Alkenes Reactions

Hydrohalogenation (Electrophillic Addition of H-X)

H-X = HCI, HBr, HI, H3O+

Follows Marikovnikov’s Rule (X- adds to more substituted carbon)

Racemic Mixtures

Carbocation Intermediate

Front or backside attack

Acid-Catalyzed Hydration

Same as hydrogenation WITH a deprotonation step

Follows Marikovnikov’s Rule (X- adds to more substituted carbon)

Racemic mixtures

Catalytic amount of acid

Oxymercuration/Demercuration

Uses:

Step 1) Hg(OAc)2 and H2O (or ROH to form ethers)

Step 2) NaBH4

-Markovnikov addition

-NO rearrangements

-NO mechanism needed for demercuration

-Racemic mixtures of products

-H2O (Nu) will attack MOST SUBSTITUTED C (most positively charged as electron density goes to Hg)

Hydroboration/Oxidation

Uses:

Step 1) BH3 (Borane), THF (solvent)

Step 2) H2O2 (H peroxide), NaOH (base)

-ANTI- Markovnikov Product (adds to LEAST substituted carbon) boron groups bond to less statically hindered Carbon and more electro + than H

-NO rearrangements

-Racemic Mixtures

-Borane Reagents (BH3, B2H6, 9-BBN)

-Syn addition: wedges facing them same side (NOT / absolute configuration)

Halogenation

X-X is NOT polar (may be polarizable due to close pi bond or dipole)

Step 1) Replace X-X with Cl2, Br2, or I-Cl

Step 2) CCI4 = non nucleophillic solvent

-Products are racemic (both enantiomers should be drawn)

Anti addition of X2

-Trans product

Halohydrin Formation

Step 1) X2 = Cl or Br

Step 2) H2O, ROH (nucleophillic solvent)

-Trans, racemic products

-Witb ROH (alcohol) solvent: No wedges/dashes only ONE chiral center

Hydrogenation of ALKENES

R = C or H

Step 1) H2

Step 2) Pd/C or Pt

-Syn addition of hydrogen

-Racemic products

-NO mechanisms

-Assume excess is H2

Exploitation with mCPBA

R = C or H

Step 1) mCPBA

Step 2) Any peracid

Expoxide: 3 ring structure

Mechanism NOT be asked on exam

Anti Dihydroxylation

Step 1) mCPBA

Step 2) H3O+

Trans, racemic

Syn Dihydroxylation

Step 1) OsO4

Step 2) NaHSO3, H2O

cis, racemic

MEMORIZE.

Glycolate Cleavage

Step 1) HIO4, H2O, THF

must be cis

MEMORIZE

Ozonolysis

R = C or H

Step 1) O3

Step 2) DMS (dimethyl sulfide) or Zn, H3O+

Oxidative cleavage, NOT an addition reaction

Cleaves double bonds

No mechanism

MEMORIZE

Permanganate Cleavage

Step 1) KMnO4

Step 2) Acid, heat

-Cleaves double bonds and oxidizes H bonded to alkene

-NO mechanism

-MEMORIZE

Free Radical Addition of HBr

Step 1) HBr

Step 2) ROOR

-Anti Markovnikov addition

-limited to HBR/peroxides

Initiation, Propagation, Termination