Reagents for Addition Reactions
1. Electrophilic Additions to Alkenes
A. Non-Redox
| Elements Added | Reagent | |
| H-Cl | HCl | Markovnikov regiochemistry; random stereochemistry; rearrangements possible |
| H-I | HI | Markovnikov regiochemistry; random stereochemistry; rearrangements possible |
| H-I | 1) BH3 THF
2) I2/NaOMe/MeOH | anti-Markovnikov regiochemistry; overall stereospecific anti stereochemistry; no rearrangement. |
| H-Br | HBr (gas)
or NaBr/H2SO4/H2O | Markovnikov regiochemistry; random stereochemistry; rearrangements possible |
| H-Br | 1) BH3 THF
2) Br2/NaOMe/MeOH | anti-Markovnikov regiochemistry; overall stereospecific anti stereochemistry; no rearrangement. |
| H-Br | HBr/peroxide | anti-Markovnikov regiochemistry; random stereochemistry; free radical mechanism (rearrangements unlikely) |
| H-OH | H2SO4/H2O | Markovnikov regiochemistry; random stereochemistry; rearrangements possible |
| H-OH | 1) Hg(OCOCH3)2/THF/H2O
2) NaBH4/NaOH/H2O | Markovnikov regiochemistry; stereochemistry of first step is anti; second step is stereorandom. C-OH bond is formed in first step; C-H bond in second step. No rearrangements. |
| H-OH | 1) BH3 THF
2) H2O2/NaOH/H2O | anti-Markovnikov regiochemistry; stereospecific syn stereochemistry; no rearrangement. |
| H-OH | 1) BH3 THF 2) NMMO | anti-Markovnikov regiochemistry; stereospecific syn stereochemistry; no rearrangement. |
| H-OR | ROH/H2SO4 | Markovnikov regiochemistry; random stereochemistry; rearrangements possible |
| H-OR | 1) Hg(OCOCF3)2/THF/ROH 2) NaBH4/NaOH/H2O | Markovnikov regiochemistry; stereochemistry of first step is anti; second step is stereorandom. C-OR bond is formed in first step; C-H bond in second step. No rearrangements. |
| HOCH2-OH | 1) Hg(OCOCF3)2/THF/ROH 2) NaBH4/NaOH/H2O | Markovnikov regiochemistry; stereochemistry of first step is anti; second step is stereorandom. C-OR bond is formed in first step; C-H bond in second step. No rearrangements. |
B. Redox: Oxidation
| Elements Added | Reagent | |
| Cl-Cl | Cl2/CCl4 | anti stereochemistry; no rearrangements |
| Br-Br | Br2CCl4 | anti stereochemistry; no rearrangements |
| I-I | I2/CCl4 | anti stereochemistry; no rearrangements; reaction sluggish with all but most reactive alkenes. |
| Br-Cl | BrCl/CCl4
or Br2/LiCl (sat.)/H2O | Markovnikov regiochemistry; anti stereochemistry; no rearrangements
(first reagent is better) |
| HO-Cl | Cl2/H2O | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| HO-Br | Br2/H2O | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| HO-OH | HCO3H/HCO2H/H2O
or 1) Br2/H2O 2) KOH/H2O | anti stereochemistry; no rearrangements |
| HO-OH | HCO3H/HCO2H/H2O
or 1) Br2/H2O 2) KOH/H2O | anti stereochemistry; no rearrangements. Both reagent sets work fine. The reagent based on bromine is more vigorous. |
| HO-OH | KMnO4/KOH/H2O/5°C | syn stereochemistry; no rearrangements |
| HO-OH | 1) OsO4/CCl4
2) NaHSO3/H2O | syn stereochemistry; no rearrangements. |
| HO-OH | OsO4/Me3C-O-OH/Me3C-OH
or OsO4/CCl4/NaClO3/H2O | syn stereochemistry; no rearrangements.
These reactions are both catalytic in osmium, and are much preferred to the reaction above. |
| C6H5S-Br | C6H5SBr/CCl4 | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| C6H5Se-Cl | C6H5SeCl/CCl4 | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| C6H5Se-Br | C6H5SeBr/CCl4 | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| I-N3 | IN3/CCl4
or IN3/MeCN | Markovnikov regiochemistry; anti stereochemistry; no rearrangements |
| O | RCO3H/CH2Cl2 | syn stereochemistry; no rearrangements.
The most common reagfent is the one based on meta-chloroperoxybenzoic acid (m-CPBA). |
C. Redox: Reduction
| Elements Added | Reagent | |
| H-H | H2/Ni
or H2/Pd-C or H2/Pt | syn stereochemistry. Catalyst activity increases in the order: Ni < Pd < Pt |