Stannic fluoride

Tin iy) fluoride, Snp4, stannic fluoride. Polymeric solid formed Sn plus F2 or SnCU plus HF. Very hygroscopic, forms fluoro-stannales(IV) containing [SnFgp ions. 

The main binary tin fluorides are stannous fluoride and stannic fluoride. Because the stannous ion,, is readily oxidized to the stannic ion,, most reported tin and fluorine complexes are of tin(IV) and fluorostannates. Stannous fluoroborates have also been reported. 

Ammino - derivatives of Stannic Fluoride.—Stannic fluoride unites with ammonia on heating to 439 C.., forming the white solid mon-ammino-stannic fluoride, [Sn(NH3)]F4. The compound is remarkably stable, and may be heated to 400° C. with little decomposition.1... 

Diammino-stannic Fluoride, [Sn(NFI3)2]F4, is formed if stannic fluoride and ammonia are heated together in a sealed tube to a temperature of 120° C. Both the monammine and the diammine are soluble in water, the solutions becoming cloudy due to decomposition. Stannic fluoride also forms addition derivatives with the bases pyridine and quinoline. 

In animals, data suggest inorganic tin compounds are not readily absorbed. At 48 hours after oral administration of Sn (a gamma-ray emitting radionuclide), approximately 95% or more of the administered radioactivity was recovered in feces, with 1% or less in urine (Hiles 1974). The various forms of tin ( Sn) compounds administered were stannous pyrophosphate (SnzRO7), stannous fluoride (SnF2), stannic fluoride (SnF ), stannous citrate (Sn[ll]citrate), and stannic citrate (Sn[IV]citrate). The absorption of Sn [II] from the gastrointestinal tract was reported to be 2.85% in rats, while 0.64% of the administered Sn [IV] was absorbed (Hiles 1974). 

We must not overlook, however, the fact that when the field of a polar bond is sufficiently buried within the molecule its influence upon solubility tends to disappear. Thus, in spite of the polarity of the bond between the carbon atom and the nitro-group, as shown in nitrobenzene and nitromethane, we might expect tetranitromethane to behave in its solutions as a substance of low polarity. Again, stannic chloride is nonpolar but stannic fluoride, apparently on account of the smaller halogen atoms, is so polar as to form a high-melting solid. 

CUCI2 +2 cupric chloride SnF4 +4 stannic fluoride... 

The pH of a freshly prepared 0.4% solution of stannous fluoride is between 2.8 and 3.5. Initially clear aqueous solutions become cloudy on standing owing to hydrolysis and oxidation. The insoluble residue is a mixture containing stannous and stannic species, fluoride, oxide, oxyfluorides, and hydrates. 

Of the large volume of tin compounds reported in the Hterature, possibly only ca 100 are commercially important. The most commercially significant inorganic compounds include stannic chloride, stannic oxide, potassium staimate, sodium staimate, staimous chloride, stannous fluoride, stannous fluoroborate, stannous oxide, stannous pyrophosphate, stannous sulfate, stannous 2-ethyUiexanoate, and stannous oxalate. Also important are organotins of the dimethyl tin, dibutyltin, tributyltin, dioctyltin, triphenyl tin, and tricyclohexyltin families. 

Halides. The tin haUdes of the greatest commercial importance are stannous chloride, stannic chloride, and stannous fluoride. Tin hahdes of less commercial importance are stannic bromide [7789-67-5], stannic iodide [7790-47-8], stannous bromide [10031-24-0], and stannous iodide [10294-70-9] ( ) ... 

Other studies of the toxicity of stannous fluoride, sodium pentafluorostannite, sodium pentachlorostannite, sodium chlorostannate, stannous sulfide [1314-95-0] stannous and stannic oxides, stannous pyrophosphate [15578-26 ] stannous tartrate [815-85-0] and other inorganic tin compounds are reviewed in References (dh—12. The OSHA TLV standard for inorganic tin compounds is two milligrams of inorganic tin compounds as tin per cubic meter of air averaged over an eight-hour work shift (47). 

In 1888, Turpin prepd a series of cool expls which were permissable, by incorporating materials such as alkali chlorides, Na or K bicarbonate (up to 50% content), fluorides, acetates, oxalates, Ba carbonate. 10H2O, chromates, hyposulfites, stannic acid, boric acid, borates, etc, in the expls listed above eg, a) K chiorate 45, double salt of Ca and K acetochlorate 35, tar 18, charcoal 5, and alkali bicarbonate or oxalate I5ps b) K chlorate 15, double salt of K and Amm chlorobichromate 35 K or Na nitrate 10, tar 18, charcoal 5, and K or Na bicarbonate 15ps... 

A ubiquitous co-catalyst is water. This can be effective in extremely small quantities, as was first shown by Evans and Meadows [18] for the polymerisation of isobutene by boron fluoride at low temperatures, although they could give no quantitative estimate of the amount of water required to co-catalyse this reaction. Later [11, 13] it was shown that in methylene dichloride solution at temperatures below about -60° a few micromoles of water are sufficient to polymerise completely some decimoles of isobutene in the presence of millimolar quantities of titanium tetrachloride. With stannic chloride at -78° the maximum reaction rate is obtained with quantities of water equivalent to that of stannic chloride [31]. As far as aluminium chloride is concerned, there is no rigorous proof that it does require a co-catalyst in order to polymerise isobutene. However, the need for a co-catalyst in isomerisations and alkylations catalysed by aluminium bromide (which is more active than the chloride) has been proved [34-37], so that there is little doubt that even the polymerisations carried out by Kennedy and Thomas with aluminium chloride (see Section 5, iii, (a)) under fairly rigorous conditions depended critically on the presence of a co-catalyst - though whether this was water, or hydrogen chloride, or some other substance, cannot be decided at present. 

The metal halide catalysts include aluminum chloride, aluminum bromide, ferric chloride, zinc chloride, stannic chloride, titanium tetrachloride and other halides of the group known as the Friedel-Crafts catalysts. Boron fluoride, a nonmetal halide, has an activity similar to that of aluminum chloride. 

The catalytic activity of certain of the Friedel-Crafts catalysts was shown to decrease over a very wide range in the series boron fluoride, aluminum bromide, titanium tetrachloride, titanium tetrabromide, boron chloride, boron bromide and stannic chloride (Fairbrother and Seymour, mentioned in Plesch al., 83). When boron fluoride is added to isobutylene at dry ice temperatures, the olefin is converted to a solid polymer within a very few seconds. The time required for complete polymerization with aluminum bromide hardly extends to a few minutes while reaction times of hours are required with titanium chloride and periods of days with stannic chloride. 

Many chlorides, especially those of the metals, combine with sulphur tetrachloride to produce unstable crystalline additive compounds 2 thus, iodine trichloride, antimony pentachloride, titanium tetrachloride, stannic chloride, ferric chloride, and also arsenic fluoride, yield crystalline products containing the added molecule SC14 this provides strong evidence of the definite existence of this chloride of sulphur. 

Why is calcium fluoride, CaF2, a high-melting-point crystalline solid while stannic chloride, SnCl4, is a volatile liquid ... 

Tin forms dihahdes and tetrahahdes with all of the common halogens. These compounds may be prepared by direct combination of the elements, the tetrahalides being favored. Like the halides of tile lower main group 4 elements, all are essentially covalent. Their hydrolysis requires, therefore, an initial step consisting of the coordinative addition of Iwo molecules of water, followed by the loss of one molecule of HX. the process being repeated until the end product ft S111 Oil c is obtained. The most significant commercial tin halides are stannous chloride, stannic chloride, and stannous fluoride. 

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