MeOH Addition Research Articles

Amino-Acid Based Chiral Trisubstituted Benzimidazole Supramolecules: Synthesis and Self-Assembling Behavior.

Trisubstituted 1,3,5-tri(benzimidazolyl)benzene derivatives were synthesized from l-alanine, l-valine, d-valine and glycine, and their self-assembling behavior and stimuli-response in solution and gel states were evaluated. Circular dichroism/UV-vis absorption spectroscopic and dynamic light scattering measurements revealed that the compounds formed H-aggregates via intramolecular hydrogen bonding and π-π stacking interactions in nonpolar solvents such as CHCl3, whereas collapse of the aggregates was confirmed by MeOH addition. Quantum mechanical calculations and molecular dynamics simulations also supported aggregation in CHCl3 . Rheological analysis and morphology observation revealed the formation of a fibril like structure by further assembling of aggregates at a high concentration in CHCl3 .

Influence of alcoholic polar surfactants on PEDOT:PSS for enhanced performance of organic/Si hybrid solar cell

Conducting polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), has gained prominent interests in organic/n-Si hybrid solar cells (HSCs). Alcoholic polar solvents, 2-propanol (IPA) or methanol (MeOH) addition in PEDOT:PSS by simple solution mixing process have been investigated to arrest the critical issues related to poor affinity of aqueous (aq.) PEDOT:PSS on Si surface, a key prerequisite for efficient HSCs. Remarkably enhanced electrical conductivity of the polymer layer has been found for 100 v/v% IPA and 70 v/v% MeOH addition to the aq. PEDOT:PSS. Formation and performance of the PEDOT:PSS/n-Si junction under various concentration of the IPA and MeOH addition are investigated and compared with that of aq. PEDOT:PSS. The optimum IPA or MeOH addition led to structural modification of aq. PEDOT:PSS from coil-like benzoid to linear quinoid one and hence improved electrical properties. The polar solvents not only served as the surfactant leading to conductive PEDOT:PSS conformal coverage on the micro-textured Si surface but also offered modulation of optical, electrical, structural, morphological, and passivation properties of the polymer layer. Improved solar cell performance with maximum efficiency >11.50% could be achieved for optimum IPA added PEDOT:PSS/n-Si solar cells, which is ∼2.5 fold enhanced compared to that with aq. PEDOT:PSS. The study may lead to better understanding of PEDOT:PSS/n-Si interface and efficient hybrid photovoltaic devices employing the cost-effective polar surfactants.

Separation and identification of tubocapsanolide MAP and tubocapsunolide A, and the structure-activity relationship of their anti-TNBC activity

A new withanolide, tubocaapsanolide MAP (MeOH addition product) (1), as well as its known precursor tubocaapsanolide A (2) were obtained from Tubocapsicum anomalum (Solanaceae). Compound 1 was a MeOH addition product transformed from compound 2 during the process of separation using MeOH as solvent. The structures of the two withanolides including absolute configuration were elucidated by extensive spectroscopic analysis and X-ray single crystal diffraction. In the test of anti-triple negative breast cancer (TNBC) effects, tubocapsusanlide A (2) showed potent inhibitory activity against four human TNBC cell lines, while tubocapsusanlide MAP (1) exhited significantly weaker inhibitory than that of tubocapsusanlide A (2), indicating that α-β unsaturated carbonyl unit contained in 2 was closely related to its anti-TNBC activity. The potent bioactivity displayed significant developing potential of withanolides as anti-TNBC lead compounds or drug candidates. And this report may provide some useful guidances for the preparation and bioactivity research of withanolides.

Application of Relay C−H Oxidation Logic to Polyhydroxylated Oleanane Triterpenoids

Summary Although clinical applications of abundant feedstock triterpenoids such as oleanolic acid are limited because of poor solubility and bioavailability, synthetic access to higher hydroxylated oleanane terpenoids is challenging. We now report the use of relay C−H oxidation logic to mimic the processes carried out in nature by P450 monooxygenase enzymes. To this end, we used the C-23-OH as natural handle for a hydrogen-atom transfer to access C-6, enabling the first syntheses of highly oxidized natural products uncargenin C and protobassic acid as well as uncovering the anti-leukemic activity of a synthetic intermediate.

