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The IUPAC Global Women’s Breakfast (GWB2022) was celebrated at over 400 events around the world on February 16, 2022. By all metrics, it was more successful than ever before but how are those measurements mirrored in individual experiences? During this International Year of Basic Sciences for Sustainable Development, the place of all people within science to make an impact will continue to be celebrated and we invite all scientists to join GWB2023 on February 14.

Our impact on all forms of life on land and in water could be reduced by considering the full lifecycle of chemicals. Ocean life is especially at risk via acidification, eutrophication and plastic pollution.

There is a desperate need for a solution to the ongoing waste management issues of the food processing industries. The demand for fish, including salmon, is higher than ever because of the growing global population and protein needs, however this results in large quantities of wasted by-products. This waste is problematic because it is potentially harmful to the environment and results in significant disposal costs for industries. The salmon frame (bones) is wasted once processed, however it is a potential feedstock for hydroxyapatite, a mineral for value-added applications. While other research has been done on accessing hydroxyapatite from animal wastes, these processes either use very high temperatures or chemicals that are more costly and hazardous for industrial purposes. In this study, we developed an enzymatic treatment using proteases and lipases simultaneously to clean the residual meat from salmon frames to isolate collagen-containing hydroxyapatite (sHAP) using Design of Experiment (DoE) under benign conditions. The variables were optimized using 2x3 and 2x4 factorial designs and it was determined by characterization techniques, weight loss calculations, and thermogravimetric analysis that the meat from the salmon frame was successfully hydrolyzed with 15 microliters/g Neutrase and 7.5 microliters/g Lipozyme CALB L in 40 degrees Celsius tap water for 6 h. We developed and propose a metric called Environment and Industry Hazard (EIH) for understanding the impact of such processing methods and compare the optimized procedure with existing techniques. The method reported herein is less impactful (environment, hazard, cost, carbon footprint) than others in the literature, as there are no solvents required, enzymes are easily disposed, and temperatures do not exceed 100 degrees Celsius during the entire process. Furthermore, we treated five salmon frames with the optimized conditions and determined it is possible to use this process on a larger scale.

In recent years the transformations of fructose and glucose to the platform chemical 5-hydroxymethylfurfural (5-HMF) have been studied extensively, and a variety of mechanisms have been proposed. This review summarizes the varied mechanisms proposed and methods used to study the dehydration of biomass, such as fructose and glucose, to give 5-hydroxymethylfurfural. For fructose dehydration, two main mechanisms have been suggested including a cyclic and an acyclic pathway, of which the cyclic pathway dominates. The conversion of glucose to 5-HMF can proceed either through initial isomerization to fructose or a direct dehydration. For glucose to fructose isomerization, two main reaction pathways have been proposed (1,2-hydride shift and enolization). This review discusses the mechanisms that have been determined based on the evidence from experiments and/or calculations, and briefly introduces the techniques frequently used in such mechanistic studies. Mechanisms in this field are strongly dependent on the nature of the solvent and the catalyst used, so it is important that researchers have a general idea about the existing mechanisms, and the methods and techniques used for investigation, before pursuing their own mechanistic studies.

Two manganese(III) compounds were studied as catalysts for the reaction of carbon dioxide with propylene oxide, styrene oxide, and cyclohexene oxide, and formed cyclic carbonate products selectively under solvent free conditions in the presence of an ionic co-catalyst such as TBAB or PPNCl. Variable temperature kinetic studies allowed the activation energy for propylene carbonate formation to be determined (64 kJ mol−1). The catalysts showed good stability in these reactions and overall turnover numbers (TON) of up to 6000 were observed. The complexes showed low activity for the aerobic oxidation of 4-methyoxybenzylalcohol to the corresponding aldehyde, achieving up to 40% conversion in 72 h. However, near quantitative conversion of 1,2-diphenyl-2-methoxyethanol to provide up to 90% yield of benzaldehyde could be achieved over the course of 5 days. Both complexes showed similar reactivity in the two catalytic processes, and this is likely due to the weakly coordinating nature of the pendant donor within the tetradentate ligand.

Our gradual understanding of the capabilities of organic solvent systems has allowed us to realize a rich diversity of valuable polysaccharide applications; however, their industrial scale implementation remains a challenge for the sustainable societies of the next generations. While exploring a systems thinking approach, researchers studying aqueous alkali solutions have shown that the overlooked region of subzero temperatures offers a dynamic driving force for efficient solubilization of natural carbohydrate polymers. Herein, α-chitin fibers of decreasing crystallinities/molecular weights (MW) dissolve rapidly by stirring in cold 19 wt% NaOH(aq) and freezing at − 28 °C. Kinematic viscosity measurements confirm the polymers’ stretched exponential solution dynamics for solubilities > 97% (up to ~ 130 g/L). A preliminary mechanistic hypothesis involves higher diffusion rates of the solvent’s hydrated counter ions for decreasing temperatures. The method was used with subsequent casting to fabricate 5 wt% films from high crystallinity/MW fibers. This proof of concept allows for homogeneous chitin deacetylation as well as for additive-free technology drivers towards sustainable commercial exploitation of abundant natural polysaccharide streams.

