COMPASSLearning
RegisterLogin

JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

WhatsApp Email
'A' in the given reaction is
Structure A
A
Structure B
B
  1. (A)(see structure)
  2. (B)(see structure)
    ✓ Correct
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (B)

Solution

Pivaldehyde and 2-hydroxy-2-methylpropanoic acid condense in acid: the protonated aldehyde carbon is attacked by the hydroxyl oxygen of the acid, and loss of water then closes a ring as the carboxyl oxygen bonds to the same carbon. The five-membered ring that forms is a 1,3-dioxolan-4-one carrying the tert-butyl group on the acetal carbon and the two methyl groups on the carbon next to the ring carbonyl. The major product is 2-tert-butyl-5,5-dimethyl-1,3-dioxolan-4-one.

JEE Main · 2023 · 25 Jan 2023 · 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 →