JEE Advanced 2020 · Paper 2 · Chemistry Q6

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ChemistryInteger+3 / -1Question 24 of 54

An organic compound ( $\ce{C8H10O2}$ ) rotates plane-polarized light. It produces pink color with neutral $\ce{FeCl3}$ solution. What is the total number of all the possible isomers for this compound?

Your answer

Answer and worked solution

Official answer: 6

What the tests mean.

A pink/violet colour with neutral $\ce{FeCl3}$ means a phenol.
Optical activity means a stereocentre.

The formula. $\ce{C8H10O2}$ has 4 degrees of unsaturation, all in the benzene ring. That leaves $\ce{HO-C6H4-}$ plus a $\ce{C2H5O}$ unit, which must contain the stereocentre. The only chiral choice is $\ce{-CH(OH)CH3}$ .

Counting. The side chain can be ortho, meta or para to the phenol OH: 3 structures, each a pair of enantiomers.

Answer: 6

Topics:Optical isomerism and chirality Structural isomerism Phenols

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JEE Advanced 2020 · Paper 2, Chemistry question 6