Search Results
Indirect reduction of CO2 and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
2021, Liu, Xin, Werner, Thomas
The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed. © The Royal Society of Chemistry 2021.
Comparison of transition metal (Fe, Co, Ni, Cu, and Zn) containing tri-metal layered double hydroxides (LDHs) prepared by urea hydrolysis
2019, Naseem, Sajid, Gevers, Bianca, Boldt, Regine, Labuschagné, Frederick J. W. J., Leuteritz, Andreas
This paper details a successful synthesis and comparison of a range of tri-metal hydrotalcite-like layered double hydroxides (LDHs) using urea hydrolysis. Transition-metal-substituted MgMAl-LDHs were synthesized with M = Fe, Co, Ni, Cu or Zn. 5 mol% and 10 mol% substitutions were performed, where Mg was substituted with Co, Ni, Cu and Zn, and Al with Fe. The successful synthesis of crystalline MgMAl-LDHs was confirmed using X-ray powder diffraction (XRD) analysis. Energy-dispersive X-ray (EDX) spectroscopy was used to identify substituted metals and determine changes in composition. Changes in morphology were studied using scanning electron microscopy (SEM). Thermogravimetric analysis was used to determine the effect of Fe-, Co-, Ni-, Cu- or Zn-substitution on the thermal degradation of the MgMAl-LDH phase. The structure, morphology and thermal behavior of the LDHs were shown to be influenced by the substituted transition metals. The observed thermal stability took the order MgNiAl- > MgFeAl- = MgAl- ≥ MgCoAl- > MgCuAl- > MgZnAl-LDH. The urea hydrolysis method was shown to be a simple preparation method for well-defined crystallite structures with large hexagonal platelets and good distribution of transition metal atoms in the substituted LDHs. © 2019 The Royal Society of Chemistry.
Synthesis, in Vitro Profiling, and in Vivo Evaluation of Benzohomoadamantane-Based Ureas for Visceral Pain: A New Indication for Soluble Epoxide Hydrolase Inhibitors
2022, Codony, Sandra, Entrena, José M., Calvó-Tusell, Carla, Jora, Beatrice, González-Cano, Rafael, Osuna, Sílvia, Corpas, Rubén, Morisseau, Christophe, Pérez, Belén, Barniol-Xicota, Marta, Griñán-Ferré, Christian, Pérez, Concepción, Rodríguez-Franco, María Isabel, Martínez, Antón L., Loza, M. Isabel, Pallàs, Mercè, Verhelst, Steven H. L., Sanfeliu, Coral, Feixas, Ferran, Hammock, Bruce D., Brea, José, Cobos, Enrique J., Vázquez, Santiago
The soluble epoxide hydrolase (sEH) has been suggested as a pharmacological target for the treatment of several diseases, including pain-related disorders. Herein, we report further medicinal chemistry around new benzohomoadamantane-based sEH inhibitors (sEHI) in order to improve the drug metabolism and pharmacokinetics properties of a previous hit. After an extensive in vitro screening cascade, molecular modeling, and in vivo pharmacokinetics studies, two candidates were evaluated in vivo in a murine model of capsaicin-induced allodynia. The two compounds showed an anti-allodynic effect in a dose-dependent manner. Moreover, the most potent compound presented robust analgesic efficacy in the cyclophosphamide-induced murine model of cystitis, a well-established model of visceral pain. Overall, these results suggest painful bladder syndrome as a new possible indication for sEHI, opening a new range of applications for them in the visceral pain field.
Synthesis and characterization of MgAl-DBS LDH/PLA composite by sonication-assisted masterbatch (SAM) melt mixing method
2019, Quispe-Dominguez, Roger, Naseem, Sajid, Leuteritz, Andreas, Kuehnert, Ines
This research work is based on the comparison of the mixing phenomena of magnesium-aluminum (MgAl) layered double hydroxides (LDHs) intercalated by dodecylbenzene sulfonate (MgAl-DBS) in poly(lactic acid) (PLA). Two mixing techniques were used to compare the dispersion of LDHs in PLA such as sonication-assisted masterbatch (SAM) melt mixing and direct melting (DM) methods. MgAl LDHs synthesized by the urea hydrolysis method and intercalated with DBS anions using anion exchange reaction and were used in different ratios in PLA (1.25, 2.5, and 5 wt%). MgAl LDHs and their anion intercalation were studied by the X-ray diffraction analysis (XRD) method. Different properties of LDH/PLA composites were compared to analyze the effect of these mixing techniques. Dispersion and exfoliation of LDHs in PLA were investigated by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). Influences on the rheological properties were evaluated by analyzing the complex viscosities (η*), storage modulus (G′) and loss modulus (G′′) by using a rheometer. The thermal properties, thermal stability and effect on crystallinity of composites made with the two mixing techniques were analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) respectively. The mixing mechanism and amount of MgAl-DBS LDHs have a notable effect on the properties of PLA composites with sonication-assisted masterbatch melt mixing techniques giving better dispersion of LDHs in PLA composites as compared to direct melt mixing. © The Royal Society of Chemistry.