Sulfur Modification of Au via Treatment with Piranha Solution Provides Low-Pd Releasing and Recyclable Pd Material, SAPd

Abstract

We have found in the SR-HXPS measurement of Piranha-treated Au(111)/mica that the gold surface underwent sulfur modification during this treatment, which was believed to have only removed impurities from the gold surface. We also successfully developed a practical Pd material, SAPd, whose Pd was immobilized on sulfur-modified Au. With the lowest Pd-releasing levels and high recyclability, this is one of the best Pd materials thus far developed. Because it leaches extremely low levels of Pd into reaction mixtures, removal of the residual Pd is unnecessary using SAPd, even in syntheses involving pharmaceutical ingredients.

Development of a Sulfur-Modified Glass-Supported Pd Nanoparticle Catalyst for Suzuki–Miyaura Coupling

“…As reported in our previous research, [17][18][19][20][21][22][23][24][25][26][27] SAPd absorbs very few organic compounds and can therefore be used in combinatorial synthesis because of its small surface area. It was envisaged that SGlPd would perform in a similar manner to SAPd.…”

“…Organic materials containing sulfate and xylene as the major ingredients are distributed between the Pd nanoparticles, allowing for the formation of stable high-density PdNPs without condensation. [17][18][19][20][21][22][23][24][25][26][27] The results of the XANES analysis suggest that the oxidized sulfur preserves the structure of the PdNPs in SGlPd as well as SAPd.…”

“…Notably, this catalyst exhibited good recyclability properties in all cases with low palladium leaching. [17][18][19][20][21][22][23][24][25][26][27] In 2015, we successfully analyzed the structure of our SAPd catalyst by X-ray absorption fine structure (XAFS) and transmission electron microscopy (TEM) analyses and found that the Au particles in this material simply acted as a solid support for the SAPd membrane. 27) SAPd is now commercially available as a safe, facile, recyclable and low-leaching PdNP catalyst.…”

Density functional theory calculations for Pd adsorption on SO4 adsorbed on h-BN

“…Recently, Arisawa et al [6,7] found that SO 4 exist on gold surfaces after a Piranha treatment [8] during a process of making a Pd catalyst. The Piranha treatment had been traditionally used to remove organic residues from gold surfaces [9][10][11][12][13][14] and to make self-assembled monolayers (SAMs) of alklthiols (RSH) on metal surfaces [9][10][11][12][13][14][15].…”

“…Moreover, h-BN is cheaper than gold. It means that Pd and SO 4 on h-BN is a promising candidate substrate for catalysts like SAPd[6,33,35], Pd and SO 4 on gold substrate for the SuzukiMiyaura coupling reactions…”