Answer to Question #24131 in Organic Chemistry for Brittney

Question

In the Nitration of Salicylic Acid, how would I show the formation of the nitronium ion from concentrated H2SO4 & HNO3? Is this right?
NO2+
---------- \------------
/benzene\ double bond O / benzene\ double bond O
/ ring \ ---/ \ / ring \---/ \
\ / OH H2SO4 \ / OH
\-----------/ ------> \-----------/
\ HNO3 \
OH OH

Answer 1

Yes, that's right!
HNO₃ + 2H₂SO₄ = NO₂⁺ + H₃O⁺ + 2HSO4^-

The nitronium ion is the electrophile in the nitration of salycic asid. Although concentrated nitric acid produces the nitronium ion by itself, the equilibrium is so far to the left that the process is slow. Adding concentrated sulfuric acid to the reaction mixture increases the concentration of the nitronium ion, thereby increasing the rate of the nitration reaction. The nitronium ion forms via a pathway similar to the first step in the dehydration of an alcohol.