Alkyne...........to Ketone

[image]

[image]

• Acid-catalysed Hydration
• Internal Alkyne
• Markovnikov addition
• H₂SO₄ + H₂O + HgSO₄
• Enol & Ketone Tautomers

Alkyne.........to Aldehyde

[image]

[image]

• Hydroboration-oxidation
• Anti-Markovnikov Addition
• Terminal Alkyne
• R₂BH + H₂O₂, NaOH (aq)
• Aldehyde & Enolate (basic conditions) Tautomers
• Aldehyde & Enol (acidic conditions) Tautomers

Alkene.............to Alkyne

[image]

[image]

• Bromination followed by Elimination
• BR₂ / CCl₄
• xs NaNH₂
• H₂O

Alkyne......................to Alkene

   R-C≡C-R   +         &         →  cis R-CH=CH-R

                 R-C≡C-R   +                     →  trans R-CH=CH-R   +   

R-C≡C-R   +   H2   &   Lindlar catalyst   →  cis R-CH=CH-R

• Hydrgenation with a Poisoned Catalyst (e.g. CaCO₃/Quinoline)

R-C≡C-R + 2 Na in NH3 (liq)→trans R-CH=CH-R+2 NaNH2

• Dissolving Metal Reduction
  

Alkyne.........to Alkyl Halide 

• Markovnikov

 [image]

• Anti-Markovnikov

 [image] 

• Markovnikov                [image]
• Hydrohalogenation→Vinyl Halide (One Equivalent)
• HBr
• xs HBr → Alkyl Dihalide (Two Equivalents)

• ---

  Anti-Markovnikov   

                          [image]

• Hydrohalogenation→Vinyl Halide (One Equivalent)
• HBr, ROOR (A Peroxide)
• Radical addition of HBr
• xs HBr → Alkyl Halide (Two Equivalents)

Alkyne ......to Carboxylic Acids (or CO₂)

RC≡CR'   +   ?    then   ?   —>  RCO2H   +   R'CO2H

RC≡CR'   +   O₃    then    H₂O  —>  RCO2H   +   R'CO2H

• Ozonolysis
• Ozone then water
• Internal Alkynes produce Carboxylic Acids
• Terminal Alkynes produce Carbon Dioxide

Alkyne.......to Alkane

HC≡CH +       → CH₃-CH₃

HC≡CH +  2H₂  ————→ CH₃-CH₃           

Pt catalyst

• Hydrogenation
• H₂ + Pt Catalyst
• cis Alkene is difficult to isolate - it is even more reactive toward hydrogenation than starting Alkyne

Alkyne.......to Vinyl Dihalide......to Alkyl Tetrahalide

                                            Br                         Br Br

                         ?                 ¦           ?              ¦  ¦

CH₃-C≡CH ———>CH₃-C=C-CH₃ ———>CH3-C-C-H

                                        ¦                              ¦  ¦

                                       Br                            Br Br

                                          Br                        Br Br

                       Br₂              ¦          Br₂            ¦  ¦

CH₃-C≡CH ———>CH₃-C=C-CH₃ ———>CH3-C-C-H

                                      ¦                              ¦  ¦

                                     Br                            Br Br

• Each step is Halogenation (Two Equivalents)
• Each step uses Br₂
• First step produces a trans Vinyl Halide