Fluorinated 2-arylchroman-4-ones and their derivatives: synthesis, structure and antiviral activity.

A number of new biologically interesting fluorinated 2-arylchroman-4-ones and their 3-arylidene derivatives were synthesized based on the p-toluenesulfonic acid-catalyzed one-pot reaction of 2-hydroxyacetophenones with benzaldehydes. It was found that obtained (E)-3-arylidene-2-aryl-chroman-4-ones reacted with malononitrile under base conditions to form 4,5-diaryl-4H,5H-pyrano[3,2-c]chromenes. The structures of the synthesized fluorinated compounds were confirmed by 1H, 19F, and 13C NMR spectral data, and for some representatives of heterocycles also using NOESY spectra and X-ray diffraction analysis. A large series of obtained flavanone derivatives as well as products of their modification (35 examples) containing from 1 to 12 fluorine atoms in the structure was tested in vitro for cytotoxicity in MDCK cell line and for antiviral activity against influenza A virus. Among the studied heterocycles 6,8-difluoro-2-(4-(trifluoromethyl)phenyl)chroman-4-one (IC50 = 6 µM, SI = 150) exhibited the greatest activity against influenza A/Puerto Rico/8/34 (H1N1) virus. Moreover, this compound appeared active against phylogenetically distinct influenza viruses, A(H5N2) and influenza B (SI's of 53 and 42, correspondingly). The data obtained suggest that the fluorinated derivatives of 2-arylchroman-4-ones are prospective scaffolds for further development of potent anti-influenza antivirals.

Detoxification of lignocellulosic prehydrolyzate by lignin nanoparticles prepared from biorefinery biowaste to improve the ethanol production.

This study proposed a recyclable p-toluenesulfonic acid (p-TsOH) fractionation process for co-producing lignin nanoparticles (LNPs) and fermentable sugars from lignocellulosic biorefinery biowaste (enzymatic hydrolysis residue (EHR)). The prepared LNPs were used to detoxify the inhibitors in the xylose-rich prehydrolyzate for improving ethanol production. Results showed that the EHR was fractionated into a cellulose-rich water-insoluble solid (WIS) fraction and a lignin-rich spent liquor (SL) fraction. Cellulase hydrolysis of WIS produced 97.7% of glucose yield, while the LNPs of an average particle size of 98.0 nm with 76.3 % yield (based on the untreated EHR) were obtained from the diluted SL. LNPs demonstrated higher detoxification ability than EHR at the same dosage. Moreover, the fermentability of the detoxified xylose-rich prehydrolyzate was significantly improved. The sugar utilization ratio was 94.8%, and the ethanol yield reached its peak value of 85.4% after 36 h of fermenting the detoxified xylose-rich prehydrolyzate.

Kinetics of Lignin Separation during the Atmospheric Fractionation of Bagasse with p-Toluenesulfonic Acid.

As a green and efficient component separation technology, organic acid pretreatment has been widely studied in biomass refining. In particular, the efficient separation of lignin by p-toluenesulfonic acid (p-TsOH) pretreatment has been achieved. In this study, the mechanism of the atmospheric separation of bagasse lignin with p-TsOH was investigated. The separation kinetics of lignin was analyzed. A non-simple linear relationship was found between the separation yield of lignin and the concentration of p-TsOH, the temperature and the stirring speed. The shrinking nucleus model for the separation of lignin was established based on the introduction of mass transfer and diffusion factors. A general model of the total delignification rate was obtained. The results showed that the process of lignin separation occurred into two phases, i.e., a fast stage and a slow stage. The results provide a theoretical basis for the efficient separation of lignin by p-TsOH pretreatment.

Catalytic Conversion of Xylose to Furfural by p-Toluenesulfonic Acid (pTSA) and Chlorides: Process Optimization and Kinetic Modeling.

