SYNTHETIC RUBBER 86 



devising methods for (1) the production of isoprene 

 cheaply, and (2) the conversion of the isoprene into rubber. 

 Subsequently it was found that other hydrocarbons such 

 as butadiene (C4H6) and diisopropenyl (CeHio), which 

 contain two conjugated double linkages like isoprene, 

 also polj-merise in the same way with the production of 

 rubber-like products, and butadiene and its derivatives 

 have recently been adopted instead of isoprene in many 

 processes for the production of synthetic rubber. 



The rubbers obtained by the polymerisation of the two 

 hj- drocarbons isoprene and butadiene will not be identical, 

 but they will be closely related (possibly homologues), 

 and they appear to possess very similar physical pro- 

 perties. The butadiene rubber may, therefore, prove to be 

 as suitable for technical piu-poses as the isoprene rubber, 

 although differing somewhat from it in composition, but 

 this point will require to be demonstrated by actual 

 trials. 



A very large number of patents have been taken out 

 during the last few years for methods of preparing syn- 

 thetic rubber, and it is quite impossible to deal with the 

 subject in detail. The principal recent workers have 

 been Professor C. Harries of Berlin, who has published 

 a nmnber of very valuable papers on the subject, the 

 chemists of the Baeyer Farbenfabrik at Elberfeld, the 

 Badische Anilin und Soda Fabrik, and Messrs. Schering 

 in Germany, whilst in this comitry the group of chemists 

 associated with the Synthetic Products Company, Ltd., 

 have been prominent. 

 ^ The credit of first producing synthetic rubber in 

 quantity belongs to the Baeyer Farbenfabrik at Elberfeld, 

 v/here sufficient of the product was obtained to make 

 two complete sets of motor tyres as well as numerous 

 manufactm-cd articles. It was stated at the International 

 Congress of Applied Chemistry held at New York in 1912 

 that one set of these tyres had run over 10,000 miles. 

 The process used at Elberfeld for the preparation of 

 synthetic rubber was worked out by Dr. F. Hofmann, 

 and consists of the production of isoprene from 

 2)-cresol, a coal-tar distillation product, and the sub- 

 sequent conversion of the isoprene into rubber by 

 means of heat or by the addition of certain substances 

 such as albumen, blood serum, starch, and glycerin. The 



