Final answer:
The appropriate compounds to promote cationic polymerization of isobutylene are sulfuric acid (H2SO4) and boron trifluoride (BF3), both of which can help stabilize carbocation intermediates necessary for the reaction.
Step-by-step explanation:
The compounds appropriate for promoting the cationic polymerization of isobutylene are substances that can act as strong Lewis acids or protic acids, which help stabilize the carbocation intermediates necessary for this type of polymerization. Both sulfuric acid (H2SO4) and boron trifluoride (BF3) are suitable for this role. Sulfuric acid is a strong protic acid that can donate a proton to initiate the polymerization, while boron trifluoride is a strong Lewis acid that can stabilize carbocation intermediates. Thus, the correct answer is: E) both H2SO4 and BF3.
Substances like sodium hydroxide (NaOH) are not useful in this context because NaOH is a strong base and would promote deprotonation rather than supporting carbocation formation. Peroxides (ROOR) are typically used to initiate free radical polymerizations, not cationic ones. Hence, options A), B), and E) are correct.