Stannous-stannic reaction

This low value of the equilibrium constant means that when equilibrium is attained in the ferrous-ferric and stannous-stannic mixture, the concentrations (activities) of ferric and stannous ions must be negligibly small in comparison with those of the ferrous and stannic ions. In other words, when these two systems are mixed, reaction occurs so that the ferric ions are virtually completely reduced to ferrous ions while the stannous are oxidized to stannic ions. This fact is utilized in analytical work for the reduction of ferric to ferrous ions prior to the estimation of the latter by means of dichromate. 

In some cases, particularly with iaactive metals, electrolytic cells are the primary method of manufacture of the fluoroborate solution. The manufacture of Sn, Pb, Cu, and Ni fluoroborates by electrolytic dissolution (87,88) is patented. A typical cell for continous production consists of a polyethylene-lined tank with tin anodes at the bottom and a mercury pool (ia a porous basket) cathode near the top (88). Pluoroboric acid is added to the cell and electrolysis is begun. As tin fluoroborate is generated, differences ia specific gravity cause the product to layer at the bottom of the cell. When the desired concentration is reached ia this layer, the heavy solution is drawn from the bottom and fresh HBP is added to the top of the cell continuously. The direct reaction of tin with HBP is slow but can be accelerated by passiag air or oxygen through the solution (89). The stannic fluoroborate is reduced by reaction with mossy tin under an iaert atmosphere. In earlier procedures, HBP reacted with hydrated stannous oxide. 

Stannic and stannous chloride are best prepared by the reaction of chlorine with tin metal. Stannous salts are generally prepared by double decomposition reactions of stannous chloride, stannous oxide, or stannous hydroxide with the appropriate reagents. MetaUic stannates are prepared either by direct double decomposition or by fusion of stannic oxide with the desired metal hydroxide or carbonate. Approximately 80% of inorganic tin chemicals consumption is accounted for by tin chlorides and tin oxides. 

Anhydrous stannous chloride, a water-soluble white soHd, is the most economical source of stannous tin and is especially important in redox and plating reactions. Preparation of the anhydrous salt may be by direct reaction of chlorine and molten tin, heating tin in hydrogen chloride gas, or reducing stannic chloride solution with tin metal, followed by dehydration. It is soluble in a number of organic solvents (g/100 g solvent at 23°C) acetone 42.7, ethyl alcohol 54.4, methyl isobutyl carbinol 10.45, isopropyl alcohol 9.61, methyl ethyl ketone 9.43 isoamyl acetate 3.76, diethyl ether 0.49, and mineral spirits 0.03 it is insoluble in petroleum naphtha and xylene (2). 

Instead of copper one can use zinc, iron, stannous chloride, or cuprous chloride, the last-named two being oxidized to stannic and cupric chloride respectively. The reactions are carried out at low temperature ( — 10 to — 20°C) in acetone or ethyl acetate (Nesmeyanov et al., 1934 a). 

B. Reduction of Dinitrodurene.—A solution of 90 g. of dini-trodurene in 1 1. of glacial acetic acid is boiled in a 12-I. flask (Note 6) 700 g. of stannous chloride is dissolved in 800 cc. of concentrated hydrochloric acid and heated to boiling. The heat is removed from the acetic acid solution of the nitro compound, and the stannous chloride solution is poured very carefully (during about ten minutes) into the dinitrodurene solution. The reaction is complete in fifteen minutes, and as the solution cools the stannic chloride compound of the diamine begins to crystallize. The reaction mixture is cooled to io° in an ice-water bath, and the solid is filtered off by suction, washed twice with 50 cc. of 95 per cent ethyl alcohol and twice with 50 cc. of ether, and dried. The filtrates from the tin compound contain very little of the reduction product and may be discarded. The composition of this compound is [G (CH i)4(NH2-HCI)2l2-SnCl4, and it crystallizes from the reaction mixture in fine, glistening plates which are almost colorless. The yield is 145 g. (97 per cent of the theoretical amount). 

Anhydrous sodium tungstate, 25 382 Anhydrous stannic chloride, 24 803 Anhydrous stannous chloride, 24 802-803 Anhydrous zinc chloride, 26 617 Anhydrous zinc sulfate, 26 617 Aniline, 2 783-809, 17 250, 259 alkylation, 2 197 Bechamp process, 2 490 from benzene, 3 619t, 620 chemical reactions, 2 783-789 derivatives, 2 783-809 economic aspects, 2 790-791... 

Zinc chloride is much less reactive than aluminum chloride and usually requires higher reaction temperatures. However, it has the advantage that, unlike aluminum chloride, it is less sensitive to moisture and can sometimes even be used in aqueous media.88 Concentrated aqueous solutions of ferric chloride, bismuth chloride, zinc bromide, stannous chloride, stannic chloride, and antimony chloride are also alkylation catalysts, particularly in the presence of hydrochloric acid.89... 

Concentrated hydrochloric acid also dissolves the trichloride, about 100 g. of the latter dissolving in 1 litre of acid at 100° C.7 Dissolution in hydriodic acid is accompanied by evolution of heat and the triiodide is formed.8 Ethyl iodide reacts similarly.9 Double decomposition reactions occur w hen arsenic trichloride is heated with phosphorus triiodide, stannic iodide or germanium iodide, the reactions being complete.10 Similarly, potassium iodide heated with arsenic trichloride in a sealed tube at 210° C., and potassium bromide at 180° to 200° C., form respectively arsenic triiodide and tribromide.11 Stannous chloride, added to the solution in hydrochloric acid, causes reduction to arsenic (see p. 29). Arsenic trichloride may be completely separated from germanium chloride by extraction with concentrated hydrochloric acid.12 Ammonium, sodium and cobaltic chlorides react with arsenic trichloride to form additive compounds with magnesium, zinc and chromic chlorides there is no reaction.13... 

