N-oxide Monohydrate Research Articles

Kapok/regenerated cellulose based carbon aerogel prepared at a low-temperature carbonization for oil/water separation

With the requirement of sustainable development in modern society, selective filtration and separation of oils and organic solvents from polluted wastewater is a critical and very important goal. Herein, a novel hydrophobic and oleophilic cellulose-based carbon aerogel composed of kapok fiber/regenerated cellulose was prepared at a low-temperature carbonization technique (300 ℃) directly using kapok and hardwood pulp as raw material, the N-methyl N-oxide monohydrate (NMMO·H2O) as a green cellulose solvent, and NH4H2PO4 (ADP) as a carbonization promotor, which is denoted as AX-KRCA(AX: A indicates the ADP used, x is the concentration of ADP solution (g/L)) The regenerated cellulose (RC) was converted from hardwood pulp via NMMO·H2O treatment, and further combined with kapok fiber to form a 3D porous structure. By adding ADP, AX-KRCA can be rapidly dehydrated into carbon at 300 ℃, which not only saves energy consumption but also retains the basic form of kapok fiber and regenerated cellulose, making it have excellent compressibility, elasticity, and fatigue resistance. The ultra-light porous AX-KRCA samples can be an efficient oil/water adsorbent, with an adsorption capacity from 98.0 to 232.1 g g−1 for various oils, and can maintain 87.3 % adsorption capacity after 20 cycles and 99.6 % separation efficiency after 5 times of filtration.

Biocompatible chemical network of α-cellulose-ESBO (epoxidized soybean oil) scaffold for tissue engineering application

Despite many desirable properties, the use of α-cellulose in biomedical applications is limited because of its poor processability. Here we demonstrate that the chemical network of α-cellulose and epoxidized soybean oil (ESBO) can be adequately processed into biocompatible, self-standing, highly-porous scaffolds for tissue engineering applications. First, α-cellulose was dissolved in N-Methylmorpholine N-oxide monohydrate (NMMO.MH) and chemically crosslinked by ESBO. Then, the porous scaffolds of α-cellulose-ESBO were fabricated by solvent exchange and freeze-drying techniques. The scaffolds were evaluated for morphology, thermal and mechanical stability, and in vitro cell attachment and cell viability. Scanning electron microscopy images and Brunauer-Emmett-Teller results suggested that porous scaffolds provide a good surface and internal structure for cell adhesion and growth. Specifically, the α-cellulose-ESBO scaffolds support the homogeneous attachment and proliferation of MG63 cells. Overall, our results suggest that α-cellulose-ESBO chemically crosslinked networks are biocompatible and demonstrate a remarkable capacity for the development of tissue engineering platforms.

Influence of the position of the methyl substituent and N-oxide formation on the geometry and intermolecular interactions of 1-(phenoxyethyl)piperidin-4-ol derivatives.

Aminoalkanol derivatives have attracted much interest in the field of medicinal chemistry as part of the search for new anticonvulsant drugs. In order to study the influence of the methyl substituent and N-oxide formation on the geometry of molecules and intermolecular interactions in their crystals, three new examples have been prepared and their crystal structures determined by X-ray diffraction. 1-[(2,6-Dimethylphenoxy)ethyl]piperidin-4-ol, C15H23NO2, 1, and 1-[(2,3-dimethylphenoxy)ethyl]piperidin-4-ol, C15H23NO2, 2, crystallize in the orthorhombic system (space groups P212121 and Pbca, respectively), with one molecule in the asymmetric unit, whereas the N-oxide 1-[(2,3-dimethylphenoxy)ethyl]piperidin-4-ol N-oxide monohydrate, C15H23NO3·H2O, 3, crystallizes in the monoclinic space group P21/c, with one N-oxide molecule and one water molecule in the asymmetric unit. The geometries of the investigated compounds differ significantly with respect to the conformation of the O-C-C linker, the location of the hydroxy group in the piperidine ring and the nature of the intermolecular interactions, which were investigated by Hirshfeld surface and corresponding fingerprint analyses. The crystal packing of 1 and 2 is dominated by a network of O-H...N hydrogen bonds, while in 3, it is dominated by O-H...O hydrogen bonds and results in the formation of chains.

