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Organic Chemistry > Alkene and Alkyne Reagents > Flashcards

Alkene and Alkyne Reagents Flashcards

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1
Q

2 NaNH2/ NH3

A

Double E2: Alkyne

Bases strong enough to deprotonate terminal alkynes:
- Butyl lithium (strongest organic base) https://assets.fishersci.com/TFS-Assets/CCG/Chemical-Structures/chemical-structure-cas-109-72-8.jpg-650.jpg

  • Sodium Hydride (NaH)

https://www.chemistrysteps.com/wp-content/uploads/2019/12/alkyl-dihalide-e2-terminal-and-internal-alkynes.png

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2
Q

3 NaNH2/ NH3 or xs (-)NH2

A

Double E2 and formation of Ion:

Alkyne Ion (negative charge)

Note: If a proton source (H2O, HCl, HBr, H2SO4, NH4Cl) is present, the ion can steal hydrogen from it to get rid of the negative charge.

https://www.chemistrysteps.com/wp-content/uploads/2019/12/alkyl-dihalide-e2-sodum-amide-nanh2-protonation.png

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3
Q
  1. X2 (Br2 or Cl2)
  2. h v (Planche constant and frequency)
A

Radical reaction

More substituted carbon will get X. 3°>2°>1°

Count R-groups for substitution rather than carbons in this case.

https://www.chemistrysteps.com/wp-content/uploads/2019/12/Regioselectivity-of-Radical-Halogenation-for-Cl2-and-Br2.png

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4
Q

Alkyne
(-)NH2

A

Converts terminal alkyne to terminal alkyne with a negative charge.

Alkyne to Sn2 addition of carbons/structure

https://www.studyorgo.com/blog/wp-content/uploads/2019/04/alk-1-1.gif

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5
Q

Alkyne
1. O3
2. H2O

A

Ozonolysis: Cuts the Alkyne in half.

Terminal Alkyne: Carboxylic acid and CO2
Internal Alkyne: Two carboxylic acid

https://chemistryscore.com/wp-content/uploads/2019/11/Ozonolysis1-768x467.png

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6
Q

Alkyne
1. BH3, THF
2. H2O2, NaOH

A

Hydroboration-Oxidation: Anti-Markovnikov edition of H-OH (Syn)

Goes through Enol, Enol tautomerizes to aldehyde

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Hydroboration-oxidation-two-steps.png

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7
Q

Alkyne
9-BBN

A

Hydroboration-Oxidation: Anti-Markovnikov edition of H-OH

Goes through Enol, Enol tautomerizes to aldehyde

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Hydroboration-oxidation-two-steps.png

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8
Q

Alkyne
1. disiamyl borane (Aka Sia2BH)
2. H2O2, NaOH

A

Hydroboration-Oxidation: Anti-Markovnikov edition of H-OH (syn add)

Goes through Enol, Enol tautomerizes to aldehyde

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Hydroboration-oxidation-two-steps.png

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9
Q

Alkene
1. H-Br
or
2. H-Cl

A

Hydrohalogenation

  1. Markovnikov Addition: H of H-X gets added to the side with more H’s

Adds Br or Cl to the alkene with less hydrogens.

https://i.ytimg.com/vi/6O-xSRC5Wg8/hq720.jpg?sqp=-oaymwEhCK4FEIIDSFryq4qpAxMIARUAAAAAGAElAADIQj0AgKJD&rs=AOn4CLC-WHgfdup-Be1XYSransrWYnz2Ug

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10
Q

Alkene
1. H-Br
2. ROOR
or
1. H-Cl
2. ROOR

A

Hydrohalogenation

  1. Anti-Markovnikov Addition: H of H-X gets added to the side with less hydrogens.

Uses a free radical mechanism.

Adds Br or Cl to the alkene with more hydrogens

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11
Q

Alkene
1. H+ source (H2SO4 or H3O+)
2. H2O

A

Acid-Catalyzed Hydration

Markovnikov Addition: Attaches an OH group.

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12
Q

Alkene
1. Hg(OAc)2 ; H2O
2. NaBH4

A

Oxymercuration-Demercuration (Hydration): Prevents carbocation rearrangement.

Markovnikov Addition of H-OH

Adds an Alcohol (OH) because of H2O

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13
Q

Alkene
1. Hg(OAc)2 ; CH3-OH
2. NaBH4

A

Oxymercuration-Demercuration (Hydration): Prevents carbocation rearrangement.

Markovnikov Addition of:
H-OCH3

Adds an ether because of CH3-OH

https://chemistryscore.com/wp-content/uploads/2019/11/OxymercurationROH1-768x252.png

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14
Q

Alkene
1. BH3 THF
2. H2O2, NaOH

A

Hydroboration-Oxidation (Hydration)

Anti-Markovnikov addition of H-OH

Same side (syn addition)

Step 1: Adds H-BH2, BH2 added to the less sterically crowded side.
Step 2: replaces BH2 with OH

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15
Q

Alkene
1. X2 (Cl2 or Br2)
2. CCl4

A

Halogenation (addition of X-X)

Anti Addition. Results in enantiomers. One on wedge one on dash.

