02325nas a2200277 4500008004100000022001400041245009700055210006900152260000800221300001500229490000700244520139000251653003301641653003701674653002101711653002001732653002601752100001901778700002201797700002201819700002501841700001801866700001801884700001701902856012801919 2024 eng d a1864-563100aHeterogeneous acid-base organocatalyst for cascade deacetalisation-knoevenagel condensations0 aHeterogeneous acidbase organocatalyst for cascade deacetalisatio cDEC ae2024008660 v173 a

Multifunctional heterogeneous catalysts are an effective strategy to drive chemical cascades, with attendant time, resource and cost efficiencies by eliminating unit operations arising in normal multistep processes. Despite advances in the design of such catalysts, the fabrication of proximate, chemically antagonistic active sites remains a challenge for inorganic materials science. Hydrogen-bonded organocatalysts offer new opportunities for the molecular level design of multifunctional structures capable of stabilising antagonistic active sites. We report the catalytic application of a charge-assisted, hydrogen-bonded crystalline material, bis(melaminium)adipate (BMA), synthesised from melamine and adipic acid, which possesses proximate acid-base sites. BMA exhibits high activity for the cascade deacetalisation-Knoevenagel condensation of dimethyl acetals to form benzylidenemalononitriles under mild conditions in water; BMA is amenable to large-scale manufacture and recycling with minimal deactivation. Computational modelling of the melaminium cation in protonated BMA explains the observed catalytic reactivity, and identifies the first demethoxylation step as rate-limiting, which is in good agreement with time-dependent 1H NMR and kinetic experiments. A broad substrate scope for the cascade transformation of aromatic dimethyl acetals is demonstrated.

10aAntagonistic acid-base sites10aCharge-assisted hydrogen bonding10aChemical cascade10aorganocatalysis10aSustainable catalysis1 aChhetri, Ashis1 aMaibam, Ashakiran1 aManiam, Subashani1 aBabaRao, Ravichandar1 aWilson, Karen1 aLee, Adam, F.1 aMitra, Joyee uhttps://library.ncl.res.in/content/heterogeneous-acid-base-organocatalyst-cascade-deacetalisation-knoevenagel-condensations01781nas a2200157 4500008004100000245010600041210006900147260000800216490000700224520118600231100002001417700002201437700001801459700001801477856012801495 2024 eng d00aRu/MgO-catalysed selective aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid0 aRuMgOcatalysed selective aerobic oxidation of 5hydroxymethylfurf cSEP0 v773 a

Biomass valorisation through the selective oxidation of carbohydrate and lipid derivatives offers access to an array of platform chemicals through energy- and atom-efficient catalytic processes. Supported metal nanoparticles are promising catalysts for the aerobic selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), but typically require strong liquid base to achieve high selectivity. Here, we explore the utility of MgO as a solid base support for the Ru-catalysed aerobic oxidation of HMF, obtaining 68% FDCA yield at 160°C and 1.5 MPa of O2 using <1 mol-% metal.

1 aLokhande, Priya1 aDhepe, Paresh, L.1 aWilson, Karen1 aLee, Adam, F. uhttps://library.ncl.res.in/content/rumgo-catalysed-selective-aerobic-oxidation-5-hydroxymethylfurfural-25-furandicarboxylic