Breathable dual-layer textile composed of cellulose dense membrane and plasma-treated fabric with enhanced comfort

The superiority of dense polymer membranes intended for protective clothing has been well demonstrated in literature. However, the best protection provided by dense membranes may be balanced out by less breathability and retention of liquid sweat on the skin surface, both of which contribute to wearer discomfort. Despite being imperative, the simultaneous investigation of breathability and liquid sweat transfer in dual-layer textiles composed of a dense membrane and a fabric has received less attention. This issue is addressed in the present work through developing dual-layer textiles composed of commercially available as-received fabric with slow water absorption rate and cellulose dense membrane. To this end, three cellulose dense membranes are produced through two different techniques: (1) solution casting of linter/(4-methylmorpholine N-oxide monohydrate (NMMO)/water) and linter/(LiCl/N,N-Dimethylacetamide (DMAc)) solutions, (2) Treatment of dry cast cellulose acetate (CA) solution with NaOH aqueous solution to convert CA dense membrane to cellulose dense membrane. The prepared dense membranes are integrated with fabric to develop dual-layer textiles. It is demonstrated that although the developed dual-layer textiles have acceptable breathability (water vapor transmission rate > 400 g/(m2 day)), however, they perform poorly to transfer liquid sweat from the inner layer (fabric with slow water absorption rate) to the outer layer (cellulose dense membrane) where the transferred sweat is air-dried. Through implementing moisture management test, it is shown that cost-effective and non-destructive treatment of the inner layer by O2 plasma imparts excellent moisture management properties to the produced dual-layer textile. Therefore, it can be said that the developed dual-layer textile may be considered to represent the best compromise between wearer comfort (breathability and liquid sweat transfer) and protection.

Polypyrrole nanocomposite with water-dispersible graphene

Scalable water-dispersible graphene (eGPNc) powders were prepared with consecutive chlorosulfonic acid (CSA)/H2O2 and methylmorpholine N-oxide monohydrate (NMMOm) treatments, followed by the common filtering, sonication, and drying processes. The yield of graphene from expanded graphite (EG) powders prepared by the combined CSA/H2O2 and NMMOm treatments (3.0 wt%) was more than five times that from only the NMMOm treatment (0.6 wt%). The produced eGPNc powders had an almost defect-free graphitic structure with good redispersibility in water and an electrical conductivity of 86.9 S/cm from the filtered eGPNc film. The eGPNc film was dispersed at 0.28 mg/mL in water after centrifugation of the 2 mg/mL aqueous solution at 5000 rpm. The aqueous eGPNc solution was utilized as the reaction medium for the in situ polymerization of pyrrole to produce the polypyrrole (PPy)/graphene nanocomposite. The capacitance of PPy measured from cyclic voltammetry (CV) was improved from 122.8 to 278.6 F/g by loading 1 wt% eGPNc onto the nanocomposite. The capacitance of PPy after 1000 CV cycles was improved from 54.0% to 91.0% by loading 3 wt% eGPNc onto the nanocomposite. This improvement in the capacitance and capacitance-stability is due to the in situ formation of PPy in the well-dispersed aqueous graphene solution. Thus, this simple in situ preparation of PPy with eGPNc in water demonstrated the potential for the diverse applications of water-dispersible eGPNc in various water-based systems such as conducting inks, silver wires, and watersoluble conducting polymers (e.g. poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PSS/PEDOT)) for improving their electron conductivity and stability.

Preparation of water-dispersible graphene using N-methylmorpholine N-oxide monohydrate and its application for the preparation of nanocomposites using PEDOT

SEM and TEM images (inset: selective area electron diffraction (SAED) pattern) of mono-layered water dispersible graphene (GPN) sheet by treatment ofN-methylmorpholineN-oxide monohydrate (NMMOm).

Biomimetic Films of BLMs Based on Conductive Hybrid Films of Au NPs and Cellulose

A new type of biomimetic films of bilayer lipid membrane (BLM) supported by conductive hybrid film of Au nanoparticles (Au NPs) and cellulose is developed. The facile preparation method of the conductive hybrid films and the relevant micro conducting mechanism under electrochemical redox environment are revealed. The regenerated cellulose film is prepared from the cellulose/N-methylmorpholine N-oxide monohydrate solution. After the cellulose film is regenerated by deionized water, Au NPs in the colloid react with the newborn cellulose film. Rectangular pieces of dry hybrid films with one ends clamped with copper foil are used as electrodes. The lipid solution of phospholipid and cholesterol with a ratio of 3:1 is brushed onto the surface of dry hybrid films. There are only reducing currents in the cyclic voltammetry responses of biomimetic films under the aqueous electrolyte solution of 0.1 mol/L KCl, 1 mmol/L K3[Fe (CN)6] and 1 mmol/L K4[Fe (CN)6]. It means that the anions of [Fe (CN)6]4- are almost impossible to be oxidized into [Fe (CN)6]3- by the positively charged surfaces of Au NPs under voltages below 0.3 V.