Sulfides. Stannous sulfide SnS, dark brown precipitate, by reaction of stannous salt solution and H2S, insoluble in sodium sulfide solution but soluble in sodium polysulfide solution, forming sodium thiostannate stannic sulfide SnS , yellow precipitate, by reaction of stannic salt solution and H>S, soluble in sodium sulfide solution, forming sodium thiostannate. 

B. C. Dutt and S. N. Sen found that when nitric oxide is passed into a suspension of barium dioxide in water, barium nitrite, not nitrate, is formed. P. Sabatier and J. B. Senderens observed no change when nitric oxide is passed over Cuprous Oxide at 500°. H. A. Auden and G. J. Fowler observed that dry nitric oxide and Silver oxide, at ordinary temp., form silver and silver nitrate P. Sabatier and J. B. Senderens also obtained silver and silver nitrite by passing nitric oxide into water with silver oxide in suspension. C. F. Schonbein found gold oxide is reduced by moist nitric oxide, forming nitrous acid. P. Sabatier and J. B. Senderens found that titanium sesquioxide forms white titanic oxide when heated in an atm. of nitric oxide and that stannous oxide below 500° burns in an atm. of nitric oxide, forming stannic oxide. If nitric oxide be passed into water with lead dioxide in suspension, the water is coloured, and in about 3 hrs., lead nitrite and nitrate are formed, and later, rhombic crystals of a basic nitrite. B. C. Dutt and S. N. Sen said that the nitrate is formed by the action of the dioxide on the nitrite. Lead dioxide is reduced to lead oxide by nitric oxide at 315°, and H. A. Auden and G. J. Fowler found that the reaction begins at 15°, when a basic lead nitrite is... 

There are two series of compounds of tin and the halogens those related to stannous oxide, SnO, in which the metal has a valence of 2 (stannous salts), and those related to stannic oxide, Sn02, in which it has a valence of 4 (stannic salts). The compounds with lower valence are usually prepared by the action of the halogen acids on the metal. Stannous chloride, for example, is formed when hydrochloric acid reacts with tin. Stannic salts, on the other hand, are prepared by the reaction of tin and the free halogen. In this preparation stannic bromide results from the reaction of bromine and tin. The reaction between the two ele-... 

Nitriles may be converted to their imino chloride salts by the action of dry hydrogen chloride in ether. These intermediates ate reduced by anhydrous stannous chloride to stannic aldimonium chlorides, which on hydrolysis yield aldehydes. Chloroform may be added to facilitate the solution of the nitrile. The quality of the stannous chloride catalyst is important the preparation of an active and dependable form has been described. The yields are usually high for many aromatic nitriles, as in the preparation of /3-naphthaldehyde (95%). The reaction has also been employed in the heterocyclic series, as in the synthesis of 4-methyl-thiazole-5-aldehyde (40%). The reduction of the cyano group in the... 

The next step is to balance the ecjnation for the reaction. In balancing the equation for an oxidation-reduction reaction it is often vise to write the electron reactions separately (as they would occur in an electrolytic cell), and then to add them so as to cancel out the electrons. For example, ferric ion, Fe- +", oxidi/es stannous ion, Sn, to stannic ion, Sn + + + + that is, from the bipositive state to the quadripositive state. The ferric ion is itsell reduced to ferrous ion, Fe++. The two electron reactions are... 

To 1 molecule of a mononitro-compound, i atoms of tin, or 3 molecules of stannous chloride, are therefore used. In calculating tire amount of the latter necessary for a reaction, it is to be remembered that the salt crystallises with two molecules of water (SnCl,+ 2H,0). If the reduction is to be effected by metallic tin, double the above quantity is frequently used, i.e. to 1 nitro-group, 3 atoms of tin. In this case, the tin is not converted into stannic chloride, but into stannous chloride ... 

Since, in the cases mentioned, hydrochloric acid is always present in excess, and the amines unite with it to form soluble salts, the end of the operation occurs when no more of the insoluble nitro-compound is present, and the reaction-mixture dissolves clear in water. In order to get the free amine from the add mixture, various methods may be employed. If, as in the above example, the amine is volatile with Steam, and insoluble in alkali, then the acid solution is treated with caustic potash, or caustic soda, until the oxide of tin which separates out at first is redissolved in the excess of alkali the liberated amine is driven over with steam. Further, volatile or non-volatile amines can be extracted from an alkaline solution by a proper solvent, like ether. But this process is often troublesome, since the alkaline tin solution forms an emulsion with ether, which subsides with great difficulty. If the free amine is solid, it may be obtained by filtering off the alkaline liquid. In many cases, where a non-volatile amine is under examination, it is advisable to predpitate the tin before liberating the amine. This is done by diluting the add solution with much water, heating on the water-bath, and as soon as the liquid has reached the temperature of the bath, hydrogen sulphide is passed into it. The tin is predpitated as stannous or stannic sulphide this is separated from... 

Derivation By the reaction of a neutral solution of gold trichloride with stannous and stannic chlorides, yielding a mixture of colloidal gold and tin oxide in varying proportions. 

Furthermore, an undesirable side reaction between tin and technetium may occur. As outlined above, there is a high excess of tin - as Sn(II) and Sn(IV) - over technetium and this fact leads to the idea that mixed-metal complexes maybe formed in radiopharmaceutical preparations. Interest in the question, whether stannous or stannic tin could be involved in the radiopharmaceutical was further stimulated by the formation of a tin-capped Tc-dimethylglyoxime complex, Tc(oxime)3(/i-OH)SnCl3 (Deutsch et al. 1976). However, this compound was prepared under the condition of carrier-added technetium its ready conversion to uncapped species gives no evidence for the existence of mixed-metal type compounds. 

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