Alkene and Alkyne Reagents Flashcards
2 NaNH2/ NH3
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
3 NaNH2/ NH3 or xs (-)NH2
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
- X2 (Br2 or Cl2)
- h v (Planche constant and frequency)
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
Alkyne
(-)NH2
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
Alkyne
1. O3
2. H2O
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
Alkyne
1. BH3, THF
2. H2O2, NaOH
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
Alkyne
9-BBN
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
Alkyne
1. disiamyl borane (Aka Sia2BH)
2. H2O2, NaOH
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
Alkene
1. H-Br
or
2. H-Cl
Hydrohalogenation
- 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
Alkene
1. H-Br
2. ROOR
or
1. H-Cl
2. ROOR
Hydrohalogenation
- 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
Alkene
1. H+ source (H2SO4 or H3O+)
2. H2O
Acid-Catalyzed Hydration
Markovnikov Addition: Attaches an OH group.
Alkene
1. Hg(OAc)2 ; H2O
2. NaBH4
Oxymercuration-Demercuration (Hydration): Prevents carbocation rearrangement.
Markovnikov Addition of H-OH
Adds an Alcohol (OH) because of H2O
Alkene
1. Hg(OAc)2 ; CH3-OH
2. NaBH4
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
Alkene
1. BH3 THF
2. H2O2, NaOH
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
Alkene
1. X2 (Cl2 or Br2)
2. CCl4
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.
Alkene
1. X2 (Cl2 or Br2)
2. H2O (Nu Solvent)
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.
Alkene
1.R-CO3H
2. H3O+
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
Alkene
1. MCPBA
2. H3O+
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.
Alkene
1. O3
2. DMS
Oxidative Cleavage
(Ozonolysis)
Severs C=C bond and forms a ketone and an aldehyde.
Alkene
1. OsO4
2. NaHSO3 / H2O
Dihydroxylation (adds 2 OH groups)
Syn-dihydroxylation: OHs on same side
2-Steps; Recycles OsO4
Alkene
1. OsO4
2. Tert-O-OH
Dihydroxylation (adds 2 OH groups)
Syn-dihydroxylation: OHs on same side
1-Step; Recycles OsO4
Alkene
1. KMnO4, NaOH
Cold
Dihydroxylation (adds 2 OH groups)
Syn-dihydroxylation: OHs on same side.
Strong Oxidizer: Could make ketones instead of alcohol.
1-Step
Alkene
1. OsO4
2. NMO
Dihydroxylation (adds 2 OH groups)
Syn-dihydroxylation: OHs on same side
1-Step; Recycles OsO4
Alkenes
1. H2
2. Pt (catalyst)
Catalytic Hydrogenation: Addition of H-H
Syn-addition: same side
Catalyst can also be Pd and Ni
Alkyne
1. H2SO4, H2O
2. HgSO4 (Proton source)
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
Alkyne
1. Br2
2. CCl4
OR
1. Cl2
2. CCl4
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
Alkyne
1. H-Br
OR
2. H-Cl
What happens when there is excess?
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
Alkyne
1. HBr
2. ROOR
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
Alkyne
1. Na
2. NH3(l)
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
Alkyne
1. H2
2. Lindlar’s Catalyst
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
Alkyne
1. 2 H2
2. Pt (catalysts)
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
