42 



Messrs. Letts and Collie on a new Method 



Vapour-density of Found. 



Tin tetrethyl 

 Calculated. 



8-09 . . . 



As the usual methods for the preparation of tin tetrethyl 

 are rather troublesome and. tedious (viz. either by the action 

 of zinc ethyl on tin tetrachloride *, or on tin trie thy 1 iodide, or 

 on tin diethyl iodide f , or by adding fused anhydrous stannous 

 chloride to zinc ethyl and distilling!), it occurred to us that 

 the accidental discovery we have described might indicate 

 a simpler and more satisfactory process for obtaining it. As 

 the commercial zinc we employed could only contain a small 

 percentage of tin, it seemed probable (as we had obtained fair 

 quantities of the tetrethyl compound) that the whole of the 

 tin had possibly been converted into its organo-metallic deri- 

 vative ; and we argued that, by employing an alloy of zinc rich 

 in tin for the couple, or by using pure tin without admixture 

 of zinc, we ought to obtain a good yield of tin tetrethyl. 



A rough experiment showed that tin tetrethyl is obtained 

 in considerable quantity by employing a couple containing a 

 fair percentage of tin, and that the process is easily executed. 



We next made a series of experiments to ascertain the 

 conditions for obtaining the best yield of the organo-metallic 

 body, and also for ascertaining what proportion of tin, in 

 alloys with zinc, of varying composition would be converted 

 into the tetrethyl compound. The following table illustrates 

 our results : — 



Preparation of Tin Tetrethyl. 





Couple used = 50 grms., 











containing 45 grms. alloy 











and 5 grms. Cu. 





Tin 



tetrethyl 

 obtained. 



Per cent, of 



Exp. 





Ethyl 

 iodide. 



Tin converted 

 into Tin 

 tetrethyl. 



Alloy. 







Zn. 



Sn. 



Per cent. 

 Sn. 



Copper. 









1. ... 



44-45 



0-45 



1-0 



5 



• 60 



0-5 



55 



2.... 



43'87 



113 



2-5 



5 



60 



10 



45 



3.... 



42-75 



2-25 



5-0 



5 



60 



2-5 



56 



4. ... 



40-50 



4-50 



100 



5 



60 



40 



45 



5.... 



38-25 



6-75 



15-0 



5 



60 



5-0 



37 



6.... 



36-00 



9-00 



20-0 



5 



60 



100 



56 



7. ... 



30-00 



15-00 



33-3 



5 



60 



120 



40 



8.... 



22-50 



22-50 



50-0 



5 



60 



10-0 



22 



* Buckton, Phil. Trans. 1859, p. 426. 



f Ibid. p. 424. 



X Frankland and Lawrance, Chem. Soc. Journ. 1879, i. p. 130 



