September 1, 1911.] 



THE INDIA RUBBER WORLD 



477 



Actual Synthetic Rubber. 



FOR tlie rirst time in the history of the rubber trade what ap- 

 pears to be real rubber produced by synthesis has been upon 

 exhibition in England. Nor was it shown by charlatans or 

 self-deceived inventors. The producers are reputable chemists and 

 deceived inventors. The producers are reputable chemists and 

 physicists, and there is no indication of stock promotion, sale of 

 rights or attempt at trade revolution. 



Dr. Silberrad, Ph.D., M. R. S. A., F. C. S., etc., thus takes the 

 world into his confidence : — 



The synthesis of substances originally obtained from natural 

 sources is by no means new. Among a multitude of others now 

 of considerable mercantile importance the following may be men- 

 tioned as examples: Indigo, vanilline, and oil of wintergrcen. 

 Thus synthetic rubber, although prepared "chemically," is not a 

 substance adulterated with chemicals and not therefore inferior 

 from that point of view. It has been suggested that synthetic 

 rubber, while it might be of use for such purposes as insulation 

 in electric work, would not be sufficiently strong for rough wear 

 as in tires, etc. This is altogether a wrong suggestion. Synthetic 

 rubber is rubber, and rubber only, and should 'be as well adapted 

 for all work in which rubber is used as the natural product. 



The basis from which we finally produce rubber is isoprene. 

 This is converted into rubber by a process of polymerization, that 

 is to say, two or more molecules become linked together, the 

 component elements simultaneously assuming a different con- 

 figuration. This reaction may thus be graphically represented : 



X CH, = C— CH = CH, + X CH. = C — CH = CH, 



I I 



CH, CHs 



2x molecules ot Isoprene yield 



f — CH = C — CH, — CH.. — CH = C— CH,-CH., — ] 



1 I ^ 



[ CH. CHs \x 



one molecule of rubber. 



Precisely what value x has or whether the first and last carbon 

 atoms are linked together to form a ring is still a matter of un- 

 certainty, and need not be further discussed here. 



Synthetic rubber, then, is obtained from Isoprene by a process 

 of polymerization. It will be found to possess the same physical 

 features and constitution as natural rubber, and may be used for 

 the same purposes and in the same way. 



Although the process is patented in England and Germany, and 

 patents arc pending all over the world, we are unable at this stage 

 to give the names of the materials used, as it is obvious that some 

 reserve must be maintained in this relation. The raw materials 

 have a commercial value, and there is not an unlimited supply; 

 and although the quantity available is very considerable, the 

 sudden demand for thousands of tons would cause the price to 

 rise ; so that the quantity of rubber it would eventually pay to 

 manufacture would depend on the price of the natural product. 



The cost of manufacture also depends so much on variable 

 conditions that only a rough approximation can be arrived at at 

 this stage. Also by-products have to be considered, and until 

 the market values of these are established on a manufacturing 

 scale, it is impossible to state an exact price at which the finished 

 product can be produced. Taking all known data into account, 

 however, we arrive at a cost of about 17 cents per lb. for Isoprene, 

 so that 20 cents may be regarded as a very conservative estimate. 



As regards the conversion of Isoprene into rubber, there is yet 

 much work to be done, both as regards yield and purity. At 

 present it is questionable whether the synthetic product could. b,e, 

 manufactured to compete with the natural even at present prices. 

 We have, however, made great strides of late, and are now able 



to produce a hard rubber quite distinct from the soft and sticky 

 material so lacking in strength, which is all that has heretofore 

 been synthetically produced. 



The process is absolutely unburdened in any way; no expendi- 

 ture other than that directly necessary to the pursuance of the 

 work and obtaining of the patents having been incurred ; the re- 

 sults have proved so promising that it has "been decided to form 

 a small powerful syndicate to pursue a more energetic policy. 



In conclusion, it should be clearly pointed out that no sug- 

 gestion as to the possibility of synthetic rubber ousting the 

 natural product from the market is entertained. Thus, although 

 there is every prospect of this process becoming of the greatest 

 commercial importance, we deprecate any suggestion that these 

 statements be made the cause of apprehension on the part of 

 planters or shareholders in rubber companies. 



Dr. Heinemann, of the Caoutchouc Syndicate, when inter- 

 viewed by an Indi.a Rubber World correspondent gave out the 

 following : 



"Regarding the manufacture of isoprene rubber, the present 

 method adopted to manufacture isoprene consists in the destruc- 

 tive distillation of turpentine by passing the turpentine over 

 contact substances like copper or silver which allow a lower 

 temperature, so as to prevent the polymerization of the already 

 formed isoprene. The yield obtained varies according to the 

 turpentine used. American gives, of course, a higher yield of 

 isoprene than Russian. This depends on the quantity of pineine 

 present. (See English patent 14040/1910. American patent not 

 yet published.) 



"Another method is the conversion of carbohydrates like starch, 

 sawdust, etc., into isoprene by first making laevulinic acid and 

 the latter being transformed into thioholene, which is again 

 reduced to isoprene. A full description of this process is pub- 

 lished in the English patent No. 13252, 1908, and the American 

 patent No. 951,072. Either of the above mentioned methods is 

 fully satisfactory-, so that isoprene can now be called a com- 

 mercial article. 



"The conversion of isoprene into rubber is, of course, quite 

 well known, but our method is in so far new as I have succeeded 

 in improving the process, that is, I get a better yield in rubber 

 from isoprene in a short period of time. 



"One of our processes consists in treating the isoprene with 

 ozone, followed by heating the ozonized isoprene. (English 

 patent No. 14041, 1910, American patent not yet printed.) A 

 second way of polymerization is the treatment of the isoprene 

 with certain organic substances to gain a material absolutely like 

 the natural, genuine rubber. (Patent applied for.) 



"Either method gives a yield of about 40 to 50 per cent, of 

 rubber. The cost of material for producing one pound of 

 isoprene is about 6 cents whilst the cost of the pound of rubber 

 is 12 cents. This sum, of course, does not include expenses of 

 manufacture, etc., which will be about 4 to 6 cents per pound." 



The German chemists say of the process: 



"The Caoutchouc Syndicate employs, ostensibly, as the basic 

 material for the production of isoprene, carbohydrates (saw- 

 dust, starch, sugar) from which in a manner that could not be 

 definitely ascertained, with laevulinic acid CH;^ CO CH, CHj 

 CO OH and the thiotol of which the formula is: 

 C H C H 



isoprene was produced. The firm exnioit large quantities of 

 isoprene and samples of synthetic rubber. Ostensibly 4.409 