A non-covalent supramolecular enzyme system, which is formed by non-covalent interactions of an enzyme with substrate analogs, shows better enzyme catalytic activity than the enzyme itself. A non-covalent supramolecular laccase-dye substrate analog system (SL-DSA) was designed to confirm the enzyme catalyzing mechanism. A range of spectral and electrochemical methods showed that the non-covalent interaction is important in the catalytic degradation reaction of 13 dyes. The decolorization rate was 10–54% higher than with laccase (LAC) alone. Thus, the SL-DSA has better catalytic activity than LAC itself in the three-step degradation reaction of dyes. The enzymatic mechanism of SL-DSA identified may act to supplement the mechanism of the enzyme binding directly with the substrate.

The catalytic coupling and polymerization of CO2 and epoxides has been studied for over 50 years. While traditionally dominated by catalytic systems containing cobalt, chromium, and zinc, the use of iron catalysts has emerged in the past 10 years. This review provides an overview of the homogeneous iron-catalyzed transformations of carbon dioxide and epoxides to yield cyclic and/or polycarbonates. It is important to note the potential for cyclic carbonates to be used as monomers for polymer formation via transesterification or by ring-opening polymerization in some cases, e.g., cyclohexene carbonate. Typical catalytic systems are composed of a Lewis acidic iron center and an anionic nucleophilic source, either through an anionic group weakly bound to the metal center or the addition of an external cocatalyst, cooperatively described as a binary catalytic system. This review is divided into two sections: (1) iron catalysts for cyclic carbonates and (2) iron catalysts for polycarbonates. At the end of each section, a table summarizes each catalytic system and the reaction conditions utilized in an attempt to provide a clearer comparison across the literature. Focus is given to highlighting differences in product selectivity, reaction conditions, and relative amounts of cocatalyst used. The use of iron catalysts in CO2/epoxide chemistry has been less explored compared with zinc, cobalt, and chromium catalysts. This review highlights recent examples including iron complexes that deoxygenate epoxides in situ and geometry-dependent selectivity towards either polycarbonate or cyclic carbonate production. Reaction conditions (temperature, CO2 pressure, and amount of nucleophilic cocatalyst) and catalyst structure are all critical in accessing efficient catalysis for polycarbonate formation.

Triphenylborane catalyzes the polymerization of anhydrides and epoxides along with the block co-polymerization of anhydride/epoxides with epoxides/CO2. Switching to the more Lewis acidic borane, tris(pentafluorophenyl)borane, the carbonate block of the polymer could be selectively depolymerized to yield the corresponding cyclic carbonate opening the door towards chemical repurposing of the polymer.

Two series of monometallic aluminum complexes were prepared and characterized by elemental analyses, 1H and 13C{1H} NMR spectroscopy, and X-ray crystallography: Al[L]X, where [L] = dimethylaminoethylamino-N,N-bis(2-methylene-4,6-tert-butylphenolate) and X = Cl, OEt, and Al[L]2Cl, where [L] = 6-{[(2R,6R)-2,6-dimethyl-4-morpholino]methylene}-2,4-bis(tert-butyl)phenolate or 6-(piperidinomethylene)-2-(tert-butyl)-4-(methyl)phenolate. All the complexes, including the previously reported morpholinyl complex Al[L]Cl, where [L] = 4-(2-aminoethyl)morpholinylamino-N,N-bis(2-methylene-4,6-tert-butylphenolate), were tested as catalysts for copolymerization of cyclohexene oxide and CO2 in the presence and absence of PPNCl. When coupled with 1 equiv. PPNCl, the complexes exhibit similar activities and the best selectivity for poly(cyclohexenecarbonate) vs. the cyclic product, cyclohexene carbonate, was obtained with the morpholinyl complex (ca. 90%) whereas significantly lower selectivities (