Exergy losses in auto-ignition processes of DME and alcohol blends

The exergy losses in the auto-ignition processes of binary blends of dimethyl ether (DME) and methanol (MeOH)/ethanol (EtOH) were numerically studied in an adiabatic constant-volume system. Three detailed kinetic mechanisms for the DME/alcohol blends were employed in the auto-ignition simulation at changed temperature, pressure, equivalence ratio and oxygen concentration conditions. Four reaction stages, namely the fuel-series reaction stage, the fuel-fragment reaction stage, the H2O2 loop reaction stage and the H2-O2 reaction stage were defined for the auto-ignition processes based on the reaction pathway analysis, and the exergy destructions in each stage were evaluated for different fuels. It was observed that the exergy loss characteristics calculated by three mechanisms were consistent. Meanwhile, increased initial pressure and reduced oxygen concentration could lower down the overall exergy losses. In addition, MeOH/EtOH addition does not show significant effects on the total exergy losses but the MeOH addition was more effective than EtOH in extending the area of the minimum exergy losses. Furthermore, the interaction effects between the reaction kinetics of alcohols and DME on the exergy loss characteristics were analyzed at the low and high initial temperatures, respectively. The exergy loss rates of different fuels featured triple-peak traces as the initial temperature was located at the low temperature region, while double-peak traces were shown at the high initial temperature condition. At the low initial temperature conditions, MeOH/EtOH addition to DME suppressed the low-temperature reactions, causing the reduced magnitude of the first peak in the exergy loss rate curves. In addition, the magnitude of the second peak increased with MeOH addition while decreased with EtOH addition. The magnitude of the third peak showed insignificant change with MeOH/EtOH addition. At both low and high initial temperatures, the addition of MeOH to DME increases the exergy losses by the H2O2 loop reactions while decreases the exergy losses by the fuel-fragment reactions. In contrast, the addition of EtOH decreases the exergy losses by the H2O2 loop reactions while increases the exergy losses by the fuel-fragment reactions.

Securamine Derivatives from the Arctic Bryozoan Securiflustra securifrons.

Bryozoans belonging to the Flustridae family have proven to be a rich source of structurally unique secondary metabolites. As part of our continuing search for bioactive secondary metabolites from Arctic marine invertebrates, the organic extract of Securiflustra securifrons was examined. This resulted in the isolation of three new halogenated, hexacyclic indole-imidazole alkaloids, securamines H-J (1-3), together with the previously reported compounds securamines C (4) and E (5). The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR and analysis of HRMS data. Through NMR and HRMS analysis, we were also able to prove that 1, 2, 4, and 5, when dissolved in MeOH, were converted into their corresponding artifacts, the securamine MeOH adducts m1, m2, m4, and m5. When redissolved in a non-nucleophilic solvent, the native variants were re-formed. We also found that 3 was a MeOH addition product of a native variant. Even though the structures of several securamines have been reported, their bioactivities were not examined. The securamines displayed various degrees of cytotoxicity against the human cancer cell lines A2058 (skin), HT-29 (colon), and MCF-7 (breast), as well as against nonmalignant human MRC-5 lung fibroblasts. Compounds 1, 2, and 5 were found to be active, with IC50 values against the cancer cell lines ranging from 1.4 ± 0.1 to 10 ± 1 μM. The cytotoxicity of 1 was further evaluated and found to be time-dependent.

