Chemistry - GOC Question with Solution | TestHub

NaH is a very strong base (conjugate acid ${\mathrm{H}}_2$, $\mathrm{p}{K}_{\mathrm{a}}$ ≈ 35) and 4-methylphenol is far more acidic than ${\mathrm{H}}_2$ ($\mathrm{p}{K}_{\mathrm{a}}$ ≈ 10), so the hydride ion removes the phenolic proton and hydrogen gas is evolved. Note that 4-methylphenol is too weak to react with $\mathrm{NaHC}{\mathrm{O}}_3$, but reacts readily with NaH.