Iodide normal values

An interesting bicyclic germyl anion 42 K was readily prepared by the reduction of bicyclic iodide 78 with KCg (Scheme 2.71). The Ge anionic center in 42 [K (dme)2] was highly pyramidalized with the normal value of the Ge-K bond distance (3.4324(10) A). However, in polar solvents (THF) the Ge-K bond dissociates to produce 42 as an SSIP featuring the free anion 42 . 

The capacity of the Stern layer (Cj = CIS) does not depend on electrolyte concentration except in so far as C is affected. In the case of the silver iodide-aqueous electrolyte interface, Stern layer capacities of c. 0.1 to 0.2 F m 2 have been calculated taking 8- 5 x 10 10 m, this corresponds to a dielectric constant in the Stern layer of c. 5-10, which, compared with the normal value of c. 80 for water, suggests considerable ordering of water molecules close to the surface. 

Cyclohexene exists in the half chair [1] conformation la as confirmed from the X-ray structures of many species including morphine [2] and cholesteryl iodide [3]. Relative to cyclohexane, cyclohexene is flattened and only C4 and C5 bear the tmly axial and equatorial bonds. The bonds on C3 and C6, which are slightly off from the tmly axial and equatorial positions, are called pseudo-axial (a ) and pseudo-equatorial (e ), respectively. The dihedral angle between a substituent on Cl (like R1 in the structure lb) and an equatorial substituent on position C6 (like equatorial R2 in the structure lb) is about 43-44° (significantly less than the normal value of 60 ). This allows them to interfere with each other sterically. 

Few other reactions of series of substituted pyridines have been investigated extensively. Dondoni, Modena, and Todesco have measured the rate of N-oxidation of a limited series of pyridines and found a good correlation with normal u-values with a p-value of — 2.23. The A-alkylation of pyridines with alkyl iodides in nitrobenzene has been studied by Brown and Cahn and by Clarke and Rothwell. Unfortunately, the only data available are for the parent compound and for alkyl derivatives, and, since the a-values for the various alkyl groups in a given position are substantially constant, this leaves a correlation of only three independent points. However, the rates of A-alkylation of the j8- and y-alkyl derivatives are so nearly equal that it appears as if no correlation existed. Clarke and Rothwell have also studied the alkylation with allyl bromide in nitromethane at various temperatures, and in this case a more extensive series is available. The authors state that no overall Hammett correlation is obtained however, the j8-substituted derivatives fall on one straight line and the y-derivatives on another one with a different slope. The data are shown in Fig. 2. The line for the j8-compounds, p = — 2.53 0.31, r = 0.95, is seen not to be very good the line for the y-derivatives, p = — 1.42 0.06, r = 0.99, is much more satisfactory. It does not seem likely that the discrepancy is due to the intervention of resonance effects, since in this case one would expect the correlation for the y-derivatives to be poorer than that for the j8-analogs. More extensive studies with a wider variety of substituents would seem very desirable. 

The normal reduction potential of the iodine-iodide system is independent of the pH of the solution so long as the latter is less than about 8 at higher values iodine reacts with hydroxide ions to form iodide and the extremely unstable hypoiodite, the latter being transformed rapidly into iodate and iodide by self-oxidation and reduction ... 

Iodine was determined by an iodometric titration adapted from White and Secor.(3) Instead of the normal Carius combustion, iodide was separated from the samples either by slurrying in 6M NaOH, or by stirring the sample with liquid sodium-potassium (NaK) alloy, followed by dissolving excess NaK in ethanol. Precipitated plutonium hydroxides were filtered. Iodine was determined in the filtrate by bromine oxidation to iodate in an acetate buffer solution, destruction of the excess bromine with formic acid, acidifying with SO, addition of excess KI solution, and titrating the liberated iodine with standard sodium thiosulfate. The precision of the iodine determination is estimated to be about 5% of the measured value, principally due to incomplete extraction of iodine from the sample. 

In other crystals an octahedral metal atom is attached to six non-metal atoms, each of which forms one, two, or three, rather than four, bonds with other atoms. The interatomic distance in such a crystal should be equal to the sum of the octahedral radius of the metal atom and the normal-valence radius (Table VI) of the non-metal atom. This is found to be true for many crystals with the potassium chlorostannate (H 61) and cadmium iodide (C 6) structures (Table XIB). Data are included in Table XIC for crystals in which a tetrahedral atom is bonded to a non-metal atom with two or three covalent bonds. The values of dcalc are obtained by adding the tetrahedral radius for the former to the normal-valence radius for the latter atom. 

The lowering of the vapour pressure of water by ammonium iodide measured by G. Tammann 9 shows that the fall is 12"5 mm. for JN-soln. 25"1 mm. for N-soln. and 243 5 for lON-soln. According to L. C. de Coppet, the soln. of a mol. of the salt in water lowers the temp, of maximum density 1T1°. The degree of ionization calculated by S. M. Johnston from the raising of the boiling point of water by normal soln. of ammonium iodide agrees with the value of N. Zelinsky and S. Krapiwin and S. Arrhenius from the electrical conductivities of soln. of a mol. of the salt in v litres of water ... 

Equation 7-18 relates the volume of added M+ to [M+], [X-], and the constants V7, C, and CjJ,. To use Equation 7-18 in a spreadsheet, enter values of pM and compute corresponding values ofVM, as shown in Figure 7-10 for the iodide titration of Figure 7-7. This is backward from the way you normally calculate a titration curve in which VM would be input and pM would be output. Column C of Figure 7-10 is calculated with the formula [M+l = 10 pm, and column D is given by [X-] = k sp/[M+]. Column E is calculated from Equation 7-18. The first input value of pM (15.08) was selected by trial and error to produce a small V You can start wherever you like. If your initial value of pM is before the true starting point, then VM in column E will be negative. In practice, you will want more points than we have shown so that you can plot an accurate titration curve. 

The oxidation-reduction potential of arsenious-arsenie acid solutions has been determined.10 A small quantity of iodide was added as catalyst,11 and it was found that true equilibrium values, varying normally with the concentration ratio, are obtained only if the solutions are acidified to an extent corresponding at least with X-HC1. For the cell... 

Agl (g). Jellinek and Rudat2 computed the heat of vaporization from vapor pressure data. From the spectroscopic absorption limit and the assumption that the products of dissociation are a normal silver atom and an excited iodine atom, Franck and Kuhn1 computed a value for the energy of dissociation of gaseous silver iodide which leads to the value Qf= —38 for Agl (g). 

A new, more accurate electron diffraction study of gaseous mercuric chloride has been reported.159 The interatomic distances (Hg—Cl = 2.25 A, Cl—Cl = 4.48 A) are shorter than previously reported values by 0.02 to 0.09 A. A complete normal-co-ordinate analysis of bis(methylthio)mercury has also been reported.160 The Raman spectra of gaseous mercuric chloride, bromide, and iodide have been reported.161 The bond polarizability derivatives calculated from the data increase in the order Cl < Br < I, suggesting an increased degree of covalence in the mercury-halogen bond with increasing size of the halogen atom. 

Equivalent Conductance Minima.—Provided the dielectric constant of the medium is greater than about 30, the conductance behavior in that medium is usually similar to that of electrolytes in water the differences are not fundamental and are generally differences of degree only. With solvents of low dielectric constant, however, the equivalent conductances often exhibit distinct abnormalities. It is frequently found, for example, that with decreasing concentration, the equivalent conductance decreases instead of increasing at a certain concentration, however, the value passes through a minimum and the subsequent variation is normal. In other cases, e.g., potassium iodide in liquid sulfur dioxide and tetra-... 

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