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Friday, 9 October

JEE Main 2017 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 2 April 2017 (offline), Chemistry Q56

Question 56 of 90 in this shift, Chemistry question 26 of 30.

The major product obtained in the following reaction is : [reaction: (+)-C6H5CH(Br)CH2C6H5\mathrm{C_6H_5CH(Br)CH_2C_6H_5} (Br on wedge, H on hash at the stereocentre) with tBuOK\mathrm{{}^tBuOK}, Δ\Delta]

The figure, in words

Reactant drawn in wedge/hash form: stereocentre carries Br (bold wedge, up), H (hashed, up-right), C6H5 (lower left) and CH2C6H5 (lower right); labelled (+). Arrow with reagent tBuOK and heat.
  1. (1)(+)C6H5CH(OtBu)CH2C6H5(+)\mathrm{C_6H_5CH(O^tBu)CH_2C_6H_5}
  2. (2)(−)C6H5CH(OtBu)CH2C6H5(-)\mathrm{C_6H_5CH(O^tBu)CH_2C_6H_5}
  3. (3)(±)C6H5CH(OtBu)CH2C6H5(\pm)\mathrm{C_6H_5CH(O^tBu)CH_2C_6H_5}
  4. (4)C6H5CH=CHC6H5\mathrm{C_6H_5CH{=}CHC_6H_5}Official answer

Official answer

Option 4

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

Chapter
Haloalkanes and Haloarenes
Topic
Alkenes and Alkynes
Idea tested
Saytzeff vs. Hofmann Elimination

Same idea in other shifts

Asked 3× in all
  1. 2 Apr 2025, Shift 2 · Q75Consider the above sequence of reactions. 151 g of 2-bromopentane is made to react. Yield of major product P is 80% whereas Q is 100%.…MediumNumerical valueHas a figure
  2. 2 Apr 2017 (offline) · Q52Which of the following, upon treatment with *tert*-BuONa followed by addition of bromine water, fails to decolourize the colour of bromine ?HardSingle correctHas a figure

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 42 of the 174 JEE Main shifts held from 2017 to 2026.