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Imprecise control of fluid flows in paper-based devices is a major challenge in pushing the innovations in this area towards societal implementation. Assays on paper tend to have low reaction yield and reproducibility issues that lead to poor sensitivity and detection limits. Understanding and addressing these issues is key to improving the performance of paper-based devices. In this work, we use colorimetric analysis to observe the mixing behaviour of molecules from two parallel flow streams in unobstructed (on unpatterned paper) and constricted flow (through the gap of a patterned hourglass structure). The model system used for characterization of mixing involved the reaction of Fe3+ with SCN− to form the coloured, soluble complex Fe(SCN)2+. At all tested concentrations (equal concentrations of 50.0 mM, 25.0 mM or 12.5 mM for KSCN and FeCl3 in each experiment), the reaction yield increases (higher colorimetric signal) and better mixing is obtained (lower relative standard deviation) as the gap of the flow constriction becomes smaller (4.69–0.32 mm). This indicates enhanced passive mixing of reagents. A transition window of gap widths exhibiting no mixing enhancement (about 2 mm) to gap widths exhibiting complete mixing (0.5 mm) is defined. The implementation of gap sizes that are smaller than 0.5 mm (below the transition window) for passive mixing is suggested as a good strategy to obtain complete mixing and reproducible reaction yields on paper. In addition, the hourglass structure was used to define the ratio of reagents to be mixed (2 : 1, 1 : 1 and 1 : 2 HCl–NaOH) by simply varying the width ratio of the input channels of the paper. This allows easy adaptation of the device to reaction stoichiometry., Efficient passive mixing can be achieved by contricting the reagent flow using structures having narrow gaps.

Chromogenic probe with oxidized bis-indolyl scaffold has been synthesized for the detection of a nerve gas mimicking agent, DCNP (diethyl cyanophosphonate) at pH 8.0 in water. The mechanism of interaction was proposed as the release of cyanide ion through the indole group mediating the hydrolysis of phosphorous-hetero atom bond and, thereafter, the Michael addition of the liberated CN- ion to the electron deficient C[double bond, length as m-dash]C bond of the bis-indolyl moiety. The reaction featured a remarkable change in color from red to colorless at ambient condition. Then, low-cost and portable paper strips were designed for a rapid and on-site vapor phase detection of DCNP without involving any sophisticated instrument or skilled personnel. Finally, a dye assembled inorganic nanocomposite material was devised to achieve a more sensitive 'turn-on' detection of DCNP in water.

© 2016 The Royal Society of Chemistry. Lithium-ion batteries (LIBs) are widely implemented to power portable electronic devices and are increasingly in demand for large-scale applications. One of the major obstacles for this technology is still the low cost-efficiency of its electrochemical active materials and production processes. In this work, we present a novel impregnation-carbothermal reduction method to generate a LiFePO4-carbon paper hybrid electrode, which doesn't require a metallic current collector, polymeric binder or conducting additives to function as a cathode material in a LIB system. A shell of LiFePO4 crystals was grown in situ on carbon fibres during the carbonization of microcrystalline cellulose. The LiFePO4-carbon paper electrode achieved an initial reversible areal capacity of 197 μA h cm-2 increasing to 222 μA h cm-2 after 500 cycles at a current density of 0.1 mA cm-2. The hybrid electrode also demonstrated a superior cycling performance for up to 1000 cycles. The free-standing electrode could be potentially applied for flexible lithium-ion batteries.

To date, the employment of developed adsorbents in antibiotic wastewater treatment practices is still limited due to their low adsorption capacity, slow kinetics and especially high cost. Thus, in this work, we first report the conversion of obsolete copy paper to highly porous carbon materials (PCMs) via a two-step method: low-temperature carbonization and alkali activation. The influence of activation temperature and KOH content on the porosity and adsorption capacity of PCMs was also studied. Notably, copy paper (CP) is consumed in extremely large quantities with a high proportion being obsoleted; it mainly consists of micro- and nano-cellulose fibers that can be used as an ideal carbon source. The PCMs were characterized by several techniques and methodologies. The PCMs-850-4 exhibited an ultrahigh BET surface area of 3598.95 m2 g−1 and total pore volume of 1.887 cm3 g−1. The influence of temperature, initial concentration, contact time, pH and ionic strength on the adsorption of tetracycline (TC) from water to PCMs-850-4 was investigated through batch adsorption studies. Analyses of adsorption isotherm, kinetics and thermodynamics property were conducted to understand the adsorption behavior. The equilibrium experimental data was well fitted to the Langmuir model, and the kinetic data was best described by the pseudo-second-order rate model. Importantly, the PCMs-850-4 displayed an ultrahigh adsorption of 1437.76 mg g−1 at 298 K, and increasing temperature benefited the adsorption. Also, their fast kinetics and great regeneration make the PCMs-850-4 a promising adsorbent for the low-cost, highly efficient and fast removal of organic pollutants from water environments.

