Hemant Choudhary

Direct Synthesis of 1,6‐Hexanediol from HMF over a Heterogeneous Pd/ZrP Catalyst using Formic Acid as Hydrogen Source

A new approach is developed for hydrogenolytic ring opening of biobased 5-hydroxymethylfurfural (HMF), dehydration product of hexoses, towards 1,6-hexanediol (HDO) under atmospheric pressure. The highest yield of HDO, 43%, is achieved over reusable Pd/zirconium phosphate (ZrP) catalyst at 413 K in the presence of formic acid as hydrogen source. In comparison with various Brønsted and/or Lewis acidic supports, the specific Brønsted acidity on ZrP support effectively accelerated the cleavage of C-O bond in a furan ring.

Tailored design of palladium species grafted on an amino functionalized organozinc coordination polymer as a highly pertinent heterogeneous catalyst

The design of a highly active and stable heterogeneous palladium catalyst is gaining a lot of attention because of its increasing importance in the organic syntheses of commodity chemicals. Herein, we report the tailored synthesis of palladium species grafted on a highly stable amino functionalized organozinc coordination polymer (denoted as Pd/AZC) and its extraordinary catalytic performances in the Suzuki–Miyaura coupling (SMC) reaction. It achieved the highest turnover number of 2 106 720 (>99% yield) in air among the most reported palladium catalysts for the SMC reaction of bromobenzene. The as-prepared Pd/AZC composite is also successfully applied for the catalysis of Mizoroki–Heck coupling, hydrogenation of nitro, and –CC– functional groups. Since the developed AZC support has thermal stability at least up to 573 K, it possesses high potential for grafting various metal species as catalytically active centers for a wide range of metal-catalyzed reactions.

Selective Oxidation of 1,6‐Hexanediol to 6‐Hydroxycaproic Acid over Reusable Hydrotalcite‐Supported Au–Pd Bimetallic Catalysts

Selective oxidation of 1,6-hexanediol into 6-hydroxycaproic acid was achieved over hydrotalcite-supported Au-Pd bimetallic nanoparticles as heterogeneous catalyst using aqueous H2 O2 . N,N-dimethyldodecylamine N-oxide (DDAO) was used as an efficient capping agent. Spectroscopic analyses by UV/Vis, TEM, XPS, and X-ray absorption spectroscopy suggested that interactions between gold and palladium atoms are responsible for the high activity of the reusable Au40 Pd60 -DDAO/HT catalyst.

Hydrothermal Preparation of a Robust Boehmite‐Supported N,N‐Dimethyldodecylamine N‐Oxide‐Capped Cobalt and Palladium Catalyst for the Facile Utilization of Formic Acid as a Hydrogen Source

Bimetallic CoPd nanoparticles (NPs) on boehmite (AlOOH) were synthesized under hydrothermal conditions using three different capping agents for the facile utilization of formic acid (FA) as a hydrogen source. The CoPd NPs capped with N,N‐dimethyldodecylamine N‐oxide (DDAO) supported on AlOOH (CoPd‐DDAO/AlOOH) exhibited superior catalysis and recyclability in the hydrogenation of maleic anhydride (MAn) in water without metal leaching. The formation of monodispersed CoPd‐DDAO NPs on AlOOH that contained both cobalt oxides and CoPd alloy in each NP was indicated by TEM with energy‐dispersive spectroscopy, XRD, and X‐ray absorption spectroscopy (XAS) studies. X‐ray photoelectron spectroscopy and XAS supported the partial electron transfer phenomenon in CoPd‐DDAO NPs. The as‐prepared CoPd‐DDAO/AlOOH catalyst showed activity for the utilization of FA formed in situ from biomass for the hydrogenation of MAn. It suggested that the DDAO capping agent contributed strongly to the favorable electronic/geometric changes in CoPd alloy for the facile utilization of FA.