Q. 26

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Answer :

S

A = acetic anhydride (CH3COO)2O


B = acetic acid, CH3COOH


C = ethyl acetate, CH3COOC2H5


D = ethanol, C2H5OH


E = acetone, CH3COCH3



OR


(a) (i)



(ii)


(b) (i) Pentan-2-one and Pentan-3-one can be distinguished by iodoform test. Aldehydes or ketones having at least one methyl group linked to the carbonyl carbon atom are oxidized by NaOI.


Pentan-2-one have one methyl group attached to carbonyl carbon so it reacts with NaOI and gives yellow ppt of CHI3 whereas there is no methyl group attached to carbonyl carbon in Pentan-3-one so it does not give this test.



(ii) Benzaldehyde and Acetophenone can be distinguished by iodoform test. Aldehydes or ketones having at least one methyl group linked to the carbonyl carbon atom are oxidized by NaOI.


Acetophenone have one methyl group attached to carbonyl carbon so it reacts with NaOI and gives yellow ppt of CHI3 whereas there is no methyl group attached to carbonyl carbon in Benzaldehyde so it does not give this test.



(c) Carboxylic acids do not give characteristic reactions of carbonyl group because of resonance stabilisation of carboxylate ion as shown below. Due to this there is no nucleophilic addition reaction on carbonyl group of carboxylic acid and therefore, it do not give characteristic reactions of carbonyl group.



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