Alkyne Reactions

Alkene Elongation

1. Create a Acetylide ion with NaNH2

2. Acetylide Ions are strong nucleophiles and thus can do SN2 substitution to unhindered alkyl-halide

Addition of Acetylide Ions to Carbonyl Groups

1. When an acetylide Ion performs a backside attack on a carbonyl group it results in the formation of an alkoxide anion

2. This alkoxide anion then becomes a alcohol by taking a proton from water

Elimination to synthesize alkynes

Using either KOH or sodium amide at these elevated temperatures implies brutal

reaction conditions, encouraging side reactions and rearrangements. Yields are often

poor

Mega question all 3 ways to synthesize alkyne

Catalytic Hydration of Alkenes

1. Use a metal catalyst to add hydrogen to Alkynes

   1. Using a catalysts such as pure Pd or platinum or whatever results in reduction to alkane

   2. Using a poison catalyst like Lindlar’s catalyst (aka quinoline) or Ni2B will result in SYN hydration alkene

Anti Reduction of an alkene

Reagents: Na NH3

Neither Mark nor AntiMark

Anti-Addition

Addition of halogen

Just need to know that X2 ands anti in equimolar and completely in 2 Molar

Addition of Hydrogen Halide

Reagents: H—X

Mark orientation (geminal halide if double)
Both Syn and Anti

Hydration of Alkynes (Ketone)

Reagents: HgSO4/H2SO4

Mark Orientation of the OH

REARANGEMENT TO KETONE

Mechanism (Acid catalyzed)

Hydration of Alkynes (Aldehyde)

Reagents: Sia2BH followed by H2O2/NaOH

Anti Mark Orientation

Base Catalyzed Keto-Enol Transformation

Oxidation of Alkynes

You only need to know cold KMnO4 adds 2 carbonyls (one to each carbon in a triple bond). Also if there are any spare H its make that an alcohol

Clevage of Alkanes

Reagents:

1. KMnO4/KOH

2. O3 + H2O

Results: Cleavage and creation of Carboxylic acid (or CO2)