COMPASSLearning
RegisterLogin

JEE Main · 2020 · 03 Sep 2020 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

WhatsApp Email
The increasing order of the reactivity of the following compounds in nucleophilic addition reaction is:
Propanal, Benzaldehyde, Propanone, Butanone
  1. (A)Benzaldehyde < Propanal < Propanone < Butanone
  2. (B)Butanone < Propanone < Benzaldehyde < Propanal✓ Correct
  3. (C)Propanal < Propanone < Butanone < Benzaldehyde
  4. (D)Benzaldehyde < Butanone < Propanone < Propanal

Answer: (B)

Solution

Nucleophilic addition at a carbonyl runs faster when the carbonyl carbon is more electrophilic and less crowded. Aldehydes beat ketones on both counts. Among the aldehydes, propanal is more reactive than benzaldehyde, whose carbonyl is deactivated by conjugation with the ring. Among the ketones, propanone is more reactive than the bulkier butanone. Arranged from least to most reactive, the order is butanone, then propanone, then benzaldehyde, then propanal.

JEE Main · 2020 · 03 Sep 2020 · Shift 2 · Single correct option

Practise more: all JEE Main PYQs on Aldehydes Ketones and Carboxylic Acids →

More JEE Main questions on Aldehydes Ketones and Carboxylic Acids

  1. An organic compound "P" of molecular formula gives positive iodoform test but negative Tollen's test. When "P" is treated with dilute acid, it produces "Q". "Q" gives positive Tollen's test and also iodoform test. The structure of …
    JEE Main 2026View solution →
  2. Match List-I with List-II.

    List-I (Reaction Name - Involving aldehydes):
    I. Etard Reaction
    II. Rosenmund Reduction
    III. Gatterman-Koch Reaction
    IV. Stephen Reaction

    List-II (Reagents):
    A. , Pd-
    B. , HCl
    C. …
    JEE Main 2026View solution →
  3. The compound A, reacts with acetophenone to form a single product via cross-Aldol condensation. The compound A on reaction with conc. NaOH forms a substituted benzyl alcohol as
    JEE Main 2026View solution →
  4. ' ' is the product which is obtained from propanenitrile and stannous chloride in the presence of hydrochloric acid followed by hydrolysis. ' y ' is the product which is obtained from the but-2-ene by the ozonolysis followed by hydrolysis. From the following, which product is …
    JEE Main 2026View solution →
  5. From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :
    JEE Main 2026View solution →
  6. Iodoform test can differentiate between
    A. Methanol and Ethanol
    B. and
    C. Cyclohexene and cyclohexanone
    D. Diethyl ether and Pentan-3-one
    E. Anisole and acetone

    Choose the correct answer from the …
    JEE Main 2026View solution →