oat orgo unit 5

Peanut butter is falling out of every orifice. I'm sorry. That was a bit personal.

addition

adding two groups on either side of a double bond (opposite of elimination)

hydrohalogenation

a hydrogen and halogen are added across a double bond.

markovnikov product

Non-hydrogen group bonds to the MORE substituted alkene carbon.

anti-markovnikov product

Non-hydrogen group bonds to the LESS substituted alkene carbon.

markovnikov addition of H&X

H bonds to less substituted carbon to make the carbocation more stable.

X = halogen

• Exception: HBr + ROOR = anti-markovnikov product.

H₂O addition

H and OH are each added across a double bond, which makes an alcohol.

• Reagents:

  • Dilute H₃O⁺ or H₂O + H₂SO₄ for alkene to alcohol.

  • Concentrated H₃O⁺ or H₂O + H₂SO₄ for alcohol to alkene.

Acid catalyzed hydration mechanism

acid catalyzed addition of alcohols

adds an ether, rearrangement is possible, markovnikov addition, can be syn or anti.

Oxymercuration-demercuration

markovnikov, rearrangement is not possible, can by syn or anti.

• Reagents: Hg(OAc)₂ + H₂O + THF + NaBH₄

hydroboration oxidation

results in syn addition of H and OH, anti-markovnikov, no rearrangement possible.

• Reagents: BH₃ + THF and H₂O₂ + NaOH

H₂O addition reaction comparison

halonium ion

Dihalogenation

alkene to vicinal dihalide (2 halogens connected to adjacent carbons), results in anti addition. A holonium is the intermediate. It gives both enantiomers.

• Reagents = X₂ and CCl₄. X = any halogen

Halohydrin formation

alkene to halohydrin (OH on one side, halogen on the other), gives both enantiomers with anti addition. OH bonds to the more substituted carbon, and a halonium is the intermediate.

• Reagents: X₂ and H₂O

epoxide

reactive and unstable

epoxide formation

start with an alkene, and use RCO₃H or mCPBA as the reagent, and the epoxide can form on either side of the alkene.

anti dehydroxylation

start with an alkene and use 1: RCO₃H and 2: H₃O⁺ or NaOH. It makes a vicinal diol (2 OH on neighboring carbons) with anti addition and an enantiomer.

anti dehydroxylation mechanism

syn dehydroxylation

start with alkene, then use OsO₄ + H₂O₂ as reagents or KMnO₄ + NaOH + cold as reagents, and 2x OH do syn addition with an enantiomer.

epoxidation and dihydroxylation summary

ozonolysis cleavage

alkene is cut down the middle to make two carbonyl containing compounds.

• Reagents:

  • 1: O₃

  • 2: H₂O₂ for oxidative (carboxylic acid or carbon dioxide)

  • 2: DMS or Zn,HOAc for reductive (aldehyde or formaldehyde)

• Fully substituted: makes two ketones

• Non-fully substituted: makes an aldehyde if DMS or Zn,HOAc, or a carboxylic acid if H₂O₂.

• Terminal alkene: terminal side makes a formaldehyde if DMS or Zn,HOAc, or carbon dioxide if H₂O₂.

catalytic hydrogenation

2 hydrogens are added to bring an alkene to an alkane

• Reagents: 1: H₂, 2: Pt or Pd/C

• Results in syn addition

Elijah’s cleavage