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Molecules having exact mirror images of itself and has non- super imposable mirror image is known as a chiral molecule. Enantiomers or optical isomers are two mirror images of a chiral molecule.

Epoxides react under both acidic and basic conditions. The products of the acid-catalyzed ring opening depend primarily on the solvent used.

Epoxides are considered to be more reactive since opening the epoxide ring relieves the strain of the three-membered ring. Strong bases can attack and open epoxides, even though the leaving group is an alkoxide. Amines can also open epoxides.

(a) The enantiomers of propylene oxide are $\text{(}S)\text{-2-methyoxirane}$ and$\text{(}R)\text{-2-methyoxirane}$ .

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(b)The acid-catalyzed hydrolysis of pure $\text{(}R\text{)-propyleneoxide}$ gives $\left(S\right)\text{-propane-1,2-diol}$.

$\text{acid-catalyzedhydrolysisof(}\mathrm{R}\text{)-propyleneoxide}$

(c) The base-catalyzed hydrolysis of pure$\text{(}R\text{)-propyleneoxide}$ gives $\left(\mathrm{R}\right)\text{-propane-1,2-diol}$.

$\text{base-catalyzedhydrolysisof(}R\text{)-propyleneoxide}$

(d) Acid catalyzed hydrolysis of epoxides gives the diols with anti-stereochemistry. The mechanism for this hydrolysis process involves protonation of oxygen (epoxide) that is followed by${{\text{S}}_{\text{N}}}^{\text{2}}$ attack by a water molecule. Anti-stereochemistry results since there is a back side attack of water on the protonated epoxide. Hence, we get the inversion of configuration. This is the reason for low enantiomeric excess of the product formed by acid-catalyzed hydrolysis.