Iodides, alkali

Alkali iodides can be manufactured via iron(II) iodide as follows  

After the iron hydroxide formed has settled, the alkali iodides are separated by concentration and crystallization. Neutralization of hydrogen iodide with alkali hydroxides also provides alkali iodides. 

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Figure 7.4 Thermodynamic data needed in evaluation of the enthalpy of formation of MX(s). (a) Lattice enthalpy of sodium halides (b) lattice enthalpy of alkali iodides (c) electron gain and dissociation enthalpies of halides (d) ionization and atomization enthalpies of alkali metals.

Chlorine and bromine can be replaced by iodine by means of alkali iodide, and this is of importance in cases where direct treatment of alcohols with hydriodic acid gives a bad yield or none at all, e.g. in the preparation of ethylene iodohydrin ... 

Results obtained from the alkali iodides on the isomer shift, the NMR chemical shift and its pressure dependence, and dynamic quadrupole coupling are compared. These results are discussed in terms of shielding by the 5p electrons and of Lbwdins technique of symmetrical orthogonalization which takes into account the distortion of the free ion functions by overlap. The recoilless fractions for all the alkali iodides are approximately constant at 80°K. Recent results include hybridization effects inferred from the isomer shifts of the iodates and the periodates, magnetic and electric quadrupole hyperfine splittings, and results obtained from molecular iodine and other iodine compounds. The properties of the 57.6-k.e.v. transition of 1 and the 27.7-k.e.v. transition of 1 are compared. 

Calibration of the Isomeric Shift Scale with Isomeric and NMR Chemical Shift Data. The alkali iodide isomeric shifts (5) relative to ZnTe are displayed in Table I and in Figure 3. 

The alkali iodide isomeric shifts (13) number of iodine ion p holes calculated rupole resonance data (25) the sum of overlap integrals (11) the fractional iodine ion density computed from the isomeric shift data. Equation 7, and 8. 

Figure 3. Isomer shifts, O (13), and number of iodine p holes, hp, obtained from NMR chemical shift (4), X, and from dynamic quadrupole coupling (25), A, vs. alkali atomic number for alkali iodides. Data points for each alkali spread horizontally for clarity...

Interpretating Alkali Iodide Data. The alkali iodide data given above show that the idealized model of ionic crystals is inadequate since 8 9 constant and hp 9 0. To interpret the data one must consider the effects on the iodine 5p population by covalency, deformation of the charge cloud by electrostatic interaction, and deformation by overlap. 

F or a completely ionic bond the ionicity, I, must be 1 for a completely covalent bond, 1 = 0. For the alkali iodides the ionicity and hence the number of iodine 5p electrons (y = 5 + 1) should increase from Lil to Csl since the electronegativity difference between iodine and the alkali increases. This implies that the iodine ion configuration, 5 5p, should most closely approach the 5s 5p xenon configuration for Csl. Since is decreased by increases in the 5p population, we would... 

Such serious deviations from the predictions of electronegativity are not often found in Mossbauer experiments. In particular, Alexsandrov et al. ( ) and others have found a linear relation between 8 and electronegativity for the tin tetrahalides. Since the differences in electronegativity are much larger for the halogens than the alkalies, the difference in ionicity is much more important for the tin tetrahalides than for the alkali iodides. 

The simple theory of electronegativity fails in this discussion because it is based merely on electron transfer energies and determines only the approximate number of electrons transferred, and it does not consider the interactions which take place after transfer. Several calculations in the alkali halides of the cohesive energy (24), the elastic constants (24), the equilibrium spacing (24), and the NMR chemical shift 17, 18, 22) and its pressure dependence (15) have assumed complete ionicity. Because these calculations based on complete ionicity agree remarkably well with the experimental data, we are not surprised that the electronegativity concept of covalency fails completely for the alkali iodide isomer shifts. 

Figure 4, Experimental (13) and calculated (11) isomer shifts for alkali iodides. Overlapping ion model predicts that shifts will be proportional to the sum of the overlaps. Equation 13...

Since only 5 electrons have a nonzero density at the nucleus, a good approximation to the 5 electron density at the iodine nucleus in the alkali iodide lattices is... 

The alkali iodide shifts are greatest at the extreme Z iodides, Lil and Csl, and are smallest at the middle alkali iodide, KI. The Nal and Rbl shifts are between these extremes. This same variation has been observed (15) in the NMR chemical shifts. Figure 5 shows the values of the chemical shifts which were calculated (15) with the wave function given by Equation 8. 

