ORGO 1: Alkene Reactions (CH 8)

10 Reactions, good freaking luck man

What are the 10 alkene reactions?

Hydrohalogenation, Acid-catalyzed hydration, oxymercuration-demercuration, hydroboration-oxidation, catalytic hydrogenation, halohydrin formation, halogenation, syn dihydroxylation, epoxidation + antidihydroxylation, ozonlysis

Hydrohalogenation

REAGENTS

HBR

• Markovnikov Addition

HBR + ROOR

• Antiaddition

MECHANISM

• Protonation → Nuc attack

STEROCHEM

• Considered with enantiomers

Acid-Catalyzed Hydration

REAGENTS

H₂SO₄, H₂O

= H₃0

MECHANISM

• Markovnikov Addition

• Protonation → (carbocation) → nuc attack → (oxonium ion) → deprotonation

STEREOCHEM

• Considered

• Product is 1:1 racemic mixture of enantiomers

More stable cation → more reactive reaction

Oxymercuration-Demercuration

REAGENTS
1. Hg(OAc)₂, H2O — Oxymercuration

2. NaBH4 — Demercuration

MECHANISM

• Markovnikov Addition

• If no carbocation → No rearrangements/methyl shifts

• Mechanism not required

STEREOCHEM

• Considered

• Product is mixture of enantiomers

Hydroboration-Oxidation

REAGENTS

1. BH₃, THF (Solvent) — Hydroboration

2. H₂O₂, NaOH — Oxidation

MECHANISM

• Steps Not Required

• Antimarkovnikov Addition

STEROCHEM

• Not considered

Catalytic Hydrogenation

REAGENTS

• H₂ , metal catalyst (Pt, Pd, Ni)

MECHANISM

• Not required

• Syn addition

• For pairs, no enantiomers (meso compounds)

STEROCHEMISTRY

• Considered

• Look at chiral centers

• DO NOT represent meso compounds

Halogenation

REAGENTS

• Br2 or Cl2 + non nucleophilic solvent (not H2O)

MECHANISM

• Anti addition

• Nuc attack + Loss of leaving group

• Repeat

STEROCHEMISTRY

• Considered

• Consider enantiomers

Halohydrin Formation

REAGENTS

• Br2 or Cl2 + H2O (nucleophilic solvent)

MECHANISM

• Considered

• nuc attack → Loss of LG → nuc attack → Loss of LG → Deprotonation

• Forms diol as intermediate (NOT final)

• Consider enantiomers

Syn Dihydroxylation

REAGENTS

1. OSO4

2. NaSO3 (or NaHSO3), H2O

or

1. KMnO4, NaOH

MECHANISMS

• Considered

• Syn addition

STEROCHEMISTRY

• Considered (Anti addition)

Epoxidation & Antidihydroxylation

REAGENTS

1. MCPBA

2. H3O+ (Aqueous Acid)

MECHANISM

Double Bond site → 1. MCPBA → 3 Member Ring (Epoxide) → 2. H3O+ → Anti Diol

• Epoxide → Diol

STEREOCHEMISTRY

• Considered (Anti diol)

• Enantiomers

Epoxidation: Syn

Antidihydroxylation: Cis alkene → trans diol; trans alkene → cis diol

Ozonolysis

REAGENTS

1. O3

2. DMS (or Zn + H2O)

MECHANISM

• Steps not required

STEREOCHEM

• Not considered

Most likely will product 2 products UNLESS original is a closed ring

• Keep carbons consistent

• Ketone added to replace double bond

• Multiple of the same molecule can form

Synaddition

Addition of two substituents on the same plane (dash or wedge)

• Example. two OH groups are added on wedges

Antiaddition

Addition of two substituents on different planes (dash or wedge)

• Example. OH group on dash and OH group on wedge

Markovnikov Addition

OH added to side of alkene with MOST substituents

H added to side of alkene with LEAST substituents

AntiMarkovnikov Addition

OH added to side of alkene with LEAST substituents

H added to side of alkene with MOST substituents