Fully Automated Flow Protocol for C(sp3)-C(sp3) Bond Formation from Tertiary Amides and Alkyl Halides.

Herein, we present a novel C(sp3)-C(sp3) bond-forming protocol via the reductive coupling of abundant tertiary amides with organozinc reagents prepared in situ from their corresponding alkyl halides. Using a multistep fully automated flow protocol, this reaction could be used for both library synthesis and target molecule synthesis on the gram-scale starting from bench-stable reagents. Additionally, excellent chemoselectivity and functional group tolerance make it ideal for late-stage diversification of druglike molecules.

Mechanically recyclable melt-spun fibers from lignin esters and iron oxide nanoparticles: towards circular lignin materials.

The inferior thermoplastic properties have limited production of melt-spun fibers from lignin. Here we report on the controlled esterification of softwood kraft lignin (SKL) to enable scalable, solvent-free melt spinning of microfibers using a cotton candy machine. We found that it is crucial to control the esterification process as melt-spun fibers could be produced from lignin oleate and lignin stearate precursors with degrees of esterification (DE) ranging from 20-50%, but not outside this range. To fabricate a functional hybrid material, we incorporated magnetite nanoparticles (MNPs) into the lignin oleate fibers by melt blending and subsequent melt spinning. Thermogravimetric analysis and X-ray diffraction studies revealed that increasing the weight fraction of MNPs led to improved thermal stability of the fibers. Finally, we demonstrated adsorption of organic dyes, magnetic recovery, and recycling via melt spinning of the regular and magnetic fibers with 95% and 83% retention of the respective adsorption capacities over three adsorption cycles. The mechanical recyclability of the microfibers represents a new paradigm in lignin-based circular materials.

Microwave radiation-assisted synthesis of levulinic acid from microcrystalline cellulose: Application to a melon rind residue.

The circular economy considers waste to be a new raw material for the development of value-added products. In this context, agroindustrial lignocellulosic waste represents an outstanding source of new materials and platform chemicals, such as levulinic acid (LA). Herein we study the microwave (MW)-assisted acidic conversion of microcrystalline cellulose (MCC) into LA. The influence of acidic catalysts, inorganic salt addition and ball-milling pre-treatment of MCC on LA yield was assessed. Depolymerization and disruption of cellulose was monitored by FTIR, TGA and SEM, whereas the products formed were analyzed by HPLC and NMR spectroscopy. The parameters that afforded the highest LA yield (48 %, 100 % selectivity) were: ball-milling pre-treatment of MCC for 16 min at 600 rpm, followed by MW-assisted thermochemical treatment for 20 min at 190 °C, aqueous p-toluenesulfonic acid (p-TSA) 0.25 M as catalyst and saturation with KBr. These optimal conditions were further applied to a lignocellulosic feedstock, namely melon rind, to afford a 51 % yield of LA. These results corroborate the suitability of this method to obtain LA from agroindustrial wastes, in line with a circular economy-based approach.

Valorization of Wastewater from Table Olives: NMR Identification of Antioxidant Phenolic Fraction and Microwave Single-Phase Reaction of Sugary Fraction.

The table olive industry is producing a huge amount of wastewater, which is a post-processing cost and an environmental concern. The present study aims to valorize this processing by-product to obtain a value-added product, thereby enhancing resource efficiency and contributing to achieving sustainable development goals (SDGs). In this sense, a chemical reaction-based platform was developed to obtain valuable components, such as levulinic acid (LA) and 5-hydromethylfurfural (HMF). The products were then analyzed using NMR identification of the antioxidant phenolic fraction and microwave single-phase reaction of the sugary fraction. According to the results, the highest concentration of phenolic compounds does not correspond to the sample directly obtained from NaOH treatment (S1), indicating that water washing steps (S2-S5) are fundamental to recover phenolic substances. Moreover, glucose was presented in the sugary fraction that can be transformed into levulinic acid by a single-phase reaction under microwave irradiation. The information provided in this manuscript suggests that the wastewater from the olive processing industry can be valorized to obtain valuable products.