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entree SiliaCat

Kumada Coupling Using SiliaCat Pd Catalysts

The Kumada coupling is the direct cross-coupling between an alkyl or an aryl Grignard and a halocarbon. It can be catalyzed by a Pd or a Ni catalyst.

KumadaCouplingReaction1.gif

 

Catalyst Concentration Effect

At a constant concentration of substrate, an increase of the amount of SiliaCat from 0.1 (or 0.2) to 1.0 will increase the kinetics (completed in only 15 minutes).

 

 

By increasing the concentration of the catalyst, thus thereby increasing the number of active sites, conversion of the substrate will be favored.
KumadaCouplingBromoStyreneReaction.gif KumadaCouplingAliphaticAlkenes.gif
Catalyst Concentration Effect
SiliaCat DPP-Pd
(mol %)
Solvent
(M)
Time
(min)
Conversion
(%)
1.0
THF (0.07 M)
15 min
96
0.5
THF (0.07 M)
15 min
95
0.2
THF (0.08 M)
2 h
94
 
Catalyst Concentration Effect
SiliaCat DPP-Pd
(mol %)
Solvent
(M)
Time
(min)
Conversion
(%)
1.0
THF (0.08 M)
15 min
98
0.5
THF (0.08 M)
90 min
96
0.2
THF (0.08 M)
4 h
98

 

Catalyst Reusability and Leaching

Minimal leaching and the robustness of the organoceramic matrix are important factors that allow it to be reused several times.

KumadaResabilityandLeaching.gif

 

SiliaCat Reusability and Leaching
Reusability
Conversion
(%)
Pd Leaching
(ppm)
Pd Si
1st
98
0.20
1.5
2nd
95
0.20
2.3
3rd
94
0.50
1.7
4th
77
0.02
1.9

 

Catalytic Activity and Leaching

SiliaCat DPP-Pd showed good reactivity for aryl iodides and bromides. Inert conditions are required for Kumada couplings due to the presence of Grignard reagent.

Catalytic Activity and Leaching
Substrate (R) / Halide (X)
R-MgBr
(2 eq.)
Solvent
(M)
Time
(h)
Conversion
(%)
Leaching (ppm)
Pd Si
4-OCH3 / Br
Ph-MgBr
THF (0.05 M)
18
98
0.3
0.2
4-OCH3 / Br
i-Bu-MgBr
THF (0.05 M)
18
95
-
-
4-CH3 / Br
Ph-MgBr
THF (0.05 M)
18
96
-
-
4-CH3 / Br
i-Bu-MgBr
THF (0.05 M)
18
98
-
-
4-F / Br
Ph-MgBr
THF (0.08 M)
24
94
< 0.01
1.5
H / I
Ph-MgBr
THF (0.08 M)
24
99
-
-
4-OCH3 / I
Ph-MgBr
THF (0.08 M)
24
94
-
-
4-CH3 / I
Ph-MgBr
THF (0.08 M)
24
95
< 0.01
1.0
Note: R'SnBu3 was vinyl (1.1 eq.)

 

Kumada Coupling Typical Experimental Procedure

Conventional Experimental Conditions

Reaction - All products under inert conditions (catalyst, solvent, substrates, and Grignard reagent) are added to a Schlenk or a dry round bottom flask equipped with a magnetic stirrer. The mixture was stirred at room temperature until the TLC or GC-MS analysis confirmed reaction completion (18-24h).

Work-up

Once the reaction is completed, inert conditions are not necessary. Follow same work-up procedure as for Suzuki coupling conventional experimental conditions.

Experimental Conditions - Kumada Coupling
Products
Standard Conditions for 1 eq of:
Ar-Iodide & Ar-Bromide
R-MgBr
2.0 eq.
SiliaCat Catalyst
2.0 - 10.0 mol %
(usually 5 mol %)
Best Solvents
(HPLC Grade)
Tetrahydrofuran (0.05 - 0.08 M)
(usually 0.08 M)
*Note: molar concentration is related to the substrate. Reaction need to be done at room temperature under inert atmosphere.

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  1. SiliaCat DPP-Pd heterogeneous catalyst

    SiliaCat® Heterogeneous Catalysts DPP-Pd

    The significant costs associated with precious metal catalysts and their undesired tendency to remain in organic products has generated interest for an increase in reactivity and ways to recover and reuse these metals. SiliaCat DPP-Pd is a unique diphenylphosphine palladium (II) heterogeneous catalysts made from a leach-resistant organoceramic matrix.
  2. SiliaCat® Heterogeneous Catalysts TEMPO

    SiliaCat® Heterogeneous Catalysts TEMPO

    SiliaCat® TEMPO is a heterogeneous catalyst/reagent made from a proprietary class of organosilica-entrapped radicals suitable for the selective oxidation of delicate substrates into valued carbonyl derivatives.

  3. SiliaCat® Heterogeneous Catalysts Pd0

    SiliaCat® Heterogeneous Catalysts Pd0

    SiliaCat Pd0 is a new series of patent-protected sol–gel-entrapped Pd nanocatalysts. It is made from highly dispersed Pd nanoparticles (uniformly in the range 4.0–6.0 nm) encapsulated within an organosilica matrix.
  4. SiliaCat® Heterogeneous Catalysts Pt0

    SiliaCat® Heterogeneous Catalysts Pt0

    SiliaCat Pt0 is made of organosilica physically doped with nanostructured platinum (0), and is both stable and efficient. This catalyst was successfully prepared by a novel and simple sol-gel route.
  5. SiliaCat® complete heterogeneous catalysts kit

    SiliaCat® complete heterogeneous catalysts kit

    Containing : SiliaCat DPP - Pd, Pd0, Pt0 and TEMPO

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