What measure may be needed to prevent polymerization or peroxide formation?

• A. Inhibitors
• B. Aldehydes
• C. Additional heating
• D. Additional primary reactant

Answer: (A)

The key idea is that runaway polymerization and peroxide formation are driven by radical chain reactions, so the way to prevent them is to stop those radicals from starting or propagating. Inhibitors are added to reactive liquids to scavenge free radicals (like initiating ROO• or R•) and interrupt the chain-propagating steps, effectively slowing or stopping polymer growth and peroxide buildup. They work by forming relatively stable radicals themselves or by quickly terminating reactive radicals, which keeps the material from reaching an exothermic, dangerous runaway. Aldehydes aren’t a reliable, general solution for this purpose and can introduce other side reactions; adding heat will usually accelerate polymerization; adding more reactant would supply more material for the reaction to proceed. So the preventive measure is to use an inhibitor.