What is Tollen's reagent? Explain its reaction with aldehydes.

Ammonical silver nitrate solution is called Tollen's reagent. On warming an aldehyde with Tollen's reagent a bright silver mirror is produced due to the formation of silver metal. The aldehydes are oxidsied to correspoinding carboxylate ion
$\mathrm{R}-\mathrm{CHO}+2{\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\right]}^{+}+3{\mathrm{OH}}^{-}\stackrel{ }{\to \mathrm{R}-{\mathrm{COO}}^{-}+2\mathrm{Ag}\downarrow +2{\mathrm{H}}_2\mathrm{O}+4{\mathrm{NH}}_3}$