1888.] On Silicon Compounds and their Derivatives. 37 



II. " Report of Researches on Silicon Compounds and their 

 Derivatives. Part I." By J. EMERSON REYNOLDS, M.D., 

 F.R.S., Professor of Chemistry, University of Dublin. 

 Received September 27, 1888. 



The present investigation was undertaken some years ago with a 

 view to examine the action of the silicon haloids but more especially 

 of silicon tetrabromide on various compounds containing nitrogen, as 

 our knowledge of the relations of silicon and nitrogen is extremely 

 limited. 



It was ascertained at an early stage of the inquiry that the bromide 

 of silicon is much superior to the chloride as a reagent with nitro- 

 genised compounds, but since the bromide had apparently not been 

 obtained in any quantity even by its discoverer, Serullas, considerable 

 time had to be devoted to working out a method for the production 

 of a sufficiently large supply of this material. 



In the purification of the crude tetrabromide a new chlorobromide* of 

 silicon was discovered, which boils at 141 C. This proved to be the 

 compound SiClBr 3 , which was required to complete the series of 

 possible chlorobromides of silicon. 



The first group of nitrogen compounds subjected to the action of 

 silicon tetrabromide included the primary thiocarbamide or sulphur 

 urea, obtained by the author in 1869, and the allyl-, phenyl-, and 

 diphenyl-thiocarbamides. 



All these are shown to unite with silicon tetrabromide and afford 

 the highly condensed compounds 



(H 4 N 2 CS) 8 SiBr 4 , 

 (C 3 H 5 ,H 3 N 2 CS) 8 SiBr 4 , 

 (C 6 H 5 ,H 3 tf 2 CS) 8 SiBr 4 , 

 ((C 6 H 5 ) 2 H 3 N 2 CS) 8 SiBr 4 . 



These are more or less vitreous solids, with the exception of the 

 allylic compound, which is a transparent and singularly viscous 

 liquid. All are dissolved and decomposed by water and by alcohol. 



The action of alcohol on the compound (H 4 N 2 CS) 8 SiBr 4 , was 

 studied in detail, and it is shown that not only do ethyl bromide, 

 thiocyanate, and diethylic silicate result, but that the representatives 

 of two new classes of thiocarbamide derivatives are formed. 



* The chlorine required for the production of this compound was derived from 

 the crude bromine (which always contains chloride of bromine) used in preparing 

 the tetrabromide. 



