Inductive electron-donating groups

The secondary carbonium ion is the more stable, because it has two electron donating groups inductively feeding electrons towards it. Furthermore, these groups are able to interact favourably with the positive charge by hyperconjugation, and this increases the stabilisation. 

A tertiary carbonium ion is more stable than a secondary carbonium ion, which is in turn more stable than a primary carbonium ion. Therefore, the alkylation of ben2ene with isobutylene is much easier than is alkylation with ethylene. The reactivity of substituted aromatics for electrophilic substitution is affected by the inductive and resonance effects of a substituent. An electron-donating group, such as the hydroxyl and methyl groups, activates the alkylation and an electron-withdrawing group, such as chloride, deactivates it. 

Methide ion is eliminated more easily than the ethide ion because the methide ion has greater stability. This stability results from the electron-donating ability (inductive effect) of the methyl group. This agrees with the... 

If the electrophile attacks the benzene ring at a position ortho or para to a + / substituent (i.e., to one electron-donating by inductive effect), the activated complex will be similar to 81 or 82, respectively. Resonance structures 81c and 82c are of particularly low energy because in these the positive charge is localized on the carbon that bears the + / group. Attack at the meta position does not allow such a resonance structure to be drawn. 

Inductive effects Electron-withdrawing groups make the carbonyl carbon more electrophilic and increase the reaction rate electron-donating groups make the carbonyl carbon less electrophilic and decrease the reaction rate. 

By use of Pybox substituted at the 4-position of the pyridine skeleton, the remote electronic substituent effect for asymmetric induction was found to show that enantiomeric excesses became higher with electron-withdrawing groups and lower with electron-donating groups, but the ratios of the trans-to-cis products were not influenced by the substituents [27]. 

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