Background:
There are a number of protocols for Ullmann coupling–type S-arylation
reactions, many of them suffer from the use of homogenous and often corrosive catalyst,
cumbersome workup procedures, and long reaction times. Besides, many of these reagents are
expensive and non-recoverable, leading to the generation of a large amount of toxic waste
particularly when large-scale applications are considered.
Objective:
The aim of this study was to prepare a new Pd catalyst bonded on the surface of zeolite
as a heterogeneous catalyst.
Methods:
A heterogeneous palladium catalyst has been prepared by immobilizing Pd ions on
Clinoptilolite. This novel developed heterogeneous catalyst was thoroughly examined for Ullmann
coupling–type S-arylation reaction using different bases, solvents and 0.003 mg of the catalyst. The
structural and morphological characterizations of the catalyst were carried out using XRD, TGA,
BET and TEM techniques.
Results:
Highly efficient heterogeneous palladium catalyst has been developed by immobilizing Pd
ions on Clinoptilolite, as one of the most abundant naturally occurring zeolites for Ullmann Sarylation.
By using this method, we provide an efficient way to a wide variety of substituted thiolic
compounds. Moreover, the catalyst is easily recovered using simple filtration and reused for 5
consecutive runs.
Conclusion:
In this effort, we developed a new Pd catalyst bonded on the surface of zeolite as a
substrate to prepare the heterogeneous catalyst. We demonstrate that this novel catalyst offers
reliable and convincing data that may offer a valuable application in further developing the science
and technology of Ullmann reaction protocols and allied industries. Additionally, the catalyst was
reusable and kept its high activities over a number of cycles.
Silk Fibroin‐Supported Palladium Catalyst for Suzuki‐Miyaura and Ullmann Coupling Reactions of Aryl Chlorides