Alkali Metal Cyanides Research Articles

Infrared spectral studies of ion association in nonaqueous solutions of cyanide salts with consequences for their nucleophilic reactivity

An infrared spectrometric study of alkali metal and tetraphenylarsonium cyanide (AsΦ4CN) solutions in DMSO or DMF shows that even for concentrations of 0.1M a large proportion of the ions are associated. The order of basicity established through methanol Δν(OH) frequency shifts is CN−>Cl−>Br−. Addition of common ions or cyclic polyether to these solutions, as well as correlations between the ν(CN−) frequencies and those of the ν(C≡N) bands of CH3CN bonded to the same cations, suggests assignments of the observed bands to solvated contact ion pairs M+ CN−, triple ions M+ CN− M+, and aggregates (M+ CN) n − . The nucleophilic reactivity of these salts is related to the structure of these solutions.

Infrared studies of matrix isolated sodium and potassium chloride and cyanide dimers

The infrared spectra of matrix isolated sodium and potassium chlorides and cyanides in different inert gas matrices were examined over the range 4000 cm −1 to 33 cm −1. A study of the effect of superheating the vapor species on the spectra has been carried out. Temperature cycling experiments have been pursued in an attempt to differentiate between bands due to monomers, dimers, and higher polymers. Isotopic frequency shifts were measured for a carbon-13 enriched sample of sodium cyanide and carbon-13 and nitrogen-15 enriched samples of potassium cyanide in the CN region. Symmetry force constants were calculated assuming a cyclic rhombic structure for the dimers. In the case of the cyanide dimer, the CN group of the molecule was considered as a halide atom. Finally a comparison is given between the symmetry force constants of the dimers of the alkali metal fluorides, cyanides and chlorides.

ChemInform Abstract: HYDROGENATION OF 6‐CYANOHEXANOIC ACID

AbstractDie durch Umsetzung von e‐Caprolacton (I) mit Natriumcyanid erhältliche 6‐Cyanhexansäure (II) ergibt durch Reduktion mit Raney‐ oder Urushibara‐Kobalt in ver= dünntem Ammoniak in hoher Ausbeute 7‐Aminoheptansäure (III).

Hydrogenation of 6-Cyanohexanoic Acid

Reduction of 6-cyanohexanoic acid, obtained by the reaction of e-caprolactone with alkali metal cyanide, was studied with cobalt or nickel catalysts. Cobalt catalysts such as Raney Co and Urushibara Co gave 7- aminoheptanoic acid in high yields in dilute ammonia solutions. On the other hand nickel catalysts gave much more iminodiheptanoic acid and much less ω-amino acid. In addition, separation of nickel ion generated in the reaction was more difficult than that of cobalt ion. Some other ω-amino acids were obtained by the above-mentioned operation.

Infrared Spectra of the Alkali Metal Cyanides in the Solid State

The infrared spectra of lithium isocyanide and of sodium and potassium cyanides in the solid phase were examined over the range 4000 to 140 cm−1 at room temperature. A study of the effect of cooling the solids to liquid nitrogen temperature has been carried out.

Reactions of pyrylium salts with nucleophilic agents

The reaction of γ-unsubstituted pyrylium salts with alkali-metal cyanides gives cyano- and carboxy-substituted pyrans and pyrylium salts, while the reaction with sodium sulfide gives dipyranyl sulfides. A phthalimide derivative of pyran is obtained from 2,6-diphenylpyrylium perchlorate and potassium phthalimide, while pyrylium cations react with zinc to give the corresponding dipyranyls.

Unstable intermediates. Part CVI. γ-Irradiation of frozen aqueous solutions of alkali-metal cyanides

Exposure of aqueous solutions of alkali-metal cyanides to 60Co γ-rays at 77 K yields hydroxyl radicals, (CN)2–, H2CN, and HCN–. The magnetic parameters of these species are compared with existing data. Under these conditions the radical HCN– is readily protonated to H2CN even in strongly alkaline rigid solutions. Some evidence for the formation of the radical HCNO– was also obtained. If this is correct, then this radical, having Aiso(1H)= 78 G, is probably structurally similar to H2CN. Possible mechanisms for the formation of these radicals are outlined.

Electron spin resonance evidence for protonation of the radical anions NH? and HCN? in frozen aqueous solutions

Clear e.s.r. evidence is provided for the formation of NH2 and H2CN radicals during the radiolysis of frozen aqueous solutions of alkali metal azides and cyanides respectively; these unexpected products may be formed by protonation of NH– and HCN–.

A uranium(IV) chlorocyanide complex

Uranium tetrachloride does not react with alkali metal cyanides in liquid hydrogen cyanide, from which only a uranium tetrachloride solvate can be isolated. Replacement of chloride by cyanide ion occurs in anhydrous liquid ammonia, and the complex UCl 3CN·4NH 3 has been obtained.

Energetics of uni-electrovalent cyanides, and the distribution of charge on the cyanide ion

The crystal energies of the alkali metal cyanides and of ammonium cyanide have been calculated. The distribution of the negative charge on the cyanide ion has been determined, and thermodynamic parameters relating to formation, to hydration and to solution have been evaluated.

Complex-ions in molten salts. Iodo- and cyano- complexed of silver in molten LiCl + KCl (59 : 41 mole %)

The deviations from ideality which occur when alkali metal iodides and cyanides are added to solutions of silver chloride in the molten solvent lithium chloride + potassium chloride have been determined potentiometrically. They have been interpreted quantitatively in terms of the stability constants of complex ions. The K1 values are compatible with the predictions of the quasi-lattice theory. The results have also been compared with the results of similar investigations in molten nitrate solvents, on the basis of a reciprocal coulomb effect.

Unstable intermediates. Part XLVII. Electron spin resonance study of the radical (CN)2 ? in irradiated alkali metal cyanides and potassium chloride crystals

γ-Irradiation of sodium and potassium cyanide yields the radical (CN)2–, the cyanogen negative ion, which is analogous to the Vk- centres formed by irradiation of alkali halides. The electron spin resonance spectrum of the radical trapped in a single crystal of potassium chloride is reported and used to derive information about its shape and electronic structure.

Reactions of metal cyanides with polyfluorobenzenes

Hexafluorobenzene and chloropentafluorobenzene react with alkali-metal cyanides in methanol to give products in which fluorine has been replaced by both cyano- and methoxy-groups. The formation of these products is rationalised in terms of initial attack by cyanide ion, followed by attack on the resulting nitrile by methoxide ion. Pentafluorobenzonitrile is substituted in the 4-position by methoxide ion (sodium cyanide in methanol) or by dimethylamine (derived from dimethylformamide).

Zone-Melting Apparatus for Alkali Metal Cyanides and Alkali Metal Halides

A zone-melting apparatus is described that can be largely assembled from commercially available components. Details of a technique are given for zone refining alkali metal cyanides and halides in reinforced, flexible metal boats.

Preparation of Trimethylsilyl Azide

Trimethylsilyl cyanide, (CH3)3 Si-CN, is obtained by reacting trimethylsilyl chloride with an approximately equimolar amount of an alkali metal cyanide in the absence of water and in the presence of catalytic, sub-stoichiometric amounts of both an alkali metal iodide and N-methylpyrrolidone, at a temperature of from 15°-25° C.