Mechanisms Flashcards

1
Q

Reagents: HX

A

HydroHalide Addition to Pi Bond

  • Markovnikov Regiochemistry
  • Carbocation Rearrangement
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2
Q

Reagents: Weak Nucleophile, Strong Acid Catalyst (Typically H2O, H3O+)

A

Acid-Catalyzed Hydration of Pi Bond - Markovnikov Regiochemistry - Carbocation Rearrangement

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3
Q

Reagents: 1) Hg(OAc)2, HOH, THF

2) NaBH4

A

Oxymercuration / Demercuration

  • Markovnikov Regiochemistry
  • Anti/Trans Stereochemistry
  • No Carbocation Rearrangement
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4
Q

Reagents: 1) Hg(OAc)2, HOR, THF

2) NaBH4

A

Alkoxymercuration / Demercuration

  • Markovnikov Regiochemistry
  • Anti/Trans Stereochemistry
  • No Carbocation Rearrangement
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5
Q

Reagents: 1) BH3, THF

2) H2O2, NaOH, H2O

A

Hydroboration Oxidation

  • Anti-Markovnikov Regiochemistry
  • Syn / Cis Stereochemistry
  • Carbocation Rearrangement
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6
Q

Reagents: HX, ROOR (peroxides), heat or light

A

Anti-Mark HydroHalide Addition to Pi Bond

  • Anti-Markovnikov Regiochemistry
  • Carbocation Rearrangement
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7
Q

Reagents: Br2 or Br2, HOR

A

Electrophilic Addition of Br2 to Pi Bond (Bromonium Ion)

  • Markovnikov Regiochemistry
  • Anti / Trans Stereochemistry
  • No Carbocation Rearrangement
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8
Q

Reagents: Peroxy Acid (ROOOH) (Typically MCPBA)

A

Epoxide Ring Formation

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9
Q

Reagents: 1) MCPBA

2) H+, HOR

A

Epoxide Ring Opening (Acidic Conditions)

  • Markovnikov Regiochemistry (follows the carbocation)
  • Anti / Trans Stereochemistry
  • No Carbocation Rearrangement
  • Can Add 2 OH or 1 OH & 1 OR Group
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10
Q

Reagents: 1) MCPBA

2) Strong Base (HOR, NR2-, NaR)
3) Dilute Acid or RX

A

Epoxide Ring Opening (Basic Conditions)

  • Anti-Markovnikov Regiochemistry (goes for spot with less steric hindrance)
  • Anti / Trans Stereochemistry
  • Can Add 2 OH, 2 OR, or 1 OH & 1 OR Group
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11
Q

Reagents: CHCl3, KOH or CH2I2, Zn(Cu)

A

Cyclopropane Ring from a Pi Bond

  • Carbene addition to the pi bond
  • Carbenes need to be made in situ
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12
Q

Reagents: H2, Pt or Pd metal

A

Strongly Catalyzed Reduction of Pi Bonds

  • Syn / Cis Stereochemistry
  • Reduces all Pi Bonds in Alkenes and Alkynes
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13
Q

Reagents: H2, Ni2B or H2, Lindlar Catalyst

A

Weakly Catalyzed Reduction of Pi bonds

  • Syn / Cis Stereochemistry
  • Only Reduces first Pi Bond in Alkenes and Alkynes
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14
Q

Reagents: Na metal, NH3 liquid

A

Weakly Catalyzed Reduction of Pi Bonds

  • Anti / Trans Stereochemistry
  • Only Reduces first Pi Bond in Alkenes and Alkynes
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15
Q

Reagents: PCC

A

Oxidation of Primary Alcohol to Aldehyde

  • Removes two H’s to form double bond across C-O
  • Weaker oxidizing agent
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16
Q

Reagents: KMnO4 or Na2Cr2O7, acid, water or CrO3, acid, water

A

Oxidation of Secondary Alcohol to Ketone or Oxidation of Aldehyde to Carboxylic Acid

  • Removes two H’s to form double bond across C-O
  • Oxidizes vinyl H’s on Aldehydes into OH’s
  • Stronger oxidizing agents
17
Q

Reagents: 1) OsO4

2) H2O2 or NaHSO3

A

Syn Addition of 2 OH’s to a Pi Bond

  • Syn / Cis Stereochemistry
  • No epoxide ring necessary to get similar product
18
Q

Reagents: 1) O3 (ozone)

2) Zn, acetic acid

A

Ozonolysis

  • Oxidative Cleavage of Sigma and Pi Bond
  • “Cauterized” by oxygen molecule to create two new molecules
  • Weak oxidizing agent, so vinyl H’s are untouched
19
Q

Reagents: 1) hot KMnO4

2) H3O+, H2O

A

Permanganate

  • Oxidative Cleavage of Sigma and Pi Bond
  • “Cauterized” by oxygen molecule to create two new molecules
  • Strong oxidizing agent, so vinyl H’s are oxidized into OH’s
20
Q

Reagents: Excess HX

A

HX Addition to Alkynes

  • Markovnikov Regiochemistry
  • Creates Geminal Dihalide (adds on same C)
21
Q

Reagents: Excess X2

A

X2 Addition to Alkynes

  • Markovnikov Regiochemistry
  • Anti / Trans Products
  • Creates Geminal Tetrahalides (adds on same 2 C’s)
22
Q

Reagents: H30+, Vinyl Alcohol (OH on a C=C)

A

Tautomerization

  • The Enol form (vinyl alcohol) shifts to it’s more stable Keto form (ketone with C=O)
  • Reversible
  • Exception to stability is phenols (benzylic more stable than allylic)
23
Q

Reagents: Catalytic Acid, H2O or H2SO4 or HgSO4 (+ Alkyne)

A

Acid-Catalyzed Hydration of Alkyne

  • Markovnikov Regiochemistry
  • Produces an Enol that tautomerizes into a Ketone
24
Q

Reagents: 1) BH3, THF (+ Alkyne)

2) H202, NaOH, H2O

A

Hydroboration Oxidation of Alkyne

  • Anti-Markovnikov Regiochemistry
  • Syn / Cis Stereochemistry
  • Produces an Enol that tautomerizes into a Ketone
25
Q

Reagents: NaNH2

A

Produces Acetylide Anion

  • Deprotonates an Alkyne to create a nucleophile
26
Q

Reagents: H2O, H2SO4 (+ Nitrile)

A

Nitrile Hydrolysis

  • Like other alkynes, this creates an Enol product that tautomerizes to a Ketone