In this work, the composites of polyaniline/nano-hematite (α-Fe2O3)/Prussian Blue (PB) were successfully synthesized via a sonochemical method. This nanocomposite (PB/CPANI) has been used for the modification of paper-based sensors for cholesterol detection. The electrochemical studies of this nanocomposite showed a well-defined cyclic voltammogram for hydrogen peroxide (H2O2) with a remarkable electrochemical sensitivity. This nanocomposite modified paper-based electrode also showed excellent electrocatalytic activity towards H2O2 in the interference-free cathodic region. In addition, cholesterol oxidase was immobilized on the PB/CPANI-modified paper-based electrode for selective detection of cholesterol. Under optimum conditions, a linear range of 0.6–6.0 mM with a very low detection limit of 0.52 mM for cholesterol and a good sensitivity of 411.7 μA mM−1 cm−2 were obtained which indicated that the method presented is outstandingly appropriate to determine cholesterol in bovine serum albumin. This work might be an alternative, interference-free, and cost-effective approach for biomonitoring of cholesterol both in methodological studies and in clinical laboratories.

We study the dielectric relaxation in paper of different density and in microcrystalline cellulose in a temperature range between 150 K and 350 K. Qualitatively the spectra display the same relaxations α, β, γ. An additional relaxation, βwet, is found in humidified samples. The adsorption of water is determined and related to the humidity of the surrounding. Two adsorption processes are identified as primary and secondary adsorption at the hydroxyl groups in the amorphous domains of the cellulose. The γ process in the dielectric spectrum is found to be directly related to the amount of water adsorbed in the sample. While qualitatively the differences to unprocessed, microcrystalline cellulose are negligible, quantitatively the less localised β-relaxation shows an increased relaxation strength induced by the geometrical confinement and orientation effects due to the processing into cellulose fibres. While the manufacturing process leads to paper with different density and porosity there is no significant change in water uptake, structure or dynamics.

International audience; Hydrophobic paper has inspired advances in low-cost technologies.Of importance is the use of perfluorinated reagents, due to suspectedrelease of HF. Surprisingly, by using a coupled TGA-IR-MS, wedemonstrate that polymerization of a perfluorinated silane on paper,leads to rapid degradation, low-ash residue, and no toxic HF gas isproduced under thermolysis.

Two unique aggregation-induced emission (AIE) active polymers poly(triphenyl ethene) (PTriPE) and poly(tetraphenyl ethene) (PTPE), comprising sole repeating units, triphenyl and tetraphenyl, respectively, were synthesized through the Suzuki coupling of (2,2-dibromoethene-1,1-diyl)dibenzene and related di-boronic acid or ester compounds. The polymers PTriPE and PTPE had number-molecular weights (10 100–17 400) with polydispersity indices of 1.5–1.7, and they were soluble in common organic solvents. The polymers in THF/H2O mixtures were able to form remarkably stable nanoparticles and no agglomeration was observed even when stored at 4 °C for several months. The polymer PTriPE and PTPE exhibited much more significant AIE activities when compared to their corresponding small AIE molecule 1,1,2,2-tetraphenylethene (TPE) and 4,4′-(2,2-diphenylethene-1,1-diyl)dibiphenyl (DPDB) in THF–H2O mixtures. The fluorescence of polymer nanoparticles in THF/H2O mixture could be quenched by various nitro-compounds, and PTriPE nanoparticles demonstrated a better fluorescence quenching response than PTPE. The film formed by PTriPE nanoparticles showed a reasonable fluorescence quenching response to nitro-compounds, for example, ∼5 ppb in the case of 2,4,6-trinitrotoluene vapor, despite its thickness approaching the micrometer level. Furthermore, PTriPE-based paper sensors were fabricated from its polymer nanoparticles’ solution, and is still effective with a polymer surface concentration as low as 1.0 μg cm−2 in detecting various nitro-compounds at a scale less than 1 ng, making it a useful tool for a quick, inexpensive and most importantly, highly sensitive detection of nitro-compounds based explosives.

