Anhydrous Stannic Bromide

What is the purpose of the wash bottles as arranged for the chlorine gas  

Suggest how hydrated stannic chloride, SnCl4-5H20, might be made, starting with stannous chloride. 

What happens if hydrated stannic chloride is heated (Compare aluminum chloride and bromide, Preparations 25 and 26.) 

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- 

Pyrex test tubes, ring stand, burette clamp. 

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Make a solution of stannic bromide by mixing in a graduated cylinder 1 cc. of your preparation of anhydrous stannic bromide, 4 cc. of 6iV HC1, and 15 cc. of water. Shake the mixture until solution is complete. Use this solution for the following tests. 

Arsenic triiodide also dissolves, the saturated solution at 15° C. having density 3-661. Other soluble halides are potassium bromide, anhydrous ferric and aluminium chlorides 6 and tetramethyl ammonium iodide but the iodides of rubidium, cadmium, manganese and cobalt, also mercuric and stannic iodides, and cobalt and stannic bromides, are insoluble or only very slightly soluble in arsenic tribromide. The liquid also dissolves phosphoryl bromide and, very slightly, ammonium thiocyanate. In the mixed solutions of halides, the components may react chemically (cf. p. 106), but such is not always the case for example, with antimony tribromide a continuous series of solid solutions is formed.7... 

As stated above, one of the routes to thienothiophene 2 is cyclization of (3-thienylthio)acetic acid in the presence of concentrated sulfuric acid followed by action of the 2,3-dihydrothieno[3,2-i]thiophen-3-one (22, R = H) formed with lithium aluminum hydride.26,28 Attempts by the present authors41,33 as well as those of Gronowitz and Moses47 to obtain thienothiophene 1 by cyclizing (2-thienylthio)acetic acid or its chloride by various catalysts (stannic chloride, aluminum chloride or bromide, polyphosphoric acid or anhydrous HF) were unsuccessful. Synthesis of 2-ethyl-3-hydroxythieno[2,3-A]thiophene33 by procedures commonly used for the preparation of 3-hydroxybenzo[A]thiophene72-74 also failed. 

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