Depolymerization of organosolv lignin to aromatic compounds over Cu-doped porous metal oxides

Isolated, solvent-extracted lignin from candlenut (Aleurites moluccana) biomass was subjected to catalytic depolymerization in methanol with an added pressure of H-2, using a porous metal oxide catalyst (PMO) derived from a Cu-doped hydrotalcite-like precursor. The Cu-PMO was effective in converting low-molecular weight lignin into simple mixtures of aromatic products in high yield, without char formation. Gel permeation chromatography was used to track changes in molecular weight as a result of the catalytic treatments and product mixtures were characterized by H-1 and C-13 NMR spectroscopy. In the temperature range 140-220 degrees C, unusual C9 catechols were obtained with high selectivity. Lignin conversion of > 90% and recovery of methanol-soluble products in yields of was > 70% was seen at 180 degrees C with optimized catalyst and biomass loadings. At 140 degrees C, 4-(3-hydroxypropyl)-catechol was the major product and could be isolated in high purity

Depolymerization of organosolv lignin using doped porous metal oxides in supercritical methanol

An isolated, solvent-extracted lignin from candlenut (Aleurites moluccana) biomass was subjected to catalytic depolymerization in the presence of supercritical methanol, using a range of porous metal oxides derived from hydrotalcite-like precursors. The most effective catalysts in terms of lignin conversion to methanol-soluble products, without char formation, were based on copper in combination with other dopants based on relatively earth-abundant metals. Nearly complete conversion of lignin to bio-oil composed of monomers and low-mass oligomers with high aromatic content was obtained in 6 h at 310 degrees C using a catalyst based on a Cu- and La-doped hydrotalcite-like precursor. Product mixtures were characterized by NMR spectroscopy, gel permeation chromatography, and GC-MS. (C) 2014 Published by Elsevier Ltd

Magnetic Field Alignment of a Diblock Copolymer Using a Supramolecular Route

Large-area uniform magnetic alignment of a self-assembled diblock copolymer has been achieved by the selective sequestration of rigid moieties with anisotropic diamagnetic susceptibility within one block of the system. The species is based on a biphenyl core and is confined in the acrylic acid domains of a poly­(styrene-<i>b</i>-acrylic acid) block copolymer by hydrogen bonding between an imidazole headgroup and the acrylic acid units. Microphase separation produces hierarchically ordered systems of smectic layers within lamellae and smectic layers in the matrix surrounding hexagonally packed poly­(styrene) cylinders, as a function of imidazole/acrylic acid stoichiometry. The magnetic field aligns the smectic layers as well as the block copolymer superstructure in a manner dependent on the anchoring condition of the biphenyl species at the block copolymer interface. Surprisingly, this is found to depend on the composition of the system. This approach is synergistic with recent efforts to engineer functional supramolecular block copolymer assemblies based on rigid chromophores. It offers a facile route to large area control of microstructure as required for full exploitation of functional properties in these systems

Life cycle inventory improvement in the pharmaceutical sector: Assessment of the sustainability combining PMI and LCA tools

Pharmaceutical chemicals are complex, high value added products that typically impose significantly greater impacts on the environment per kilogram compared to basic chemicals. A variety of green metrics have been developed to guide the design of chemistries and processes that are more sustainable. Among these, Process Mass Intensity (PMI) was selected by the American Chemical Society Green Chemistry Institute Pharmaceutical Roundtable as the key parameter to express sustainability. However, researchers were concerned that these metrics could miss relevant factors that would be addressed by a more comprehensive Life Cycle Assessment (LCA). Lack of inventory data for many chemicals poses a significant barrier to more extensive implementation of LCA for pharmaceuticals. A cradle-to-gate LCA of Viagra\u2122 is used to present a practical approach to construct inventories using patent and literature data. Details of the improved inventory data were presented for four chemicals to illustrate the methodology and highlight the importance of considering out-sourced processing of reagents used in pharmaceutical synthesis. A more comprehensive impact assessment was conducted using ReCiPe v1.11 at both midpoint and endpoint levels. A comparison of two synthesis routes rated them well against results from the simpler green metrics. An area for future work is to address the lack of characterization factors for toxicity and other impact categories for many chemicals

Quantum Chemistry Analysis of Reaction Thermodynamics for Hydrogenation and Hydrogenolysis of Aromatic Biomass Model Compounds

Designing effective and selective reactions at sustainable or mild conditions is key for the valorization or refinery of lignin biomass using H₂ reduction methods. However, it remains unclear what are the feasible mildest conditions for the reductive valorization of lignin, at which transformations can be designed. Here, we aim to exploit this critically important question using quantum chemistry calculations to systematically analyze the thermodynamics of hydrogenation and hydrogenolysis of typical functional groups found in lignin based on a set of aromatic model compounds. Our results show that it is thermodynamically feasible to break ether linkages and remove oxygen content in the model compounds even at room temperature, room pressure, and in aqueous solvent (i.e., the global mildest conditions). Interestingly, the potential influence on the thermodynamics by reaction variables is ranked in the order of temperature > H₂ pressure > solvent dielectric constant; a strategically chosen solvent may enable increased selectivity for hydrogenolysis over hydrogenation. Our predicted reaction thermodynamics is consistent with our experimental findings of probed reaction pathways. This work may inspire researchers to pursue the design of “ultimate” green biomass conversion processes closer to the global mildest conditions

Considerations on Integrating Prostate-Specific Membrane Antigen Positron Emission Tomography Imaging Into Clinical Prostate Cancer Trials by National Clinical Trials Network Cooperative Groups

PurposeAs prostate-specific membrane antigen (PSMA) positron emission tomography (PET) becomes increasingly available in the United States, the greater sensitivity of the technology in comparison to conventional imaging poses challenges for clinical trials. The NCI Clinical Imaging Steering Committee (CISC) PSMA PET Working Group was convened to coordinate the identification of these challenges in various clinical scenarios and to develop consensus recommendations on how best to integrate PSMA PET into ongoing and upcoming National Clinical Trials Network (NCTN) trials.MethodsNCI CISC and NCI Genitourinary Steering Committee members and leadership nominated clinicians, biostatisticians, patient advocates, and other imaging experts for inclusion in the PSMA PET Working Group. From April to July 2021, the working group met independently and in conjunction with the CISC to frame challenges, including stage migration, response assessment, trial logistics, and statistical challenges, and to discuss proposed solutions. An anonymous, open-ended survey was distributed to members to collect feedback on challenges faced. Representatives from each NCTN group were invited to present an overview of affected trials. From these discussions, the consensus document was developed and circulated for the inclusion of multiple rounds of feedback from both the Working Group and CISC.ResultsThe current consensus document outlines the key challenges for clinical prostate cancer trials resulting from the increasing availability of PSMA PET. We discuss implications for patient selection and definition of end points and provide guidance and potential solutions for different clinical scenarios, particularly with regard to best practices in defining eligibility criteria and outcome measures.RecommendationsThis article provides guidance regarding clinical trial design and conduct, and the interpretation of trial results