ALKYNE REACTIONS - CSUSM

[Pages:2]ALKYNE REACTIONS

HX Addition X=Halogen

Acetylide Ion

Reagent Guide

Markovnikov:

1 mol Br

HBr CH2Cl2

H

H Br

Br Br 1 mol Br

i

1. NaNH2 2. R-Br

Anti Markovnikov:

Br

H

HBr

H2O2

Br

Halogenation, Addition of X2

Reductions

Cis:

H2

Br2 Ether

Br

Br Br Br Br

Pd/CaCO3 Quinoline

Trans: Pb(OAc)2 [Lindlar's Catalyst]

Li

1 mol Br2

1 mol Br2

NH3 or NaNH2

Br

Oxymercuration (Hydration)

HgSO4, H2O H2SO4 unstable enol

Mechanism: H

tautomers =equilibrium between enol and

Li-?

J

y HNH

- Li+

Carbanion Radical

H

H

H

HNH Li+

iNH2 Trans

H

ketone

-> structural

isomeres OH

Hydroboration (Hydration)

Markovnikov:

1. B2H6 or BH3

2. H2O2, KOH or NaOH H

Oxidations

Antimarkovnikov:

Internal Alkynes:

RuO4 or SeO2

H2SO4

OH

Diketones 1. KMnO4 or O3

Alkynes:

? HBr/CH2Cl2 =

Markovnikov addition

of bromine (2 Br)

? HBr/H2O2 =

Antimarkovnikov

addition of Br (2 Br)

R

? Br2/Ether = Addition

of 4 Br (2 on each side

of triple bond)

? HgSO4,H2O/H2SO4

= ketone formation

? 1.B2H6 or

BH3/2.H2O2, KOH or

NaOH = Aldehyde

formation

? RuO4 or SeO2/

H2SO4 = diketone

H Li? formation

JSP ? Internal Alkynes

NH2

1.KMnO4 or O3/2.

H2O = 2 carboxylic

acids (cleavage rxn)

? Terminal Alkynes 1.

KMnO4 or O3/2. H2O

= Carboxylic Acid &

CO2 (cleavage rxn)

? Heck RXN = see

example

? Terminal Alkyne

1.NaNH2/2.R-Br =

Addition of "R." R could

be CH3, CH2CH3, CH2

CH2CH3, etc. New

carbon-carbon bond

formed

? H2/Lindlar's Catalyst

= Cis reduction

? Li/NH3 or NaNH2 =

trans reduction

2. H2O

OH

Terminal Alkynes:

1. KMnO4 or O3 2. H2O

OH

CO2

Heck Reaction

Br

Pd-catalyst

Na2CO3

Chem 201 Handout

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