NEET Aldehydes Ketones and Carboxylic Acids — Set 13

Question 1

What is the product when butanal reacts with $ \ce{NaBH4} $?

Accepted Answer

$ \ce{NaBH4} $ reduces aldehydes to primary alcohols. Butanal ($ \ce{CH3CH2CH2CHO} $) forms butan-1-ol ($ \ce{CH3CH2CH2CH2OH} $).

Question 2

Which reaction sequence converts pentan-2-one to 2-methylpentane?

Accepted Answer

Step 1: $ \ce{NaBH4} $ reduces pentan-2-one ($ \ce{CH3COCH2CH2CH3} $) to pentan-2-ol ($ \ce{CH3CH(OH)CH2CH2CH3} $). Step 2: Clemmensen reduction (or dehydration + hydrogenation) yields 2-methylpentane ($ \ce{CH3CH(CH3)CH2CH2CH3} $), but Wolff-Kishner fits PDF scope directly.

Question 3

Which compound forms a cyclic acetal when treated with ethylene glycol?

Accepted Answer

Cyclohexanone ($ \ce{C6H10O} $), a ketone, reacts with ethylene glycol ($ \ce{HO-CH2CH2-OH} $) under acidic conditions to form a cyclic acetal, protecting the carbonyl group.

NEET Chemistry: Aldehydes Ketones and Carboxylic Acids — Practice Set 13

Q1. What is the product when butanal reacts with \( \ce{NaBH4} \)?

Q2. Which reaction sequence converts pentan-2-one to 2-methylpentane?

Q3. Which compound forms a cyclic acetal when treated with ethylene glycol?

Q4. Which reagent can oxidize an aldehyde to a carboxylic acid?

Q5. Which test produces a brick-red precipitate with propanal but not with propanone?

Q6. Which compound gives a positive Tollens' test and a negative Fehling’s test?

Q7. What is the product of the Clemmensen reduction of pentan-2-one?

Q8. Which test distinguishes propanal from propanone?

Q9. What is the product when cyclohexanecarbaldehyde reacts with \( \ce{PhMgBr} \) followed by hydrolysis?

Q10. What is the common name of \( \ce{C6H5COOH} \)?