Furfural is one of the most promising precursor chemicals with an extended range of downstream derivatives. In this work, conversion of xylose to produce furfural was performed by employing p-toluenesulfonic acid (pTSA) as a catalyst in DMSO medium at moderate temperature and atmospheric pressure. The production process was optimized based on kinetic modeling of xylose conversion to furfural alongwith simultaneous formation of humin from xylose and furfural. The synergetic effects of organic acids and Lewis acids were investigated. Results showed that the catalyst pTSA-CrCl3·6H2O was a promising combined catalyst due to the high furfural yield (53.10%) at a moderate temperature of 120 °C. Observed kinetic modeling illustrated that the condensation of furfural in the DMSO solvent medium actually could be neglected. The established model was found to be satisfactory and could be well applied for process simulation and optimization with adequate accuracy. The estimated values of activation energies for xylose dehydration, condensation of xylose, and furfural to humin were 81.80, 66.50, and 93.02 kJ/mol, respectively.

Performance of p-Toluenesulfonic Acid-Based Deep Eutectic Solvent in Denitrogenation: Computational Screening and Experimental Validation.

Deep eutectic solvents (DESs) are green solvents developed as an alternative to conventional organic solvents and ionic liquids to extract nitrogen compounds from fuel oil. DESs based on p-toluenesulfonic acid (PTSA) are a new solvent class still under investigation for extraction/separation. This study investigated a new DES formed from a combination of tetrabutylphosphonium bromide (TBPBr) and PTSA at a 1:1 molar ratio. Two sets of ternary liquid-liquid equilibrium experiments were performed with different feed concentrations of nitrogen compounds ranging up to 20 mol% in gasoline and diesel model fuel oils. More than 99% of quinoline was extracted from heptane and pentadecane using the DES, leaving the minutest amount of the contaminant. Selectivity was up to 11,000 for the heptane system and up to 24,000 for the pentadecane system at room temperature. The raffinate phase's proton nuclear magnetic resonance (1H-NMR) spectroscopy and GC analysis identified a significantly small amount of quinoline. The selectivity toward quinoline was significantly high at low solute concentrations. The root-mean-square deviation between experimental data and the non-random two-liquid (NRTL) model was 1.12% and 0.31% with heptane and pentadecane, respectively. The results showed that the TBPBr/PTSADES is considerably efficient in eliminating nitrogen compounds from fuel oil.

p-Toluenesulfonic acid enhanced neutral deep eutectic solvent pretreatment of soybean straw for efficient lignin removal and enzymatic hydrolysis.

Deep eutectic solvent (DES) is a newly-emerged green solvent for efficient pretreatment of lignocellulosic feedstock. To improve the component fractionation performance of neutral DES, p-toluenesulfonic acid (p-TsOH) was employed as catalyst to form a novel ternary DES with benzyltriethylammonium chloride (TEBAC) and glycerol (Gly) for pretreatment of soybean straw. Under the optimum reaction conditions (TEBAC:Gly = 1:12, 1.6 wt% p-TsOH and reacted at 90 °C for 160 min), the lignin and hemicellulose removal from soybean straw were amounted to 92.0 % and 88.2 %, respectively. The pretreated substrate showed satisfactory enzymatic hydrolysis performance, as the glucose and reducing sugar concentrations reached 37.3 g/L and 42.3 g/L, respectively, after 72 h saccharification under the action of cellulase with a relatively low enzyme loading of 10 FPU/g cellulose.This method provides an efficient and mild route for utilization of agricultural waste and production of platform monosaccharides.

p-Toluenesulfonic Acid Modified Two-Dimensional ZrSe2 as a Hole Transport Layer for High-Performance Organic Solar Cells.