Liquid-phase exfoliation (LPE) is a process frequently used to overcome the interactions between layers in layered materials to produce small sheets of material, with remarkable properties and high value applications. Materials are prepared via direct or indirect sonication in a solvent that must be able to effectively disperse and stabilize the sheets produced. Unfortunately, the preferred solvents for exfoliation processes are often toxic and possess several health risks. In this work, we show that LPE in greener solvents can be used to access nanostructures of biochar and further improve the applications of this renewable and bio-based material. Herein, pristine and oxidized biochars prepared from hardwood and softwood biomass waste (e.g. sludge, bark, and sawdust) are exfoliated in a range of solvents to allow the identification of benign alternatives that could afford highly concentrated dispersions. The majority of biochar nanostructures produced after exfoliation are stacked nanosheets containing between 2-8 layers (average 15 nm thickness). Correlations between effective LPE of biochar in solvents and different solvent parameters, including Kamlet-Taft, were established and allowed greener solvents to be used. Surface modification of biochars (e.g. via oxidation) has potential to increase their dispersibility in more benign solvents. LPE of oxidized biochars is more efficient in hydrogen-bond accepting solvents due to the increased concentration of carboxylic acid and alcohol functional groups on the surface of particles, when compared to non- functionalized biochars. Dispersions containing 0.20-0.75 mg/mL exfoliated oxidized biochar were obtained in solvents such as polyethylene glycols, glycerol formal and e-caprolactone. Moreover, LPE of pristine biochars in dimethyl carbonate, ethyl acetate, and solketal gave similar yields to more commonly used solvent for this process, N-methyl-2-pyrrolidone (NMP) a known reprotoxic molecule.

Waste-derived fish oil (FO) can be epoxidized and reacted with CO2 to produce a cyclic carbonate containing material. Upon reaction with a bioderived amine, this leads to the formation of nonisocyanate polyurethane materials. The FO used is extracted from the by-products produced at fish processing plants, including heads, bones, skin, and viscera. Three different methods are used for the epoxidation of the FO: (i) oxidation by 3-chloroperoxybenzoic acid, (ii) oxidation by hydrogen peroxide and acetic acid, catalyzed by sulfuric acid, and (iii) oxidation by hydrogen peroxide catalyzed by formic acid. Synthesized FO epoxides are reacted with CO2 to yield FO cyclic carbonates with high conversions. The products are characterized by 1 H and 13 C NMR spectroscopy, IR spectroscopy, thermogravimetric analysis, and viscometry. Using a biomass-derived amine, nonisocyanate polyurethane materials are synthesized. This process can lead to new opportunities in waste management, producing valuable materials from a resource that is otherwise underutilized.

Two series of monometallic aluminum complexes were prepared and characterized by elemental analyses

Effective utilization of carbon dioxide as a C1 feedstock is an ongoing challenge for chemists. The catalytic reaction of epoxides and carbon dioxide to produce cyclic or polycarbonates has become ...

Blue mussel (Mylitus edulis) shells are composed of an outer prismatic calcite layer and an inner nacreous aragonite layer. They are a by-product of the seafood industry and a potential feedstock in the ocean- or marine-biorefinery. Heat treatment of these shells can yield four CaCO3 materials with differing ratios of aragonite and calcite, and separation of the aragonite and calcite. Infrared spectroscopy (IR) and powder X-ray diffraction (XRD) revealed that when shells are heated (120–220 °C, 48 h), the ratios of aragonite and calcite change. The organic matrix, made up of silk-fibroin like proteins, β-chitin and glycoproteins, was revealed by 1H MAS NMR spectroscopy and shows previously unreported resonances in mollusc shells at chemical shifts typical for amides and aromatic groups. Heat treatment of the shells caused a large decrease in organic matrix levels as shown by 1H MAS NMR spectroscopy and this reduction in matrix content leads to a simple way to separate the prismatic calcite layer from the nacreous layer, allowing easy isolation of natural platelets of nacre. The prismatic calcite layer still contains some organic matrix whereas only about 0.02 wt% matrix remains in the nacreous layer. Using mussel protein hydrolysate (another by-product of the seafood industry) as an additive, artificial nacre was synthesized using a CaCl2 and Na2CO3 mixing method. Good polymorph control was seen, and new platelets of nacre can be seen growing on the surface of a mussel shell that was used for seeding in the presence of mussel protein hydrolysate.

Triphenylborane catalyzes the copolymerization and terpolymerization of epoxides and CO2 to yield polycarbonates with excellent dispersity. Via assisted tandem catalysis, these materials could be hydrosilylated in a one-pot fashion yielding modified polymeric materials. Using only a few reagents, materials with glass transition temperatures ranging from 37–110 °C were obtained.

