JEE Main 2017 · 2 Apr · Shift 1 · Chemistry Q52

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ChemistrySingle correct+4 / -1Question 52 of 90

Which of the following, upon treatment with tert-BuONa followed by addition of bromine water, fails to decolourize the colour of bromine ?

1-Bromoethyl phenyl ether

2-Bromo-1-cyclohexylpropan-1-one

Bromomethyl cyclohexyl ether

1-Bromo-1,2-diphenylethane

Answer and worked solution

Official answer: C

With $tert$ -BuONa, a bromide that has β-hydrogens eliminates to an alkene, which then decolourises bromine water. In $\ce{C6H11-O-CH2Br}$ the carbon bearing Br has no β-hydrogen (its neighbour is O), so no alkene forms and the bromine colour stays.

Topics:Elimination reactions

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JEE Main 2017 · 2 Apr · Shift 1, Chemistry question 52