Stannic chloride determination

Since there is inherent in reactions which give low selectivities, the possibility that non-competitive conditions are responsible, Olah and Overchuck359 have measured directly the rates of benzylation, isopropylation, and fer/.-butylation of benzene and toluene with aluminium and stannic chlorides in nitromethane at 25 °C. Apparent second-order rate coefficients were obtained (assuming that the concentration of catalyst remains constant), but it must be admitted that the kinetic plots showed considerable departure from second-order behaviour. The observed rate coefficients and kreh values determined by the competition method are given in Table 88, which seems to clearly indicate that the competitive ex-... 

Vesely [2b] concluded that since the value of 1/DP obtained (by extrapolation) at [A1C13] = 0, was approximately the same as that obtained from Norrish and Russell s results with stannic chloride [5], the fundamental mechanism of polymerisation by both catalysts must be the same. Whilst this may be so, it does not follow from this evidence, because the extrapolations are afflicted by considerable uncertainty and, moreover, it is now known that the transfer coefficients which determine the intercept depend on the nature of the catalyst. 

Recently, Mazzocchin et al. have studied several titration methods for determining relatively large amounts of technetium. The most precise results have been obtained by coulometric titration of TcO ions With electrogenerated tin (II) according to the procedure suggested by Bard and Lingaiie . The supporting electrolyte consists of 2.5 M sodium bromide, 0.15 M stannic chloride and 0.2 M hydrochloric acid. The titration reaction is very fast and currents up to 40 mA can readily be employed in the detection of the equivalence point. 

Dennison, J. E., and H. Freund Separation and Determination of Arsenic Trichloride and Stannic Chloride by Gas Chromatography. Anal. Chem. 37, 1766 (1965). 

Since the Braggs first determination, thousands of structures, most of them far more complicated than that of sodium chloride, have been determined by x-ray diffraction. For covalently bonded low molecular weight species (such as benzene, iodine, or stannic chloride), it is often of interest to see just how the discrete molecules are packed together in the crystalline state, but the crystal structures affect the chemistry of such substances only to a minor degree. However, for most predominantly ionic compounds, for metals, and for a large number of substances in which atoms are covalently bound into chains, sheets, or three dimensional networks, their chemistry is very largely determined by the structure of the solid. 

In addition to the initiation of gaseous formaldehyde with formic acid, HCl, boron trifluoride and stannic chloride were studied and found to be more active than formic acid (Fig. 17). The rate of gaseous formaldehyde polymerization with the initiator was measured under the same conditions as the formic acid initiated polymerization by determining the decrease in pressure of formaldehyde. HCl as initiator (at about 3—4% in the mixture) caused kinetic branching, i.e. a rapid increase in the rate of polymerization. 

Discussion As would be predicted from the position of tin in the electromotive series, non-oxidizing acids will react with this metal to form salts and evolve hydrogen. If hydrochloric acid is used, mercuric chloride can be used to determine whether stannous chloride, or stannic chloride is produced. This is the same reaction which was employed in the reduction of mercuric chloride to mercurous chloride, studied in Experiment 128 a. 

A similar synthetic method was used by Bott (1975) for preparing 2-chloro-3-methylbut-l-ene-diazonium tetrachloro-(4-toluenesulfinato)stannate (2.184) from 2,2-dichloro-3-methylbutyraldehyde-4-toluenesulfonylhydrazone (2.283) in dichloro-methane using stannic chloride as reagent (2-109). Whereas HCl was added in the reactions with SbCls, this is apparently not the case for the reaction with stannic chloride. Bott did not investigate or explain this difference, nor did he determine the configuration at the C=C double bond. 

Coumarone-indene resin n. Any of a family of resins produced by polymerizing a coal-tar naphtha containing coumarone and indene. The naphtha is first washed with sulfuric acid to remove some impurities, then is polymerized in the presence of sulfuric acid or stannic chloride as a catalyst. Remaining impurities determine the quality of the resin, which can range from a clear, viscous liquid to a dark, brittle solid. Coumarone-indene resins have no commercial applications when used alone. 

Dumas determined the vapour densities of mercury, phosphorus, arsenic hydride, and stannic and titanium chlorides, the last two being redetermined in 1830, and the vapour density of phosphorus again (with those of iodine and sulphur), and again in 1832. The vapour density of phosphorus was 4-355 or 4 420 (air = i) and that of sulphur at 493° 6 495, at 506 " 6 512, at 524° 6 617 and 6 581. The vapour density of phosphorus, he found, corresponded with four times, that of sulphur with six times, and that of mercury with half, the chemical atomic weights. Since Dumas thought that the molecules of all elementary gases contain two atoms, he was unable to resolve these difficulties. 

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