JEE Main 2026 — Jan 23, Shift 1 — Chemistry solution

JEE Main2026Jan 23, Shift 1Chemistry

The correct sequence of reagents for the conversion of X to Y is :

A
(i) NaOH (aq) (ii) Jones reagent (iii) H $_{3}$ O $^{+}$
B
(i) B $_{2}$ H $_{6}$ /H $_{2}$ O $_{2}$ (ii) NaOEt (iii) Jones reagent
C
(i) Jones reagent (ii) NaOEt (iii) Hot KMnO $_{4}$ /KOH
D
(i) NaOEt (ii) B $_{2}$ H $_{6}$ /H $_{2}$ O $_{2}$ (iii) Jones reagent

Solution

The chain has to be both moved from the benzylic carbon onto the next carbon and oxidised to —COOH. The sequence that does this cleanly:

Step 1 — NaOEt (E2): elimination of HBr from PhCH(Br)CH $_{3}$ gives styrene PhCH=CH $_{2}$ .

Step 2 — B $_{2}$ H $_{6}$ / H $_{2}$ O $_{2}$ (anti-Markovnikov hydration): styrene → PhCH $_{2}$ CH $_{2}$ OH (2-phenylethanol). The OH lands on the terminal carbon, moving the functional group away from the benzylic position.

Step 3 — Jones reagent (CrO $_{3}$ / H $_{2}$ SO $_{4}$ ): oxidation of the primary alcohol straight through to the carboxylic acid PhCH $_{2}$ COOH.

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