Phenol Answers
 

Qu1:	In order to establish acidity, it is often a good idea to consider the simple acidity equilibria,  HA <=>  H+ + A- and look for factors that stabilize the conjugate base, A- since that implies that HA is a stronger acid....
(a)	Carboxylic acids (pKa»5) are more acidic than phenols (pKa»10) which in turn are more acidic than simple alcohols (pKa»16 - 20). The carboxylate anion is stabilized by resonance that allows the negative charge to be delocalised onto a second electronegative oxygen atom.  The phenolate ion can also be stabilized by resonance but the charge ends up on C atoms.  In contrast, the alkoxide ion has no resonance stabilisation since there is no p system.
(b)	All these structures are p-substituted phenols, so the substituent must be the controlling factor.  The effect the substituent exerts on the benzene ring will influence the stability of the phenolate ion.  A strong electron withdrawing group will stabilize the phenolate making the phenol more acidic whereas a strong electron donor will destabilize the phenolate making the phenol less acidic. A nitro group is strongly withdrawing due to resonance, a chloro group is weakly electron withdrawing due to inductive effects, a methyl group is a weak electron donor and a methoxy group a strong electron donor due to resonance.
(c)	All nitrophenols. As we saw in part (b) nitro groups stabilize the phenolate ion by resonance electron withdrawal that allows the negative charge to be moved to an electronegative oxygen atom in the nitro group when the nitro group is ortho- or para- to the -OH group. The more nitro groups there in these positions, the greater the stabilisation of the phenolate and the more acidic the phenol.
Qu2:	In each of the reactions the phenol is the nucleophile, either the aromatic ring or at the oxygen atom:
Qu3:	The aromatic ring of methoxybenzene undergoes similar reactions to those of phenol discussed above:

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