Exercise2 Question 14
How does the presence of double bonds in rubber molecules influence their structure and reactivity?
Natural rubber is a linear cis-1,4-polyisoprene in which double bonds are present between C2 & C3 of isoprene units.The cis configuration about double bonds does not allows the chains to come closer for effective intermolecular attraction due to weak intermolecular attractions.Therefore,the natural rubber has coiled structure & shows elasticity & is non crystalline.
On the other hand, all trans configurations occur in gutta-percha(synthetic rubber) which is trans-polyisoprene.These zig-zag chains pack more closely in gutta-percha & hence it is highly crystalline & non elastic & is more hard & brittle than rubber.
