1. Tardigrade
  2. Question
  3. Chemistry
  4. A basic volatile nitrogen compound gave a foul smelling gas when treated with chloroform and alcoholic KOH. A 0.295 g sample of the substance dissolved in aq. HC1 and treated with NaNO2 solution at 0°C, liberated a colourless, odourless gas whose volume corresponds to 112 mL at STP. After evolution of the gas was complete, the aqueous solution was distilled to give an organic liquid which did not contain nitrogen and which on warming with alkali and iodine gave a yellow precipitate. Identify the original substance assuming that it contains one N-atom per molecule.

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Q. A basic volatile nitrogen compound gave a foul smelling gas
when treated with chloroform and alcoholic KOH. A 0.295 g
sample of the substance dissolved in aq. HC1 and treated with
NaNO$_2$ solution at 0$^{\circ}$C, liberated a colourless, odourless gas
whose volume corresponds to 112 mL at STP.
After evolution of the gas was complete, the aqueous solution
was distilled to give an organic liquid which did not contain
nitrogen and which on warming with alkali and iodine gave a
yellow precipitate. Identify the original substance assuming that
it contains one N-atom per molecule.

IIT JEEIIT JEE 1993

Solution:

Starting compound is a primary amine.
$R-NH_2+CHCI_3 +KCI \rightarrow _{foul \ smell}^{R-NC}$
Also, $ \ \ \ \ R-NH_2+HNO_2 \rightarrow R-OH+N_2$
Moles of $N_2 =\frac{112}{22500}=5 \times ^{-3}$
$\because One \ mole \ of \ N_2 $ 2 is obtained from 1.0 mole of R- NH$_2$, mole
$of \ R-NH_2=5 \times 10^{-3}$
$\Rightarrow \\ 5 \times 10^{-3} mol \ R-NH_2 weight=0.295 g$
1 mole of $R-NH_2 \ will \ weigh =\frac{0.295}{5 \times 10^{-3}}=59 g$
$In \ R-NH_2 -NH_2$has molar mass =16
$\Rightarrow \ \ \ R-has \ molar \ mass=43$
Also, the alcohol R-OH gives iodoform test; it must has the
following skeleton :

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