Two-dimensional (2D) materials have attracted attention due to their excellent optoelectronic properties, but their applications are limited by their defects and vacancies. Surface modification is an effective method to restore their performance. Here, ZrSe2 is modified with conductive polymer p-toluenesulfonic acid (PTSA). It is found that PTSA can obtain electrons of ZrSe2 through the combination of -SO3H and ZrSe2, thus forming interfacial dipoles, which improve the work function of ZrSe2. In addition, -OH in PTSA can effectively fill the Se vacancy in ZrSe2 to form P-type doping, thereby improving its conductivity. ZrSe2 modified by the PTSA material is first used as a hole transport layer (HTL) in organic solar cells (OSCs). The efficiency of OSCs based on the PBDB-T:ITIC and PM6:L8-BO binary active layer with ZrSe2:PTSA as the novel HTL reaches 10.66 and 18.14%, which are obviously higher than the efficiency of OSCs with pure ZrSe2 as the HTL (8.48 and 15.64%). More interestingly, the stability of the device with ZrSe2:PTSA as HTL is significantly better than that of PEDOT:PSS. This study shows that the modification of the organic material can effectively improve the photoelectric performance of ZrSe2 and explores the physical mechanism of the interaction between the organic modifier and 2D materials.

Effect of alkali treatment on enzymatic hydrolysis of p-toluenesulfonic acid pretreated bamboo substrates.

The comprehensive separation and utilization of whole components of lignocellulosic materials has received extensive attention in present research. This study focused on the efficacy of alkali treatment for enzymatic saccharification of cellulose based on p-toluenesulfonic acid (p-TsOH) pretreated bamboo substrate. The results showed that the cellulose to glucose conversion yield was 94.69 % under optimized conditions of 0.4 g NaOH/g, 160 °C and 4 h (soaked), which after only 6 h enzymatic hydrolysis time. Alkali lignin recovery was 88.51 %, with potential for conversion to lignin derivatives. The yield of hemicellulose in the pretreated filtrate was 51.85 % after the 4th cycling reuse of p-TsOH. This work has borrowed the advantages of p-TsOH pretreatment of depolymerized hemicellulose from bamboo, combined with a low-priced weak alkali secondary treatment method, which can be effectively applied to the co-production of lignin, xylooligosaccharide, xylose and glucose, and the whole process is green and economically sustainable.

Oxidation of p-toluenesulfonic acid fractionated hybrid Pennisetum by different methods for carboxylated nanocellulose preparation: The evaluation of efficiency and sustainability.

An innovative two-step process with p-toluenesulfonic acid (p-TsOH) and oxidation treatment was proposed for the efficient preparation of carboxylated nanocellulose from hybrid Pennisetum. Approximately 90 % of lignin was dissolved by p-TsOH acid under the optimal condition (80 °C, 20 min). Near-complete delignification (down to 0.5 %) and introduction of carboxylate groups (up to 1.48 mmol/g) could be achieved simultaneously during cellulose oxidation treatments without the requirement for bleaching. However, different oxidation methods expressed different efficiency and sustainability. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) oxidation has higher selectivity for the carboxylation reaction but with detriment to the aquatic environment. Fenton oxidation is more energy-consuming due to the lower carboxylate contents of products (maximum 188 µmol/g), with the carboxylic groups present as carboxylic acids, but competitive in terms of environmental sustainability, especially when renewable energy sources are available. The nanocelluloses obtained by the two oxidation methods differ in morphology and have different application prospects.

Efficient preparation of high-purity cellulose from moso bamboo by p-toluenesulfonic acid pretreatment.

This work proposed a promising biorefinery method for the deconstruction of moso bamboo by using p-toluenesulfonic acid (P-TsOH) pretreatment to product high-purity cellulose (dissolving pulp). The cellulose pulp with high α-cellulose content (82.36 %) was successfully prepared for 60 min at low pretreatment temperature (90 °C) and atmospheric pressure. After the simple bleaching and cold caustic extraction (CCE) processes, the properties of cellulose pulp, such as α-cellulose content, polymerization, ISO brightness, all met the standard of dissolving pulp. In general, the cooking method through P-TsOH pretreatment can shorten the preparation time, which can effectively reduce energy consumption and chemical consumption. Therefore, this work may provide a new perspective for the green preparation of dissolving pulp that can be used to produce lyocell fiber after ash and metal ion treatment.

Pretreatment of moso bamboo with p-toluenesulfonic acid for the recovery and depolymerization of hemicellulose.

