L19 - Aromaticity 2
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What are the types of reactions that benzene can go through?
• Friedal crafts acylation • friedal crafts alkylation • sulfonylation • nitration • halogenation
What is the geneal mechanism for the reactionf with benzene?
• e- from db attack E+ • B- deprotenates the benzene • db reformed
What is the position called when it’s 1,2?
Ortho
What is the position called when it’s 1,3?
Meta
What is the position called when it’s 1,4?
Para
What is SnAr?
Nucleophilic aromatic substitution
What is the simple outline for SnAr?
Benzene with R group and X -> Nu Benzene with R group and Nu
What are the steps in SnAr?
• Nu- attacks the d+ C on C-X • e- moves from db to C • forms C- [ • • charge moves to form db • moves around to C • db from X kicks it out ]
What is sangers reagent?
Benzene with NO2 at 1 X at 2 NO2 at 5
What happens when R ist strongly e- donating?
Activating - stabilises ortho and para - direct ortho and para
What are examples of R that are strongly e- donating?
• NH2 • NHR • NR2 • OH • OR (Mesomeric effects)
What happens when R is weakly e- donating?
Activating - stabilises ortho and para - direct ortho and para
What are examples of R that are weakly e- donating?
• Me • Et • Ph (Inductive effects)
What happens when R is strongly e- withdrawing?
Deactivating - destabilises ortho and para - direct mete
What are examples for R that are strongly e- withdrawing?
• ketone • ester • amide • NO2 • CN
What happens when R is weakly e- withdrawing?
Deactivating - destabilises ortho and para - direct ortho and para
What are examples of R that are weakly e- withdrawing?
• F • Cl • Br (Withdrawing, but can donate through mesomeric effects)