alkyne rxns

Question 1

hydrohalogenation

Answer 1

*HCl or HBr

1. HBr
2. HBr

-mark

final product: add 2 H and 2 Br (or Cl). Go from triple to single bond

Question 2

halogenation

Answer 2

*Cl2 or Br2

1.Cl2
2.Cl2

-stereochemistry
-antiaddition

final product: add Cl (or Br) diagonal after step 1. There should be 4 Cl (or Br) at end. Goes from triple to single bond.

Question 3

hydration (mark)

Answer 3

*creates enol (<1%) or keto (>99%)

1. H2O, H2SO4/HgSO4

enol FP: triple to double bond. add OH and H.

keto FP: triple to single bond. Add double bonded O.

Question 4

hydration (non-mark)

Answer 4

*creates enol or aldehyde

1. BH3
2. H2O2, OH

enol FP: triple to double bond. add OH and H.

aldehyde FP: triple to single bond. Add double bonded O.

Question 5

hydrogenation (creates alkane)

Answer 5

1. 2H2/Pd, Pt, or Ni

-syn

final product: adds 4 H’s. triple to single bond.

Question 6

hydrogenation (cis alkene)

Answer 6

1.H2/Lindlar catalyst

-syn

final product: adds 2 H’s in cis formation. triple to double bond

Question 7

hydrogenation (trans alkene)

Answer 7

1. Li/NH3

-anti

final product: adds 2 H’s in trans formation. triple to double bond.

Question 8

oxidation

Answer 8

1.KMnO4

-splits triple bond

final product: double bond to O and OH on one product. CO2 for other.