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Renewal in the world production of plastics with growing amounts of building blocks from biomass is a pressing demand among society. Adipic acid is one of the monomers of nylon 6,6, and, traditionally, is obtained from fossil sources, but it is possible to reduce the muconic acids, deriving it from biomass, to obtain adipic acid. However, these catalyzed reactions use commonly hazardous conditions or reagents; in this study, a pathway to obtain a bio-adipic acid, following the Green Chemistry, is reported. Metal nanoparticles (M NPs; M = Pd, Pt, Ru, Rh) were synthesized in water at 80 °C using sodium lignosulphonate as a reducing and stabilizing agent. They were characterized by TEM and XRD techniques: Pd NPs were larger (21 nm) and spherical in shape; Pt NPs were irregular; Ru and Rh NPs were smallest (1.9 and 5.3 nm, respectively). M NPs were tested as catalyst in the hydrogenation reactions of dicarboxylic acids (fumaric, malonic, trans,trans- and cis,cis-muconic acids) in water at room pressure and temperature. The NPs transformed selectively fumaric and malonic acids to succinic acid, although with different yields. Ru and Pt NPs were moderately active while with Pd NPs, 80% of succinic acid was obtained and with Rh NPs, 100% was observed. Carrying out the hydrogenations on muconic acids at pH 5, the formation of adipic acid was observed with all NPs but selectivities in the presence of Ru, Pt and Pd NPs were not excellent. The selectivity with Rh NPs was remarkable (86% from cis,cis- and about 100% from trans,trans-muconic acid) considering the mild conditions; furthermore, it is attractive that the adipic acid was obtained also from the cis,cis isomer which can be produced from biomass.

Cellulose Nanocrystals, CNC, opportunely functionalized are proposed as reactive fillers in bio-based flexible polyurethane foams to improve, mainly, their mechanical properties. To overcome the cellulose hydrophilicity, CNC was functionalized on its surface by linking covalently a suitable bio-based polyol to obtain a grafted-CNC. The polyols grafted with CNC will react with the isocyanate in the preparation of the polyurethane foams. An attractive way to introduce functionalities on cellulose surfaces in aqueous media is silane chemistry by using functional trialkoxy silanes, X-Si (OR)3. Here, we report the synthesis of CNC-grafted-biopolyol to be used as a successful reactive filler in bio-based polyurethane foams, PUFs. The alkyl silanes were used as efficient coupling agents for the grafting of CNC and bio-polyols. Four strategies to obtain CNC-grafted-polyol were fine-tuned to use CNC as an active filler in PUFs. The effective grafting of the bio polyol on CNC was evaluated by FTIR analysis, and the amount of grafted polyol by thermogravimetric analysis. Finally, the morphological, thermal and mechanical properties and hydrophobicity of filled PUFs were thoughtfully assessed as well as the structure of the foams and, in particular, of the edges and walls of the cell foams by means of the Gibson–Ashby model. Improved thermal stability and mechanical properties of PU foams containing CNC-functionalized-polyol are observed. The morphology of the PU foams is also influenced by the functionalization of the CNC.

Over the last several years many publications have focused on sustainable monomers to synthesize polymeric materials such as bio-based polyurethane foams (PUs). PUs is a class of materials with a lot of industrial applications (from insulation panels, structural reinforcement, sandwich construction to medical application)1 and are generally composed by polyol, isocyanate and several additives. PUs mechanical and functional properties are determined by the typology of polyols and isocyanate precursors, the distribution of the soft and hard segments from which PUs are composed and by the morphological structure in terms of open or closed cells. To avoid the problem of the big amount of chemicals produced from petroleum source, such as polyols and isocyanate utilized in the PUs formulation (the goal to produce sustainable PUs where both precursors are obtained from renewable resources is still a challenge), nanoparticles made from green and renewable materials are added replacing partially the polyol. Furthermore by modifying the surface of nanoparticle with isocyanate functional group also the amount of isocyanate can be reduced. An example of suitable nanoparticles that could be used is nanocrystalline cellulose (CNC). The combination of cellulose properties, such as low cost, chemical modification capacity, high Young's modulus, biodegradability, and abundance in nature, with features of the nanosized materials such as very large specific surface area, high aspect ratio, light weight, and outstanding reinforcing potential justifies the big interest of scientists towards this issue. On the other hand the cellulose hydrophilicity leads a bad dispersion in non polar matrices, the consequential nanocrystal aggregation decreases thermo-physical and mechanical properties of the nanocomposite. Herein, we propose the use of modified CNC (m-CNC) as reactive filler in polyurethane foams (PUs, fig. 1). To overcome the cellulose hydrophilicity, the CNC has been modified by linking covalently the bio-polyols on the m-CNC surface. In our strategy the silylation reaction in water to modify the surface of CNC followed by bio-polyol grafting was used. The CNC-grafted-polyols has been tested in the preparation of different composite PUs.

