[boswell] 



THE CONSTITUTION OF RUBBER 



31 



which should decompose in a manner similar to the ozonides of other 

 diethylenic compounds. Accordingly rubber would have the con- 

 stitution of polymerized symmetrical dimethyl cyclo octadiene: 



QH^ 





CHo~~ C — CH —~ CHz 





Until quite recently Harries has been an ardent advocate ^of this 

 constitution. Indeed, it does appear, as Harries has pointed out, to 

 represent many of the conclusions just referred to. ïi consists of 

 C10H16 groups linked together, each C10H16 containing two double 

 bonds, which is, as we have seen, in harmony with the conclusions 

 arrived at by investigators up to that time, and it is apparently in 

 harmony with the formation of a diozonide yielding upon decom- 

 position, laevulinic aldehyde and acid. Harries also maintained that 

 it satisfactorily represents the formation of isoprene and dipentene, 

 upon distillation of rubber. It will be observed that in the formation 

 of isoprene the molecule is represented as breaking at two single 

 bonds and not at the double bonds, which are the usual points of 

 weakness. Also in the formation of dipentene a marked inter- 

 molecular displacement must be assumed, unless the dipentene has 

 been produced, by polymerization of isoprene first formed in the 

 distillation. 



Harries also maintained that still further support for this con- 

 stitutional formula for rubber was obtained from, the fact that the 

 synthetic rubber obtained by him by the polymerization of butadiene 

 was identical with a hydrocarbon which Willstatter had prepared 

 from a naturally occurring alkaloid pseudo-pelletierin, and which 

 Harries showed to have the constitution cyclo octadiene. This 

 synthetic rubber and this hydrocarbon gave a diozonide C8H12O6 

 which on decomposition yielded succinic acid in the normal fashion. 



CHs-CH'CH-CH^ 



CH^'CH=CH-CH2 



CYCLO -OCTADIENE 



00-0 

 Cf-O-O 



CH2-CH-CH-CH2 

 piozoNiDE or 



CYCLO - OCTADIENE 



CH2-C-OH 



CH^-C'OH 



SUCCINIC ACID 



