Question

Which of the following combinations can be used for the preparation of cis vis diol?
A.Alkene, Baeyer reagent
B.Alkene, $Os{O_4}$
C.Alkene, MMPP and ${H_2}O/{H^ + }$
D.Both A and B

Answer 1

Alkenes are unsaturated compounds consisting of one or more double-bonded carbon atoms. Alcohols are compounds consisting of $- OH$ functional groups. Alkenes can be converted into alcohols by the action of some reagents like osmium tetroxide and oxidizing agents like potassium permanganate.

Complete answer:
Chemical compounds are classified into functional groups based on the groups present in them. Alkenes are double-bonded carbon compounds consisting of only carbon and hydrogen atoms. Alcohols are the functional groups consisting of $- OH$ group.
When alkenes are treated with Baeyer’s reagent which is potassium permanganate, the alcohols will be formed. But the formed alcohols were formed as anti-products.
Alkenes when treated with osmium tetraoxide, whose molecular formula is $Os{O_4}$ forms a compound known as cyclic osmate ester. Upon treatment of this ester by $O{H^ - }$ which can hydrolyze ester leads to the formation of cis-diol.
Magnesium monoperoxy phthalate simply known as MMPP, is used for the epoxidation of alkenes but not leads to the cis vis diol.
Thus, alkenes when treated with $Os{O_4}$ can be used for the preparation of cis vis diol.

Option B is the correct one.

Note:
When a compound contains two hydroxyl groups it is known as a diol. Vicinal diols are the alcohols that have the hydroxyl groups on the adjacent carbon atoms. If the two hydroxyl groups were present on the same carbon atom, it is known as a geminal diol.