Over the last several years many publications have focused on sustainable monomers to synthesize polymeric materials such as bio-based polyurethane foams (PUs). PUs is a class of materials with a lot of industrial applications (from insulation panels, structural reinforcement, sandwich construction to medical application)1 and are generally composed by polyol, isocyanate and several additives. PUs mechanical and functional properties are determined by the typology of polyols and isocyanate precursors, the distribution of the soft and hard segments from which PUs are composed and by the morphological structure in terms of open or closed cells. To avoid the problem of the big amount of chemicals produced from petroleum source, such as polyols and isocyanate utilized in the PUs formulation (the goal to produce sustainable PUs where both precursors are obtained from renewable resources is still a challenge), nanoparticles made from green and renewable materials are added replacing partially the polyol. Furthermore, by modifying the surface of nanoparticle with isocyanate functional group also the amount of isocyanate can be reduced. An example of suitable nanoparticles that could be used is nanocrystalline cellulose (CNC). The combination of cellulose properties, such as low cost, chemical modification capacity, high Young's modulus, biodegradability, and abundance in nature, with features of the nanosized materials such as very large specific surface area, high aspect ratio, light weight, and outstanding reinforcing potential2 justifies the big interest of scientists towards this issue. On the other hand, the cellulose hydrophilicity leads a bad dispersion in non polar matrices, the consequential nanocrystal aggregation decreases thermo-physical and mechanical properties of the nanocomposite3. Herein, we propose the use of modified CNC (m-CNC) as reactive filler in polyurethane foams (PUs, fig. 1). To overcome the cellulose hydrophilicity, the CNC has been modified by linking covalently the bio-polyols on the m-CNC surface. In our strategy the silylation reaction in water to modify the surface of CNC followed by bio-polyol grafting was used. The CNC-grafted-polyols has been tested in the preparation of different composite PUs.

The combination of metal nanoparticles (Pd or Pt NPs) with NAD-dependent thermostable alcohol dehydrogenase (TADH) resulted in the one-flask catalytic double reduction of 3-methyl-2-cyclohexenone to 3-(1S,3S)-methylcyclohexanol. In this article, some assumptions about the interactions between a chemocatalyst and a biocatalyst have been proposed. It was demonstrated that the size of the NPs was the critical parameter for the mutual inhibition: the bigger the NPs, the more harmful for the enzyme they were, even if the NPs themselves were only moderately inactivated. Conversely, the smaller the NPs, the more minimal the TADH denaturation, although they were dramatically inhibited. Resuming, the chemocatalysts were very sensitive to deactivation, which was not related to the amount of enzyme used, while the inhibition of the biocatalyst can be strongly reduced by minimizing the NPs/TADH ratio used to catalyze the reaction. Among some methods to avoid direct binding of NPs with TADH, we found that using large Pd NPs and protecting their surfaces with a silica shell, the overall yield of 3-(1S,3S)-methylcyclohexanol was maximized (36%).

9-Amino-9-deoxy-epi-quinine, properly modified by suitable linkers, was anchored on highly cross-linked polystyrene, poly(ethylene glycol), and silica. The resulting species were characterized by NMR spectroscopy and tested as supported organocatalysts in the reaction between isobutyric aldehyde and trans-β-nitrostyrene. Polystyrene- and poly(ethylene glycol)-supported catalysts outperformed their nonsupported counterpart affording the desired product in high yield and ee (>90 % ee). Silica-supported catalysts proved to be less efficient in terms of both chemical yield and enantioselectivity. Polystyrene- and poly(ethylene glycol)-supported 9-amino-9-deoxy-epi-quinine were then used in the same reaction with different substrates, leading to the desired products in high yield and ee, as well as in three other reactions operating with different mechanism. An investigation of the recyclability of the polystyrene- and poly(ethylene glycol)-supported systems showed that these could be recovered and recycled with no loss of stereochemical activity but with a marked erosion of chemical efficiency occurring at the fifth reaction cycle. This was ascribed to chemical degradation of the alkaloid occurring during the reaction.