A series of iron(III) chloride and iron(III) μ-oxo compounds supported by tetradentate amino-bis(phenolate) ligands containing a homopiperazinyl backbone were prepared and characterized by electronic absorption spectroscopy, magnetic moment measurement, and MALDI-TOF mass spectrometry. The solid-state structures of three iron(III) μ-oxo compounds were determined by single crystal X-ray diffraction and revealed oxo-bridged bimetallic species with Fe–O–Fe angles between 171.7 and 180°, with the iron centers in distorted square pyramidal environments. Variable temperature magnetic measurements show the oxo complexes exhibit strong antiferromagnetic coupling between two high-spin S = 5/2 iron(III) centers. The oxo complexes exhibit poor activity for the reaction of carbon dioxide and epoxides in the presence of a cocatalyst, under solvent free conditions to yield cyclic carbonates. The least active iron oxo compound bears tert-butyl groups on the phenolate donors, and we propose that steric congestion around ...

Mechanochemical treatment offers great potential for environmentally sustainable processing of chitin within the context of biomass valorization. Using powder X-ray diffraction, we show that crystallinity can be reduced by 50% in 2 h in a controlled way using a ball mill. We correlate this crystallinity reduction with a decrease in interchain hydrogen bonding using infrared spectroscopy as a structural probe. Furthermore, our quantitative interpretation of the spectra reveal a decrease in glycosidic linkage content and retention of N-acetyl groups. The addition of a natural clay, kaolinite, in the ball mill leads to a significant increase in the solubility of the milled materials (up to 75.8% water-soluble products in 6 h, cf. 35.0% without kaolinite). The products of this process were characterized as oligomers of N-acetyl-d-glucosamine (chitin oligomers) with degrees of polymerization (DP) between 1 and 5 using a new quantitative matrix-assisted laser desorption-ionization (MALDI-ToF) mass spectrometric...

Mussels are a high protein food grown using aquacultural methods around the world. By-product streams from this industry include raw discards (small or damaged product) and cooked shells that retain their posterior adductor muscle. Mollusc shells are primarily calcium carbonate and for blue mussels, Mytilus edulis, the shell accounts for up to 70% of their mass. The shell by-product streams could be used in a range of applications but shell storage without protein removal is problematic. In this study, we studied the potential of two enzymes (Multifect PR 6L and PR 7L) to remove protein from mussel shells using an initial screening and Design of Experiments approach. The enzymatic cleaning experiments were monitored using either thermogravimetric analysis or via manual recovery and weighing of protein residue still on shells. 20 g mussel shells with raw protein attached were efficiently cleaned using 1.0–2.0 μL g−1 Multifect PR 6L in seawater or tap water for 4 h at 55.0 °C. 20 g mussel shells with cooked protein attached were efficiently cleaned using 6.0 μL g−1 Multifect PR 7L in seawater or synthetic seawater for 10 h at 25.0 °C. As the developed methods do not require any additives (i.e. no need for pH adjustment), scale up to integrate into existing seafood processing facilities will be relatively straightforward and would provide two product streams: a biorenewable calcium carbonate and protein hydrolysate. Initial trials using freeze-dried mussel protein hydrolysate from this work to feed zebrafish (Danio rerio) over the course of 18 months have shown success.

The reactivity of the renewable amide 3-acetamido-5-acetylfuran (3A5AF) was explored. Hydrolysis of the amido group to yield the amino-substituted furan, 2-acetyl-4-aminofuran (1), was achieved via NaOH catalysis. Reduction of the acetyl group could be achieved stoichiometrically using NaBH4 or catalytically via transfer hydrogenation using an Ir catalyst. The product alcohol, 3-acetamido-5-(1-hydroxylethyl)furan (2), underwent dehydration during analysis via GC-MS to yield an alkene (3). The potential reactivity of 3A5AF and 1 toward carbon dioxide was studied, but no reaction was observed due to the inherent acidity of 3A5AF and 1 despite the latter being an amine. The computationally determined pKa values for 3A5AF and 1 are reported. Interestingly, in this work, tautomerism of 3A5AF was observed in CD3OD as evidenced by H–D exchange within the acetyl group.

Triphenylborane catalyzes the copolymerization and terpolymerization of epoxides and CO

