THE CHEMISTRY OF INDIARUBBER 



509 



ozonide C 10 H 16 O 6 is decomposed with water. This decompo- 

 sition can be expressed — 



CioH te O s +H,0 = CH,-CO-CH 2 -CH,-CHO + CH 8 - C -CH,-CH,- CH 



Ozonide 



Levidinic aldehyde 



0=0= o =0 



Levulinic aldehyde peroxide. 



On boiling with water the peroxide decomposes into levulinic 

 aldehyde and hydrogen peroxide, H 2 2 . These were the only 

 products formed by the decomposition of the ozonide, and, 

 indirectly, of the caoutchouc molecule. The arrangement of 

 carbon atoms and double bonds is identical in both the aldehyde 

 and the aldehyde peroxide, viz. 



CH 3 - C - CH.. - CH, - CH 



so it is necessary to have a formula for caoutchouc which 

 contains multiples of this complex. Moreover, it must contain 

 a closed, not an open, carbon chain, and, as the molecular weight 

 of the ozonide was found to agree with the formula C 10 H 16 O 6 , 

 Harries concluded that the closed chain consisted of two of the 

 above groups, forming an eight-carbon ring, thus : 



CH, - C - CH, - CH 3 - CH 



II II 



CH- CH., - CH, - C - CH 3 



1 : 5 Dimeth) 1-cyclo-octadiene A 1 ■ 5 



Accepting this formula for the chemical molecule of caoutchouc, 

 the ozonide would be represented — 



CH - CH., - CH, - C - CH 3 



Splitting up as indicated by the dotted line, this would give 

 one molecule of levulinic aldehyde peroxide, and one molecule 

 of levulinic aldehyde — 



CH 3 - C - CH, - CH, - CH 



1 molecule 

 1 molecule 



0=0 = 0=0 

 CHO - CH 2 - CH, - CO - CH 3 



+ 



the scheme thus providing a reasonable explanation of the 

 observed facts. 



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