Alkyne Reactions

Acetylide Anion Formation

Reactants: Terminal alkyne, carbanion with alkali, Product: Acetylide anion (Terminal alkyne carbanion

Internal Alkyne Synthesis

Reactant: Acetylide anion, Reagent: 1° electrophile, Product: Internal alkyne

2° Alcohol Synthesis

Reactants: Acetylide anion, aldehyde, Reagents: H3O+ workup, Product: 2° alcohol

3° Alcohol Synthesis

Reactants: Acetylide anion, ketone, Reagents: H3O+ workup, Product: 3° alcohol

Alkyne Synthesis via KOH Dihalide Elimination

Reactant: Antiperiplanar vicinal dihalide alkane, Reagent: Molten KOH, Product: Internal Alkyne

Alkyne Synthesis via NaNH2 Dihalide Elimination

Reactant: Geminal dihalide, Reagent: NaNH2, H3O+ workup, Product: Terminal Alkyne

Hydrogenation to Alkane

Reagent: H2, Pd/C, Product: Alkane

Hydrogenation to Cis Alkene

Reagent: H2, Lindlar’s catalyst (Pd/BaSO4), quinoline, MeOH, Product: Cis Alkene

Hydrogenation to Trans Alkene

Reagent: Na/NH3, under 33°C, Product: Trans Alkene

Halogenation to Alkene

Reagents: 1 X2, Product: Racemic mix depending on selectivity (Trans is major prod)

Hydrohalogenation

Reagent: 1 HX, Product: Markovnikov

Mercury-catalyzed Hydration

Reagents: HgSO4, H2SO4, H2O, Products: Enol ⇌ Ketone

Hydroboration Oxidation

Reagents: Sia2BH, H2O2, NaOH, Product: Aldehyde

Internal Alkyne Oxidation (Neutral Conditions) 

Reactant: Internal alkyne, Reagents: KMnO4, H2O, pH=7, Product: 1,2 diketone

Internal Alkyne Oxidation (Basic Conditions)

Reactant: Internal alkyne, Reagents: KMnO4, KOH, H2O, heat, pH>7, Product: Carboxylic acids

Terminal Alkyne Oxidation (Neutral Conditions)

Reactant: Terminal alkyne, Reagents: KMnO4, H2O, pH=7, Product: Keto-acid

Ozonolysis

Reactant: Internal alkyne, Reagents: O3, H2O, Product: Carboxylic acids