In an electrophilic aromatic substitution reaction does the


Need help with these aromaticity questions. Please explain briefly.

1. In an electrophilic aromatic substitution reaction, does the aromatic ring act as an electrophile or a nucleophile? Please show the first step in electrophilic aromatic substitution using a mechanism. Please show the electrophile as a generic cation "E+".   

2. Substituents on an aromatic ring can alter both the stereoselectivity and reactivity of an electrophilic aromatic substitution. Please describe/explain "activating" and "deactivating" substituents, in addition to mentioning the positions strongly affected on the aromatic ring by such substituents. Please give one example of an activating substituent and one example of a deactivating substituent.

3.

a) Please illustrate using resonance structures how a moderate, to strong, electron-donating group (e.g. -OR, -NRR', etc.) increases the nucleophilicty of particular sites on an aromatic ring (before the addition of an electrophile).

b) Please illustrate using resonance structures how a moderate, to strong, electron-withdrawing group (e.g. -NO2, -COR, etc.) decreases the nucleophilicty of particular sites on an aromatic ring (before the addition of an electrophile).

4. Is there a reason why bromination is favoured at a 2'-postion, as opposed to a 3'-position, of an aromatic ring?

5. Please give a full mechanism for the synthesis of 2'-bromo-4'methylacetanilide starting from HOBr and 4'-methylacetanilide. Please show all nonzero formal charges, intermediates and important resonance structures. Please use arrows to clearly show bonds forming or breaking between atoms.

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Biology: In an electrophilic aromatic substitution reaction does the
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