The benefits of transitioning to chemical and material circularity are readily apparent. However, identifying and developing the necessary chemical transformations for platform chemical recycling is a significant challenge. Alcohols are an important industrial platform class owing to existing demand and the potential for their renewable supply through the utilization of biomass processing waste streams. Acceptorless Dehydrogenation (AD) is a critical process in the context of circularity, particularly in the transformation of alcohols. This mini-review offers an in-depth examination of both homogeneous and heterogeneous catalytic processes used in acceptorless dehydrogenation. We primarily concentrate on two sustainable feedstocks, glycerol and ethanol. Through the assessment and juxtaposition of homogenous and heterogeneous catalysts in the context of the alcoholysis of glycerol and ethanol, we aim to establish a comparison based on activity, longevity, and the green chemistry metrics associated with the catalytic processes (specifically the E-factor; energy economy coefficient, epsilon; and environmental energy impact factor, xi). We established evaluation criteria using the matrics to provide a means for comparison among homogeneous and heterogeneous catalysts and help identify promising catalyst classes that can be further developed. This review seeks to shed light on the existing constraints that must be addressed to advance the development of catalysts that are more efficient, cost-effective, and resilient for AD reactions.

Catalytic decarbonylation is an underexplored strategy for deoxygenation of biomass-derived aldehydes owing to a lack of low-cost and robust heterogeneous catalysts that can operate in benign solvents. A family of Pd-functionalized hydrotalcites (Pd-HTs) were synthesized, characterized, and applied to the decarbonylation of furfural, 5-hydroxymethylfurfural (HMF), and aromatic and aliphatic aldehydes under microwave conditions. This catalytic system delivered enhanced decarbonylation yields and turnover frequencies, even at a low Pd loading (0.5 mol %). Furfural decarbonylation was optimized in a benign solvent (ethanol) compatible with biomass processing; HMF selectively afforded an excellent yield (93 %) of furfuryl alcohol without humin formation; however, a longer reaction favored the formation of furan through tandem alcohol dehydrogenation and decarbonylation. Yields of the substituted benzaldehydes (37-99 %) were proportional to the calculated Mulliken charge of the carbonyl carbon. Activity and selectivity reflected loading-dependent Pd speciation. Continuous-flow testing of the best Pd-HT catalyst delivered good stability over 16 h on stream, with near-quantitative conversion of HMF.

Electronic effects of supports on site-isolated organometallic complexes are poorly understood, despite indication that such effects impact stability and reactivity of immobilized complexes. Here we report X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) spectroscopy studies of surface-immobilized Pd-II N-heterocyclic carbene complexes on Mg-Al mixed metal oxides (MMOs) using silane-modified ligands. XPS revealed a ca. 1 eV increase in Pd binding energy as a result of immobilization on MMOs, suggesting that the Pd-II complex becomes more electropositive when appended to the surface. For MMOs doped with Fe, Ni, Co and Zn, analysis of Cl K-edge and Pd L-2- and L-3-edge showed increasing pre-edge energies that followed the order Fe = Ni < Zn = Cr < undoped Mg-Al MMO. The Pd L-3 pre-edge energies correlated to the calculated oxygen partial charge of the MMO, as estimated using the Sanderson electronegativity model. Transmission electron microscope images collected on the immobilized Pd complexes revealed nanoparticles on three of the five MMOs, whose presence can be related to the Pd XPS and XANES energies. These findings suggest that electronic differences associated with the MMO supports impact the stability of appended Pd-II complexes with respect to reduction to Pd-0.

Skin contact or exposure to sensitizers often occurs as a consequence of occupational exposures (e.g. poison ivy in forestry), wearing jewelry (e.g. nickel), or use of cosmetics (e.g. fragrances). However, many of the known skin sensitizers or their chemical variants are also consumed orally through foods or other sources. Since oral exposure to antigenic substances can lead to tolerance, consumption of sensitizers may impact the development and potency of skin sensitization, especially if the sensitizer is consumed early in life, prior to the first skin contact. To address this issue, we have reviewed human clinical and epidemiological literature relevant to this subject and evaluated whether early oral exposures to relevant sensitizers, or their chemical variants, are associated with reduced prevalence of skin sensitization to three main allergic sensitizers - nickel, urushiols of poison ivy, and sesquiterpene lactones of chrysanthemum and other plants.

New atom-economical alternatives to Wittig chemistry are needed construct olefins from carbonyl complexes, but none have been developed to-date. Here we report an atom-economical olefination of carbonyls via aldol-decarbonylative coupling of aldehydes using robust and recyclable supported Pd catalysts, producing only CO and H 2 O as waste. The reaction accommodates homocoupling of aldehydes with an a a-methylene groups, as well as heterocoupling. Computations provide insight into the selectivity of the reaction. The tandem aldol-decarbonylation reaction opens the door to exploration of new carbonyl reactivity to construct olefins.

Here we report the synthesis, characterization andactivity of tunable Pd-doped hydrotalcites (Pd-HTs) for the decarbonylation offurfural, hydroxymethylfurfural (HMF),aromatic and aliphatic aldehydes under microwave conditions. Thedecarbonylation activity reported is a notable improvement over priorheterogeneous catalysts for this process. Furfural decarbonylation is optimizedin a benign solvent compatible with biomass processing - ethanol, underrelatively mild conditions and short reaction times. HMF selectively affordsexcellent yields of furfuryl alcohol with no humin formation, but longerreaction can also afford furan via tandem alcohol dehydrogenation anddecarbonylation. Yields of substituted benzaldehydes are related to calculatedMulliken charge of the carbonyl carbon. The activity and selectivitydifferences can be traced to loading-dependent differences in Pd speciation onthe catalysts. Poisoning studies show inverse correlation between Pd loadingand metal leaching: Pd-HTs with lowest Pd loading, which consist of highlydispersed and oxidized Pd species, operate heterogeneously withnegligible metal leaching. Recycling experimentsare consistent with this trend, offering potential for further optimization toimprove robustness.

