ochem 51b final

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  3. what forms a cis alkene from an alkane?
    • lindlar's cat
    • H2
  4. what makes an C=O go to an C-OH?
    LAH- Lithium Aluminum Hydride
  5. If HBr is present with Hv or heat or ROOR then is it markovnikov or anti-markovnikov?
    anti-markovnikov
  6. Initiation?
    Br-Br split by homolysis into 2 free radicals
  7. Propagation?
    • 3 arrows
    • Br free radical and H will form a bond and leave the major compound forming HBr and a radical on the major compound
  8. Termination?
    any 2 radicals forming a bond will terminate the reaction
  9. mCPBA (meta-chloroperoxy benzoic acid)
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    • can substitute benzene w/ chlorine for "R"
    • forms epoxides from alkenes
    • 5 arrow mechanism
  10. mCPBA and Cyclohexane w/ Alkene Mechanism (cycloalkene)
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  11. Dihydroxylation: clyclohexane w/alkene reacts with what to make cyclohexane with two -OH substituents (each on a C of alkene)? (2 possibilities)
    • KMnO4, H2O, KOH
    • 1.) OsO4 2.) NaHSO3, H2O
  12. Oxidative Cleavage: (alkene to ketone)
    • 1.) O3
    • 2.) Me2S
  13. Oxidative Cleavage: alkyne to carboxylic acid
    • 1.) O3
    • 2.) Me2S
  14. Ozonolysis
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  15. 2° Alcohol to Ketone
    • Harsher Oxidant: K2CrO7, H2O, H2SO4
    • PCC (pyridinium chlorochromate)
  16. Alcohols reacting with PCC makes:
    aldehydes
  17. Alcohols reacting with Harsher Oxidant: K2CrO7, H2O, H2SO4 makes:
    carboxylic acid
  18. 3 Rules for Resonance Stability
    • 1.) Res. structure with more bonds and fewer charges is better
    • 2.) Res. structure with every atom having octet is better
    • 3.) Res. structure with the neg. charge on more electronegative atom is better
  19. Electrophile Addition 1,2 vs. 1,4
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  20. Diels-Alder Reaction
    • awarded Nobel Prize in 1950
    • 3 arrows
    • cis comformation diene reacts with alkene (dienophile) and using heat creates 2 new C-C bonds (cyclohexane)
    • stereochemistry of dienophile retained in product
  21. Benzene and Br2 will or will not react?
    will not react
  22. Criteria for Aromaticity (Huckel's Rule)
    • 1.)Cyclic: no open chains
    • 2.) Planar: on exam everything should be planar
    • 3.) Complete Conjugation: p-orbitals on every atom in ring (pi bond attached to every atom)
    • 4.) # of e-: 4n+2=#pi e- (n is whole number: 0,1,2,3)
    • If 1-4 pass then it is aromatic
    • If 1-4 pass with #4 as 4n= #pi e- (n is whole number: 0,1,2,3) then it is anti-aromatic
    • neither is when one or more do not pass
  23. Aromaticity Stability: (least to most stable)
    anti-aromatic < neither < aromatic
  24. Requirements for SN1
    • Alkyle halide: tertiary > secondary > primary
    • weak generally neutral nucleophile
    • polar protic solvent (water, alcohols, and carboxylic acids)
    • sterechemistry: mix of retention and inversion
  25. Requirements for SN2
    • Alkyle halide: primary > secondary > tertiary
    • strong generally negative nucleophile
    • polar aprotic solvent (acetone, DMSO, acetonitrile, or DMF)
    • stereochemistry: inversion
  26. Requirements for E1
    • Reactivity: primary < secondary < tertiary
    • Base: weak base, good nucleophile (+ SN1 product: backside attack)
  27. Requirements for E2
    • strong base, but weak nucleophile
    • better leaving group
    • polar aprotic solvent
    • R-X Substrate (primary < secondary < tertiary)
    • Hydrogen atom and halide atom must be in anti-periplanar position
  28. Primary Halides Reactivity
    • E1/SN1-not possible
    • SN2-good nucleophile
    • E2- strong/hindered base
  29. Secondary Halides Reactivity
    • Strong Nucleophile ---> SN2
    • Strong not hindered base ---> SN2 + E2
    • Strong bulky base ---> E2
    • Weak Base and nucleophile ---> SN1/E1
  30. Tertiary Halides Reactivity
    • SN2 ---> not possible
    • Strong base ---> E2
    • Weak base/nucleophile ---> E1/SN1
  31. Primary Alcohols
    • Strong, weak nucleophilic acid ---> E2
    • strong nucleophile and acid (HBr, HI) ---> SN2 (racemic mixture)
  32. Reducing Agents
    • 1. H2 (acid catalyzed)
    • 2. Na + NH3
    • 3. LiAlH4 or NaBH4
  33. Reduction of Alkenes
    • 1. Use H2 with palladium/carbon catalyst
    • 2. Syn addition of hydrogen atoms
Author
jocelyn0399
ID
346028
Card Set
ochem 51b final
Description
finaal
Updated