Electron donating groups are generally ortho/para directors for electrophilic aromatic substitutions, while electron withdrawing groups are generally meta directors with the exception of the halogens which are also ortho/para directors as they have lone pairs of electrons that are shared with the aromatic ring.
Which is the best electron donating group?
Examples of good electron donating groups are groups with lone pairs to donate, such as: The oxygen anion, -O. Alcohol groups, -OH.
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The strongest EWGs are groups with pi bonds to electronegative atoms:
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The strongest EWGs are groups with pi bonds to electronegative atoms:
- Nitro groups (-NO2)
- Aldehydes (-CHO)
- Ketones (-C=OR)
- Cyano groups (-CN)
- Carboxylic acid (-COOH)
- Esters (-COOR)
Which group is electron withdrawing or donating?
Electron donating groups are generally ortho/para directors for electrophilic aromatic substitutions, while electron withdrawing groups are generally meta directors with the exception of the halogens which are also ortho/para directors as they have lone pairs of electrons that are shared with the aromatic ring.
