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Complete Guide to Alkyne Reactions

Electrophilic Addition to Alkynes


Addition of Bromine and Chlorine to Alkynes


The reagent for this reaction is 1mol Br2 or Cl2


Product: Turn triple bond into a double bond and add two bromines or chlorines, one on each carbon on the double bond.


If the reagent is 2 moles of Br2 or Cl2

Product: Turn triple bond into single and add four bromines or chlorines, two on each carbon from the triple bond.

addition of bromine or chlorine to an alkyne
addition of bromine or chlorine to an alkyne


Addition of Hydrogen Halides to Alkynes


The reagent for this reaction is 2HX where X is Cl, Br or I


Product: Turn triple bond into a single bond and add two halogens, both on the most substituted carbon from the triple bond.

addition of hydrogen halides to alkynes
addition of hydrogen halides to alkynes

Hydration of Alkynes to Aldehydes and Ketones


Hydroboration-Oxidation of Alkynes


The reagent for this reaction is 1.BH3 or (Sia)2BH 2. H2O2, NaOH


Product: Turn triple bond into a single bond and add =O to the LEAST submitted carbon from the triple bond. If there is no least substituted carbon, then add to either carbon.


Hydroboration-Oxidation of alkynes
Hydroboration-Oxidation of alkynes

Acid-catalyzed Hydration of Alkynes


The reagent for this reaction is H2O, H2SO4, HgSO4


Product: Turn triple bond into a single bond and add =O to the most substituted carbon from the triple bond.


Acid- catalyzed hydration of alkynes
Acid- catalyzed hydration of alkynes

Reduction of alkynes


Catalytic Reduction of Alkynes


The reagent for this reaction is 2 H2 with Pd, Pt or Ni


Product: Turn triple bond into a single bond by adding four hydrogens one on each carbon from the triple bond.


catalytic reduction of alkynes
catalytic reduction of alkynes

Lindlar Catalyst


The reagent for this reaction is H2 with Lindlar's catalyst


Product: Turn triple bond into a CIS double bond.


alkyne with lindlar catalyst
alkyne with lindlar catalyst

Alkynes with 2Na NH3(l)


The reagent for this reaction is 2 Na NH3(l)


Product: Turn triple bond into a TRANS double bond


Alkyne Reaction Cheat Sheet for Organic Chemistry by Brown, Iverson, Anslyn, Foote
Alkyne Reaction Cheat Sheet for Organic Chemistry by Brown, Iverson, Anslyn, Foote

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