The first structures exhibiting bidentate (N, O) chelation of a morpholine group to a p-block element (aluminum) have been prepared and characterized by X-ray diffraction methods: Al[L]+ [WCA]-, where [L] = 4-(2-aminoethyl)morpholinylamino- N, N-bis(2-methylene-4,6- tert-butylphenolate) and [WCA]- is a weakly coordinating anion. These compounds are easily synthesized by reacting Al[L]Cl with an equimolar amount of anhydrous Lewis acid and were characterized by elemental analyses, ESI-MS, MALDI-TOF MS, 1H, 13C{1H}, and multinuclear NMR spectroscopy. DFT calculations showed that Al[L]+ cations containing bidentate NO coordination of the morpholine group are at least 21.1 kJ/mol more stable when compared to hypothetical monodentate (N bound) structures. When combined with protic co-initiators (EtOH, glycerol carbonate), the cationic complexes, where [WCA]- = [GaCl4]- or [InCl4]-, are living catalyst systems for the polymerization of e-caprolactone, producing polycaprolactone with narrow dispersity ( D = 1.00-1.05). Employing glycidol as a co-initiator furnished polymers with narrow dispersity ( D = 1.01-1.07) but experimental molecular weights diverged considerably from the calculated values. Similar reactivity toward ROP was observed for all complexes containing a stable [WCA]- but where [WCA]- = [AlCl4]-, upon combination with alcohols, alcoholysis was observed. Kinetic studies (Eyring analyses) allowed the determination of activation parameters, which were consistent with a coordination-insertion mechanism for the catalysts containing [WCA]- = [GaCl4]- or [InCl4]-. End group analyses using MALDI-TOF mass spectrometry and 1H NMR spectroscopy showed hydroxyl and ester end groups within the polymer, corroborating the proposed mechanism. Stoichiometric reactions of EtOH, glycidol or tert-butyl alcohol with the complex, where [WCA]- = [GaCl4]-, showed protonation of the ligand at the N-morpholine site, which leads to dissociation of this pendent group.

Biochar has proven to be an effective tool in several aspects of environmental management; as well as many other applications. Herein we report biochar derived from the capsule-like interior of the seeds of Cedrela odorata L, prepared via pyrolysis at 400 °C. The biochar was characterized using: Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA) and Raman Spectroscopy. Results demonstrate that a biochar of high thermal stability and porosity was obtained, with surface functional groups that enhance the adsorption process. Equilibrium adsorption data were consistent with the Langmuir isotherm model, indicating surface homogeneity, with maximum adsorption capacity of 158.8 mg/g. These results demonstrate that the biochar is an efficient adsorbent for the removal of MB dye from aqueous solution; and suggests its utility for further exploration in removing heavy metals from water as well as its use as a solid support in catalysis.

A series of vanadium compounds supported by tetradentate amino-bis(phenolate) ligands were screened for catalytic reactivity in the reaction of propylene oxide (PO) with carbon dioxide, [VO(OMe)(O2NOBuMeMeth)] (1), [VO(OMe)(ON2OBuMe)] (2), [VO(OMe)(O2NNBuBuPy)] (3), and [VO(OMe)(O2NOBuBuFurf)] (4) (where (O2NOBuMeMeth) = MeOCH2CH2N(CH2ArO-)2, Ar = 3,5-C6H2-Me, tBu]; (ON2OBuMe) = -OArCH2NMeCH2 CH2NMeCH2ArO-, Ar = 3,5-C6H2-Me, tBu; (O2NNBuBuPy) = C5H4NCH2N(CH2ArO-)2, Ar = 3,5-C6H2-tBu2; (O2NOBuBuFurf) = C4H3OCH2N(CH2ArO-)2, Ar = 3,5-C6H2-tBu2). They showed similar reactivities but reaction rates were greater for 2, which was studied in more detail. TOF for conversion of PO over 500 h-1 were observed. Activation energies were determined experimentally via in situ IR spectroscopy for propylene carbonate (48.2 kJ mol-1), styrene carbonate (45.6 kJ mol-1) and cyclohexene carbonate (54.7 kJ mol-1) formation.

Vanadium compounds supported by tetradentate amino-bis(phenolate) ligands, [VO(OMe)(O2NOBuMeMeth)] (1), [VO(OMe)(ON2OBuMe)] (2), [VO(OMe)(O2NNBuBuPy)] (3), and [VO(OMe)(O2NOBuBuFurf)] (4) [where (O2NOBuMeMeth) = MeOCH2CH2N(CH2ArOH)2, Ar = 3,5-C6H2-Me, tBu; (ON2OBuMe) = HOArCH2NMeCH2CH2NMeCH2ArOH, Ar = 3,5-C6H2-Me, tBu; (O2NNBuBuPy) = C5H4NCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2; (O2NOBuBuFurf) = C4H3OCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2] were synthesized and characterized by NMR spectroscopy, MALDI-TOF mass spectrometry and UV/Vis data. The catalytic activity of 1–4 as homogeneous catalysts in the aerobic oxidation of 4-methoxybenzyl alcohol and 1,2-diphenyl-2-methoxyethanol was explored. 1 and 2 showed moderately superior activity compared with 3 and 4, which might be due to increased stability of these complexes. 1–4 showed limited reactivity in H2O2-mediated oxidation of diphenyl ether and benzyl phenyl ether.

