Alkali metal cyanides

The alkali metal cyanides MCN are produced by direct neutralization of HCN they crystallize... 

Heterocyclic N-oxides such as pyridine, quinoline, or isoquinoline N-oxides can be converted into a mixture of 2- and some 4-cyanopyridines, 2- or 4-cyanoquino-lines, or 1-cyanoisoquinolines, in 40-70% yield, in a Reissert-Henze reaction, by activation of the N-oxide function by O-acylation [1] or O-alkylation [2, 3] followed by treatment with aqueous alkali metal cyanide in H2O or dioxane. 

Alkali metal boratabenzenes may be liberated from bis (boratabenzene) cobalt complexes 7 and 13 by reductive degradation with elemental Li, sodium amalgam, or Na/K alloy (60), or alternatively by degradation with cyanides (61). The latter method has been developed in detail (Scheme 4). It produces spectroscopically pure ( H-NMR control) solutions of the products 26 the excess alkali metal cyanide and the undefined cyanocobalt compounds produced are essentially insoluble in acetonitrile. 

CN" Metal cyanides In the presence of excess metals alkali metal cyanides very soluble alkaline earth metal cyanides not very soluble Callahan et al. 1979 EPA 1992f... 

The alkali metal cyanides are very soluble in water. As a result, they readily dissociate into their respective anions and cations when released into water. Depending on the pH of the water, the resulting cyanide ion may then form hydrogen cyanide or react with various metals in natural water. The proportion of hydrogen cyanide formed from soluble cyanides increases as the water pH decreases. At pH <7, >99% of the cyanide ions in water is converted to hydrogen cyanide (Towill et al. 1978). As the pH increases, cyanide ions in the water may form complex metallocyanides in the presence of excess cyanides however, if metals are prevalent, simple metal cyanides are formed. Unlike water-soluble alkali metal cyanides, insoluble metal cyanides such as are not expected to degrade to hydrogen cyanide (Callahan et al. 1979). 

This process is superior to classical hydrocyanation methods using an alkali metal cyanide and to the improved method using potassium cyanide and ammonium chloride with respect to reactivity, stereospeciific.ity, and absence of side reactions. Also, the process is applicable to onjuga.te hydrocyanation of... 

Alternatively, the compound can be prepared by heating boric oxide or boric acid with ammonium chloride or an alkali metal cyanide. Purified product can be obtained by high temperature reaction of boron halide with ammonia ... 

Silvery-white lustrous metal when pure or dark gray amorphous powder orthorhombic crystals hardness 2.3 Mohs density 6.25 g/cm melts at 452°C vaporizes at 990°C modulus of elasticity 6.0x10 psi thermal neutron absorption cross section 4.7 0.1 barns insoluble in water, carbon disulfide, and benzene also insoluble in HCl soluble in sulfuric acid, nitric acid, and aqua regia also soluble in caustic potash and in solutions of alkali metal cyanides. 

Caution. The cyanide anion is a strong respiratory inhibitor. Ai such, it is a strong base, thus producing the weak, highly toxic, hydrocyanic acid on protonation. Hence, alkali metal cyanide salts must be handled with great care. Toxic CO is evolved in Section 37.A. All operations should be conducted in an efficient fume hood. 

Alkylation of Alkali Metal Cyanides by Alkyl Halides Activated in the a-Posi-tion by a Double Bond. When a mixture consisting of 4 to 8 moles of an alkyl halide activated in the apposition by a double bond is heated with 1 mole of alkali metal ferrocyanide, several alkylation products of the ferrocyanide anion can be isolated from the reaction mixture (12). The relative proportions of the tetra-, penta-, and hexaalkylated complexes can be varied by varying the alkyl halide to ferrocyanide ratio and the time of reaction. When potassium ferrocyanide is alkylated with benzyl bromide at a ratio of 4 alkyl halides to ferrocyanide anion, short reaction times favor the tetraalkylated complex an 8 to 1 ratio and long reaction times favor the hexaalkylated complex of the alkylating agents tested benzyl bromide provided the fastest alkylation ... 

Alkali metal cyanides catalyze the condensation of benzaldehyde to form benzoin. 

Arylmethyl chlorides or bromides are quite reactive compounds that are readily available or easily prepared, and as a result they are useful intermediates for the synthesis of other side-chain derivatives. Thus phenylmethyl chloride can be hydrolyzed to phenyl methanol, converted to phenylethanenitrile with alkali-metal cyanides, and oxidized to benzenecarbaldehyde (benzaldehyde) ... 

