What is Stephen reaction ?

Explanation

Stephen's reaction : The partial reduction of alkyl or aryl cyanides to the corresponding aldehyde with a suspension of anhydrous `SnCl_(2)` in either saturated with `HCl` at room temperature followed by hydolysis.
`SnCl_(2)+2HCl rarr underset("Nascent hydrogen")(SnCl_(4)+2[H])`
`underset(("Methyl"),("Cyanide"))(CH_(3)-C)equiv N+2[H]+2HCl rarr underset(("Acetaldoxime"),("hydrochloride"))(CH_(3)CH=NHHCl) overset(H_(2)O("Soil"))(rarr) underset("Acetaldehyde")(CH_(3)CHO)+NH_(4)Cl`