XXXVII.—A simple method of preparing potassium stannichloride
Journal of the Chemical Society Transactions
THE methods used to prepare potassium stannichloride, K,SnCl" usually involve the employment of excess of potassium chloride in order to diminish the hydrolysis of the stannic chloride. Analyses of the products obtained from mixed solutions of the1 two chlorides frequently indicate too high a percentage of potassium. It is now found that a highly satisfactory product may be rejadily obtained by the oxidation of potassium stannochlorides by means of chlorine. The potassium stannochloride need
... nnochloride need not be isolated; a solution of stannous chloride in a concentrated solution of potassium chloride made slightly acid with hydrochloric acid may be used instead. The reaction proceeds quite well when a concentrated solution of the salts in the molecular proportion of 2 parts of potassium chloride to 1 part of stannous chloride is used. It was found unnecessary, if not, inadvisable, to elmploy an excess of potassium chloride. With weak solutions hydrolysis takes place ; thus i t is necessary to use concentrated solutions of the salts. A concentrated solution of 16 grams of potassium chloridel was prepared and 22 grams of stannous chloride were dissolved in it by warming, with the addition of a few drops of concentrated hydrochloric acid. A slow stream of chlorine was passed in for about three hours, after which the oxidation was complete. The solution, after saturation with the gas, was treated with a, little Concentrated hydrochloric acid and slowly evaporated on a water-bath a t 50-70° for about two hours. Small, octahedral crystals of potassium stannichloride separated out on remaining overnight. These were collected, dried on a porous plate, and analysed without recrystallisation. (Found, K = 19-25 ; Sn=28*69; C1=51*99. CaJc., K=19.19; Sn=28*72; C1-52.02 per cent.) Experiment s were carried out in which potassium stannochloride was first isolated before the chlorination. The stannous double salt was prepared by adding the calculated amount of stannous chloride to a. saturated solution of potassium chloride containing a little hydrochloric acid. The solution was concentrated somewhat on a water-bath a t a temperature not exceeding 60°; it was then filtered, and allowed to crystallise. The crystals were dried on a porous plate. (Found, K = 20.72 ; S'n = 31.58 ; C1= 37.89 ; H,O = 9-60. K2SnC1"2H20 requires K = 20.80 ; Sn = 31.74 ; C1= 37.86; H20=9.60 per cent.) The method employed was as follows.