Alkali Metal Iodides Research Articles

Ligands for the alkali metals. Part 4. Nuclear magnetic resonance of crown ethers with alkali-metal ions

The solution 1H n.m.r. spectra of the crown ligands 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclo-pentadecin(benzo-15-crown-5) and 2,3,5,6,8,9,11,12,14,15,17,18-dodecahydro-1,4,7,10,13,16,19-benzoheptaoxacycloheneicosin (benzo-21-crown-7) as free ligands and in mixtures with alkali-metal iodides or thiocyanates are reported and analysed to provide shifts and coupling constants. The signals of some or all the hydrogens in the mixtures are upfield of those of the free ligands for complexes of 2 : 1 ligand: cation ratio, but downfield when only a 1 : 1 complex is present, and this finding may be used diagnostically. An empirical explanation of the direction of the shift on complexation is given in terms of the electric-field effect, ring-current variations, and specific ion pairing. The gross conformation of the two complexes in solution is shown to be similar to that found in the crystal by X-ray methods.

Mass spectra of metal iodides

The mass spectra of LiI, NaI, KI, RbI, CsI, AsI 3, SbI 3, SnI 4, CuI and PbI 2 have been recorded, and trace contaminants in alkali metal iodides detected.

Temperature inversion of the concentration dependences of the dielectric constant of solutions of alkali metal chlorides and iodides in D2O

Temperature inversion of the concentration dependences of the dielectric constant of solutions of alkali metal chlorides and iodides in D2O

Trends in Ion Pair Association for Alkali Metal Salts in Nonaqueous Solvents

For a number of experimental properties of alkali metal salts measured in nonaqueous solvents, the magnitude of the solute parameter undergoes a systematic shift with increasing atomic number of the cation or anion. Representative of the fundamental quantities exhibiting such trends are: (a) the half-wave potentials for alkali metal iodides and perchlorates in isobutyronitrile (4); (b) single ion activity coefficients for anions in protonic solvents (2); (c) ion pair dissociation constants for alkali metal acetates in acetic acid (13); and (d) single ion enthalpies of transfer for both group IA cations and simple anions in several solvents ( 1 ) . Although the influence of changing ion solvation is large in comparisons of properties between different solvents, the regularity for ionic behavior withint a given solvent medium often follows exact periodic sequences. For example, the Drago-Wayland E,i-parameter for the gaseous alkali metal iolls follows a smooth decrease with increasing cationic radius (15); and it can be easily demonstrated that the free energy of transfer ( AG t ) for these ions in acetonitrile ( 1 ) is described by the linear equation 1.

Synthesis of iodomethyl sulphoxides

Iodomethyl sulphoxides may be synthesized in good yields by the reaction of diazomethane with sulphinyl chlorides in the presence of alkali metal iodides.

Reactions of alkali metal iodides with diisopropyl methylphosphonate

Alkali metal iodides dissolve in diisopropyl methylphosphonate (DIMP) and react at elevated temperatures (70–120°C) to yield isopropoxy methylphosphonato (IMP) M 1 (M=Li, Na, K) complexes and a mixture of isopropyl iodide, HI and propene. Li(IMP) was isolated in crystalline form. This complex redissolves in the reaction mixture at 125°C, while the Na 1 and K 1 analogs are soluble in the reaction mixture and were not obtained in crystalline form. Solutions of M(IMP) in the reaction mixture yield metal hydrogen methylphosphonate (M(MPH)), possibly through reaction with HI. M(MPH) is subsequently condensed to the corresponding metal pyromethylphosphonate (M 2- (PMP); M=Li, Na, K), which is precipitated in crystalline form. Li(IMP) and the M 2(PMP) complexes were characterized by means of infrared and conductance studies. Possible structures for these compounds are discussed.

Solubility of alkali metal and ammonium thiocyanates and iodides in tri-n-butyl phosphate

The solubilities of lithium, sodium, potassium, caesium, and ammonium thiocyanates and iodides, and of rubidium thiocyanate, in tri-n-butyl phosphate (TBP), have been measured. In general, the solubilities decrease with increasing cation size, but the values for the ammonium salts are anomalously high. This is shown to be due to hydrogen-bonding between NH4+ and the phosphoryl oxygen of the solvent. The results are compared with those reported for other alkali metal salts in TBP.

Effects of cations upon absorption spectra. Part 5.—Charge-transfer-to-solvent spectrum of iodide and ion-pair formation

Energies Emax and temperatures coefficients dEmax/dT of the first ultra-violet absorption maxima of various alkali metal and quaternary ammonium iodides have been measured for 27 solvents. The results are interpreted in terms of three different structures of ion-pairs in the solvent, and their relative concentrations in solution are correlated with the relative permittivity Iµ of the solvent. When 11 >Iµ>5 solvent-shared ion-pairs are the predominant species, and a simple electrostatic treatment supports this conclusion. When 23 >Iµ>11, solvent separated ion-pairs are also present, and when Iµ>23 solvent separated ion-pairs are at times detected. The presence of contact ion-pairs is deduced when Iµ<5. Some large shifts of Emax on addition of a common cation, in low concentrations (< 10–1 M) in non-aqueous solvents, are reported.

Thermal Positive Ion Emission from Alkali-Metal Iodide Mixtures

Time variation of the emission of both positive ions and neutral particles was simultaneously examined with one-and two-component systems of alkali-metal iodides on a platinum wire heated to 1080°C. A “suppression effect” was observed: - by the presence of the heavier alkali-metal iodide, MHI, (1)the emission pattern of the lighter alkali-metal ion, ML+, was much changed, (2)the integrated emission current of ML+ was reduced to 40-60%, and(3)the reduction of ML+ emission current was accompanied by an increase in ML emission in the form of neutral particles by 20-30%, while the MH+ emission was not affected by the presence of WLI. Discussion on a mechanism of this effect is given from three view-points of the work function change, charge transfer, and recombination reaction. The conclusion is that the suppression effect is due to the recombination of ML+ and I- on the filament surface enhanced by the presence of MHI.

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.

Iodide Ion Catalysis in the Benzylation of Cotton Cellulose

The presence of alkali metal iodides accelerated the reaction of benzyl chloride with alkali cellulose. The alkali metal iodide was added to the mercerizing alkali used to activate the cotton yarn. The degree of benzylation observed with iodide present was 74% to 110% greater than with iodide absent. A D.S. of 0.7 could readily be obtained within a reaction period of thirty minutes at 115°C. The breaking strength retention at this D.S. was 93% to 119%, based on unmercerized, untreated yarn. Other salts tended to retard benzylation. Borax and neutralized boric acid were ineffective as catalysts, contrary to previous reports. Catalysis by iodide salts is considered to be due to the in situ formation of benzyl iodide from benzyl chloride within the cellulose fibers, the organic iodide being a more active alkylating agent than the chloride. Hydrotropic effects of the alkali iodides appear to be of secondary importance in the catalysis.

Time variation of ionic and neutral evaporation from alkali metal iodides on a heated platinum surface

Time variation of ionic and neutral evaporation from alkali metal iodides on a heated platinum surface

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.