Mechanisms Flashcards
Halogenation
What is being added?
Br2 or Cl2
What intermediate is within a bromination mechanism?
bromonium ion
What is the expected stereochemistry of halogenation?
Anti addition
Hydroboration Oxidation
What is being added?
H and OH
What are the reagents used in Hydroboration?
- BH3, THF/ 2. H2O2 or NaOH
What are the reagents used in Halogenation?
Bromine/Chlorine and CCl4
What is the regioselectivity in Hydroboration?
H to less H, OH to less substituted.
Anti- Markovinov
What is the expected stereochemistry in hydroboration?
Syn Addition
What reagents are used in Halohydrin
Bromine/Chlorine and H2O
Halohydrin
What are we adding across DB?
Br/Cl and OH
Regioselctivity of Halohydrin
OH adds to more substituted
Sterochemistry of Halohydrin
Anti Addition
Water adds anti to halide
Acid-Catalyzed Hydration
What is being added?
H and OH
Regioselectivity of Acid-Catalyzed hydration
Markovinov
OH to more substituted, H to more H
Hydrogenation
What is being added?
H2
What is the stereochemistry of hydrogenation?
Syn Addition
Epoxidation
What is being added?
An O, from a peroxy acid
What reagent is used in Epoxidation?
MCPBA or peroxyacetic acid
What is the stereochemistry of epoxidation?
Syn addition
O binds to both carbons on same plane
What reagents do you use for substitution with triple bonds?
NaNH2, NH3, ether, or THF
What hints at an SN2 mechanism?
A full negative charge on the nucleophile
When can we do an alkylation using triple bonds?
Only when theres a leaving group on a primary or methyl carbon
Which radical structure is most stable
3 prime
What is the major product of a reaction with H-halogen and HOOH?
Radical on most substituted, halogen on least substituted
Major product of a reaction with Br2 and light?
Br on most substituted carbon
Strong bases?
KOH, NaOH, OMe, OEt
First way to reduce an alkyne?
H2 and Pt, to give an alkane
Second way to reduce an alkyne?
H2 and Lindlar’s, to give a cis alkene
Third way to reduce an alkyne?
Na and NH3 (l)
Strong bases lead to…
Elimination (E2)
Good Nucleophiles (-) lead to..
Substitutions (SN2)