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Saturday, 31 October

JEE Main 2017 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 2 April 2017 (offline), Chemistry Q60

Question 60 of 90 in this shift, Chemistry question 30 of 30.

The major product obtained in the following reaction is : [reaction: bicyclic lactone (cyclopentene fused to a five-membered lactone, with COOH on the ring double bond carbon) with DIBAL-H]

The figure, in words

Starting material: cyclopentene-fused γ-lactone (O in ring, C=O) with COOH on the alkene carbon; reagent DIBAL-H; options are substituted cyclopentenes.
  1. (1)[structure: cyclopentene ring with CH2CHO\mathrm{CH_2CHO} and COOH substituents on the double-bond carbons]
  2. (2)[structure: cyclopentene ring with CH2CHO\mathrm{CH_2CHO} and CHO substituents on the double-bond carbons]
  3. (3)[structure: cyclopentene ring with OH, CH2CHO\mathrm{CH_2CHO} and COOH substituents]Official answer
  4. (4)[structure: cyclopentene ring with OH, CH2CHO\mathrm{CH_2CHO} and CHO substituents]

Official answer

Option 3

CBSE answer key (25/04/2017, used for result).

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Carboxylic Acids and Derivatives
Idea tested
DIBAL-H Selective Reduction

Same idea in other shifts

Asked 4× in all
  1. 25 Jul 2022, Shift 1 · Q75Which one of the following reactions does not represent correct combination of substrate and product under the given conditions ?MediumDiagram basedHas a figure
  2. 29 Jul 2022, Shift 1 · Q78Consider the following reaction sequence : [figure: 4-aminobenzonitrile (benzene ring with NH2\mathrm{NH_2} at top, CN at bottom)…MediumDiagram basedHas a figure
  3. 25 Feb 2021, Shift 1 · Q46Which one of the following reactions will not form acetaldehyde ?MediumSingle correct

Question text from the official JEE Main paper published by NTA (CBSE ran the 2017 exam); answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.