Chemical Characterization and Physical Properties of Solvents Derived from Epoxidized Methyl Soyate

AbstractReactions of epoxidized methyl soyate (EMS) with alcohols, carbon dioxide, and acetone yielded liquids with solvent properties that make them more suitable than methyl soyate for dissolving polar substances. The reactions of EMS in the presence of Amberlyst‐15 with alcohols, including methanol, ethanol, n‐butanol, and 2‐methoxyethanol, produced a series of solvents containing ether (–OR) and alcohol (–OH) groups. Reactions of EMS with carbon dioxide and acetone gave products with carbonate and ketonide functional groups, respectively. The complex mixture of compounds present in the product, EMS(MeOH), resulting from the reaction of EMS with MeOH, was characterized by MS and NMR investigations. In addition to products resulting from MeOH addition across the epoxide ring, were major amounts of cyclic tetrahydrofuran derivatives that were derived from reactions of methyl linoleate (18:2) with MeOH. All of the solvents were characterized by high boiling points and low vapor pressures. Their viscosities were higher than that of methyl soyate. Especially notable were their very high Kauri‐butanol values, which ranged from 280 to 852, all of which are much higher than that (57) of methyl soyate. Such high KB values indicate that these solvents have very favorable solubilizing properties, which is illustrated by the ability of EMS(MeOH) to readily dissolve both polar (e.g., MeOH) and non‐polar (e.g., hexane) compounds.

The role of methanol addition to water samples in reducing analyte adsorption and matrix effects in liquid chromatography–tandem mass spectrometry

Liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis coupled simply with water filtering before injection has proven to be a simple, economic and time-saving method for analyzing trace-level organic pollutants in aqueous environments. However, the linearity, precision and detection limits of such methods for late-eluting analytes were found to be much poorer than for early-eluting ones due to adsorption of the analytes in the operating system, such as sample vial, flow path and sample loop, creating problems in quantitative analysis. Addition of methanol (MeOH) into water samples as a modifier was shown to be effective in alleviating or even eliminating the negative effect on signal intensity for the late-eluting analytes and at the same time being able to reduce certain matrix effects for real water samples. Based on the maximum detection signal intensity obtained on desorption of the analytes with MeOH addition, the ratio of the detection signal intensity without addition of MeOH to the maximum intensity can be used to evaluate the effectiveness of methanol addition. Accordingly, the values of <50%, 50–80%, 80–120% could be used to indicate strong, medium and no effects, respectively. Based on this concept, an external matrix-matched calibration method with the addition of MeOH has been successfully established for analyzing fifteen pesticides with diverse physico-chemical properties in surface and groundwater with good linearity (r2: 0.9929–0.9996), precision (intra-day relative standard deviation (RSD): 1.4–10.7%, inter-day RSD: 1.5–9.4%), accuracy (76.9–126.7%) and low limits of detection (0.003–0.028μg/L).

F−/OH− Triggered Optical Switching Functions of Naphthalimide Chromophoric Materials

Two naphthalimide based chemosensors were synthesized. Upon the addition of OH− or F−, the solution color turned from pink to blue due to the proton elimination of N-H/O-H. The electron density increased on the nitrogen atom and enhanced the intramolecular charge transfer, which resulted in a red-shift of the absorption band. This color change was reversible with H+/MeOH addition and can be detected with the naked eye. The selectivity of the two dyes toward OH−/F− compared with other anions was investigated. The underlying signal mechanism was interpreted by the HOMO/LUMO potentials. Significantly lowered energy gap supported the red-shift absorption band.

Electro-oxidation of BH4− in dimethylsulfoxide and dimethylformamide studied by rotating disk electrode voltammetry

Borohydride (BH4−) is a promising new fuel for fuel cells, yet its practical implementation has been hindered by a deleterious hydrolysis reaction to form H2 in aqueous solvents, especially at the high BH4− concentrations necessary for high-power fuel cells. We investigated a wide array of nonaqueous solvents for their ability to hold BH4− at higher concentrations and allow effective electro-oxidation at Pt and Au, two well-studied BH4− anode materials. Only dimethylsulfoxide and dimethylformamide were found to be suitable, and precluded BH4− decomposition to H2 in bulk solution (hydrolytic or otherwise). BH4− decomposition at electrode surfaces was still observed, however. Current densities in these solvents were about an order of magnitude below those observed in aqueous solution, and onset potentials were 0.7V less favorable. MeOH addition, to stabilize oxidized states of boron, did not increase current.