Bamboo and its mechanical processing residues have broad prospects for high value-added utilization. In this research, p-toluenesulfonic acid was used for the pretreatment of bamboo to investigate the effects of extraction and depolymerization of hemicellulose. The response and behavior of changes of cell-wall chemical components were investigated after different solvent concentration, time, and temperature pretreatment. Results indicated that the maximum extraction yield of hemicellulose was 95.16 % with 5 % p-toluenesulfonic acid at 140 °C for 30 min. The depolymerized components of hemicellulose in the filtrate were mainly xylose and xylooligosaccharide, with xylobiose accounting for 30.77 %. The extraction of xylose from the filtrate reached a maximum of 90.16 % with 5 % p-toluenesulfonic acid at 150 °C for 30 min pretreatment. This research provided a potential strategy for the industrial production of xylose and xylooligosaccharide from bamboo and for the future conversion and utilization.

Curing Behavior of Sucrose with p-Toluenesulfonic Acid.

With respect to the fossil resources shortage, the development of bio-based wood adhesives is an important research topic in wood science. There has been research on using sucrose for bio-based adhesives. However, a high acid catalyst content and a high hot-pressing temperature are required when manufacturing particleboards. In this study, to explore the possibility of p-toluenesulfonic acid (PTSA) as a promising acid catalyst for sucrose-based adhesives, the curing behavior of sucrose with PTSA (Suc-PTSA) was clarified. The thermal analysis results showed that the thermal properties of sucrose decreased significantly with the addition of PTSA. Based on the results of the insoluble matter rate, the optimal mixture ratio and heating conditions were determined to be 95:5 and 180 °C for 10 min, respectively. According to the results of FT-IR, the heat-treated Suc-PTSA contained furan compounds. In the context of the dynamic viscoelasticity, the onset temperature at which the storage modulus (E') begins to rise was significantly lower than those of the other sucrose-based adhesives. PTSA has the potential to cure sucrose more efficiently and at lower temperatures than previous sucrose-based adhesives, making it a promising acid catalyst for sucrose.

A simple, flexible, and high-efficiency western blot analysis for age-related human induced neurons.

High-throughput western blot (WB) analysis can be used to obtain more consistent, comparable, and informative data from precious samples and materials with extremely limited availability, such as various age-related, subtype-specific human induced neurons (hiNs). In this study, p-toluenesulfonic acid (PTSA), an odorless tissue fixative, was used to inactivate horseradish peroxidase (HRP) and develop a high-throughput WB method. PTSA-treated blots demonstrated rapid and efficient HRP inactivation without detectable protein loss or epitope damage. With a brief PTSA treatment (1 min at room temperature [RT]) before every subsequent probing, 10 dopaminergic hiN proteins could be sequentially, sensitively, and specifically detected in the blot. The resulting WB data confirmed the age-associated and neuron-specific features of hiNs and revealed a significant reduction in two Parkinson's disease-associated proteins, UCHL1 and GAP43, in normal aging dopaminergic neurons. Overall, this study developed a unique and high-efficiency WB analysis method for capturing robust and useful data from limited, precious samples.

Doping of Transparent Electrode Based on Oriented Networks of Nickel in Poly(3,4-Ethylenedioxythiophene) Polystyrene Sulfonate Matrix with P-Toluenesulfonic Acid.

This work aimed to obtain an optically transparent electrode based on the oriented nanonetworks of nickel in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate matrix. Optically transparent electrodes are used in many modern devices. Therefore, the search for new inexpensive and environmentally friendly materials for them remains an urgent task. We have previously developed a material for optically transparent electrodes based on oriented platinum nanonetworks. This technique was upgraded to obtain a cheaper option from oriented nickel networks. The study was carried out to find the optimal electrical conductivity and optical transparency values of the developed coating, and the dependence of these values on the amount of nickel used was investigated. The figure of merit (FoM) was used as a criterion for the quality of the material in terms of finding the optimal characteristics. It was shown that doping PEDOT: PSS with p-toluenesulfonic acid in the design of an optically transparent electroconductive composite coating based on oriented nickel networks in a polymer matrix is expedient. It was found that the addition of p-toluenesulfonic acid to an aqueous dispersion of PEDOT: PSS with a concentration of 0.5% led to an eight-fold decrease in the surface resistance of the resulting coating.

