Biorenewable Calcite as an Inorganic Filler in Ionic Liquid Gel Polymer Electrolytes for Supercapacitors.

Supercapacitors play a crucial role in the global shift toward cleaner, renewable energy and away from fossil fuels. Ionic liquid electrolytes have a larger electrochemical window than some organic electrolytes and have been mixed with various polymers to make ionic liquid gel polymer electrolytes (ILGPEs), a solid-state electrolyte and separator combination. One way to improve the conductivity of these electrolytes is to add inorganic materials such as ceramics and zeolites to increase their ionic conductivity. Herein, we incorporate a biorenewable calcite from waste blue mussel shells as an inorganic filler in ILGPEs. ILGPEs composed of 80 wt % [EMIM][NTf2] and 20 wt % PVdF-co-HFP are prepared with various amounts of calcite to determine the effect on the ionic conductivity. The optimal addition of calcite is 2 wt % based on the mechanical stability of the ILGPE. The ILGPE with calcite has the same thermostability (350 °C) and electrochemical window (3.5 V) as the control ILGPE. Symmetric coin cell capacitors were fabricated using ILGPEs with 2 wt % calcite and without calcite as a control. Their performance was compared using cyclic voltammetry and galvanostatic cycling. The specific capacitances of the two devices are similar, 110 and 129 F g-1, with and without calcite, respectively.

Borane catalyzed polymerization and depolymerization reactions controlled by Lewis acidic strength.

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.

Synthesis of a Renewable, Waste-Derived Nonisocyanate Polyurethane from Fish Processing Discards and Cashew Nutshell-Derived Amines.

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.

Copolymerization of CHO/CO2 catalyzed by a series of aluminum amino-phenolate complexes and insights into structure-activity relationships.

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 (<1-63%) were obtained with the other complexes. Preliminary DFT calculations investigating this difference in selectivity were carried out by analyzing the aluminum partial atomic charges in the Al-carbonate intermediates.

Iron Complexes for Cyclic Carbonate and Polycarbonate Formation: Selectivity Control from Ligand Design and Metal-Center Geometry.

A family of 17 iron(III) aminobis(phenolate) complexes possessing different phenolate substituents, coordination geometries, and donor arrangements were used as catalysts for the reaction of carbon dioxide (CO2) with epoxides. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of the iron complexes with a bis(triphenylphosphine)iminium chloride cocatalyst in negative mode revealed the formation of six-coordinate iron "ate" species. Under low catalyst loadings (0.025 mol % Fe and 0.1 mol % chloride cocatalyst), all complexes showed good-to-excellent activity for converting propylene oxide to propylene carbonate under 20 bar of CO2. The most active complex possessed electron-withdrawing dichlorophenolate groups and for a 2 h reaction time gave a turnover frequency of 1240 h-1. Epichlorohydrin, styrene oxide, phenyl glycidyl ether, and allyl glycidyl ether could also be transformed to their respective cyclic carbonates with good-to-excellent conversions. Selectivity for polycarbonate formation was observed using cyclohexene oxide, where the best activity was displayed by trigonal-bipyramidal iron(III) complexes having electron-rich phenolate groups and sterically unencumbering tertiary amino donors. Those containing bulky tertiary amino ligands or those with square-pyramidal geometries around iron showed no activity for polycarbonate formation. While the overall conversions declined with decreasing CO2 pressure, CO2 incorporation remained high, giving a completely alternating copolymer. The difference in the optimum catalyst reactivity for cyclic carbonate versus polycarbonate formation is particularly noteworthy; that is, electron-withdrawing-group-containing phenolates give the most active catalysts for propylene carbonate formation, whereas catalysts with electron-donating-group-containing phenolates are the most active for polycyclohexene carbonate formation. This study demonstrates that the highly modifiable aminophenolate ligands can be tailored to yield iron complexes for both CO2/epoxide coupling and ring-opening copolymerization activity.

Morpholine-Stabilized Cationic Aluminum Complexes and Their Reactivity in Ring-Opening Polymerization of ε-Caprolactone.

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 ε-caprolactone, producing polycaprolactone with narrow dispersity ( D̵ = 1.00-1.05). Employing glycidol as a co-initiator furnished polymers with narrow dispersity ( D̵ = 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.

Functionalized polycarbonates via triphenylborane catalyzed polymerization-hydrosilylation.

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.

Characterization of Oxo-Bridged Iron Amino-bis(phenolate) Complexes Formed Intentionally or in Situ: Mechanistic Insight into Epoxide Deoxygenation during the Coupling of CO2 and Epoxides.

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.

Catalytic conversion of glucose to 5-hydroxymethylfurfural using zirconium-containing metal-organic frameworks using microwave heating.

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.

Coupling Reactions of Carbon Dioxide with Epoxides Catalyzed by Vanadium Aminophenolate Complexes.

