Exam 2 concepts and mechanisms

What is the formula for Huckle’s rule?

4n+2= # of electrons

What is typically planar?

Sp2 or Sp bonded carbons all around (no Sp3)

Benzene is the _____ that reacts with some _______ species in the ____

nucleophilic (Nu:-), electropilic (E+), RDS

_________ _____________ is resonance stabilized despite temporarily losing ________

Carbocation intermediate, aromaticity

_________ is restored when a ____-_______ ________ is removed, leading to the __________ product

Aromaticity, beta-carbon hydrogen, substitution

What are the 5 electrophilic aromatic substitution RXNs?

Halogenation, nitration, sulfonation, friedel-crafts acylation, friedel-crafts alkylation

How is an electrophile formed?

a molecule or ion with a partial + charge (or an incomplete octet) is reactive toward a nucleophile (this occurs through protonation, resonance stabilization, or the generation of a carbocation)

What are the steps to an iodation halogenation reaction?

Form electrophile (E+) with an oxidizing reagent (e.g., H2O2, H2SO4) , form carbocation intermediate, attack by base to form products

What are the steps to an bromination halogenation reaction?

Form electrophile (E+) with Br2, form carbocation intermediate, attack by base (e.g., FeBr4) to form products

What are the steps to an chlorination halogenation reaction?

Form electrophile (E+) with Cl2, form carbocation intermediate, attack by base (e.g., FeCl4) to form products.

How can sulfonation reaction be moved forward or reversed?

• Add heat to move forward

• Add H+ (acid) to reverse

What are the steps to a sulfonation reaction?

Form electrophile (E+) with SO3, form carbocation intermediate, attack by some base (e.g., HSO3/SO3H) to form products.

What are the steps to a nitration reaction?

Form electrophile (NO2+) from HNO3 and H2SO4 or solvents (MeOH), electrophilic attack on the aromatic ring, formation of carbocation intermediate, deprotonation to restore aromaticity and form product

What are the oxidizing agents?

Substances that accept electrons, causing oxidation of another substance; commonly include……

What are the solvents that can be used in a nitration reaction?

Solvents such as methanol (MeOH) or acetic anhydride

Why are the substitution products formed?

• (The electrophile replaces a hydrogen atom on the aromatic ring), maintaining the aromaticity of the compound in a way that allows for the stabilization of the resulting carbocation intermediate

• The product is a lower energy state than the starting material or addition reaction