EAS Flashcards
What is EAS?
Electrophilic Aromatic Substitution. this substitution method is used to make derivatives of the benzene molecule. Knowing what the electrophile in each reaction is, is key.
What is the electrophile in Nitration?
NO2+ ion. formed by acid catalyst reacting with HNO3.
What is the electrophile in Sulfonation?
SO3. heat is required as reagent.
What the electrophile in Halogenation of Benzene?
X2-FeX3 complex. this complex is more electrophilic than X2 itself.
Name both Friedel-Crafts reactions with benzene.
Alkylation (all single bond) Acylation (carbonyl)
What is the electrophile in Alkylation of benzene?
carbocation from alkyl halide, alkene or alcohol. help made by AlCl3.
What is the electrophile in Alkylation of double bonds?
protonated double bond, due to acid, causes cation intermediate.
What is the electrophile in Acylation of benzene?
carbocation from acyl halide. help made by AlCl3. Can also use an acyl anhydride.
Name 2 Acylation-Reduction strategies. What are the used for?
only for ketones/aldehydes. Clemmensen-Reduction (with Zg(Hg) and acid) and Wolff-Kishne Reduction (with heat, NH2NH2 and base). These link primary alkyl groups to ring.
Which groups are Meta directors?
strong deactivating groups (-CN, -NO2,-CF3,-carbonyl,-SO3R) “EWG”
Which groups are Ortho/Para directors?
halogens, and activating groups (-alkyl, -ester, -OR, -amide, -OH, -amine) “ERG”
Consider what 4 things for correct disubstituted EAS regioselectivity?
- Electronic Effect, then Steric Effect
- order of sub. introduction
- friedel-crafts rxn can’t occur on deactivated aromatics
- may need to transform functional group.
Name 6 groups/ electrophiles that can NOT be directly substituted onto benzene.
- H2C=CHCl
- ClC(O)H
- ClCCH
- ClC(O)OH
- OH+
- NH2+
Which cyclic compounds are more reactive to EAS?
heterocyclic aromatic compounds with less than 6 cyclic atoms and not N, since N is much more electronegative. Furan, Pyrrole, Thiophene are more reactive then Pyridine