Thermostability of imidazolium ionic liquids as direct solvents for cellulose

Ionic liquids (ILs) exhibit a far lower degradation potential compared to the established direct cellulose solvent N-methylmorpholine- N-oxide monohydrate used in the Lyocell process. Safety parameters such as onset temperature, pressure rise and heat release during exothermicity were measured in imidazolium ILs and solutions of cellulose in ILs by means of DSC, dynamic reaction calorimetry and UV/VIS spectroscopy with a special designed cuvette. Onset temperatures were determined using pressure rise measurement at a threshold value. Initial thermal activities in ILs occurred at much lower temperatures compared to DSC measurements and TGA literature data. For 1-ethyl-3-methylimidazolium acetate (EMIMAc) and 1-butyl-3-methylimidazolium acetate (BMIMAc) the onset temperatures 181 and 179 °C, respectively, were stated first time. Endothermic decomposition of pure EMIMAc is turned to an exothermic event by addition of cellulose accompanied by increased slope of pressure.

N-Methylmorpholine- N-oxide ring cleavage registration by ESR under heating conditions of the Lyocell process

Thermal cleavage processes of N-methylmorpholine- N-oxide monohydrate (NMMO) were observed in pure NMMO as well as in cellulose/NMMO solutions by ESR at temperatures of the industrial Lyocell process (∼370 K). Generated radicals were attributed to the alkylnitroxyl type radicals –CH 2-NO –CH 3 in NMMO and additional (and dominated) –CH 2-NO –CH 2– in cellulose/NMMO solutions. Formation of both radical types formed due to NMMO ring scission is suggested.

Interplay of hydrogen bonding and π–π interactions in the molecular complex of 2,6-lutidine N-oxide and water

The crystal and molecular structure of 2,6-lutidine N-oxide monohydrate ( 1) has been determined by X-ray diffraction analysis. Each water molecule is acting as bridging ligand between the N→O moieties of two 2,6-lutidine N-oxide molecules through moderate strong intermolecular hydrogen bonding (O–H⋯O, O⋯O distances are 2.787(2) and 2.832 (2) Å) giving rise to a one-dimensional (1D) polymeric helical chain. A two-dimensional (2D) layered network is then formed by self-assembly of 1D helical chains via strong π–π interactions of the aromatic rings (interplanar distances 3.385 Å). The molecular structure of 1 is compared with that for the already reported molecular structures of 2-acetylamino-6-methylpyridine N-oxide monohydrate and pyridine trihydrate. Finally, on the basis of the present studies a possible explanation for the formation of the molecular complexes is proposed and discussed.

Kinetic and chemical studies on the isomerization of monosaccharides in N-methylmorpholine- N-oxide (NMMO) under Lyocell conditions

The Lyocell process is a modern and environmentally fully compatible industrial fiber-making technology. Cellulosic pulp is dissolved without chemical derivatization in a melt of N-methylmorpholine- N-oxide monohydrate (NMMO). In the present work, the reactions of monosaccharides under Lyocell conditions were investigated in detail, using capillary zone electrophoresis as the analytical technique to clarify the composition of reaction mixtures and to follow the kinetics. Under Lyocell conditions, xylose and glucose undergo two competitive reactions: rapid conversion to nonreducing products, and complete isomerization involving the whole carbohydrate backbone, via ketose intermediates. Sugar acids are present in minor amounts only, as demonstrated by employing isotopically labeled material for NMR techniques.

The Effect of Mechanical Treatment on Colloidal and Chemical Properties and Reactivity of Powdered Cellulose

The effect of mechanical activation on colloidal and chemical properties of aqueous dispersions of powdered cellulose (particle size, electrokinetic parameters, surface electrical properties, adsorption, etc.) and its solubility in a methylmorpholine N-oxide monohydrate–dimethyl sulfoxide mixture is studied. A rise in the number of mechanical treatment cycles increases the surface charge density, adsorbability, and solubility of cellulose, but decreases particle size and electrophoretic mobility, as well as the viscosity of cellulose solutions due to a reduction in the degree of cellulose polymerization, development of microporosity, and a rise in the internal surface area of polymer particles as a result of their disintegration.

