Short Answer TypeAlthough phenoxide ion has more number of resonating structures than Carboxylate ion, Carboxylic acid is a stronger acid than phenol. Give two reasons.
On losing a proton, carboxylic acids forms carboxylate ion and phenol forms phenoxide ion as follows:
|
RCOO-Carboxylate ion |
Phenoxide ion |
Now, the negative charge is delocalized in both molecules as follows:
The conjugate base of the carboxylic acid has two resonance structures in which negative charge in delocalized over two oxygen atoms (since O is more electronegative than C) which stabilises the carboxylate ion.
On the other hand, in phenoxide ion the charge is delocalized over entire molecule on the less electronegative atom (Carbon), thus resonance of phenoxide is not important in comparison to resonance in carboxylate ion.
Further, in carboxylate ion, the negative charge is effectively delocalized over two oxygen atoms whereas it is less effectively delocalized over one oxygen atom and a less electronegative carbon atom.
Thus, Phenol is less acidic than carboxylic acids. In other words, carboxylic acids are stronger acids than phenol
Long Answer TypeGive simple chemical tests to distinguish between the following pairs of compounds:
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol
Short Answer TypeArrange the following compounds in an increasing order of their reactivity in nucleophilic addition reactions: ethanol, propanal, propanone, butanone.
Draw the structure and name the product formed if the following alcohols are oxidised. Assume that an excess of oxidising agent is used.
(i) CH3CH2CH2CH2OH
(ii) 2-butenol
(iii) 2-methyl-1-proponal
Write chemical equation for the following conversions:
(i) Nitrobenzene to benzoic acid.
(ii) Benzyl chloride to 2-phenylethanamine.
(iii) Aniline to benzyl alcohol.
How would you obtain
(i) Picric acid (2, 4, 6-trinitrophenol) from phenol,
(ii) 2-Methylpropene from 2-methylpropanol?
How do you convert the following:
(i) C6H5CONH2 to C6H5NH2
(ii) Aniline to phenol
(iii) Ethanenitrile to ethanamine
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