Practical Organic Chemistry

A toxic compound "A" when reacted with NaCN in aqueous acidic medium yields an edible cooking component and food preservative " B ". " B " is converted to " C " by diborane and can be used as an additive to petrol to reduce emission. "C" upon reaction with oleum at 140∘C yields an inhalable anesthetic " D ". Identify " A ", " B ", " C " and " D ", respectively.