question_answer 46)

  A natural linear polymer of2-methyl-l, 3-butadiene becomes hard on treatment with sulphur between 373 to 415 K and ?S?S? bonds are formed between chains. Write the structure of the product of this treatment ?

Answer:

                  The natural polymer of 2-methyl-l, 3-butadiene is cis-polyisoprene (natural rubber). On heating with sulphur between 373-415 K, vulcanization occurs as a result of which ?S?S? bridges or cross-links are introduced between polymer chains through their reactive allylic positions as shown below :