Aniline chlorostannate

HjSnCl, with which the aniline forms a salt, aniline chlorostannate (C4HjNH )i,H SnCl4, similar in type to aniline chloroplatinate (p. 448). The crude product is therefore made strongly alkaline with sodium hydroxide, which liberates the base with the formation of sodium stannate, and the aniline can (C4H NH,),H,SnCl, + SNaOH = 2C,H,NH, + Na.SnO, +6NaCl + sHjO then be removed by steam-distillation. 

When reduction is complete, a complex amine chlorostannate may separate from which the amine is liberated by basification, using enough alkali to dissolve the tin hydroxides formed (e.g. the preparation of aniline, Expt 6.48). 

The use of tin involves a number of difficulties. The chlorides of tin produced in the presence of an excess of hydrochloric acid give chlorostannic acid, which combines with aniline and some other arylamines to form complex double salts as shown in equation (4). In order to decompose these salts alkali is used. A great excess must be employed in order to change the stannic hydroxide, which i,s formed, to soluble sodium stannate ... 

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