Cyanides table

CYANIDES Table 6. Physical Properties of Potassium Cyanide Vol7... 

Hydrogen cyanide (Table 15.1) is a colorless, flammable liquid or gas that boils at 25.7°C and freezes at minus 13.2°C. The gas rarely occurs in nature, is lighter than air, and diffuses rapidly. It is usually prepared commercially from ammonia and methane at elevated temperatures with a platinum catalyst. It is miscible with water and alcohol, but is only slightly soluble in ether. In water, HCN is a weak acid with the ratio of HCN to CN about 100 at pH 7.2, 10 at pH 8.2, and 1 at pH 9.2. HCN can dissociate into H+ and CN. Cyanide ion, or free cyanide ion, refers to the anion CN derived from hydrocyanic acid in solution, in equilibrium with simple or complexed cyanide molecules. Cyanide ions resemble halide ions in several ways and are sometimes referred to as pseudohalide ions. For example, silver cyanide is almost insoluble in water, as are silver halides. Cyanide ions also form stable complexes with many metals. 

The preparation of cyclobutanols by a homoallyl rearrangement has been described previously (see Houben-Weyl. Vol. 4/4, p 62), e.g. treatment of the but-3-enyl p-toluenesulfonate 1 with potassium methoxide in dioxane yielded the dicyanomethoxycyclobutane derivative 2 (61 %). It is also possible to introduce hydrogen into the cyclobutane product by the use of hydrides, for example, borohydrides. Methoxy- or ethoxy-substituted cyclobutanes are formed with alkoxides, while cyano compounds are obtained with potassium cyanide (Table 1). Electronegative substituents in the 1-position of the starting alkene are necessary for a good result in this preparative method. 

In the presence of 0.25M cyanide (Table I), the rate of reaction was found to decrease markedly, except in the case of hemin. With that exception, the close correlation between rates of reaction in the presence of cyanide for simple salts and for metal porphyrins shows that... 

Cyanohydrins are usually colorless to straw yellow liquids with an objectionable odor akin to that of hydrogen cyanide. Table I list physical properties of some common cyanohydrins. 

The cyanide ion in inorganic cyanides can be present as both complexed and free cyanide. In order to study the chromatography of metal cyanides, Rocklin and Johnson [48] prepared and assayed solutions of cadmium, zinc, copper, nickel, gold, iron and cobalt cyanides. Table 2.6 lists the percentage of total cyanide detected. 

The gas phase protonation of cyclopropyl cyanide is 1.0 kcal mol" more favorable than isopropyl cyanide (Table 14) and much more favorable than for the methyl or ethyl derivatives Thus, even though there may be ground-state conjugative stabilization of cyano by cyclopropyl (Section IV.F) the net effect favors protonation of this derivative, in contrast to the situation for the amines, where 7r-donation does not occur in the protonated forms. 

The approximately collinear configuration of M—C=N has been confirmed in a number of molecular cyanides (Table 21.8). In some of these cyanides there are intermolecular M—N distances less than the sums of the van der Waals radii, and in S(CN)2, for example, the two next nearest neighbours of S are coplanar with the intramolecular C atoms, suggesting that intermolecular interactions may be responsible for the small deviations of the M-C=N systems from exact collinearity. 

A series of supported chiral VO(salen) complexes anchored on silica, single-wall carbon nanotube, achvated carbon or ionic liquids have been prepared through the simple methods based on the addition of mercapto groups to terminal C=C double bonds (Scheme 7.17) [58]. The four recoverable catalysts and the standard VO(salen) complex 37 were tested for the enantioselechve cyanosilylation of benzaldehyde using trimethylsilyl cyanide (Table 7.9). It should be noted that the ionic liquid-supported IL-VO(salen) showed the highest catalyhc achvity, though the ee-value was considerably reduced compared to the soluble 37 in [bmim][PF6] (entries 4 and 5). 

This method is particularly suitable for the synthesis of a-ethylenic and aromatic acyl cyanides but it also provides a valuable method of preparing certain aliphatic acyl cyanides (Table 6.6). The reaction fails with acryloyl chloride, sulphonyl chlorides, ethyl chloroformate and oxalyl chloride. 

The fact that the reaction between lead salts and dithizone takes place despite the presence of considerable amounts of potassium cyanide renders the test for lead specific among the heavy metals which are masked by excess of alkadi cyanide. Table 1 gives the hmits of sensitivity and dilution to be achieved under the varying conditions. 

The physical properties of a number of aliphatic nitriles (cyanides) are given in Table 111,115. 

Nitriles contain the —C=N functional group We have already discussed the two mam procedures by which they are prepared namely the nucleophilic substitution of alkyl halides by cyanide and the conversion of aldehydes and ketones to cyanohydrins Table 20 6 reviews aspects of these reactions Neither of the reactions m Table 20 6 is suitable for aryl nitriles (ArC=N) these compounds are readily prepared by a reaction to be dis cussed m Chapter 22... 

Section 20 18 Nitnles are prepared by nucleophilic substitution (8 2) of alkyl halides with cyanide ion by converting aldehydes or ketones to cyanohydrins (Table 20 6) or by dehydration of amides... 

The physical properties of cyanoacetic acid [372-09-8] and two of its ester derivatives are Hsted ia Table 11 (82). The parent acid is a strong organic acid with a dissociation constant at 25°C of 3.36 x 10. It is prepared by the reaction of chloroacetic acid with sodium cyanide. It is hygroscopic and highly soluble ia alcohols and diethyl ether but iasoluble ia both aromatic and aUphatic hydrocarbons. It undergoes typical nitrile and acid reactions but the presence of the nitrile and the carboxyUc acid on the same carbon cause the hydrogens on C-2 to be readily replaced. The resulting malonic acid derivative decarboxylates to a substituted acrylonitrile ... 

Thousands of compounds of the actinide elements have been prepared, and the properties of some of the important binary compounds are summarized in Table 8 (13,17,18,22). The binary compounds with carbon, boron, nitrogen, siUcon, and sulfur are not included these are of interest, however, because of their stabiUty at high temperatures. A large number of ternary compounds, including numerous oxyhaUdes, and more compHcated compounds have been synthesized and characterized. These include many intermediate (nonstoichiometric) oxides, and besides the nitrates, sulfates, peroxides, and carbonates, compounds such as phosphates, arsenates, cyanides, cyanates, thiocyanates, selenocyanates, sulfites, selenates, selenites, teUurates, tellurites, selenides, and teUurides. 

Dorex is very toxic (see Table 2) and must be handled with extreme care. Because it may produce severe dermatitis on moist skin, it is difficult to use in hot, humid climates inhalation of the dust or spray may irritate the mucous membranes. Whereas symptoms may include a flushed face, tachycardia, headache, vertigo, and hypotension, it does not produce the typical cyanide effect. 

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