Question

trans-But`-2-`ene reacts with cold dilute `KMnO_(4)` solution to yield
A. butane`-2,3-`dione
B. `(+-)`butan`-2-`ol
C. meso-butane`2-,3-`diol
D. `(+-)`butane`-2,3-`diol

Answer 1

Correct Answer - D
It is syn hydroxylation with basic aqueous `KMnO_(4)`

We get the same result with cataytic amounts of `OsO_(4)` (osmiun tetroxide) in `H_(2)O_(2)` but `KMnO_(4)` is preferred to `OsO_(4)` because `OsO_(4)` is expensive and very toxic as it causes blindness. This problem can be minimized by using a catalytic amount of `OsO_(4)` with `H_(2)O_(2)` which regenerates the `OsO_(4)` by oxidizing the reduced form of `Os` resulting form the hydroxylation.
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