Question

JEE Mains Chemistry question is in the image

Answer 1

which of the following product will not show Kjeldahl test in the given reactions ?

1. ph - CN ----(LiAlH₄)-->
2. ph - NH₂ ---(NaNO₂/HCl) --->
3. ph - CH₂- CN to----(SnCl₂/HCl) --->
4. ph - CN --(H₂/Ni) ----->

solution : we know, Kjeldahl test is a method for quantitative determination of nitrogen contained in a compound.

let see which product will show Kjeldahl test.

ph - CN ----(LiAlH₄)--> ph - Ch₂ - NH₂ ( N - present in product so it will show Kjeldahl test)

ph - NH₂ ---(NaNO₂/HCl) ---> ph - N₂⁺Cl¯ ( here -N₂⁺ (ionic bond) can't show Kjeldahl test)

ph - CH₂- CN to----(SnCl₂/HCl) ---> ph - CH₂- CHO (N absent so, can't show Kjeldahl test )

ph - CN --(H₂/Ni) -----> ph - CH₂ - NH₂ (N - Preston, so it will show Kjeldahl test)

Therefore the correct option is (2) (b)& (c)