Effect of temperature on simultaneous separation and extraction of hemicellulose using p-toluenesulfonic acid treatment at atmospheric pressure.

Hemicelluloses were effectively separated using p-toluenesulfonic acid (p-TsOH) treatment at high temperature. High temperature and pressure promoted hydrolysis of hemicellulose, which limited its value upon recovery. In this study, bagasse hemicellulose was separated and extracted by p-TsOH treatment at atmospheric pressure. The effects of temperature, p-TsOH concentration, and time on hemicellulose separation and extraction were investigated. The optimal conditions were 80 °C, 3.0% p-TsOH, and 120 min. The separation and extraction yield of hemicellulose was 73.23% and 36.02%, respectively. Extraction hemicellulose with 95.60% purity was obtained. In addition, the dissolution mechanism of hemicellulose was analyzed. Degradation of ß-glycosidic bonds was inhibited. Benzyl ether bond between carbohydrates and lignin was selectively cleaved. The skeleton structure of xylan in hemicellulose was protected while the functional groups of branch chain were severely damaged. It provides a valuable theoretical basis for the efficient separation and extraction of hemicellulose.

Enhancement of separation selectivity of hemicellulose from bamboo using freeze-thaw-assisted p-toluenesulfonic acid treatment at low acid concentration and high temperature.

The cellulose-rich residual solids are obtained with p-toluenesulfonic acid (p-TsOH) treatment. However, better fractionation of hemicellulose and separation is difficult to obtain during treatment. This study aims at investigating the separation selectivity of bamboo hemicellulose using freeze-thaw-assisted p-TsOH (F/p-TsOH) treatment. The desired separation effect was achieved at freezing temperature -40 °C, freezing time 20 h, p-TsOH concentration 3.0 %, treatment temperature 130 °C and time 80 min. 93.26 % hemicellulose separation was found, which was 32.88 % higher than that of conventional p-TsOH treatment. Furthermore, the separation yield of lignin decreased significantly from 69.29 % to 13.98 %. The distinct lignin characteristic absorption peaks were found, while that of hemicellulose was difficult to observe. The fiber crystallinity index increased from 50.42 to 56.55 %. Furthermore, greater selectivity for hemicellulose separation was achieved. The results provide a new research thinking for efficient fractionation of lignocellulosic biomass by organic acid treatment.

p-Toluenesulfonic acid combined with hydrogen peroxide-assisted pretreatment improves the production of fermentable sugars from walnut (Juglans regia L.) shells.

This study presents p-toluenesulfonic acid (p-TsOH) pretreatment combined with subsequent hydrogen-peroxide pretreatment for the fractionation of all lignocellulosic components from walnut shells (WNS). The main focus of this study is the production of fermentable sugars. During p-TsOH pretreatment (55% p-TsOH, 1:10 solid-to-liquid ratio, 90 °C, 120 min), 50.2% of lignin and 88.3% of xylan were dissolved. Subsequently, the p-TsOH pretreated WNS without washing (to reduce water consumption) was further pretreated with 40% (v/v) H2O2 and 74.6% of lignin was removed at 60 °C for 120 min. Compared with the glucose yield of 10.2% from p-TsOH pretreated WNS, the glucose yield from the p-TsOH/H2O2 pretreated WNS could be significantly improved to 94.4%. Structural characterization analysis showed increases in porosity, biomass disruption, and cellulose crystallinity during p-TsOH/H2O2 pretreatment. Mass balance demonstrated that 1000 g of WNS produced 295.1 g of fermentable sugars (263.6 g glucose and 31.5 g xylose).

Efficient separation of bagasse lignin by freeze-thaw-assisted p-toluenesulfonic acid pretreatment.

