Identifying Alkene Reactions

Hydrohalogenation of Alkene

Electrophilic addition of HCl or HBr

• reagent, either HCl or HBr

• follow Mark’s rule

• no stereo selectivity

Acid-catalyzed Hydration

A hydration reaction

• H+ as a catalyst or H2SO4

• transfer of water follows Mark’s rule

• rearrangements possible (halide or alkyl shift)

• no stereo selectivity

Halogenation of Alkenes

Electrophilic addition of Cl2 or Br2

• addition of water follows Mark’s Rule

• stereo selectivity through anti-addition

• reagents usually CCl4 or CH2Cl2

• water or other nucleophile present, then halohydrin is formed 

Hydroboration of Alkene

Hydration of an alkene through oxidation

• 1) reagent is BH3 (some type of boron) with THF (can also be 9-BBN or HB(SIA)2

• 2) reagent is H2O2 and NaOH

• Addition of boron and H to pi bond follows anti-Mark’s rule

• Stereo selectivity follows syn-addition

• BH2 gets subbed out for OH - don’t need to know why

Catalytic Hydrogenation

Reduction of an alkene

• reagents are H2 and a metal catalyst (Pd, Pt, Ni)

• just adds hydrogen to both sides of pi bond

Osmolysis/Syn-dihydroxilation

Oxidation of an Alkene

• reagents are KMnO4 or OsO4

• adds -OH to both sides of the pi bond

• stereo selectivity through syn-addition

• produces enantiomers 

Epoxidation/Anti-dihydroxilation

Oxidation of an Alkene

• reagent is mCPBA

• creates an expoxide where ends of pi bond connect the same 

• stereo selectivity through syn-addition

• creates enantiomers 

Ozonolysis

Oxidative cleavage - pi bond(s) get cleaved

• 1) reagent is always O3

• 2) reagent is either ZN, H2O or S(CH3)2, H2O

• every pi bond gets cleaved and the end is replaced with O at the end of the double bond

• leave the ends of chains as they are (either H or CH3)