Synthesis of a class of 5-((5-(pyrrol-2-yl-methylene)-pyrrol-2-yl)methylene)furan-2-ones and the formation of a furanone dipyrrin imino ether

A class of α-furanyl dipyrrins 2 were prepared by refluxing THF solutions of DDQ adducts 1 with the appropriate alcohols in the presence of AlCl3 and further subsequent reaction of the cyano-group results in the formation of an imino ether upon MeOH addition.

Gaseous dimethyl sulphide removal in a membrane biofilm reactor: Effect of methanol on reactor performance

In this study, removal of dimethyl sulphide (DMS) vapours in a membrane biofilm reactor (MBfR) and the effect of the presence of methanol (MeOH) is reported. Results obtained from continuous flow experiments showed that MeOH had a positive effect (maximum 1.3 times higher) on DMS biodegradation. A decrease in MBfR performance was observed during periods without MeOH addition, indicating that MeOH addition is necessary to sustain high DMS removal rates in the MBfR. In this study, a maximum elimination capacity (EC) of 6.2 kg DMS m(-3) d(-1) was observed at an optimum MeOH dose of 1.1-2.3 g m(-3). The observed EC is higher than any reported previously for biofilters or biotrickling filters. Thus, MBfR is a promising technology and can be used for the treatment of mixture of compounds operated under optimum ratios.

Theoretical Investigations on Reactions of a Series of Stable Dialkyl-Substituted Silicon−Chalcogen Doubly Bonded Compounds

The potential energy surfaces for the formation, addition, and cycloaddition reactions of dialkylsilanechalcogenone (2) species have been studied using three levels of theories, i.e., B3LYP/LANL2DZdp, CCSD theory, and Gibbs free energy (at the B3LYP level). Four dialkylsilanechalcogenone species with a Si═X bond, where X = O, S, Se, and Te, have been chosen as model reactants in this work. Also, both MeOH addition and isoprene cycloaddition have been used to study the chemical reactivities of these species (2). The present theoretical investigations suggest that the relative reactivity of 2 increases in the order X = O < S < Se ≪ Te. That is, the species with a less electronegative and a heavier chalcogen atom will have a smaller ΔEst, which facilitates its addition with MeOH and its cycloaddition reaction to isoprene. Furthermore, the singlet−triplet energy splitting, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict the ...

Modeling the Biofiltration of Dimethyl Sulfide in the Presence of Methanol in Inorganic Biofilters at Steady State

The presence of methanol (MeOH) improves DMS removal (up to 11-fold) by enhancing biomass growth in inorganic biofilters. Although the overall effect is positive, prolonged growth on methanol also negatively affects DMS degradation as a result of competition with DMS. The objectives of this study were to explore the potential to optimize DMS removal with methanol addition and to develop and experimentally validate a mathematical model describing the biofiltration of DMS in the presence of MeOH. Continuous experiments using three bench-scale biofilters packed with inorganic material were performed to examine the removal of DMS under different MeOH addition rates ranging from 0 to 140 g/m3/h. For a constant DMS loading of 3.5 g/m3/h, a maximum DMS removal rate of 1.8 g/m3/h was achieved at a MeOH addition rate of 20 g/m3/h in the inorganic biofilters. A steady-state model incorporating the competitive and activation effects of MeOH on DMS biodegradation was developed, and the modeled results on DMS and MeOH removal were in close agreement with experimental data. Both the experimental data and model simulation suggest that there is an optimum MeOH addition rate for a given DMS loading. A step-feeding strategy for MeOH addition was proposed and tested by the model to optimize DMS removal. The model-predicted results demonstrate that six-step feeding of MeOH enhances DMS treatment by 46% in the biofilters when compared to conventional feeding (one-step) of MeOH at the same total mass loading.

