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Orgo 2 > Nucleophilic Additions to Carbonyl Compounds > Flashcards

Nucleophilic Additions to Carbonyl Compounds Flashcards

1
Q

Which is more reactive toward nucleophilic addition-aldehyde or ketone? Why?

A

Aldehyde-H makes for less steric hindrance

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2
Q

Nucleophilic addition under basic conditions general mechanistic steps

A
  1. AdN of nucleophile at carbonyl carbon, one bond of double bond moves up onto oxygen
  2. Pt, oxygen uses lone pair to take H from H2O
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3
Q

Nucleophilic addition under acidic conditions general mechanistic steps

A
  1. Pt, lone pair on oxygen takes H from H3O, resonance moves bond of double bond onto oxygen, making the carbonyl carbon a carbocation
  2. AdN of nucleophile at carbocation
  3. Pt, H2O takes the hydrogen from the nucleophile
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4
Q

General reagents for nucleophilic addition under basic conditions

A
  1. EtMgBr(Et can be replaced with whatever you want to add)
  2. H2O
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5
Q

General reagents for nucleophilic addition under acidic conditions

A

H3O+(or some strong acid), EtOH(or some other nucleophile with an H attached)

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6
Q

Grignard reagent

A

Organomagnesium halide (RMgX)

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7
Q

Go from a ketone to a tertiary alcohol

A
  1. R^2MgX (X=halogen)
  2. H2O
    OR
  3. R^2Li
  4. H2O
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8
Q

General mechanistic steps of addition via Grignard reagent (RMgX) or RLi

A
  1. AdN of the R group at the carbonyl carbon, push a bond onto the oxygen
  2. Pt, lone pair from oxygen grabs hydrogen from H2O
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9
Q

What happens when you add HCl, KCN to ketone/aldehyde

A

Replace the carbonyl with an alcohol and cyanide

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10
Q

Ylide

A

Contain a negatively charged atom (typically carbon) adjacent to a positively charged heteroatom

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11
Q

Wittig reaction

A

Treatment of a ketone or aldehyde with a phosphonium ylide (R=PPh3) yields an alkene and triphenylphosphine oxide

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12
Q

General mechanism of Wittig reaction

A

[2+2] cycloaddition of ketone/aldehyde with phosphonium ylide, followed by retro-[2+2] cycloaddition to give alkene and triphenylphosphine oxide

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13
Q

General mechanism of hydration of ketohydes under acidic conditions

A
  1. Pt, lone pair of oxygen takes H from acid HA, leaving A-
  2. Adn, O of H2O attacks at carbonyl carbon, pushes bond up on oxygen of carbonyl
  3. Pt, A- of earlier acid takes H from H2O, ultimately going from double bonded carbon to two OH groups
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14
Q

General mechanism of hydration of ketohydes under basic conditions

A
  1. Adn, oxygen of OH- attacks carbonyl carbon, pushes bond up onto oxygen
  2. Pt, lone pair of oxygen takes hydrogen from H2O, ultimately going from double bonded carbon to two OH groups
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15
Q

How to form an acetal (two OR groups)

A

React a ketohyde with an alcohol in the presence of an acid catalyst (ROH, [H+])

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16
Q

General mechanism of acetal formation

A
  1. Pt, lone pair on oxygen takes H from H-A, leaving A-
  2. AdN, oxygen of alcohol (ROH) attacks carbonyl carbon, pushes bond onto oxygen
  3. Pt, A- of HA takes H from alcohol, hemiacetal (one OR group) formed!
  4. Pt, lone pair on what was the oxygen of the carbonyl (now OH), takes H from H-A, leaving A-
  5. Eb, lone pair from oxygen of OR group forms double bond, kicks off H2O
  6. AdN, oxygen of alcohol (ROH) attacks carbonyl carbon, pushes bond onto oxygen
  7. Pt, A- of HA takes H from alcohol, acetal formed!
17
Q

Thioacetal formation

A

Analagous to reactions of alcohols with ketohydes

18
Q

Reduction of thioacetal carbon to methylene(R-CH2-R)

A

H2, Raney Ni

19
Q

How to go from ketohyde + primary amine to imine

A

Use a weak acid, most often acetic acid (HOAc)

20
Q

Mechanism of ketohyde + primary amine to imine

A
  1. AdN, nitrogen of amine attacks carbonyl carbon, bond goes up on oxygen
  2. Pt, lone pair of oxygen takes hydrogen from HA
  3. Pt, A- from HA takes hydrogen from amine, forming a carbinolamine
  4. Pt, lone pair of oxygen takes hydrogen from HA
  5. Eb, lone pair on nitrogen forms double bond, kicks off water
  6. Pt, A- takes H from nitrogen, leaving imine
21
Q

How to go from ketohyde + secondary amine to enamine

A

Use a weak acid, most often acetic acid (HOAc)

22
Q

Mechanism of ketohyde + secondary amine to enamine

A
  1. AdN, nitrogen of amine attacks carbonyl carbon, bond goes up on oxygen
  2. Pt, lone pair of oxygen takes hydrogen from HA
  3. Pt, A- from HA takes hydrogen from amine, forming a carbinolamine
  4. Pt, lone pair of oxygen takes hydrogen from HA
  5. Eb, lone pair on nitrogen forms double bond, kicks off water
  6. Pt, A- takes H from alpha carbon, leaving a double bond, bond goes up on nitrogen

Orgo 2 (4 decks)

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