A novel lithium complex was prepared from the reaction of 1,4-bis(2-hydroxy-3,5-di-tert-butyl-benzyl)imidazolidine H2[O2N2]BuBuIm (L1H2) with n-butyllithium to provide the corresponding tetralithium amine-bis(phenolate) complex {Li2[L1]}2·4THF, 1. Variable temperature 7Li NMR revealed that this complex is labile in solution, dissociating at elevated temperatures to afford two dilithium entities. Additionally, 7Li MAS NMR was performed on 1 to provide information regarding the lithium coordination environment in the bulk solid-state. The reactivity of 1 was assessed in the ring-expansion polymerization of e-caprolactone (e-CL), which was first order in e-CL with an activation energy of 50.9 kJmol−1. Reaction of 1 and a related Li complex (formed in situ) with BiCl3 afforded hydrolytically unstable bismuth phenolate species, as evidenced by the isolation and structural characterization of [Bi4(Cl)3(μ-Cl)(μ-O)(O)2{[O2N2]BuBuPip}2], 2, where [O2N2]BuBuPip is the homopiperazine-containing analog of L1.

A series of iron(III) chloride and iron(III) μ-oxo compounds supported by tetradentate amino-bis(phenolate) ligands containing a homopiperazinyl backbone were prepared and characterized by electronic absorption spectroscopy, magnetic moment measurement, and MALDI-TOF mass spectrometry. The solid-state structures of three iron(III) μ-oxo compounds were determined by single crystal X-ray diffraction and revealed oxo-bridged bimetallic species with Fe-O-Fe angles between 171.7 and 180°, with the iron centers in distorted square pyramidal environments. Variable temperature magnetic measurements show the oxo complexes exhibit strong antiferromagnetic coupling between two high-spin S = 5/2 iron(III) centers. The oxo complexes exhibit poor activity for the reaction of carbon dioxide and epoxides in the presence of a cocatalyst, under solvent free conditions to yield cyclic carbonates. The least active iron oxo compound bears tert-butyl groups on the phenolate donors, and we propose that steric congestion around the iron center reduces catalytic activity in this case. We provide evidence that an epoxide deoxygenation step occurs when employing monometallic iron(III) chlorido species as catalysts. This affords the corresponding μ-oxo compounds which can then enter their own catalytic cycle. Deoxygenation of epoxides during their catalytic reactions with carbon dioxide is frequently overlooked and should be considered as an additional mechanistic pathway when investigating catalysts.

5-Hydroxymethylfurfural (5-HMF) can be prepared by the catalytic dehydration of glucose or fructose using a range of homogeneous or heterogeneous catalysts. For our research, a selection of closely related Metal–Organic Frameworks (MOFs) were used as catalysts in the conversion of glucose to 5-HMF due to their chemical and thermal stability as well as the Lewis acidity of zirconium. Our initial study focused on the use of UiO-66–X (X = H, NH2 and SO3H), optimization of the dehydration reaction conditions, and correlation of the catalytic activity with the MOF's properties, in particular, their surface area. The highest yield of 5-HMF (28%) could be obtained using UiO-66 under optimal reaction conditions in dimethylsulfoxide and this could be increased to 37% in the presence of water. In catalyst recycling tests, we found the efficiency of UiO-66 was maintained across five runs (23%, 19%, 21%, 20%, 22.5%). The post-catalysis MOF, UiO-66–humin, was characterized using a range of techniques including PXRD, FT-IR, 13C Solid State NMR and N2 gas adsorption. We continued to optimize the reaction using MOF 808 as the catalyst. Notably, MOF 808 afforded higher yields of 5-HMF under the same conditions compared with the three UiO-66–X compounds. We propose that this might be attributed to the larger pores of MOF 808 or the more accessible zirconium centres.

A series of iron(III) compounds supported by tetradentate amino-bis(phenolate) ligands were synthesized and characterized using electronic absorption spectroscopy, magnetic moment measurement and MALDI-TOF mass spectrometry. The solid-state structures of 1 and 2 were determined by X-ray diffraction and reveal iron(III) square pyramidal compounds. The complexes were studied as catalysts for the reaction of carbon dioxide and epoxides in the presence of a co-catalyst, under solvent free conditions to yield cyclic carbonates. Catalytic testing with TBAB as a co-catalyst shows that 4 bearing electron withdrawing groups in the ortho and para-positions of the phenolate ring exhibits the highest catalytic activity. Kinetic studies using 1 revealed that the cycloaddition reaction is affected by temperature as expected and the activation energy for propylene carbonate formation is 98.4 kJ mol−1.