Stimuli responsive associative polyampholytes based on ABCBA pentablock terpolymer architecture

A poly(methyl methacrylate)–poly(acrylic acid)–poly(2-vinyl pyridine)–poly(acrylic acid)–poly(methyl methacrylate) (PMMA–PAA–P2VP–PAA–PMMA), ABCBA pentablock terpolymer was synthesized by “living” anionic polymerization and was studied in aqueous media at different pH conditions in the presence of MeOH. By tuning the pH and/or the solvent selectivity and dielectric constant of the medium, reversible hydrogels of different nature were formed. At low pH the hydrogel is based on a three dimensional network comprising PMMA hydrophobic cores (physical crosslinks) interconnected by complex bridging (elastically active) chains constituted of positively charged P2VP and non-ionic PAA segments. At high pH the hydrogel is transformed reversibly to a negatively charged network the bridging chains of which comprise ionized PAA segments interrupted by hydrophobic P2VP blocks, swellable on MeOH addition. Furthermore, we found conditions for the formation of flower-like micelles of different topologies and nature like core–shell–corona micelles with positively charged corona (pH<2), multicompartment micelles comprising P2VP and PMMA hydrophobic domains (pH 8.3, low MeOH content), micelles constituted of a centrosymmetric compartmentalized core and PAA negatively charged corona (pH 8.3, 30%, 40% MeOH), and core–shell micelles of PMMA cores (pH 8.3, 50% MeOH).

Homo- and R/S-copolymerizations of chiral methylpropargyl esters carrying pyrene moieties, and optical properties of the formed polymers

Pyrene-functionalized chiral methylpropargyl esters, (R)-3-butyn-2-yl-1-pyrenebutyrate [(R)-1], (S)-3-butyn-2-yl-1-pyrenebutyrate [(S)-1], (R)-3-butyn-2-yl-1-pyrenecarboxylate [(R)-2], and 3-butyn-2-yl-1-pyrenecarboxylate [(R,S)-2] were polymerized with (nbd)Rh+[η6-C6H5B−(C6H5)3] to obtain the corresponding polymers with moderate molecular weights (Mn: 10 500–66 500) in good yields (82–97%). All the polymers were soluble in CHCl3, CH2Cl2, and THF. The polarimetric and CD spectroscopic data indicated that poly[(R)-1], poly[(S)-1], and poly[(R)-2] existed in a helical structure with predominantly one-handed screw sense in these solvents. The helical structure of poly[(R)-1] and poly[(S)-1] was stable upon heating and addition of MeOH, while that of poly[(R)-2] changed upon MeOH addition. The copolymerization of (R)-1 with (S)-1 was also conducted to obtain the copolymers satisfactorily. Poly[(R)-1], poly[(S)-1], and poly[(R)-2] emitted fluorescence smaller than the corresponding racemic copolymers. The fluorescence intensity was tuned by the addition of MeOH to THF solutions of the polymers.

Role of Methanol in Supercritical Water Oxidation of Ammonia

The role of methanol (MeOH) in the supercritical water oxidation (SCWO) of ammonia (NH3) was investigated near the typical operating conditions of a commercial plant at 560−620 °C and 25 MPa using a tubular reactor. It was found that the presence of MeOH strongly affected the reaction behavior of nitrogen. With the addition of MeOH, at concentrations more than twice the initial concentrations of NH3 (1.4−5.7 mmol/mol of the feed mixture), the conversion of NH3 to N2O increased by about four times to 0.5−0.6 compared to that with no MeOH addition. The production of NO3- from NH3 increased in the liquid effluent with a conversion of up to 0.2. The productions of NO2-, NO, and NO2 from NH3 had similar behavior under the presence of MeOH at the tested conditions, and significant effects were observed at MeOH concentrations more than 2−6 times of the initial concentrations of NH3. The experimental results made it clear that NO and NO2 were produced under the SCWO conditions. Methods for the reduction of N2O and NO3- were also investigated. Results showed that SCWO is not suitable for the decomposition of N2O. Other post-treatment methods such as catalytic decomposition should be applied to reduce N2O in the gas effluent. NO3- reduction methods (e.g., two-step reaction) proposed in this study should also be considered to prevent corrosion of the reactor material.

