product is kinetically controlled in the early stages. 

For galactose (50 mg/100 ml) added to Somogyi filtrates, ten replicate analyses showed (CIO) a mean recovery of 100.2 with a standard deviation of 1.2. For endogenous glucose, ten analyses gave a mean recovery of 83.6 mg/100 ml (standard deviation, 1.3) compared with the value of 86.6 mg/100 ml when determined by an automated ferri-cyanide method. Recoveries of added sugars are shown in Tables 9 and 10. 

Alternatively, a-chiral ketones can be prepared from dialkyl-(l,l,2-trimethylpropyl)boranes by cyanidation (method ), carbonylation (method ( )) or the haloalkyne route (method )9. 

The cyanide method is better for reactive allylic (20) and benzylic" (21) halides and has the advantage that esters (e.g. 22) can be formed directly from the cyanide if required." ... 

The anhydride (24) needs the acid chloride (26), made from the acid (25) ith SOCI2. This aliphatic acid can be made by the cyanide method. 

Direct disconnection is possible at this oxidation level since CO2, especially convenient as solid dry ice , reacts once only with Grignard reagents or RLi (iv). This method complements hydrolysis of cyanides (v) since the disconnection is the same but the polarity is different. Hence the r-alkyl acid (19) could not be made by the cyanide method as displacement at the tertiary centre would be difficult. The Grignard method works well. ... 

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