Stannic salts, reactions

Acidic Properties. As a typical acid, it reacts readily with alkaUes, basic oxides, and carbonates to form salts. The largest iadustrial appHcation of nitric acid is the reaction with ammonia to produce ammonium nitrate. However, because of its oxidising nature, nitric acid does not always behave as a typical acid. Bases having metallic radicals ia a reduced state (eg, ferrous and staimous hydroxide becoming ferric and stannic salts) are oxidized by nitric acid. Except for magnesium and manganese ia very dilute acid, nitric acid does not Hberate hydrogen upon reaction with metals. 

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. 

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-... 

Carbonyl Compounds. Cychc ketals and acetals (dioxolanes) are produced from reaction of propylene oxide with ketones and aldehydes, respectively. Suitable catalysts iaclude stannic chloride, quaternary ammonium salts, glycol sulphites, and molybdenum acetyl acetonate or naphthenate (89—91). Lactones come from Ph4Sbl-cataly2ed reaction with ketenes (92). 

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). 

Schmidt showed that reaction of 1 mole of aroyl chloride with 2 moles of an aryl nitrile in the presence of stannic or zinc chloride afforded in excellent yields a 2,4,6-triaryldiazapyrylium salt (109) in which at least two of the aryl groups (at positions 2 and 4) were alike. It was presumed that the intermediate was an aroylnitrilium ion (108). 

This reaction is highly exothermic. If the heat of the reaction is not conducted thru the walls of a closed container at a rate capable of maintaining an equilibrium temperature, an increase in pressure results with an increase in reaction rate, leading to explosive conditions. Acid salts, such as stannic chloride and zinc chloride, and bases, such as alkali metal hydroxides, either solid or in aqueous solution, and tertiary amines are all effective catalysts. It is, therefore, imperative that the concentration of such contaminants be kept at a minimum when transporting or storing sizeable quantities of ethylene oxide Accdg to Hess Tilton (Ref 16), a 90% decompn takes place if 100% vapor of EtnO in a closed container is. initiated with MF. There is no upper limit of EtnO in air (the previously reported value of 80% was in error), but the lower expl limit is 3% (Ref 17, p 87)... 

A recent halogen-free benzofuran that shares many structural features with its predecessor shows activity in controlling arrythmias. The synthesis starts with an unusual scheme for building the furan ring. Reaction of the benzyl bromide (2-1) with triphenylphosphine leads to phosphonium salt (2-2). Treatment of the salt with valeryl chloride in the presence of pyridine results in acylation on the now highly activated benzylic carbon (2-3). That product cyclizes to the benzofuran (2-4) on heating with expulsion of triphenylphosphine. Friedel-Crafts acylation of (2-4) with anisoyl chloride in the presence of stannic chloride proceeds on the... 

The usual routes to 1,3-oxazinium salts consist of 1,4-cycloadditions between either a,/3-unsaturated /3-chlorocarbonyl compounds and nitriles or between N-acylimidoyl chlorides and alkynes. Stannic chloride is an effective catalyst for both reactions (c/. Scheme 62). 1,3-Thiazinium perchlorates are synthesized by reacting oxazinium salts with hydrogen sulfide in absolute acetonitrile and then treating the product amides (185) with perchloric acid (Scheme 69) (72S333). 

Stannic chloride behaves in a manner which can be regarded as intermediate between the two classes of halides. The product of the reaction seems to be the double inner oxonium salt... 

Eastham et aL ruled out reaction through the inner salt because of the absence of the precipitation and discoloration usually observed with this salt but this argument depends upon concentrations about which little is known. It was observed earlier that the stannic chloride-catalysed polymerization may perhaps proceed through the inner salt so the low yield of dioxane in the present case might result because some of the monomer enters the polymer but the complete absence of deuterium in the dioxane seems to deny this. The problem is an interesting one. 

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