Aldehydes, Ketones and Carboxylic Acids

Aldehydes, Ketones and Carboxylic Acids

Question

(a) Write a suitable chemical equation to complete each of the following transformations:

(i) Butan-1-ol to butanoic acid

(ii) 4-methylacetophenone to benzene-1, 4-dicarboxylic acid

(b) An organic compound with molecular formula C9H10O forms 2, 4-DNP derivative, reduces Tollen’s reagent and undergoes Cannizzaro’s reaction. On vigorous oxidation, it gives 1, 2-benzenedicarboxylic acid. Identify the compound.

Answer

(i) Butanoic acid can be obtained by oxidation of butan-1-ol.

The most common reagent used for oxidation of alcohols is chromium (Vl) reagents including chromic acid (H2CrO), potassium dichromate (K2Cr2O7) and chromic anhydride (CrO3).

 stack CH subscript 3 CH subscript 2 CH subscript 2 CH subscript 2 OH with Butanol below space rightwards arrow from ii right parenthesis space Dil. straight H subscript 2 SO subscript 4 to straight i right parenthesis space straight K subscript 2 Cr subscript 2 straight O subscript 7 divided by straight H subscript 2 SO subscript 4 of space stack CH subscript 3 CH subscript 2 CH subscript 2 COOH with Butanoic space Acid below

(ii)  4- methylacetophenone can be converted to benzene-1, 4- dicarboxylic acid as follows:

 

 

 

(b) It is given that the compound (with molecular formula C9H10O) forms 2, 4-DNP derivative and reduces Tollen’s reagent. Therefore, the given compound must be an aldehyde.

Again, the compound undergoes Cannizzaro reaction and on oxidation gives 1, 2-benzenedicarboxylic acid. Therefore, the -CHO group is directly attached to a benzene ring and this benzaldehyde is ortho-substituted. Hence, the compound is 2-ethylbenzaldehyde.


2 – ethyl bezaldehyde

The given reactions can be explained by the following equations.

 

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