Polystyrene-supported 9-amino-9-deoxy-epi-quinine was synthesized through co-polymerization of an ad hoc-designed chiral monomer with divinylbenzene, in the presence of azobis(isobutyronitile) (AIBN) as radical initiator and toluene and 1-dodecanol as porogenic solvents. The heterogenized catalyst efficiently promoted the reaction of isobutyric aldehyde with β-nitrostyrene, in very high yield and enantioselectivity, comparable or even higher than that of the homogeneous counterpart (up to 95% ee). The recyclability of the catalyst, its general applicability and its successful application to other reactions was also demonstrated. Finally, for the first time, a 9-amino-epi-quinine derivative was employed to perform an enantioselective Michael reaction under continuous-flow conditions; by using a home-made, packed-bed catalytic reactor, the aldehyde addition to nitrostyrene was successfully realized in flow mode, leading to the product in up to 93% ee.

Nowadays, the chemical industry is looking for sustainable chemicals to synthesize nanocomposite bio-based polyurethane foams, PUs, with the aim to replace the conventional petrochemical precursors. Some possibilities to increase the environmental sustainability in the synthesis of nanocomposite PUs include the use of chemicals and additives derived from renewable sources (such as vegetable oils or biomass wastes), which comprise increasingly wider base raw materials. Generally, sustainable PUs exhibit chemico-physical, mechanical and functional properties, which are not comparable with those of PUs produced from petrochemical precursors. In order to enhance the performances, as well as the bio-based aspect, the addition in the polyurethane formulation of renewable or natural fillers can be considered. Among these, walnut shells and cellulose are very popular wood-based waste, and due to their chemical composition, carbohydrate, protein and/or fatty acid, can be used as reactive fillers in the synthesis of Pus. Diatomite, as a natural inorganic nanoporous filler, can also be evaluated to improve mechanical and thermal insulation properties of rigid PUs. In this respect, sustainable nanocomposite rigid PU foams are synthesized by using a cardanol-based Mannich polyol, MDI (Methylene diphenyl isocyanate) as an isocyanate source, catalysts and surfactant to regulate the polymerization and blowing reactions, H2O as a sustainable blowing agent and a suitable amount (5 wt%) of ultramilled walnut shell, cellulose and diatomite as filler. The eect of these fillers on the chemico-physical, morphological, mechanical and functional performances on PU foams has been analyzed.

Silica nanoparticles of different morphological properties were functionalized with enantiomerically pure imidazolidinones, through different immobilization techniques; stainless-steel columns were then loaded with silica bearing chiral organocatalysts to realize chiral “homemade” reactors. The influence of the material properties and immobilization procedures on the chemical and stereochemical activities of the chiral HPLC columns was studied by performing organocatalyzed DielsAlder reactions between cyclopentadiene and α,β-unsaturated aldehydes under continuous-flow conditions. In some cases, excellent enantioselectivities were obtained, thus showing that a catalytic reactor may work efficiently to continuously produce enantiomerically enriched cycloadducts for more than 200 h. Regeneration of the organocatalytic column was also partially accomplished, although associated with a slightly lower enantioselectivity, thus prolonging the “life” of the reactor to more than 300 h.

Palladium nanoparticles of a definite shape (spherical) and dimension (8–14 and 16–20 nm) were prepared employing two water soluble lignin samples as both reducing and stabilizing agent in definitely green experimental conditions, namely aqueous solution, aerobic conditions, moderate temperature, short times. The above nanoparticles were employed as catalyst for a series of carbon–carbon coupling reactions carried out in water at mild conditions. Heck and Suzuki reactions were performed for several substrates, by changing the nature of halogen, the substituents at the aromatic ring, the bases employed and the temperature. Product yields were satisfactory and selectivities very good. Other two cross-coupling reactions, namely Sonogashira and Stille, were also tested: iodine derivatives showed always the best reactivity, while chlorine derivatives did not react.

