A Spatially Orthogonal Hierarchically Porous Acid-Base Catalyst for Cascade and Antagonistic Reactions

Abstract

<p>Complex organic molecules are of great importance to academic and industrial chemistry and typically synthesised from smaller building blocks by multistep reactions. The ability to perform multiple (distinct) transformations in a single reactor would greatly reduce the number of manipulations required for chemical manufacturing, and hence the development of multifunctional catalysts for such one-pot reactions is highly desirable. Here we report the synthesis of a hierarchically porous framework, in which the macropores are selectively functionalised with a sulfated zirconia solid acid coating, while the mesopores are selectively functionalised with MgO solid base nanoparticles. Active site compartmentalisation and substrate channelling protects base catalysed triacylglyceride transesterification from poisoning by free fatty acid impurities (even at 50 mol%), and promotes the efficient two-step cascade deacetylation-Knoevenagel condensation of dimethyl acetals to cyanoates.<br></p>

Low-Field Functional Group Resolved Nuclear Spin Relaxation in Mesoporous Silica

“…6 Such measurements have been employed by the rock physics and petrochemical exploration communities for over five decades, 7,8 providing estimates of oil and gas reservoir quality indicators including porosity, permeability, and producible hydrocarbon content. 9 Further well-established applications include the observation of cement and plaster hydration kinetics, 10,11 while emergent fields within the materials chemistry research space now include characterisation of bespoke porous architectures including heterogeneous catalysts, 12,13 zeolites 14,15 and metal-organic frameworks. 16,17 The most data-rich methods for elucidating spin relaxation processes in porous media are multidimensional relaxation correlation measurements.…”

Dual metal nanoparticles within multicompartmentalized mesoporous organosilicas for efficient sequential hydrogenation

“…Similarly, TiO 2 nanotubes were reported to localize Pt and Ni NPs on their outer or inner surfaces using atomic layer deposition for transfer hydrogenation 26 – 28 . Hierarchical porous silicas were also used to position dual metal NPs through stepwise modification of their pore surfaces for sequential oxidation of cinnamyl alcohol 29 , 30 . Despite the great success in constructing cascade catalysts via such spatial separation of multiple metal NPs, these existing materials either lack compartmentalized structures to accommodate metal NPs on the outer surfaces 20 – 28 , or else are unable to provide well-defined nanochannels for connecting different metal NPs in nanoscale proximity 26 – 30 .…”

“…Hierarchical porous silicas were also used to position dual metal NPs through stepwise modification of their pore surfaces for sequential oxidation of cinnamyl alcohol 29 , 30 . Despite the great success in constructing cascade catalysts via such spatial separation of multiple metal NPs, these existing materials either lack compartmentalized structures to accommodate metal NPs on the outer surfaces 20 – 28 , or else are unable to provide well-defined nanochannels for connecting different metal NPs in nanoscale proximity 26 – 30 . The unsatisfactory integration of all the desired features in a single catalyst hinders realization of efficient synergistic catalysis.…”

Functional Group Resolved Nuclear Spin Relaxation in Porous Media

“…6 Such measurements have been employed by the rock physics and petrochemical exploration communities for over five decades, 7,8 providing estimates of oil and gas reservoir quality indicators including pore size distributions, porosity, permeability, and producible hydrocarbon content. 9 Further wellestablished applications include the observation of cement and plaster hydration kinetics, 10,11 while emergent fields within the materials chemistry research space now include characterisation of bespoke porous architectures including heterogeneous catalysts, [12][13][14] zeolites 15 and metal-organic frameworks. 16 The most data-rich methods for elucidating spin relaxation processes in porous media are multidimensional relaxation correlation measurements.…”