Question

The reaction mechanism for nitration of toluene is proposed below. Explain the differences in the abundance of the products formed.

Сна CH3 CH3 H H + H -NO2 _NO2 Ortho -NO2 63% Most stable CH3 CH3 CH3 CH3 + Meta 3% H H H NO2 + NO2 NO2 Toluene CH3 CH3 CHE Para 34% H NO2 H NO2 H NO2 Most stable

Answer 1

Witration of toluene, 13 CH3 NO NO2 ch + ene NO Clly Ortho-isomer 63074 prisomer meta-isomer 37 Mechanism 347 CHA ally CH3 ܥܐ -NG H+ H ana meta-isomer (3%) During formation of meta isomer the (t) ve charge does not come and hence in the carbon atom to which - Cty group is attached is not stabilized by the inductive affect Ptl effect) of the group. CH3 CH3 CH₃ CH₃ CH3 CH₃ Do -H NO2 NO NO2 (Most stable) Prisomer (34%) 1 WO2 NO₂ 1 During formation of prisomer, the carbocation formed (1) inductive effect of a CH3 is stabilized by -ctly group. CH₂ CH3 CH3 m2 m2 CH₂ <+ Most stable ortho- isomer (630 The cambocation formed during formation of Orthon isomer is stabilized by inductive effect of CH3 group. The stability order of the carbocation formed -> Orthen isomer) para-isomer) meta-isomer. That in why the percent. abundance of the produch follows the order as => ortho isomer (63%) > para-ismer > meta-isomer (3%). (347)