Two commercial Ca2+ and NH4 + lignin derivatives were catalytically oxidised and photooxidised both aerobically and in presence of H2O2 (Fenton system), under green conditions (water solution, 20°C, 1 atm), to obtain fractions with reduced degrees of polymerisation. Analyses of the oxidised solutions were carried out using NMR, MS and UV spectrometry. The catalytic and photocatalytic systems used showed satisfactory conservation of the organic material, except for the Fenton system. Lignins showed some mineralisation when irradiated in the presence of H5[PMo10V2O40] × H2O (POM-1), K5[Ru(H2O)PW11O39] (POM-2), K4[SiW12O40]·8H2O (POM-3) and TiO2. When the POMs were used as thermal catalysts, POM-3 was almost inactive, while the reactivities of POM-1 and POM-2 under both thermal and photochemical conditions were comparable, revealing little effect of irradiation on the reaction mechanism. The best compromise appears to be the TiO2 photosystem, which shows low carbon consumption, good preservation of aromatic rings, and greatly reduced mineralisation. Alternatively, POM-1 can be used, and particularly under thermal conditions.

A series of Pd and Pt nanoparticles (NPs) was prepared starting from the corresponding metal ions and lignosulphonates; NPs were tested as catalysts for allyl alcohols hydrogenation in water at room temperature and pressure. All NPs were active with sharp differences in conversions and selectivities: Pt NPs formed mainly saturated alcohols, whereas Pd NPS were more active, but less selective, forming, in addition to saturated alcohols, also isomeric unsaturated alcohols and aldehydes, both saturated and unsaturated.

The general applicability and the recyclability of the novel heterogeneous catalyst are demonstrated by batch reactions between carbonyl compounds and nitroolefins.

A simple HPLC column filled with silica-supported MacMillian catalyst works as a catalytic reactor for the Diels—Alder reaction between cyclopentadiene and cinnamic aldehyde affording the cycloadducts in high yields and enantioselectivities.

One-pot combinations of sequential catalytic reactions can offer practical and ecological advantages over classical multi-step synthesis schemes. In this context, the integration of enzymatic and chemo-catalytic transformations holds particular potential for efficient and selective reaction sequences that would not be 10 possible using either method alone. Here we report the one-pot combination of alcohol dehydrogenasecatalysed asymmetric reduction of 2-azido ketones and Pd nanoparticle-catalysed hydrogenation of the resulting azido alcohols, which gives access to both enantiomers of aromatic 1,2-amino alcohols in high yields and excellent optical purity (ee >99%). Furthermore, we demonstrate the incorporation of an upstream azidolysis and a downstream acylation step into the one-pot system, thus establishing a highly 15 integrated synthesis of the antiviral natural product (S)-tembamide in 73% yield (ee >99%) over 4 steps. Avoiding the purification and isolation of intermediates in this synthetic sequence leads to an unprecedentedly low ecological footprint, as quantified by E-factor and solvent demand.

A one-pot green method to synthesise Pt and Pd nanoparticles is reported. Two natural aromatic polymers, lignin and fulvic acid, were used as both reducing and stabilising agents at moderate temperature (80 °C) in water and under aerobic conditions. Full characterisation was performed using TEM, UV-vis, XRD, 195Pt and 1H NMR, FT-IR and GC-MS techniques. In the TEM images, we observed spherical nanoparticles of diameters in the range of 16 nm to 20 nm, in the case of Pd, and smaller ones of not so well defined shapes for Pt. GC-MS of the organic fractions formed during the preparation of the nanoparticles showed defined amounts of vanillin, a well known degradation product of these polymers. This finding indicates that the active participation of lignins and fulvic acids in the metal reduction step. The catalytic activity of the nanoparticles was tested for the NaBH4 reduction of 4-nitrophenol and for the aerobic oxidation of alcohols, reactions that are always conducted under green conditions. Both Pt and Pd nanoparticles show good catalytic activity in the reduction reaction, while in the aerobic oxidation reaction only the Pt nanoparticles were effective.