Figure 5. Experimental and calculated (15) NMR chemical shifts in alkali iodides. NMR chemical shifts calculated from wave function given by Equation 8 and corrected for shift of reference sample with respect to free I ion, —9 X 10 ...

Alkali Iodides. Figure 8 shows the experimental data obtained for the recoilless fraction, /, at 80°K. The area (13), line width (13), and the temperature (26) methods have all been used to analyze these data. Uncertainties in the background corrections (13) are caused by rather large errors. However, the striking feature is that the recoilless fraction changes only little from Lil to Csl. 

The recoilless fraction, /, has been calculated (13) for monotomic lattices using the Debye approximation. When the specific heat Debye temperatures of the alkali iodides are inserted in the Debye-Waller factor, a large variation of f follows (from 0.79 in Lil to 0.15/xCsI). It is not... 

Figure 8. Theoretical and experimental values of recoilless fraction, f for alkali iodides at 80°K. DEL symbolizes Ref, (9),/—(19), HDD—(13), PSH—(26)...

Other Compounds. The molecular crystal I2 has been studied by Pasternak, Simopoulos, and Hazony (26). By measuring the temperature dependence of the recoilless fraction they obtained an effective Moss-bauer temperature, Om = 60°K., which is considerably less than the range found for the alkali iodides, Om = 100° to 120 °K. Because the covalent intramolecular bonding in I2 is much stronger than the intermolecular bonding, it is reasonable to assume for data interpretation that the recoil energy is taken up by the entire I2 molecule. 

Formation of the P—N bond has been observed when the cross-coupling of dialkylphosphites (59) with amines (60) proceeds by an iodo cation [I]+-promoted electrooxidation, affording N-substituted dialkylphosphor-amidates (61) (Scheme 22) [76]. Lack of alkali iodide in the electrolysis media results in the formation of only a trace of (61), indicating that the iodide plays an important role in the P—N bond-forming reaction. In contrast, usage of sodium bromide or sodium chloride brings about inferior results since the current drops to zero before the crosscoupling reaction is completed. 

The experiments on alkali iodides, PEOx-Nal or PEOx-Lil [316-318] were performed on PEO chains of 23 or 182 (-CH2-CH2-O-) monomers and Orion ratios between 15 and 50. The incoherent scattering from protonated polymers was measured using INI 1C, which yields the intermediate scattering function of the self-correlation. The experiments were performed in the homogeneous liquid phase where the added salt is completely dissolved and no crystalline aggregates coexist with the solution, i.e. at temperatures around 70 °C. 

Mendelovici, E. Yariv, S. (1980) Infrared study of the thermal transformation of goethite to magnetite in alkali-iodide discs. Thermo-chim. Acta 36 25-38... 

Addition of a small amount of alkali iodide to mercury(II) nitrate solution... 

Orthogonal crystalline powder refractive index (for montroydite) 2.37 density 11.14 g/cm3 Moh s hardness 2.5 insoluble in water and ethanol soluble in dilute acids and aqueous solutions of alkali iodides and cyanides. 

The essential requirement for ruthenium catalysts to be active in homologation reactions of oxygenated substrates is the presence of an iodide promoter which may be I2, HI, an alkyl or metal iodide, or a quaternary ammonium or phosphonium iodide (3). With alkali iodides as promoters, ion-pairs of the [fac-Ru(CO)3l3] anion are formed in the catalytic solution of the homologation reactions starting from different precursors Ru(Acac>3, Ru3(CO)] 2> Ru(CO)4l2 etc. ( ). ... 

Yanagida176) reported similar results for the reaction of 1-bromooctane with alkali iodides in refluxing benzene (Eq. (4)). No reaction occured in the absence of solid catalyst. A mixture of 1.6 mmol of 1-bromooctane, 1 ml of benzene and 5 mol % of... 

In 1862, E. C. C. Stanford proposed the carbonization of the drift-weed in closed retorts so as to recover tar and ammoniacal liquor in suitable condensers. This modification did not flourish because of the subsequent difficulties in extracting soluble iodides from the charcoal. V. Vincent (1916) claims that soln. containing aluminium sulphate extract the alkali iodides from seaweed leaving behind the organic matter which prevents the direct precipitation of iodine or iodides. The alkali iodide soln. is treated with copper sulphate for cuprous iodide, or by soln. of sulphites for iodine. M. Paraf and J. A. Wanklyn proposed to heat the drift-weed first with alkali hydroxide so as to form oxalic and acetic acids, which could be crystallized from the lixivium. The economical treatment of seaweed for iodine has been discussed by A. Puge. 

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