The reaction needs three arrows. Forms a three-membered ring. Before adding another X.

Br: bromination
Cl: chlorination

CCl4 does not participate in the reaction.

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16
Q

Alkene
1. X2 (Cl2 or Br2)
2. H2O (Nu Solvent)

A

Halohydrin Formation: Addition of X-OH.

Anti Addition. Has enantiomers. One on wedge one on dash.

The reaction needs three arrows. Forms a three-membered ring before adding OH.

OH is added to the most substituted carbon.

17
Q

Alkene
1.R-CO3H
2. H3O+

A

Dihydroxylation (adds 2 OH groups)

Anti-dihydroxylation: OHs on different sides.

Step 1: Form a 3-membered ring with O.
Step 2: Add anti-addition OHs

Peroxyacid: R-CO3H

18
Q

Alkene
1. MCPBA
2. H3O+

A

Dihydroxylation (adds 2 OH groups)

Anti-dihydroxylation: OHs on different sides.

Step 1: Form a 3-membered ring with O.
Step 2: Adds anti-addition OHs

MCPBA: a type of peroxide.

19
Q

Alkene
1. O3
2. DMS

A

Oxidative Cleavage
(Ozonolysis)

Severs C=C bond and forms a ketone and an aldehyde.

20
Q

Alkene
1. OsO4
2. NaHSO3 / H2O

A

Dihydroxylation (adds 2 OH groups)

Syn-dihydroxylation: OHs on same side

2-Steps; Recycles OsO4

21
Q

Alkene
1. OsO4
2. Tert-O-OH

A

Dihydroxylation (adds 2 OH groups)

Syn-dihydroxylation: OHs on same side

1-Step; Recycles OsO4

22
Q

Alkene
1. KMnO4, NaOH
Cold

A

Dihydroxylation (adds 2 OH groups)

Syn-dihydroxylation: OHs on same side.

Strong Oxidizer: Could make ketones instead of alcohol.

1-Step

23
Q

Alkene
1. OsO4
2. NMO

A

Dihydroxylation (adds 2 OH groups)

Syn-dihydroxylation: OHs on same side

1-Step; Recycles OsO4

24
Q

Alkenes
1. H2
2. Pt (catalyst)

A

Catalytic Hydrogenation: Addition of H-H

Syn-addition: same side

Catalyst can also be Pd and Ni

25
Q

Alkyne
1. H2SO4, H2O
2. HgSO4 (Proton source)

A

Acid-Catalyzed Hydration

Markovnikov addition of H-OH. Will add an Ketone.

Goes through Enol (tautomerization happens)

https://www.chadsprep.com/wp-content/uploads/2020/12/hydration-of-alkynes-01.png

26
Q

Alkyne
1. Br2
2. CCl4
OR
1. Cl2
2. CCl4

A

Halogenation

Adds X-X on each side

One equivalent gives alkene. Will produce cis and trans.

Two equivalents give a single bond. 2 X’s on each side.

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Alkyne-halogenation.png

27
Q

Alkyne
1. H-Br
OR
2. H-Cl

What happens when there is excess?

A

Hydrohalogenation

Markovnikov addition of H-X

Can stop at alkene if one equivalent only is used.

2 equivalents will make it go to a single bond.

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Alkyne-hydrohalogenation-markovnikov-rule-summary.png

28
Q

Alkyne
1. HBr
2. ROOR

A

Hydrohalogenation

Anti-Markovnikov addition of H-Br

Free radical reaction

Creates a mix of trans and cis alkene isomers.

https://www.chemistrysteps.com/wp-content/uploads/2019/06/Alkyne-hydrohalogenation-anti-markovnikov-HBr.png

29
Q

Alkyne
1. Na
2. NH3(l)

A

Reduction (H-H)

Alkyne to Alkene , Stops at alkene.

Creates a trans alkene

Free radical reaction.

https://cdn.masterorganicchemistry.com/wp-content/uploads/2019/12/2-reduction-of-alkynes-to-trans-alkenes-using-sodium-metal.gif

30
Q

Alkyne
1. H2
2. Lindlar’s Catalyst

A

Reduction

Creates a Cis Alkene.

Stops at alkene. Alkyne to Alkene

Remember Lindlar (Z)

https://media.springernature.com/lw685/springer-static/image/art%3A10.1007%2Fs10967-020-07468-z/MediaObjects/10967_2020_7468_Sch1_HTML.png

31
Q

Alkyne
1. 2 H2
2. Pt (catalysts)

A

Reduction: Addition of H-H

Catalyst options: Pd and Ni

Alkyne to single bond (TRANS)

Can’t stop progress, always ends on a single bond.

https://chem.libretexts.org/@api/deki/files/202015/12.5_hydrogenation_of_alkyne.jpg?revision=1

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