A new water-soluble conjugated polyelectrolyte containing triphenylamine groups with aldehyde pendants was synthesized, which featured distinctly different emission colors according to its states, in aqueous solution and in the solid. Paper-based strips containing the polymer were prepared by simple immersion of filter paper in the polyelectrolyte solution for practical and efficient detection of biothiols including cysteine and homocysteine. The presence of aldehyde groups enables us to demonstrate noticeable fluorescence emission color changes (green-to-blue) because of the alterations in electron push–pull structure in the polymer via a reaction between the aldehyde group of the polymer and the aminothiol moiety in biothiol compounds. The presence of an aldehyde group and a sulfonate side chain was found to be indispensable for the cysteine reaction site and for a hydrophilic environment allowing the easy approach of cysteine, respectively, resulting in a simple and easy detection protocol for biothiol compounds.

We present a facile method using graphene oxide for the preparation of water/oil separation papers. We coated regular paper with graphene oxide by spraying or soaking, and performed thermal annealing at 180 °C for 1–3 hours. The thermal treatment transforms the paper from hydrophilic to hydrophobic due to the thermal reduction of graphene oxide, and thus water can hardly permeate through the separation paper. In contrast, low polarity organic solvents and oil can easily pass through the separation paper. The water/oil separation papers have very good reusable stability. The separation selectivity is above 99% for different mixtures of oily solvents and water.

The cellulosic network of artificially acidified paper has been studied by 2D NMR relaxometry, NMR diffusometry and NMR diffusion-diffraction. Results show that the acidifying treatment enlarges the macropore structure of paper increasing the pore connectivity and modifying the exchange between water populations localized in amorphous cellulose. Acidification damage suggests that simple breaking of the amorphous portion of fibrils occurs. Nevertheless, under a specific acidifying condition, a rearrangement in the cellulose network seems to take place, with a reduction of the average macropore size and a loss of pore connectivity. The identification of water populations by 2D relaxation maps allows for monitoring the changes in cellulose water mobility due to the depolymerization process. In general the relaxation and self-diffusion results confirm that water mobility increases with acidification. © 2014 the Owner Societies.

A novel sensing colloidal nanoprobe and indicator paper based on fluorescent carboxymethyl chitosan grafted poly(p-dioxanone) (CMCs-g-PPDO) copolymer nanomicelles which encapsulate hydrophobic conjugated polymer-poly(9,9-dioctylfluorene) (PFO) were developed for the fast and sensitive determination of banned food dye Sudan I. The PFO/CMCs-g-PPDO colloidal solution can selectively detect Sudan I in aqueous media among commonly appearing natural pigments: β-carotene, Monascorubrin and Lycopene. The sensing constant (Ksv) for the PFO/CMCs-g-PPDO aqueous solution toward Sudan I was 1.74 × 107 M−1, which was over 400 times larger than that of single PFO in toluene solution, due to the maximized interaction between the sensing material and the analyte within the chitosan-based nanomicelles. The fluorescent indicator paper functionalized with PFO/CMCs-g-PPDO also showed outstanding selectivity for Sudan I. By using this flexible and portable indicator paper, Sudan I dye could be immediately and visually distinguished from natural pigments. This material could be used for real-time and on-site food safety testing.

Cellulose is highly interesting from a materials science perspective, very much fuelled by its abundance, renewability and low cost. In this review, the heterogeneous grafting of cellulose fibres through controlled radical polymerization methods is highlighted. Techniques such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain-transfer (RAFT) allow for fibres with tailorable properties and built-in functionality to be produced. Undoubtedly, cellulose is a material for the future and it is foreseen that in a few years, the use of cellulose will probably extend far beyond the traditional application areas, such as in paper and cardboard.

