[boswell] the constitution OF RUBBER 35 



CHa 



CH2-CH = C-CH2 



I I 



and (2) by means of the free bonds, thus 



/CH3 

 CHo-CH-C — CH2 



Obviously one mode of polymerization consists of a union of one 

 mol of isoprene exercising the free bonds represented in (2) with two 

 mois of isoprene exercising the free bonds represented in (1) to form 

 the following: 



CHo—CH C — CHp 



CH^ jOHs CH2 CH^ 



CHj-C = CH CH=-C-CH3 



This contains three isoprene nuclei arranged in such a way as 

 also to contain a dipentene nucleus. 



This now contains two double bonds, each of which might con-" 

 ceivably link up with a mol of isoprene by means of bonds as repre- 

 sented in (2), thus: 



CHp-CH —C — CHp 



CHp CHp CHp CHp 



K / \ / 



CHj-C — CH CH- C— CH3 



CH- C-CHp-CHp-CH-C-CH^ 



I C//^ I ' 



CHp ^————^-————— \ertp 



Many other methods of polymerization can be constructed, but 

 upon examination the resultant constitutions do not fulfil the require- 

 ments just discussed so adequately as does, I believe, this one. 



It represents a compound containing a dimethyl cyclo octadiene 

 group, a dipentene group and an isoprene group. It contains no 

 ethylene linkages at all. It should admit of easy depolymerization 

 in a variety of ways. Thus it should give rise to derivatives of 



