Stannic hydroxide, preparation

Tin(II) and Tm(IV) Hydroxides. Prepare tin (I I) and tin(IV) hydroxides in separate test tubes from solutions of tin chlorides. What reagent should be used to precipitate the tin hydroxides Do tin hydroxides exhibit amphoteric properties What tin compounds are known as a- and P-stannic acids How are they prepared Write the equations of the reactions. 

Prepare a molar solution of crystallized stannic chloride and a four-molar solution of sodium acetate. Mix these two solutions in equal volumes. A firm white gel of stannic hydroxide forms almost immediately and is stable for a long time. The gel forms over a wide range in concentration, from about 35 per cent of the solution of stannic chloride up to about 60 per cent of the same solution. 

Ferric hydroxide is not unique in this respect, for stannic hydroxide has likewise been prepared both as a positive3 and a negative 4 colloid. 

Stannic hydroxide can be prepared from the chloride by precipitation by a base or it may be formed by oxidation of the metal in presence of water, when a hydrated oxide results. The former compound is called a-stannic acid, the latter / -, or meta stannic acid. 

Dissolve the stannic sulfide in 0.2 ml of concentrated hydrochloric acid, heat in boiling water and pass a current of air for a few minutes to remove hydrogen sulfide. Dilute to about 1.5 ml and make ammoniacal. Centrifuge off the stannic hydroxide and dissolve it in 0.1 ml of 6M hydrochloric acid. Dilute to 0.3-1 ml as appropriate, and prepare sources on distrene, adding 2 drops of 3M hydrofluoric acid before evaporating to prevent volatilization of tin. 

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. 

Stannous Chloride Dihydrate. A white crystalline soHd, stannous chloride dihydrate is prepared either by treatment of granulated tin with hydrochloric acid followed by evaporation and crystallisation or by reduction of a stannic chloride solution with a cathode or tin metal followed by crystallisation. It is soluble in methanol, ethyl acetate, glacial acetic acid, sodium hydroxide solution, and dilute or concentrated hydrochloric acid. It is soluble in less than its own weight of water, but with much water it forms an insoluble basic salt. 

Hydrated Stannic Oxide. Hydrated stannic oxide of variable water content is obtained by the hydrolysis of stannates. Acidification of a sodium stannate solution precipitates the hydrate as a flocculent white mass. The colloidal solution, which is obtained by washing the mass free of water-soluble ions and peptization with potassium hydroxide, is stable below 50°C and forms the basis for the patented Tin Sol process for replenishing tin in staimate tin-plating baths. A similar type of solution (Staimasol A and B) is prepared by the direct electrolysis of concentrated potassium staimate solutions (26). 

Bis(trineophyltin) oxide [60268-17-4] is prepared from the chloride in the normal manner. The chloride can either be prepared directiy from the reaction of three moles of neophylmagnesium chloride and stannic chloride or by the butyl transfer reaction between butyltrineophyltin and stannic chloride. The hydroxide derivative initially formed on hydrolysis of the chloride is readily dehydrated to the bis(oxide) at ca 100°C. 

The epoxidalion is generally conducted in iwo steps (11 the polyol is added to cpichlorohydrin in the presence of a Lewis acid catalyst (stannic chloride, boron irifluoride) to pruduce the chlorollydrin intermediate, and (2] the intermediate is dchydrohalogenaled with sodium hydroxide iu yield the aliphatic glycidyl ether. Solid epoxy resins are prepared by the Taffy or Advancement processes. 

Tricyclohexyltin hydroxide can be prepared via the Grignard reaction, by reaction of cyclohexyl magnesium halide with stannic chloride. 

Preparation from 3-(benzoyloxy)-4-methoxy-benzophenone (SM) (m.p. 95°5-96°5) [686] by saponification [162] with sodium hydroxide in refluxing ethanol (good yield) [273,686] or with potassium hydroxide in refluxing methanol (98%) [687], SM was obtained by Friedel-Crafts acylation of guaiacol benzoate with benzoyl chloride in the presence of zinc chloride [162,273,686] or in the presence of stannic chloride in nitromethane for 1 h at 20° (82%) [687],... 

Preparation by reaction of p-nitrobenzoyl chloride with hydroquinone monomethyl ether in the presence of aluminium chloride in carbon disulfide at 25° for 4 h (50%) [1110]. Preparation by reaction of p-nitrobenzoyl chloride with p-methoxyphenyl p-nitrobenzoate in the presence of stannic chloride in nitromethane at 20° for 2 days (49%). The m-keto ester formed, the 4-methoxy-3-(4-nitrobenzoyl)phenyl 4-nitrobenzoate, (49%), gave the expected ketone by saponification with sodium hydroxide in refluxing methanol for 1 h (quantitative yield) [679]. 

Tin(IV) hydroxide is not known. Hydrolysis of tin(TV) salt solutions produces a white voluminous precipitate, which is not detectably crystalline, and may contain bonded water in a tin oxide gel. The freshly prepared material is called a-stannic acid, and is easily soluble in acid. Ageing produces -stannic acid (or metastannic acid), which is more inert in acids, and has also developed an X-ray diifraction pattern characteristic of tin(IV) oxide. This metastannic acid may be obtained directly from tin and concentrated nitric acid. It remains open whether the differences between a- and /3-stannic acids are solely due to differences in particle size. 

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