251_EA.txt

Card Set Information

Author:
mish
ID:
48832
Filename:
251_EA.txt
Updated:
2010-11-17 09:11:41
Tags:
orgo organic chemistry electrophilic addition
Folders:

Description:
Flashcards about electrophilic addition in organic chemistry.
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user mish on FreezingBlue Flashcards. What would you like to do?


  1. H-X addition steps
    • 1) addition of hydrogen to less substituted carbon
    • 2) addition of X- ion to carbocation
  2. Markovnikov's rule
    • More electropositive atom adds first to less substituted carbon.
    • Carbocation that forms is maximally stable.
  3. Halonium ion
    compound containing a halogen ion carrying a positive charge
  4. X2 addition: solvents? steps?
    • inert solvents (CH2Cl2, CHCl3, or CCl4)
    • 1) creation of halonium ion
    • 2) attack by nucleophilic halide atom (anti addition)
  5. Catalytic hydrogenation: reagents? syn/anti?
    • H2; Pd, Pt, or Ni.
    • Syn addition.
  6. Creation of sodium alkynides: reagents? solvent?
    NaNH2, liquid NH3.
  7. Synthesizing longer alkynes: steps?
    • 1. Starting with an alkyne, create sodium alkynide.
    • RC|||CH + NaNH2 --> (liq NH3) --> RC|||C-Na+ + NH3
    • 2. Combine sodium alkynide with primary halide (SN2)
    • RC|||C-Na+ + R'CH2Br --> (liq NH3, 6h) --> RC|||C-CH2R' + NaBr
  8. Effect of peroxides (ROOR):
    Anti-Markovnikov additions (e.g. for hydrogen halides)
  9. How to produce anti-Markovnikov additions?
    Use a peroxide (ROOR).
  10. Hydration of alkenes: catalyst? regiochem? temperature? mechanism?
    • Acid catalyzed (e.g. H3O+.
    • Markovnikov addition.
    • 25 Celsius.
    • Reverse of alcohol dehydration.
  11. Oxymercuration/demercuration: purpose? regiochem? rearrangements? mechanism?
    • Anti hydration of an alkene.
    • Markovnikov addition.
    • Rearrangements are rare.
    • 1) Hg(OAC)2/THF + H2O
    • water and mercuric acetate add to double bond.
    • 2) NaBH4, OH-.
    • sodium borohydride group replaces acetomercury group with hydrogen.
  12. Hydroboration/oxidation: purpose? regiochem? mechanism?
    • Syn hydration of an alkene.
    • Anti-Markovnikov addition.
    • 1) BH3/ether or THF.
    • H adds to more highly substituted carbon; BH3 adds to other.
    • 2) OH-/H2O2
    • OH- replaces BH3 group, giving anti-Markovnikov product.
  13. Halohydrin formation: purpose? regiochem? mechanism?
    • Anti addition of halogen and hydroxyl group (X and OH).
    • Markovnikov addition.
    • 1) NBS / 1:1 H2O:THF
  14. NBS: structure? purpose?
    • cyclopentane with carbonyl =O on 2 and 5; N attached to Br at 1.
    • Used for halohydrin formation; contributes Br to reaction, few side products.
  15. Mercury oxoacetate (HgOAc) : structure? purpose?
    Hg attached to two carbonyl groups terminating in a methyl. Used during the oxymercuration process.

    Hg(O(CO)CH3)2
  16. Ozonolysis: purpose? reagents?
    • Turns an alkene into two carbonyls.
    • 1) O3
    • 2) Zn, H2O
  17. NMO: structure? purpose?
    • 6-membered ring with O at 1 and N+ at 4. O- and H3C attached to N+.
    • stochiometric co-oxidant for catalytic dihydroxylation.
  18. Syn 1,2 dihydroxylation: reagents (2 reactions)? Mechanism?
    • Reaction A: 1) OsO4, pyridine. 2) NaHSO3/H2O
    • Reaction B: alkene + KMnO4 --> (OH-, H2O; cold)
    • In osmium tetroxide, cyclic intermediate (carbon bonds to oxygen)and then cleavage at oxygen-metal bonds.
  19. Cleavage with Hot Basic KMnO<sub>4</sub>
    • 1: addition of KMnO<sub>4</sub>, OH<sup>-</sup>, H<sub>2</sub>O, heat
    • 2 (if necessary to make carboxylic acid): H<sub>3</sub>O<sup>+</sup>

What would you like to do?

Home > Flashcards > Print Preview