Chapter 19

Use the symbols \(+1,-1,+M,-M\) to identify the inductive and mesomeric effects of the following groups: (a) \(-E t ;(b)-C H O\) (c) \(\left.-\mathrm{NO}_{2} ;(\mathrm{d})-\mathrm{NH}_{2} ;(\mathrm{e})-\mathrm{OCH}_{3}:(\mathrm{f})-\mathrm{CO}_{2} \mathrm{CH}_{3} \text { . (Section } 19.1\right)\).

Suggest a reason why the methyl cation and primary carbocations without resonance should never be proposed in a reaction mechanism unless no other pathway is possible. (Section \(19.1)\)