Airborne particulate matter (PM) pollution significantly impacts human health, but the cellular mechanisms of PM-induced toxicity remain poorly understood. A leading hypothesis on the effects of inhaled PM involves the generation of cellular oxidative stress. To investigate PM-induced oxidative stress, analytical methods have been developed to study the chemical oxidation of dithiothreitol (DTT) in the presence of PM. Although DTT readily reacts with several forms of reactive oxygen species, this molecule is not endogenously produced in biological systems. Glutathione (GSH), on the other hand, is an endogenous antioxidant that is produced throughout the body and is directly involved in combating oxidative stress in the lungs and other tissues. We report here a new method for measuring aerosol oxidative activity that uses silver nanoparticle (AgNP) aggregation coupled to glutathione (GSH) oxidation in a paper-based analytical device. In this assay, the residual reduced GSH from the oxidation of reduced GSH to its disulfide induces the aggregation of AgNPs on a paper-based analytical device, which produces a reddish-brown product. Two methods for aerosol oxidative reactivity are presented: one based on change in color intensity using a traditional paper-based techniques and one based on the length of the color product formed using a distance-based device. These methods were validated against traditional spectroscopic assays for DTT and GSH that employ Elman's reagent. No significant difference was found between the levels measured by all three GSH methods (our two paper-based devices and the traditional method) at the 95% confidence level. PM reactivity towards GSH was less than towards DTT most likely due to the difference in the oxidation potential between the two molecules.

Based on paper substrate room temperature phosphorescence, the chiral discrimination of quinine and quinidine was achieved using Whatman No. 40 filter paper as the substrate and Pb(Ac)2 as the heavy atom perturber. The phosphorescence lifetime differences between quinine and quinidine increased from 4.45% to 27.90% upon addition of (+)-tartaric acid as the chiral modifier. This provided a rapid and simple method for the determination of the enantiomeric composition of quinine and quinidine.

The synthesis of a Tentagel®-supported peptide incorporating the reactive triad of serine, histidine and aspartic acid, found within serine protease enzymes, is described.

A range of new functionalised 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (TTFAQ) derivatives have been synthesised from the key di(halomethyl) building blocks, 10-[4,5-bis(bromomethyl)-1,3-dithiol-2-ylidene]anthracene-9(10H)-one 10, 10-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]anthracene-9(10H)-one 11 and 9-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]-10-[4,5-bis(hexylsulfanyl)-1,3-dithiol-2-ylidene]-9,10-dihydroanthracene 18. A Diels–Alder strategy comprising trapping of the transient exocyclic diene 19, which is derived from 18, with 1,4-naphthoquinone leads to the aromatised TTFAQ anthraquinone system 21. Horner–Wadsworth–Emmons olefination of 21 with the anion generated from reagent 22 gave the fused bis(TTFAQ) structure 23. Pyrrolo-annelated derivatives 30–34 have been obtained in a sequence of reactions from compound 10. Mono-formylation of the pyrrole ring of 32 and 33 under Vilsmeier conditions gave 35 and 36 which upon reaction with 2,4,5,7-tetranitrofluorene gave the donor–π-acceptor diads 38 and 39. Cyclic voltammetry (CV) in solution for all the TTFAQ derivatives shows the typical quasi-reversible two-electron oxidation wave of the TTFAQ core at potentials which vary slightly depending on the substituents. For example, the value of Eox is raised by the electron withdrawing anthraquinone and tetranitrofluorene units of 21 and 38, respectively. The CV of the conjugated TTFAQ dimer 23 showed two, two-electron oxidation waves corresponding to the sequential formation of 232+ and 234+ (ΔEox = 130 mV) providing evidence for a significant intramolecular electronic interaction, i.e. the dication 232+ acts as a conjugated donor–π-acceptor diad, thereby raising the oxidation potential of its partner TTFAQ unit. Spectroelectrochemical studies on 23 support this explanation. A strong intramolecular charge transfer band at λmax 538 nm is seen in the UV-Vis spectra of the TTFAQ–π-tetranitrofluorene diads 38 and 39. The X-ray crystal structures are reported for compounds 30, 33 and 34. The pyrrolo–TTFAQ moiety adopts a saddle-shape with the central ring of the dihydroanthracene moiety folded along the C(9)...C(10) vector in each case. Significant intermolecular interactions are observed in the structures.

Intermolecular interactions in inclusion complexes of acetylacetone allow its enol form to be stabilised in the solid state.

Enzyme horseradish peroxidase was immobilized on mesoporous silica nanorods to fabricate enzymatic bioactive papers with increased bio-stability. The new bioactive papers based on the immobilized enzyme have tremendously high stability both at room temperature and at 37 °C, in contrast to the low stability of conventional bioactive papers using free enzymes.