A series of vanadium compounds supported by tetradentate aminobis(phenolate) ligands were screened for catalytic reactivity in the reaction of propylene oxide (PO) with CO2 : [VO(OMe)(O2 NOBuMeMeth )], [VO(OMe)(ON2 OBuMe )], [VO(OMe)(O2 NNBuBuPy )], and [VO(OMe)(O2 NOBuBuFurf )]. They showed similar reactivities, but reaction rates were higher for [VO(OMe)(ON2 OBuMe )], which was studied in more detail. Turnover frequencies for conversion of PO over 500 h-1 were observed. Activation energies were determined experimentally through 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.

Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes.

Lithium and sodium compounds supported by tetradentate amino-bis(phenolato) ligands, [Li2(N2O2(BuBuPip))] (1), [Na2(N2O2(BuBuPip))] (2) (where [N2O2(BuBuPip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4,6-tert-butylphenol), and [Li2(N2O2(BuMePip))] (3), [Na2(N2O2(BuMePip))] (4) (where [N2O2(BuMePip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4-methyl-6-tert-butylphenol) were synthesized and characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. Variable temperature NMR experiments were performed to understand solution-phase dynamics. The solid-state structures of 1 and 4 were determined by X-ray diffraction and reveal tetrametallic species. PGSE NMR spectroscopic data suggests that 1 maintains its aggregated structure in CD2Cl2. The complexes exhibit good activity for controlled ring-opening polymerization of rac-lactide (LA) both solvent free and in solution to yield PLA with low dispersities. Stoichiometric reactions suggest that the formation of PLA may proceed by the typical coordination-insertion mechanism. For example, (7)Li NMR experiments show growth of a new resonance when 1 is mixed with 1 equiv. LA and (1)H NMR data suggests formation of a Li-alkoxide species upon reaction of 1 with BnOH.

Ring-opening polymerization of cyclohexene oxide using aluminum amine-phenolate complexes.

Remarkably active (down to 0.001% Al) catalysts for ring-opening polymerization of cyclohexene oxide under neat reaction conditions are reported. High molecular weight polymers with uniform dispersity are produced. Kinetic data from NMR studies and MALDI-TOF MS data of the polymers provide some mechanistic insight.

Combined experimental and computational studies on the physical and chemical properties of the renewable amide, 3-acetamido-5-acetylfuran.

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.

Aluminium coordination complexes in copolymerization reactions of carbon dioxide and epoxides.

Al complexes are widely used in a range of polymerization reactions (ROP of cyclic esters and cationic polymerization of alkenes). Since the discovery in 1978 that an Al porphyrin complex could copolymerize propylene oxide with carbon dioxide, Al coordination compounds have been studied extensively as catalysts for epoxide-carbon dioxide copolymerizations. The most widely studied catalysts are Al porphyrin and Al salen derivatives. This is partially due to their ability to act as mechanistic models for more reactive, paramagnetic Cr catalysts. However, this in depth mechanistic understanding could be employed to design more active Al catalysts themselves, which would be beneficial given the wide availability of this metal. Polymerization data (% CO3 linkages, M(n), M(w)/M(n) and TON) for these complexes are presented and mechanisms discussed. In most cases, especially those employing square-based pyramidal Al complexes, co-catalysts are required to obtain high levels of carbon dioxide incorporation. However, in some cases, the use of co-catalysts inhibits the copolymerization reaction. Lewis acidic Al phenolate complexes have been used as activators in CHO-carbon dioxide copolymerizations to increase TOF and this has recently led to the development of asymmetric copolymerization reactions. Given the ready availability of Al, the robustness of many complexes (e.g. use in immortal polymerizations) and opportunity to prepare block copolymers and other designer materials, Al complexes for copolymerization of carbon dioxide are surely worth a second look.

Alkali aminoether-phenolate complexes: synthesis, structural characterization and evidence for an activated monomer ROP mechanism.

Several monometallic {LO(i)}M complexes of lithium (M = Li; i = 1 (1), 2 (2), 3 (3)) or potassium (M = K, i = 3 (4)) and the heteroleptic bimetallic lithium complex {LO(3)}Li·LiN(SiMe2H)2 (5), all supported by monoanionic aminoether-phenolate {LO(i)}(-) (i = 1-3) ligands, have been synthesized and structurally characterized. A large range of coordination motifs is represented in the solid state, depending on the chelating ability of the ligand, the size of the metal and the number of metallic centres found in the complex. Pulse-gradient spin-echo NMR showed that 1-4 are monomeric in solution, irrespective of their (mono- or di)nuclearity in the solid-state. VT (7)Li and DOSY NMR measurements conducted for 5 indicated that the two Li atoms in the complex do not exchange positions even at 80 °C. Upon addition of 1-10 equiv. of BnOH, the electron-rich and sterically congested {LO(3)}Li complex (3) promotes the controlled living and immortal ring-opening polymerisation of L-lactide. The combination of polymer end-group analyses and stoichiometric model reactions unambiguously provided evidence that ROP reactions catalyzed by these two-component {LO(i)}Li/BnOH catalyst systems operate according to an activated monomer mechanism, and not via the coordination-insertion scenario frequently assumed for similar alkali phenolate-alcohol systems.

