91Ó°ÊÓ

Write structural formulas for substances (one for each part) that fit the following descriptions: (a) a phenol that would be a stronger acid than phenol itself (b) that isomer of dichlorophenol that is the strongest acid (c) the Claisen rearrangement product from a \(\alpha\) -methylally1 2,6 -dimethylpheny 1 ether (d) a quinone which does not undergo Diels-Alder addition (e) a quinone that would be a better charge-transfer agent than quinone itself.

Write structures for each of the following names: (a) m-cresol (b) 3 -hydroxybenzenesulfonamide (c) 3 -chloro-1, 2 -benzoquinone (d) o-methoxyphenol (e) \(\mathrm{p}(\mathrm{t}-\) tolyl \()\) azophenol (f) benzyl pheny 1 ether (g) \(3-\) (o-hydroxy phenyl pentanoic acid) (h) 2 -methoxy-1, 4 -naphthoquinone

In which of the" following compounds would you expect intramolecular hy drogen bonding to occur; o-nitroaniline, o-cresol, o-hydroxybenzoic acid (salicylic acid), o-hydro-benzaldehyde (salicylaldehyde), o-fluorophenol, o-hydroxy- benzonitrile.

How much difference in physical properties would you expect for o-and \(p\) -cyanophenol isomers? Explain.

(a) Why is phenol \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}\) a stronger acid than an alcohol? (b) Would para-acetylphenol be a stronger or weaker acid than phenol? (c) Would 2, 4 -dinitrophenol be a stronger or weaker acid than \(p\) -nitrophenol? Draw contributing structures to support the answers.

Ortho-nitrophenol L and para-nitrophenol L \(\mathrm{N}_{2}\) have different acidities, melting points, and boiling points. In all cases, the ortho- nitrophenol has lower values in these areas. Why?

How do you account for the fact that, unlike most phenols, \(2,4-\) dinitrophenol and \(2,4,6\) -trinitrophenol are soluble in aqueous sodium bicarbonate?

Write resonance structures that account for the stability of the cation of Wurster's salts. Explain why octamethyl- p-phenylenediamine does not form a similarly stable cation radical.

4-n-Hexylresorcinol is used in certain antiseptics. Outline its preparation starting with resorcinol and any aliphatic reagents.

Suggest a mechanism for the steps in the synthesis of phenolphthalein.