Polyaniline (PANI) has been recognized as an ideal candidate for electrode materials in supercapacitors. However, its relatively low electrical conductivity and poor cyclic stability greatly limit its potential applications in supercapacitors. In this study, nano-sized PANI particles have been immobilized onto a conducting paper-like substrate which utilizes graphene (G) sheets and pristine carbon nanotubes (CNTs) as building blocks, thus obtaining flexible G–CNT–PANI ternary hybrid papers with hierarchical nanostructures. The ternary hybrid paper exhibits a reversible capacity of up to 432 F g−1 at a discharge rate of 0.5 A g−1, which is much larger than that of bare G–CNT composite paper (172.4 F g−1); and, its cyclic performance is dramatically enhanced sustaining greater than 96% of its original capacitance after 600 charge–discharge cycles. The dimensional confinement of PANI particles on the surface of the all-carbon planar substrate prohibits volume expansion and shrinkage upon electrolyte soakage, and meanwhile, the immobilized PANI particles can endow the all-carbon composite paper with pseudocapacitive behavior and an improved electrode–electrolyte interfacial structure. Besides, the good electrical conductivity of the G–CNT composite paper provides improved conductive pathways for charge transfer at the electrodes thus resulting in superior capacitance during charge–discharge processes. Therefore, the method reported here provides a simple and efficient approach to fabricating G–CNT–PANI ternary hybrid papers with designed hierarchical nanostructures, and may be easily extended to the design of next generation high performance flexible supercapacitors.

The facile and direct introduction of methacryloxy groups into cellulose paper was carried out using a silane coupling technique, leading to the improvement of hydrophobicity and both dry and wet physical strengths of the paper. Immobilization of lipase enzymes onto the methacrylate-modified paper was then accomplished, possibly due to hydrophobic interaction. The as-prepared immobilized lipase on methacrylate-modified paper possessed paper-specific practical utility. During a batch process for the nonaqueous transesterification between 1-phenylethanol and vinyl acetate to produce 1-phenylethylacetate, the paper-immobilized lipase showed high catalytic activity, selectivity and reusability, suggesting that the methacryloxy groups introduced into the cellulose paper played a key role in the hyperactivation of lipases. In addition, a higher productivity of 1-phenylethylacetate was achieved in a continuous flow reaction system than in the batch system, indicating that the interconnected porous microstructure of the paper provided favorable flow paths for the reactant solution. Thus, the paper-immobilized enzyme is expected to offer a green catalytic material for the effective production of useful chemicals.

In this paper we present a new process to produce furfural and co-products of formic and acetic acids from waste aqueous hemicellulose solutions using a continuous two zone biphasic reactor. We estimate this approach uses 67% to 80% less energy than the current industrial processes to produce furfural. An economic analysis indicates that furfural can be produced with this process at 366 US$ per metric ton which is 25% of the selling price of furfural in the U.S. market today. This analysis assumes a plant capacity of 78 kiloton per year of furfural, 12 kiloton per year of formic acid and 44 kiloton per year of acetic acid (processing 160 ton per hour of hemicellulose solutions with a xylose concentration of 10.7 wt%) and is based on the data collected in this paper. Formic acid and acetic acid are probably produced from the acid hydrolysis of formylated and acetylated xylose oligomers, respectively. Furfural is produced in a two-step process consisting of the hydrolysis of xylose oligomers followed by the dehydration of xylose monomers and then extraction of the furfural into an organic solvent. Two types of hemicellulose solutions were used as the feedstock including a hot water extract and a green liquor extract derived from Northeastern hardwood trees. The hemicellulose solution contains mainly xylose oligomers as well as glucose, arabinose, lactic acid, acetic acid, formic acid, and other minor products. We found that the reaction temperature, the space velocity, the volumetric organic to aqueous phase ratio, and the acid concentration have significant effects on the furfural production. Under the optimized condition, a furfural yield of 90% can be achieved in the reactor from the hot water extract containing 10.7 wt% xylose. A conceptual design is performed for the integration of the production of furfural, formic and acetic acids, the liquid–liquid split, and subsequent three-stage distillations. We demonstrate that high purity (>99%) of furfural, formic and acetic acids can be obtained, with a final recovery of more than 97%, 56%, and 88% of the furfural, formic acid and acetic acid, respectively.

