$PCC$ is

Compound $A$ and $C$ in the following reaction are
$CH_3CHO$ $\xrightarrow[(i) \, CH_3MgBr]{(ii) \, H_2O} A$ $\xrightarrow{H_2SO_4, \Delta} B$ $\xrightarrow{\text{Hydroboration-Oxidation}} C$

$A$ compound with the molecular formula ${C_4}{H_{10}}O$ reacts with sodium and gives a carbonyl compound upon oxidation,which does not reduce Tollen's reagent. What is the original compound?

$A$ 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 $140^{\circ} C$ yields an inhalable anesthetic $D$. Identify $A, B, C$ and $D$,respectively.

$A$ better reagent to oxidize primary alcohols into aldehydes is

Product $A$ is$:-$
$H-CHO \xrightarrow[(ii) D_2O]{(i) C_6H_{11}MgBr} A$