Question

$C{H}_{3}CH=CHC{H}_3\underset{\left(i\right)A}{\overset{\left(ii\right)B}{\to }}C{H}_3-\underset{OH}{\underset{|}{C}H}-\stackrel{OH}{\stackrel{|}{C}H}-C{H}_3$, $A\&B$ are

How would you get racemic mixture of 1, 2-butane diol from cis 2- butene?

• A. $A=KMn{O}_4/O{H}^{-},B=H_{2}O$
• B. $A=C{F}_3/C{O}_{3}H,B=H_{2}O$
• C. $A=Os{O}_4/O{H}^{-},B=H_{2}O$
• D. $A=O_3/H_{2}O,B=P{h}_{3}P$

Answer 1

The correct option is B $A=C{F}_3/C{O}_{3}H,B=H_{2}O$

Alkaline solution of potassium permanganate converts an alkene into vicinal diol. Cis 2- butene can be converted to the racemic mixture of 2, 3-butane diol by reaction with trifluoroperacetic acid (A) followed by hydrolysis with water (B).
The reaction with osmium tetraoxide in presence of base can be carried out in presence of tert butyl hydroperoxide. This ensures that highly toxic osmium tetraoxide is used in catalytic quantity.