Why does pnitrophenol react with NaOH and not HCl?
NaOH is a strong base so it abstracts the proton from
p-nitrophenol resulting in the formation of p-nitrophenoxide ion
and water, but HCl is a strong acid so its conjugate base (Chloride
ion) if in-case abstracts the proton from p-nitrophenol the
resulting p-nitrophenoxide will accept the proton released from
acid and again changes into p-nitrophenol, so there will not be any
effect. Simply p-nitrophenol is also a weak acid & there will
not be any reaction of it with strong hydrochloric acid.