Enhancing and modeling the biofiltration of dimethyl sulfide under dynamic methanol addition

Recent research has shown that there is significant enhancement (up to 11-fold) of the biofiltration of dimethyl sulfide (DMS) in the presence of methanol (MeOH). The objectives of this study were to explore the potential to optimize DMS removal with MeOH addition and to develop and experimentally validate a mathematical model describing the biofiltration of DMS under dynamic MeOH addition. A dynamic model incorporating the competitive and activation effects of MeOH on DMS biodegradation was developed to describe both steady-state and transient-state behavior of inorganic biofilters treating DMS with MeOH addition less than 50 g / m 3 h . The proposed model included the effect of substrates (e.g., MeOH) on biomass growth rate to take account for biofilm growth in biofilters over time. In the model, the biofilm was considered to have variable density along the biofilter column as a function of MeOH concentration in the air stream. At steady state, the modeled results on DMS removal were in close agreement with the experimental data. The transient-state behavior of the biofilters during periodic MeOH addition periods was also effectively predicted with the model. Our results support the proposed mechanism of MeOH effects on the biofiltration of DMS. A MeOH feeding strategy (pulse feeding) that enhanced DMS treatment by 35% was experimentally demonstrated and simulated by the model.

The effects of methanol on the biofiltration of dimethyl sulfide in inorganic biofilters

Air emissions from the pulp and paper industry frequently contain reduced sulfur compounds (RSC), such as dimethyl sulfide (DMS) mixed with volatile organic compounds (VOC) (e.g., methanol, MeOH) and it is desirable to treat either one or both of these groups of compounds. The objective of this study was to assess the effects of VOC (MeOH) on the biofiltration of DMS. Results obtained from continuous experiments using three bench-scale biofilters packed with inorganic material clearly show that MeOH has a positive effect (11-fold increase) on the biofiltration of DMS. Further experiments indicate that MeOH addition enhances biomass concentration and viability (threefold) in the biofilters. However, a suspension of MeOH addition causes a rapid significant increase (twofold) in the removal rate of DMS, suggesting that the presence of MeOH also has a competitive effect on DMS biodegradation. This negative effect was also confirmed in batch experiments. The decrease of biofilter performance with time for a long-term suspension of MeOH addition indicates that MeOH addition is necessary to sustain a high removal rate of DMS in inorganic biofilters. Results on metabolic products of DMS biodegradation demonstrate that DMS is almost completely converted to sulfate in the absence of MeOH, while it is partially oxidized to elemental sulfur in the presence of MeOH. This study suggests that there exists an optimum mix of DMS and MeOH for the treatment of DMS emissions in inorganic biofilters.

Specifics of the photolysis of alkylated hydroxy-1,2-dihydroquinolines in water and methanol

Comparative study of photoinduced reactions of 6-and 8-hydroxy-2,2,4-trimethyl-1,2-dihydroquinolines (6-OH-DHQ and 8-OH-DHQ) in water and methanol was carried out by continuous and pulse photolysis. The products of MeOH addition to the dihydroquinolines under study were isolated and identified. The spectral and kinetic parameters of active transient species generated in the photolysis were measured. The rate constants of the transient carbocations strongly depend on the position of the hydroxy group on the aromatic ring and are an order of magnitude lower for 6-OH-DHQ than 8-OH-DHQ (80 versus 870 s−1, respectively). Two factors that play a significant part in the photolysis mechanism were revealed, namely, an increase in the acidity of the phenolic group in the excited state and the possibility of intramolecular hydrogen bonding between phenolic and amino groups in 8-OH-DHQ, which are in close proximity. The former factor causes the formation of by-products from the deprotonated excited state of OH-DHQ, which increases substantially in water. The latter affects the structure and the composition of transient species in the case of 8-OH-DHQ.