Amino groups were successfully introduced to cellulose paper using a silane coupling technique, through the condensation reaction between Si–OH of the organofunctional silane coupling agent and C–OH of cellulose. The as-prepared paper material, denoted amine-modified paper, had excellent handling convenience and some degree of hydrophobicity, indicating that the silane coupling treatment enhances the physical strength and the hydrophobicity of cellulose paper. In the batch process of the Knoevenagel condensation reaction, the amine-modified paper demonstrated high catalytic efficiency and reusability, suggesting that the amino groups introduced to the cellulose paper can act as an efficient base catalyst. In addition, the porous structure of the paper allowed successful use in a flow process. Thus, cellulose paper modified with amino groups is a promising material for practical use in catalytic and other applications, and the silane coupling technique has great potential to develop an array of practical new functional paper materials.

The time-dependent adsorption of 1-pyrenebutyric acid, a model compound for polyaromatic carbon adsorption, onto graphene nanoplatelet-single-wall carbon nanotube hybrid papers is investigated experimentally based upon changes in optical absorption spectra.

Pyridine and bis(TMS)ketene acetals (TMS = trimethylsilyl) react successively with methylchloroformate and iodine (or peracids) to give, via functionalized dihydropyridines, bicyclic nitrogen-containing lactones which have been characterized by X-ray crystallography.

Structural moieties including core units (such as phenyl, naphthyl and thiophenyl), linking groups (such as ethynyl), terminal substituents (such as cyano, isothiocyanato and fluoro), and lateral fluoro substituents have been incorporated into novel materials designed to confer a high birefringence on nematic mixtures. The materials have all been prepared through convergent syntheses involving palladium-catalysed cross-coupling reactions of arylboronic acids. The materials were examined for their mesomorphic behaviour as neat materials and as mixtures; some materials were found to have extremely high nematic phase stability, and others were non-mesogenic. The materials were evaluated in nematic host mixtures for their optical anisotropy, and they were all found to show promisingly high values.

The standard molar enthalpies of combustion and sublimation of 2- and 4-biphenylcarboxylic acid, 2,2′- and 4,4′-biphenyldicarboxylic acid were measured and the gas-phase enthalpies of formation, at T = 298.15 K, were determined. Ab initio calculations were performed and a theoretical study on molecular structure of all the biphenyl acid isomers has been carried out. Calculated enthalpies of formation using appropriate isodesmic reactions are compared with experimental values, and a good agreement is observed. Estimates of enthalpies of formation for the isomers, which were not studied experimentally, are presented. All the acids containing at least one ortho COOH are comparatively less stable than their isomers having just meta or para COOH group(s).

Insight in the steric and electronic parameters governing isomerization processes in artificial molecular motors is essential in order to design more advanced motor systems. A subtle balance of steric parameters and the combination of helical and central chirality are key features of light-driven unidirectional rotary molecular motors constructed so far. In an approach to decrease the steric hindrance around the central olefinic bond (rotary axis) and thereby lowering the energy barrier for helix inversion resulting in an increased rotation rate, the boundaries of our molecular motor design are explored. In a new design of a light-driven molecular motor based on a sterically overcrowded alkene the methyl substituent adjacent to the stereogenic center, which is responsible for the control of the direction of rotation, is shifted one position away from the fjord region of the molecule compared to the second-generation motor systems. In contrast to previously developed light-driven molecular motors, there is a preference for the methyl substituent to adopt a pseudo-equatorial orientation. Nevertheless, this new type of motor is capable of functioning as a rotary molecular motor, albeit not with full unidirectionality. Under the combined influence of light and heat, there is a preferred clockwise rotation of one half of the molecule. Surprisingly, the effect of shifting the methyl substituent on the energy barrier for helix inversion is small and even a slight increase in the barrier is observed.

Three thermal reactions of bicyclo[2.1.0]pentane have been studied by CASPT2–g3 and CASSCF electronic structure calculations. They are isomerization to cyclopentene, isomerization to 1,4-pentadiene, and cycloaddition to fumaronitrile. All three of these reactions exhibit unusual features that have prompted mechanistic debate. The present computational results provide a basis for understanding the experimental observations.

