Question

How would you prepare the following diols?

Short answer

Answer

a)

b)

Step-by-step solution

Step-by-Step SolutionStep 1: Diols

Diols are compounds containing two hydroxyl groups (-OH). Trans-diols are formed by the opening of epoxides on reaction with aqueous acid. The C-OH and O-H bonds are formed, and the C-O bond is broken.

The preparation of (a) compound

a. In the first step, the compound is reacted with OsO₄ , and pyridine. Both oxygens of OsO₄ approach from the same side of the alkene. In the second step, the reaction with OsNaHSO₃ , and H₂O , the break down of cyclic Os compound happens, and forms diols along with osmium salt are formed.

The formation of Diol

The preparation of (b) compound

b. In the first step, 1-methylcyclohexene is reacted with peroxy acid and forms an epoxide ring. On further reaction with H₃O⁺, trans-1,2-diols are formed.

The formation of Diol