Sustainable and Scalable Fe/ppm Pd Nanoparticle Nitro Group Reductions in Water at Room Temperature

Abstract

An operationally simple and general process for the safe and selective reduction of nitro groups utilizing ppm Pd supported on Fe nanomaterials in aqueous solution of designer surfactant TPGS-750-M has been developed and successfully carried out at a 100 mmol scale. Preferred use of KBH 4 as the hydride source, at ambient temperature and pressure, lends this process suitable for a standard reaction vessel alleviating the need for specialized hydrogenation equipment. Calorimetry data parallel those expected for a classical nitro group reduction when measuring the heat of reaction (−896 to −850 kJ/mol).

Synergistic Effects of ppm Levels of Palladium on Natural Clinochlore for Reduction of Nitroarenes

“…However, due to instability of the product, only crude product was identified by 1 H NMR (see the Supporting Information). Furthermore, we investigated the effect of added potassium salts of halides on catalyst reactivity towards a variety of nitroarenes . These results showed that KBr has a significant impact on reaction efficiency relative to other potassium salts (Table S14).…”

“…previouss tudies in which catalysts includingF e, Ni, and Pd were not recyclable andw ere utilized under homogeneous conditions, the newly found atom-economical reagent clinochlore with supported Pd benefits from the advantages of heterogeneous catalysts and allows for the reduction of nitroarenes under recyclable conditions. [17][18][19]…”

The Hydrophobic Effect Applied to Organic Synthesis: Recent Synthetic Chemistry “in Water”

“…After extraction of the product with a minimal amount of organic solvent (e.g., EtOAc), the aqueous medium could be recycled after addition of fresh NaBH 4 , emphasizing the greenness of this process. A scale‐up of this method was pursued with the use of a small amount of co‐solvent (vide infra) for enhanced dispersion of the solid starting nitro material . Replacing NaBH 4 by KBH 4 gave, in some cases, faster and cleaner reactions, avoiding nitroso/hydroxylamine condensation byproducts.…”

“…As cale-up of this method was pursuedw ith the use of as mall amount of co-solvent (vide infra) for enhanced dispersiono ft he solidstarting nitro material. [41] Replacing NaBH 4 by KBH 4 gave, in some cases, faster and cleaner reactions, avoiding nitroso/hydroxylamine condensation byproducts. Ultimately,N aBH 4 admixed with KCl was found to give equivalent results, as al essc ostly alternative to KBH 4 ,especially for large scale reactions.…”

Coolade. A Low‐Foaming Surfactant for Organic Synthesis in Water

“…The first of several reactions screened to determine the effectiveness of Coolade‐derived nanomicelles, tested against those derived from TPGS‐750‐M, involved a catalytic nitro group reduction known to produce large volumes of foam . Even though this problem can be remedied by use of a larger reaction vessel and/or introduction of a cosolvent (e.g., THF) which decreases foam volume, this issue can still present difficulties for experiments aimed at applying this technology on an industrial scale .…”