Over 4000 small chemicals have been identified as allergens capable of inducing skin sensitization. Many sensitizers are hypothesized to act as haptens producing novel antigens, which can be presented to T cells by human leukocyte antigens (HLAs). Recent studies suggest that some chemical allergens use hapten‐independent mechanisms.

The acceptorless dehydrogenation of acyclic secondary amines is a highly desirable but still elusive catalytic process. Here we report the synthesis, characterization, and activity of Pd-doped hydrotalcites (Pd-HTs) for acceptorless dehydrogenation of both primary and secondary amines (cyclic and acyclic). These multifunctional catalysts comprise Bronsted basic and Lewis acidic surface sites that stabilize Pd in 0, 2(+), and 4(+) oxidation states. Pd speciation and corresponding catalytic performance is a strong function of metal loading. High activity is observed for the dehydrogenation of secondary aliphatic amines to imines, and N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, to aromatic compounds. Oxidative transamination of primary amines is achieved using low Pd loading (0.5 mol %), without the need for oxidants. The relative yields of secondary imines afforded are consistent with trends for calculated free energy of reaction, while yields for transamination products correspond to the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative selectivity for secondary imine/amine products. Poisoning tests evidence that Pd-HTs operate heterogeneously, with negligible metal leaching. Catalysts retain over 90% of activity over six reuse cycles, but do suffer some selectivity loss, attributed to changes of Pd phases.

The synthesis, characterization, and activity of Pd-doped layered double hydroxides (Pd-LDHs) for for acceptorless amine dehydrogenation is reported. These multifunctional catalysts comprise Brønsted basic and Lewis acidic surface sites that stabilize Pd species in 0, 2+, and 4+ oxidation states. Pd speciation and corresponding cataytic performance is a strong function of metal loading. Excellent activity is observed for the oxidative transamination of primary amines and acceptorless dehydrogenation of secondary amines to secondary imines using a low Pd loading (0.5 mol%), without the need for oxidants. N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, are dehydrogenated to the corresponding aromatics with high yields. The relative yields of secondary imines are proportional to the calculated free energy of reaction, while yields for oxidative amination correlate with the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative imine:amine selectivity. Poisoning tests evidence that Pd-LDHs operate heterogeneously, with negligible metal leaching; catalysts can be regenerated by acid dissolution and re-precipitation.

The synthesis, characterization, and activity of Pd-doped layered double hydroxides (Pd-LDHs) for for acceptorless amine dehydrogenation is reported. These multifunctional catalysts comprise Brønsted basic and Lewis acidic surface sites that stabilize Pd species in 0, 2+, and 4+ oxidation states. Pd speciation and corresponding cataytic performance is a strong function of metal loading. Excellent activity is observed for the oxidative transamination of primary amines and acceptorless dehydrogenation of secondary amines to secondary imines using a low Pd loading (0.5 mol%), without the need for oxidants. N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, are dehydrogenated to the corresponding aromatics with high yields. The relative yields of secondary imines are proportional to the calculated free energy of reaction, while yields for oxidative amination correlate with the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative imine:amine selectivity. Poisoning tests evidence that Pd-LDHs operate heterogeneously, with negligible metal leaching; catalysts can be regenerated by acid dissolution and re-precipitation.

Detailed characterisation of morphology of doped hydrotalcites as catalysts precursors. Trends of material stability, pore size distribution, particle size as a function of the nature of dopants. Data on the flow synthesis method and reproducibility of materials that can be attained by this method.

A predictive method is reported for estimating skin permeation of organic chemicals exclusively from NMR spectroscopic data and molecular weight, which does not require knowledge of chemical structure.

We report a new covalent surface immobilization of silane-modified imidazolium ionic liquids on hydrotalcite-like materials (HTs) and provide detailed characterization of the resulting surface chemistry using PXRD, CP-MAS, TGA and FT-IR. We show that this immobilization interferes with the "memory effect" of HTs and explore the stability of the resulting complexes to hydrolysis.

The ability to estimate chemical and physical properties from experimental spectra is highly desirable, as it eliminates the need for a priori knowledge of exact chemical structure and allows the property estimation of mixtures. Here we report the proof of principle that a predictive method for octanol‐water partition coefficient (log P ) based on 1 H‐NMR spectra in d 3 ‐chloroform is feasible and can yield accuracy comparable to in silico log P models. The Spectrometric Data‐Activity Relationship (QSDAR) reported predicts log P of neutral organic chemicals using descriptors derived only from 1 H‐NMR chemical shifts, integrations and peak widths. Proton NMR spectra of 140 compounds with diverse structures were used to construct a Multiple Linear Regression (MLR) and a Partial Least Squares (PLS) model that predicts log P. The optimized models were internally validated by K‐fold cross validation and leave‐one‐out validation, and externally with a test set of 28 chemicals. The squared regression coefficients of prediction for the MLR and PLS regression models were 0.970 and 0.971 respectively, showing that the method allows accurate prediction of log P values exclusively from predicted 1 H NMR spectra.

Fusilev,intravenous injections of levoleucovorin calcium,which belongs to Spectrum Pharmaceuticals Incorporation,got its FDA approval in 2008.It is indicated for rescue after high dose methotraxate therapy in osteosarcoma.We review the physical activity,the mechanism of action in the adjuvant treatment of cancer and its clinical applications in this article.