Direct conversion of chitin to 3-acetamido-5-acetylfuran (3A5AF) in a range of ionic liquids (ILs) has been systematically investigated. 10 ILs with different cations and anions were tested as the solvent and 25 additives were screened. The results revealed that the presence of Cl in the IL is essential. In addition to the solubility enhancement of chitin in Cl containing ILs, the Cl anion appeared to participate in the chitin reaction cycle in IL solvents. 3A5AF can be obtained in some ILs, such as [BMIm]Cl, without any additive. Significantly enhanced yields of 3A5AF were obtained in [BMIm]Cl using boric acid and hydrochloric acid (HCl) as additives at 180 °C, a lower temperature than using organic solvents (215 °C). Kinetic studies showed that the product formed very quickly within 10 min, with much higher initial rate than using organic solvents. Recovered chitin was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). In an effort to improve the yield, extraction and distillation were attempted for both chitin and chitin monomer, N-acetyl-D-glucosamine (NAG). Further studies were performed on NAG to see if acidic ILs would lead to enhanced reactivity. However, these were less effective.

The pK(a) of 3-acetamido-5-acetylfuran (3A5AF) was predicted to be in the range 18.5-21.5 by using the B3LYP/6-311+G(2d,p) method and several amides as references. The experimental pK(a) value, 20.7, was determined through UV/Vis titrations. Its solubility was measured in methanol-modified supercritical CO2 (mole fraction, 3.23×10(-4), cloud points 40-80 °C) and it was shown to be less soluble than 5-hydroxymethylfurfural (5-HMF). Dimerization energies were calculated for 3A5AF and 5-HMF to compare hydrogen bonding, as such interactions will affect their solubility. Infrared and (1) H nuclear magnetic resonance spectra of 3A5AF samples support the existence of intermolecular hydrogen bonding. The highest occupied molecular orbital, lowest unoccupied molecular orbital, and electrostatic potential of 3A5AF were determined through molecular orbital calculations using B3LYP/6-311+G(2d,p). The π-π* transition energy (time-dependent density functional theory study) was compared with UV/Vis data. Calculated atomic charges were used in an attempt to predict the reactivity of 3A5AF. A reaction between 3A5AF and CH3MgBr was conducted. As 3A5AF is a recently developed renewable compound that has previously not been studied extensively, these studies will be helpful in designing future reactions and processes involving this molecule.

This review provides an overview of ring-opening polymerization (ROP) and copolymerization (ROCOP) reactions of epoxides catalysed by aluminum- and boron-containing compounds. We also highlight some recent examples based on the heavier group 13 elements, gallium and indium. ROP of epoxides yields polyethers whereas ROCOP of epoxides with CO2 yields polycarbonates (or polycarbonate-ethers). More recently, copolymerizations of epoxides with cyclic anhydrides have been performed to yield polyesters or gradient polyester-ether copolymers. Controlled reactions, yielding polymers with narrow dispersities, can be performed using neutral, cationic, bifunctional and bimetallic aluminum complexes. In some cases, co-catalysts (e.g. added nucleophiles) are needed to enhance reactivity and chain transfer agents can be used to control molecular weights and end-groups of polymers. More recently, trialkyl- and triarylboranes have been used as catalysts in these reactions. Given the variety of polymers that can be obtained via controlled ROP of epoxides in the presence or absence of co-monomers, it is expected that new discoveries using group 13 compounds as catalysts will continue in the foreseeable future.

Pentagonal bipyramidal (C5H5N)4BiCl3 and its pyridine solvate are reported. The (C5H5N)4BiCl3 complex exhibits both intra- and intermolecular π–π stacking, while the pyridine solvate does not, but does contain four formula units in the asymmetric unit. A comparison between the coordination geometry of these solvation isomers and a series of isostructural lanthanide complexes is discussed. The low temperature X-ray structural determinations of two solvation isomers of pentagonal bipyramidal (C5H5N)4BiCl3 are reported

This paper describes the direct conversion of chitin into a nitrogen-containing (N-containing) furan derivative (3A5AF) for the first time. Under optimized conditions, the yield of 3A5AF reaches 7.5% with ca. 50% chitin conversion by using boric acid and alkaline chlorides as additives, and NMP as a solvent. A variety of other compounds, including levoglucosenone, 4-(acetylamino)-1,3-benzenediol, acetic acid and chitin–humins, have been identified as side products, based on which a plausible reaction network involved in the process is proposed. Mechanistic investigation by NMR studies and poison tests confirms the formation of a boron complex intermediate during the reaction, shedding light on the promotional effects of boric acid. Kinetic studies show that the depolymerization of the chitin crystalline region is rate-determining, and therefore disruption of the hydrogen bonding in the crystalline region of chitin, either before or during the reaction, is the key to further improving the reaction yields.