The potential energy surfaces for the reaction between H2O and the protonated alcohols MeOH2+, EtOH2+, PriOH2+, and ButOH2+ have been explored by means of high level ab initio theoretical methods. Both nucleophilic substitution (SN2) and elimination (E2) pathways have been investigated. Front side (SNF) and the familiar back side (SNB) Walden inversion attack of the nucleophile have been found to be competing for the H2O–ButOH2+ system. In contradiction with the customary relationship between so-called “steric effects” and barrier heights—more alkyl-substituted SN2 reaction centres have higher SN2 reaction barriers—the SN2 reaction barriers are found to be Et > Me > Pri > But. This result is in excellent agreement with available experimental data.

In this communication, we explore solute–solvent and ion–ion interactions within binary ionic liquid mixtures. From the perspective of several solvatochromic reporter probes capable of a range of interactions, we have investigated the influence of mixture composition on the polarity, dielectric, hydrogen bonding interactions, and microfluidity within mixtures afforded by the ionic liquids 1-butyl-3-methylimidazolium bis(triflyl)imide, 1-ethyl-3-methylimidazolium bis(triflyl)imide, and 1-butyl-3-methylimidazolium hexafluorophosphate. Our results underscore the prevalence of hydrogen bond donor and competitive anion coordination effects, suggesting the possible use of such mixtures in the design and optimization of advanced media for separations or chemical processing.

The gas phase reactions between NH3 and the protonated amines MeNH3+, EtNH3+, PriNH3+, and ButNH3+ have been studied by high level ab initio methods. Mass spectrometric experiments yielded no significant reaction products; this result being consistent with the calculated reaction barriers. The potential energy profiles for both nucleophilic substitution (SN2) and elimination (E2) pathways have been investigated. Both back side Walden inversion (SNB) and front side (SNF) nucleophilic reaction profiles have been generated. The SNB reaction barriers are found to be higher for the more alkyl substituted reaction centres. Reaction barrier trends have been analysed and compared with the results of a similar study of the H2O–ROH2+ system (R = Me, Et, Pri, and But).

WITHIN recent years increasing use has been made in both industry and medicine of germicides whose activity is derived from the presence of surface-active quaternary ammonium or pyridinium salts, and this entails a need for their recognition. Since the publication of our Notel on the paper chromatography of cationic surface-active agents, three papers2JA have been published on this subject. An electrochromatographic method used by Fumasoni, Mariani and Torraca2 for the separation of the homologous series of n-alkylpyridinium halides requires amounts of material greater than 50 pg and the spots formed exhibit “tailing.” An ascending chromatogram described by Garcia and Couerbe3 separates commercial products having mixtures of chain lengths in the n-alkyl radical, but the minimum amount detectable is 5 pg. Negoro and Sen04 also used electrochromatography to separate quaternary bases from non-ionic surfaceactive agents when present in admixture, but they again experienced considerable “tailing.” The method described in this paper allows separations within the homologous series of saturated ut-alkyltrimethylammonium halides, n-alkylbenzyldimethylammonium halides and

Lignin, the world’s most abundant biopolymer with high aromaticity, has huge potential as a renewable feedstock replacing petroleum for the production of chemicals, fuels and functional materials. The enhanced utilization of lignin would improve the economic viability of existing pulp and paper mills, as well as lignocellulosic biorefineries, where lignin is highly available, but mostly incinerated for energy recovery. Catalysis could be of crucial importance to improve current depolymerization strategies, and hence contribute to the more sustainable and responsible use of terrestrial resources. In the present study, the impact of different homogeneous transition-metal catalysts on the oxidative depolymerization of a technical softwood kraft lignin was investigated. The reactions were carried out using molecular oxygen under rather mild operating conditions and the produced aromatic monomers included, among others, vanillin, vanillic acid and acetovanillone. The best performing system incorporated a VO(acac)2-Cu(OAc)2 (V-Cu) catalyst, resulting in a bio-oil yield of approximately 50% and a total increase in aromatic monomers of 27%, on a weight basis. Moreover, a favorable combined effect between VO(acac)2 and Cu(OAc)2 was suggested by NMR spectroscopy. UHPLC–HRMS and corresponding statistical analysis revealed a more than 30-fold increase in two aromatic molecules with an oxoacetic functionality and oxalic acid as well as a focusing effect on selected molecules, when employing the V-Cu catalyst. The findings of this study indicate that the V-Cu catalyst system is promising for the efficient conversion of technical lignin into value-added aromatic chemicals. However, catalyst recycling and reuse must be demonstrated, for successful implementation under industrial conditions.