A simple one-pot dehydration process to convert N-acetyl-D-glucosamine into a nitrogen-containing compound, 3-acetamido-5-acetylfuran.

An efficient process for converting N-acetyglucosamine (NAG) into 3-acetamido-5-acetylfuran (3A5AF) is reported. 3A5AF is proposed as an N-containing platform chemical, which contains renewable nitrogen. In the reported method NAG, in the presence of boric acid (B(OH)3) and sodium chloride (NaCl), produces 58 % yield 3A5AF in dimethylacetamide under microwave irradiation (220 °C, 15 min). A maximum yield of 62 % was obtained in the presence of 4 equivalent NaCl. Performing ICP-MS analysis on NAG from different chemical suppliers highlighted the importance of Cl and B levels in this process. Trace impurities are, therefore, important considerations in biomass transformations. This solution-phase process produces approximately 30 times more 3A5AF than a pyrolysis route reported previously.

Ring-opening polymerization of ε-caprolactone by lithium piperazinyl-aminephenolate complexes: synthesis, characterization and kinetic studies.

A series of lithium complexes were prepared from 2(N-piperazinyl-N'-methyl)-2-methylene-4-R'-6-R-phenols ([ONN](RR')) and characterized through elemental analysis, (1)H and (13)C{(1)H} NMR spectroscopy, and X-ray crystallography. Treatment of the ligands with n-butyllithium afforded {Li[ONN](RR')}(3) [R = Me, R' = (t)Bu, (1); R = R' = (t)Bu (2); R = R' = (t)Am, (3), (t)Am = C(CH(3))(2)CH(2)CH(3)], with trimetallic structures in the solid-state as shown by single-crystal X-ray diffraction. The reactivity of these complexes in the ring-opening polymerization of ε-caprolactone (ε-CL), as well as the influences of monomer concentration, monomer/Li molar ratio, polymerization temperature and time, was studied. Rates of polymerization were first order with respect to both monomer and lithium concentrations, and activation energies for the reactions were determined. MALDI-TOF MS analysis revealed that transesterification had occurred during the polymerization.

Simple copper/TEMPO catalyzed aerobic dehydrogenation of benzylic amines and anilines.

CuBr(2) with 2,2,6,6-tetramethylpiperidyl-1-oxy (TEMPO) has been successfully employed for the aerobic oxidation of primary and secondary benzyl amines in aqueous acetonitrile. Such catalytic systems have previously been used extensively in alcohol oxidation reactions. The same catalyst system was also used for oxidative cross-couplings of benzylamines with anilines. The electronic and steric properties of the aniline partner were found to be of crucial importance in determining reactivity or lack thereof. A mechanism for these reactions is proposed based on the data obtained to date. In the absence of benzyl amines, electron-rich anilines were found to undergo dehydrogenative coupling and yields of the resulting azo products could be increased by replacing CuBr(2) with CuBr. No ligand (e.g. pyridine) is required for either reaction to proceed and presumably water and acetonitrile solvate the copper-containing intermediates.

Synthesis and structure of mono-, bi- and trimetallic amine-bis(phenolate) cobalt(II) complexes.

A series of cobalt(ii) amine-bis(phenolate) complexes has been prepared and characterized. The protonated tripodal tetradentate ligand precursors; dimethylaminoethylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H(2)[O(2)NN'](BuMeNMe2), dimethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)[O(2)NN'](BuBuNMe2), diethylaminoethylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H(2)[O(2)NN'](AmAmNEt2) and 2-pyridylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H(2)[O(2)NN'](AmAmPy); were reacted with cobaltous acetate tetrahydrate under varying conditions to afford a range of monometallic, bimetallic and trimetallic species. An unusual four coordinate complex Co[O(2)NN'](AmAmNEt2) containing Co(II) in a trigonal monopyramidal environment was structurally characterized, whereas using a less sterically demanding ligand a series of five coordinate complexes Co[O(2)NN'](BuBuNMe2)(L) (L = H(2)O, CH(3)OH, (CH(3))(2)C[double bond, length as m-dash]O, propylene oxide) containing Co(II) in a trigonal bipyramidal environment was prepared. A new angular structural parameter related to tau is defined, where tau' may be used to compare complexes with trigonal monopyramidal structures. In contrast, ligands containing a pendant pyridyl donor afford dimeric species including {Co(mu-CH(3)OH)[O(2)NN'](AmAmPy)}(2). In the absence of base and in the presence of excess cobaltous acetate, trimetallic complexes were isolated containing a central Co(II) in an octahedral environment coordinated to four CH(3)OH and two bridging acetate ligands between two Co[O(2)NN'] fragments with Co(II) in a trigonal bipyramidal setting. The paramagnetic Co(II) complexes reported were also characterized by UV-vis spectroscopy, mass spectrometry, cyclic voltammetry and magnetic measurements.

Catalytic dehydrative etherification and chlorination of benzyl alcohols in ionic liquids.

Dibenzyl ethers and benzyl chloride can be obtained in moderate to excellent yields through Pd-catalysed reactions in hydrophobic ionic liquids using microwave or conventional heating.