372 CHEMICAL DISCOVERY AND INVENTION 



from the product is separated a mixture of mono-chlorinated 

 derivatives C^HnCl. These are brought into contact with 

 heated lime by which the elements of hydrogen chloride are 

 abstracted, and the result is a mixture of amylenes C 5 H 10 . These 

 hydrocarbons which belong to the series of olefmes are mixed 

 with hydrogen chloride whereby one only, namely trimethyl- 

 ethylene, combines with the acid in the cold, the two others are 

 separated and subjected to treatment by which they also are 

 converted into trimethylethylene. The product of the union of 

 this hydrocarbon with hydrogen chloride is the compound 

 CH 3 -C(CH 3 )C1-CH 2 -CH 3 , to which it is not necessary to apply a 

 name. This compound treated with chlorine yields two products 



CH 3 -C(CH 3 )C1-CHC1-CH 3 

 and CH 3 -C(CH 3 )C1-CH 2 -CH 2 C1 



both of which when deprived of HC1 by lime or soda yield 

 isoprene 



CH 2 : C(CH 3 )-CH : CH 2 . 



There are several variations of the procedure which lead to the 

 same result. In any case many operations are involved. 



The second process for rubber synthesis is the property of the 

 Synthetic Products Company. In this case isoprene is not the 

 intermediate material aimed at. Starch in any cheap form is 

 dissolved in boiling water which gelatinises it, and at the same 

 time destroys other ferments accidentally present. A peculiar 

 microbe discovered by Professor Fernbach of the Pasteur 

 Institute is then added and a fermentation ensues which results 

 in the production of a mixture of normal butyl alcohol and 

 acetone. These are easily separated by distillation as their 

 boiling points lie far apart. The butyl alcohol is converted by 

 hydrogen chloride gas into butyl chloride, CH 3 -CH 2 -CH 2 -CH 2 C1, 

 which is then acted on by chlorine gas with production of a 

 mixture of dichlorides from which, by removing hydrogen 

 chloride by passage over heated soda lime, the hydrocarbon 

 butadiene CH 2 : CH CH : CH 2 is produced. This compound is 

 more volatile even than isoprene and has to be condensed to the 

 liquid state by cooling, but like isoprene it undergoes con- 

 densation when kept in contact with sodium. The product is a 

 rubber not identical with natural rubber, but one which is 

 believed to be superior in some respects to that substance. 



As in the production of isoprene the operations which lead to 