The complications which result from the hydrolysis of alkali metal cyanides in aqueous media may be avoided by the use of non-aqueous solvents. The one most often employed is liquid ammonia, in which derivatives of some of the lanthanides and of titanium(III) may be obtained from the metal halides and cyanide.13 By addition of potassium as reductant, complexes of cobalt(O), nickel(O), titanium(II) and titanium(III) may be prepared and a complex of zirconium(0) has been obtained in a remarkable disproportion of zirconium(III) into zirconium(IV) and zirconium(0).14 Other solvents which have been shown to be suitable for halide-cyanide exchange reactions include ethanol, methanol, tetrahydrofuran, dimethyl sulfoxide and dimethylformamide. With their aid, species of different stoichiometry from those isolated from aqueous media can sometimes be made [Hg(CN)3], for example, is obtained as its cesium salt form CsF, KCN and Hg(CN)2 in ethanol.15... 

The preparation of cyanomethylbenzo[6]thiophenes by reaction of halomethylbenzo[6]thiophenes with alkali metal cyanides is discussed in Section VI,D, 4. Reduction of cyanomethylbenzo[6]thiophenes affords (2-aminoethyl)benzo[6]thiophenes (Section VI, H, 2), and they give the corresponding benzo[6]thienylacetic acid on alkaline hydrolysis (Section VI,M, 3). 

CAUTION Potassium cyanide is very poisonous and should only be handled with great care with the wearing of plastic gloves. See Note (7), Expt 5.157, for the disposal of alkali metal cyanides. All operations should be conducted in an efficient fume cupboard. 

Aromatic aldehydes when treated with an alkali metal cyanide, usually in aqueous solution, undergo condensation to the a-hydroxyketone or benzoin. The examples in Expt 6.142 are benzoin and furoin. 

This test is performed to determine the amount of cyanide in the sample that would react with chlorine. Not all cyanides in a sample are amenable to chlorination. While HCN, alkali metal cyanides, and CN- of some complex cyanides react with chlorine, cyanide in certain complexes that are tightly bound to the metal ions are not decomposed by chlorine. Calcium hypochlorite, sodium hypochlorite, and chloramine are some of the common chlorinating agents that may be used as a source of chlorine. The chlorination reaction is performed at a pH between 11 and 12. Under such an alkaline condition, cyanide reacts with chlorine to form cyanogen chloride, a gas at room temperature, which escapes out. Cyanide amenable to chlorination is therefore calculated as the total cyanide content initially in the sample minus the total cyanide left in the sample after chlorine treatment. 

The reaction of primary aliphatic halides and alkali metal cyanides - the Kolbe Nitrile Synthesis - gives nitriles in good yields. 

The excess of copper cyanide and the use of a polar, high-boiling point solvent makes the purification of the products difficult. In addition, elevated temperatures (up to 200°C) lower the functional group tolerance. The use of alkali metal cyanides or cyanation reagents such as cyanohydrins, a catalytic amount of copper(I) iodide and kalium iodide, allows a mild, catalytic cyanation of various aryl bromides. 

Tris(3-cyanomethyl-2,4-pentanedionato)chromium(III), [Cr H8CC(0)C(CH2CN)C(0)CH, 3]> has recently been prepared by the aminomethylation of tris(2,4-pentanedionato)-chromium(III) followed by quaternization of the amine and subsequent displacement of trimethylamine with alkali metal cyanide.1 The procedure described below is a modification of... 

Although alkali metal cyanides react with tellurium in liquid ammonia4 or in dimethyl sulfoxide5 8 under an inert atmosphere, alkali metal tellurocyanates cannot be isolated from such solutions. Evaporation of the solvent leaves a residue of tellurium and the... 

With alkali-metal cyanides the tetrathionate reacts in accordance with the equation 2... 

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequently used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkali catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonitrile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkali metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Giignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

The cyanide ion is isoelectronic see Isoelectronic) with CO, N2 and NO+, with an electronic configuration of (la) (2a)2(3a) (4cr) (l7r)" (5a) this corresponds to a triple bond (one a-bond see a-Bond) and two tt-bonds see n-Bond)) between the carbon and nitrogen atoms. A lone pair see Lone Pair) of electrons is present on both atoms in CN. Calculations have indicated that the negative charge of the cyanide ion is shared approximately equally between the two atoms. The carbon-nitrogen triple bond distance is 1.16 A in the free cyanide ion the fundamental vibrational frequency of the C N bond (aqueous solution) is 2080 cm. The effective Crystallographic Radius of CN, as determined in cubic alkali metal cyanides, is 1.92 A this value is intermediate between those of chloride and bromide. 

---