The use of phenols such as tert-butylcatechol as free-radical scavengers is based on the fact that phenolic hydrogens are generally abstracted by radicals, producing relatively stable phenoxyl radicals that interrupt chain processes of oxidation and polymerization. Alcohols such as cyclohexanol, on the other hand, do no function as radical scavengers. Explain why the two types of molecules differ in their ability to donate a hydrogen atom to a radical.