Properties of Flax Cellulose Solutions in Tertiary Amine N-Oxides and of Films Thereof

The solubility of flax fibers differing in the degree of purity in triethylamine N-oxide monohydrate was studied. The size and amount of the associates in equiconcentrated solutions were estimated from the turbidity spectra. Rheological properties of solutions of cotton and flax cellulose were compared. Hydrated cellulose films were obtained from solutions, and their physicomechanical properties were studied. The films were characterized by IR spectroscopy.

A syn selective dihydroxylation of cyclic allylic trichloroacetamides using catalytic osmium tetroxide

A range of cyclic allylic trichloroacetamides has been synthesised. Dihydroxylation utilising catalytic osmium tetroxide and quinuclidine- N-oxide monohydrate as the re-oxidant in dichloromethane yields diols with good levels of syn selectivity.

3,5-Difluoro-4-nitropyridine N-oxide and 3,5-diamino-4-nitropyridine N-oxide monohydrate.

The molecule of 3,5-difluoro-4-nitropyridine N-oxide, C(5)H(2)F(2)N(2)O(3), is twisted around the C-NO(2) bond by 38.5 (1) degrees, while the 3,5-diamino analogue, 3,5-diamino-4-nitropyridine N-oxide monohydrate, C(5)H(6)N(4)O(3).H(2)O, adopts a planar conformation stabilized by intramolecular hydrogen bonds, with a significant redistribution of pi electrons.

3,5-Difluoro-4-nitropyridine N-oxide and 3,5-diamino-4-nitropyridine N-oxide monohydrate

The mol­ecule of 3,5-di­fluoro-4-nitro­pyridine N-oxide, C5H2F2N2O3, is twisted around the C—NO2 bond by 38.5 (1)°, while the 3,5-di­amino analogue, 3,5-di­amino-4-nitro­pyridine N-oxide monohydrate, C5H6N4O3·H2O, adopts a planar conformation stabilized by intramolecular hydrogen bonds, with a significant redistribution of π electrons.

Pollen Sporoplasts: Dissolution of Pollen Walls

4-Methylmorpholine N-oxide monohydrate (MMNO.H(2)O), a potent solvent for polysaccharides, is an effective vehicle for release of membrane-enclosed male gametophytes (sporoplasts) from spore walls. This release occurs in minutes when pollen (Lilium longiflorum Thunb.) is suspended in a melt of MMNO.H(2)O at 75 degrees C. Continued heating at 75 degrees C leads to distintegration of the exine ;shell' which coalesces into immiscible globules in the MMNO melt. These observations provide a general procedure for preparation of pollen sporoplasts and sporoplast outer membranes, and offer a new method for dissolving the sporopollenin component of the spore wall.

Synthesis of 4-(21-nor-5-pregnen-20-yl)-1,3-thiazole derivatives

The keto sulfoxide IV, prepared from the ester III, was reduced with amalgamated aluminium to give the ketone V which after enolization and silylation afforded the silyl enol ether VI. Oxidation of VI with osmium tetroxide and N-methylmorpholine N-oxide monohydrate yielded the α-hydroxy ketone VII. This was converted into the mesylate IX and further into the bromo ketone XI which on Hantzsch reaction with ethyl thioxamate furnished the steroidal thiazole XII. Compound XII was converted into the hemisuccinate XIV.

Synthesis of 17β-[4-(1,3-thiazolyl)]androstane 3β-hemisuccinate and glycoside

The protected 20(21)-en-20-ol ether III was oxidized with N-methylmorpholine N-oxide monohydrate and osmium tetroxide to give the hydroxy ketone IV which was converted into the bromo derivative VIII via the mesylate VI. Hantzsch reaction of the bromo ketone VIII with ethyl thioxamate afforded the thiazole XI whose hemisuccinate XIII and glycoside XV were prepared.

Cellulose organic solvents. I. The structures of anhydrous N-methylmorpholine N-oxide and N-methylmorpholine N-oxide monohydrate

Cellulose organic solvents. I. The structures of anhydrous N-methylmorpholine N-oxide and N-methylmorpholine N-oxide monohydrate