Chemistry Class 12 NCERT Solutions: Chapter 12 Aldehydes Ketones and Carboxylic Acids Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

Get top class preparation for CBSE/Class-12 right from your home: get questions, notes, tests, video lectures and more- for all subjects of CBSE/Class-12.

Q: 9. Write structural formulas and names of four possible aldol condensation products from propanal and butanal. In each case, indicate which aldehyde acts as nucleophile and which as electrophile.

Answer:

(i) Taking two molecules of propanal, one which acts as a nucleophile and the other as an electrophile.

Taking Two Molecules of Propanal

(ii) Taking two molecules of butanal, one which acts as a nucleophile and the other as an electrophile.

Taking Two Molecules of Butanal

(iii) Taking one molecule each of propanal and butanal in which propanal acts as a nucleophile and butanal acts as an electrophile.

Taking One Molecule Each of Propanal and Butanal

(iv) Taking one molecule each of propanal and butanal in which propanal acts as an electrophile and butanal acts as a nucleophile.

Taking One Molecule Each of Propanal and Butanal

Q: 10. An organic compound with the molecular formula forms 2,4-DNP derivative, reduces Tollens՚ reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.

Answer:

It is given that the compound (with molecular formula ) 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 group is directly attached to benzene ring and this benzaldehyde is ortho-substituted. Hence, the compound is 2-ethylbenzaldehyde.

2-Ethylbenzaldehyde

The given reactions can be explained by the following equations.

1,2 Benzenedicarboxylic Acid

Q: 11. An organic compound (A) (molecular formula ) was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C) . Oxidation of (C) with chromic acid produced (B) . (C) on dehydration gives but-1-ene. Write equations for the reactions involved.

Answer:

An organic compound A with molecular formula gives a carboxylic acid (B) and an alcohol (C) on hydrolysis with dilute sulphuric acid. Thus, compound A must be an ester. Further, alcohol C gives acid B on oxidation with chromic acid. Thus, B and C must contain equal number of carbon atoms.

Since compound A contains a total of carbon atoms, each of B and C contain carbon atoms.

Again, on dehydration, alcohol C gives but-1-ene. Therefore, C is of straight chain and hence, it is butan-1-ol.

On oxidation, Butan-1-ol gives butanoic acid. Hence, acid B is butanoic acid. Hence, the ester with molecular formula is butylbutanoate.

All the given reactions can be explained by the following equations.

On Oxidation, Butan-1-Ol Gives Butanoic Acid

Developed by: