(R)-(3-Chloro-2-methylpropyl) methyl ether (A) on reaction with azide ion (N3-) in aqueous ethanol gives (S)-(3-azido-2-methylpropyl) methyl ether (B). Compound A has the structure ClCH2CH(CH3)CH2OCH3. Draw the wedge-dash, wedge-line formula for A and B