Lignin separation is an important procedure that benefits multiple industries and in particular biomass transformation efforts. In this study, bagasse lignin was separated by freeze-thaw-assisted p-toluenesulfonic acid (p-TsOH) pretreatment. The optimal conditions were freezing temperature -60 °C, freezing time 8.0 h, thawing temperature 15 °C, p-TsOH concentration 60%, pretreatment temperature 70 °C, and time 20 min. Lower acid concentrations and temperatures were used compared with traditional p-TsOH pretreatment. The efficiency and selectivity of lignin separation were improved. It was attributed to freeze-thawing, which provided a more efficient physical channel for the effective penetration of p-TsOH. The separation, extraction and purity of lignin were improved to 89.76%, 78.22% and 77.89%, respectively. High separation, high extraction, high purity and large molecular weight lignin samples were obtained. In addition, the recovery and reuse of p-TsOH was enhanced. This provided a new method for the efficient and clean separation of lignin.

Simultaneous chirality separation of amino acids and their derivative by natamycin based on mobility measurements.

The separation of chiral amino acids (AAs) and their derivatives has always been a research difficulty in the field of biochemistry due to the high similarity of enantiomeric structures. In this work, a simple and quick method using natamycin (Nat) as chiral selector has been developed to simultaneously separate chiral AAs and their derivatives of carbobenzoxy/benzyl-AAs (Cbz/Bzl-AAs) by trapped ion mobility spectrometry-mass spectrometry (TIMS-MS). Specifically, 12 groups of the Cbz-AAs and Bzl-AAs can get baseline mobility separation by simple mixing with Nat to form binary diastereomeric complex ions [Nat+(Cbz-D/L-AA)+H]+ and [Nat+(Bzl-D/L-AA)+H]+. While for the remained 5 groups of Bzl-D/L-AAs and 16 groups of D/L-AAs with unsatisfying separation, by further adding P-toluenesulfonic acid (PTS), the formed ternary complexes can allow their baseline chiral separation. Specifically, Bzl-D-AAs and Bzl-L-AAs get much improved separation effect by the formed diastereomeric complexes of [Nat+(Bzl-AA)2+PTS2+H]+, which the Rp-p was improved from 0 to 2.40; while the D/L-AAs can get baseline separation by the formed diastereomeric complexes of [Nat + AA + PTS + H]+, [Nat + AA+(PTS)2+H]+, and [Nat+(AA)2+(PTS)2+H]+, with the Rp-p ranged from 0.44 to 3.53. Definitely, PTS is the first time reported as the ligand to improve the separation effect for the enantiomers, and with the higher assembly of chiral analyte, Nat, and PTS might enable better chiral separation for the chiral amino acid and their derivatives. Moreover, method validation of relative quantification and accuracy for the D/L-AA and their derivatives were measured in a mixture, yielding R2 greater than 0.99 and RSD% ≤ 2.68%. Overall, Nat and PTS as chiral selector and ligand can be widely used for chiral AAs and their derivatives mobility separation, and potentially for the separation of other AA-related chiral molecules.

Extraction of Noncondensed Lignin from Poplar Sawdusts with p-Toluenesulfonic Acid and Ethanol.

The traditional pretreatment leads to the recalcitration of C-C bonds during lignin fractionation, thus hindering their depolymerization into aromatic monomers. It is essential to develop an applicable approach to extract noncondensed lignin for its high-value applications. In this work, noncondensed lignins were extracted from poplar sawdust using recyclable p-toluenesulfonic acid for cleaving lignin-carbohydrate complex bonds effectively and ethanol as a stabilization reagent to inhibit lignin condensation. Lignin yield of 83.74% was recovered by 3 mol/L acid in ethanol at 85 °C for 5 h, and carbohydrates were well preserved (retaining 98.97% cellulose and 50.01% hemicelluloses). During lignin fractionation, the acid concentration and extraction time were the major drivers of condensation. Ethanol reacted with lignin at the α-position to prevent the formation of the condensed structure. The extracted lignin depolymerized over the Pd/C catalysts gave a yield of 50.35% of aromatic monomers, suggesting that the novel extraction process provided a promising way for noncondensed lignin production.