Final answer:
Phenols react with sodium hydroxide to form salts via acid-base neutralization, while alcohols typically do not react unless a very strong base like a hydride ion is present.
Step-by-step explanation:
Alcohols and phenols exhibit different reactivity patterns towards strong bases such as sodium hydroxide (NaOH). Phenols, which have an OH group attached to an aromatic ring, are slightly acidic in water. When they react with aqueous sodium hydroxide, they form salts through an acid-base neutralization reaction:
ArOH(aq) + NaOH(aq) → ArONa(aq) + H₂O
For example, phenol (∖H₅OH), a common parent compound of phenols, will react with sodium hydroxide to form phenoxide sodium (ArONa) and water, highlighting its acidic character in the presence of a strong base. The reaction mechanism involves the hydroxide ions (OH-) from the NaOH attacking the hydrogen atom on the phenol's hydroxyl group, leading to the formation of water and the phenoxide ion, which then associates with the sodium ion to form the sodium phenoxide salt.
In contrast, alcohols with an OH group attached to an alkyl group, typically do not react with sodium hydroxide in the same way phenols do because they are less acidic (higher pKa). However, in the presence of a sufficiently strong base, such as a hydride ion (from sodium hydride, NaH), alcohols can be deprotonated to form alkoxides:
R-OH + H- → R-O- + H₂