In this mini-review, progress made in the use of ionic liquid catalysts and related systems for cycloaddition reactions of carbon dioxide with epoxides is described with the primary focus on results from the past eight years. Catalysts described range from simple onium species including tetrabutylammonium bromide, functionalized and simple imidazolium ionic liquids, to a plethora of supported ionic liquid systems. A range of supports including alumina, silica, carbon nanotubes, magnetic nanoparticles, poly(ethyleneglycol), polystyrene, cellulose and chitosan have been used with a variety of ionic groups. These include ammonium, phosphonium and both functionalized and unfunctionalized imidazolium salts. Results have been tabulated to summarize reaction conditions and TONs for styrene oxide, propylene oxide and cyclohexene oxide conversions. It is clear that metal ions used in combination with ionic liquids, particularly ZnBr2, can enhance conversions, and hydroxyl, carboxyl and other functional groups capable of hydrogen-bonding can be incorporated to improve catalysis. Some recent results using flow reactors are highlighted. Examples of ionic catalysts used in the related processes of oxidative carboxylation of alkenes, which also yields cyclic carbonate products, and carbon dioxide–aziridine coupling reactions, which yield oxazolidinone products are described. New data on catalytic styrene carbonate production using choline chloride-transition metal chloride mixtures are presented. For 3d metals, the catalytic activity of these mixtures is Cr > Co ≈ Fe ≈ Ni > Mn ≫ Cu.

Reduced use of volatile organic compounds as solvents in chemical processes is highly desirable from a sustainability point of view. This is because many conventional organic solvents have high vapor pressures, which can lead to hazards including low flash points, high flammability, toxicity, and atmospheric pollution. In order to make decisions regarding solvent use in a chemical process, it is important to evaluate the options available both from a chemical point of view and also with regards to the environment and safety. The typical physicochemical properties and parameters that need to be considered are briefly described. An overview of the environmental, health, and safety criteria used to assess all solvent systems (traditional and environmentally friendly) is provided. The concept of life-cycle assessment when applied to solvents in either a quantitative or a qualitative way is introduced. Guidance provided by industrial users of solvents, especially the pharmaceutical industry, is highlighted. A range of sustainable solvent systems are described in this chapter. These include: water, supercritical carbon dioxide, carbon dioxide-expanded liquids, solvents of switchable polarity and volatility, room temperature ionic liquids and deep eutectic solvents, bio-derived solvents (e.g., 2-methyltetrahydrofuran and glycerol), and solvent-free systems. Their advantages, disadvantages, and properties are discussed, and examples of chemistries performed in them are given. Biphasic systems based on sustainable solvents and aimed at allowing their more efficient use and potential catalyst recycling are described. These include water/bio-derived solvent, supercritical carbon dioxide/water, and supercritical carbon dioxide/ionic liquid systems. Keywords: green chemistry; water; supercritical carbon dioxide; renewable feedstock; ionic liquids; switchable solvents; mechanochemistry; solvent-free; safety; biphasic catalysis; life-cycle assessment

A series of aluminum methyl and chloride complexes bearing 2(N-piperazinyl-N′-methyl)-2-methylene-4-R′-6-R-phenolate or 2(N-morpholinyl)-2-methylene-4-R′-6-R-phenolate ([ONER1,R2]-) {[R1 = tBu, R2 = Me, E = NMe (L1); R1= R2 = tBu, E = NMe (L2); R1 = R2 = tBu, E = O (L3)} ligands were synthesized and characterized through elemental analysis, 1H, 13C{1H}, and 27Al NMR spectroscopy, and X-ray crystallography. Reactions of AlMe3 with two equivalents of L1H-L3H gave {[ONER1,R2]2AlMe} (1–3), while reaction of Et2AlCl with two equivalents of L1H and L3H afforded {[ONER1,R2]2AlCl} (4 and 5) as monometallic complexes. The catalytic activity of complexes 1–3 toward ring-opening polymerization (ROP) of e-caprolactone was assessed. These complexes are more active than analogous Zn complexes for this reaction but less active than the Zn analogues for ROP of rac-lactide. Characteristics of the polymer as well as polymerization kinetics and mechanism were studied. Polymer end-group analyses were achieved using 1H NMR spectroscopy and MALDI-TOF MS. Eyring analyses were performed, and the activation energies for the reactions were determined, which were significantly lower for 1 and 2 compared with 3. This could be for several reasons: (1) the methylamine (NMe) group of 1 and 2, which is a stronger base than the ether (O) group of 3, might activate the incoming monomer via noncovalent interactions, and/or (2) the ether group is able to temporarily coordinate to the metal center and blocks the vacant coordination site toward incoming monomer, while the amine cannot do this. Preliminary studies using 4 and 5 toward copolymerization of cyclohexene oxide with carbon dioxide have been performed. 4 was inactive and 5 afforded polyether carbonate (66.7% epoxide conversion, polymer contains 54.0% carbonate linkages).