Question

Which of the following on reaction with nitrous acid followed by treatment with NaOH produces a blood red colouration?
A. `R CH_(2)NO_(2)`
B. `R_(3)CNO_(2)`
C. `R_(2)CHNO_(2)`
D. `PhNO_(2)`

Answer 1

`R-underset(NO_(2))underset(|)(C)H_(2)+HNO_(2)rarrR-underset("Nitrolic acid")underset(NO_(2))underset(|)(C )=N-OH`
Nitrolic acid dissolve in NaOH to give blood red colouration.
`R-underset(NO_(2))underset(|)overset(R )overset(|)(C )-R+HNO_(2)rarr"No reaction"`
`R-underset(NO_(2))underset(|)overset(R) overset(|)(C)-H+HO-N=Orarrunderset("give blue colouration")underset("Does not dissolve in NaOH but")underset(("Pseudonitrole"))(R-underset(NO_(2))underset(|)overset(R )overset(|)(C )-N)=O+H_(2)O`