Question

A basic volatile nitrogen compound gave a foul smelling gas when treated with chloroform and alcoholic potash. A 0.295 g sample of the substance dissolved in aq. HCl and treated with NaNO₂ Solution at 0^oC, liberated a colourless, odourless gas whose volume corresponded to 112 mL at STP. After the 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

Answer 1

A basic, volatile, nitrogen compound is primary amine.

At STP  112 mL of colourless gas is evolved with 0.295 g of sample of substance after treatment with aq HCI and NaNO₂ at 0^oC. 

So, at STP 22400 mL colourless gas will be evolved with (0.295 x 22400) / 112 = 59 g of sample of such substance after above treatment.

Hence, the molecular weight of RNH₂ is 59. 

.'. Weight of R + 14 + 2= 59 

Weight of R = 43

So, R is C₃ H₇- (.'. weight of C₃H₇ ------- = 43)

Thus, given substance is

In these substance (i) gives CH3 ---- CH_2---CH₂OH with dil. HCI and NaNO₂ at 0"C which does not give yellow ppt. (Iodoform test) with 12 and alkali, while substance 

(ii) Gives

on treatment with dil. HCl and NaNO₂ at O^oC which gives yellow ppt. with I₂ and alkali.