Question

Which one of the following nitro compounds when react with nitrous acid followed by treatment with alkali produces blue colour?
A. 2-methyl-2-nitropropane
B. 2-methyl-1-nitropropane
C. 2-nitropropane
D. nitrobenzene

Answer 1

Correct Answer - C
Nitro group attached to secondary carbon atom will give pseudonitrol with `HNO_2` which on further treatment with alkali gives blue colour.
`Hundersetunderset(CH_3)|oversetoverset(CH_3)|C-NO_2overset"HONO"to H_3C-underset(NO)underset|overset(CH_3)overset|C-NO_2 overset"NaOH"to underset"Blue colour "(CH_3-undersetunderset(NO_2)|CH-CH_3)`