Halogen Substituents in Electrophilic Aromatic Substitution (EAS)

These flashcards cover key concepts and vocabulary related to halogen substituents and their effects on electrophilic aromatic substitution reactions.

Halogen Substituents in EAS Reactions

Halogen atoms (Cl/Br/I) act as weak de-activators and ortho/para-directors.

Activation vs De-activation in EAS

Electron-donating groups (EDGs) activate and increase reactivity, while electron-withdrawing groups (EWGs) deactivate and decrease reactivity.

Regioselectivity

The selective functionalization of ortho, meta, or para positions on an aromatic ring.

Toluene in EAS

Toluene is a better nucleophile than benzene due to its methyl group, which activates the benzene ring.

Hammond Postulate

It relates the stability of transition states to the reactivity of intermediates in chemical reactions.

Electron-Donating Groups (EDGs)

Groups that donate electrons, typically activating and directing ortho/para in EAS reactions.

Electron-Withdrawing Groups (EWGs)

Groups that withdraw electrons, typically deactivating and directing meta in EAS reactions.

Chlorine as a substituent

Chlorine acts as a weak de-activator and ortho/para-director in EAS reactions.

Alkoxy groups in EAS

Alkoxy groups (-OR) are considered electron-donating groups due to resonance effects.

Steric Effects on EAS Regioselectivity

Increased steric hindrance disfavours ortho-selectivity, shifting products towards para.

Strong Deactivators

Substituents that are exceptionally strong electron-withdrawing groups, significantly reducing reactivity.

Friedel-Crafts Acylation

A method to generate acyl-substituted aromatic compounds that can influence regioselectivity.

Multi-step Reaction Process

A sequence of reactions that leads to the formation of a desired product from initial reactants.

Major Product Determination

Analyzing chemical reactions to identify the predominant product formed.