Question

Question 1 (10 pts). When N,N-dimethylaniline is treated with bromine, ortho and para products are formed. Note that this ring is so activated that a Lewis acid catalyst is not needed. Yet, when this material is treated with nitric/sulfuric acids, only the meta product is formed indicative of a very deactivated ring). Explain these curious results. z Br2 Br HNO, H2SO4 NO

Answer 1

When N,N-dimethyl aniline is treated with beomine, ottho and pasa products are formed Sunce the ling is quite activated, lewis acid catalyst is not needed The following resonating structures clearly depicts that why Ortho and para peoducts are formed це зум, це той, і я, и сh 11 N,N-dimethyl aniline о че не си RESONATING STRUCTURES RESONANCE HYBRID mechanism и, у ди; сиз су hech ORTHO ORTHO PRODUCT + B - ATTI ATTACK Broy ne WCH3 ne Inch PARA Electrophilic ATTACK PARA AROMATIC PRODUCT 'SUBSTITUTION

meno nc HNO3 N,N-dimethyl H₂504 N-CH3 - m-nitro- - Nog anline Meta product In case of nitration meta product is the major product (only product) formed this can be understood. by the following mechanism 1) HO NOZ + 40 Sogh = 400 NO2 + 430 2) no_NO2 ~ 40 + 803 Generation of electrophile This is an acid catalysed reaction and this in the presence of strong acid N,N-démethyl HNO₃ aneline gets peotonated CH3 9,с си, а ht This in then pulls election density from of the position LI

Thus electrophile (No) will not be able to attack the positive ortho centres Also due to steane hindérance ortho products are not formed. Thus meta products are maja products even though small amount of para product is also formed The love paul on nitrogen on pustination becomes unavailable thus it reduces élection density on Oltho positions mechanism ₂ CN-CH3 na wala ne Wichs Nog NO m-nitro -NN-dimethyl aniline (MAJOR PRODUCT)