91Ó°ÊÓ

Alkene on reaction with osmium tetroxide in the presence of hydrogen peroxide gives diol as the product. Cis-alkenes on reaction with , forms syn-diol meaning, both the hydroxyl groups have same stereochemistry and product formed will be a meso product means, product which has plane of symmetry, optically inactive and has atleast two chiral centres.

Reaction (a)

Cis-alkenes on reaction with peroxy acid undergo epoxidation reaction, and epoxide ring is formed in one plane only, that is, either above or below. When water is added into the reaction, it acts as a nucleophile and attacks from different plane as that of epoxide ring, and thereby generating trans product, that is, both the hydroxyl groups are trans to each other and product formed is racemic in nature.

Reaction (b)

Trans-alkenes on reaction with peroxy acid undergo epoxidation reaction, and epoxide ring is formed in one plane only, that is, either above or below. When water is added into the reaction, it acts as a nucleophile and attacks from different plane as that of epoxide ring, and thereby generating trans product, that is, both the hydroxyl groups are trans to each other and after rotation through the single bond so as to bring both hydroxyl groups in proper orientation, both hydroxyl groups becomes cis to each other and product formed will be meso in nature.

Reaction (c)

Alkene on reaction with osmium tetroxide in the presence of hydrogen peroxide gives diol as the product.Trans-alkenes on reaction with , forms syn-diol meaning, both the hydroxyl groups have same stereochemistry and after rotation through the single bond, so as to bring both hydroxyl groups in proper orientation, both hydroxyl groups become trans to each other and product formed will be a racemic product.