P-toluenesulfonic Acid Research Articles

Synthesis of chlorophyll–thiophene conjugates through Friedel–Crafts reaction

Friedel–Crafts reactions of a chlorophyll-a derivative possessing a hydroxymethyl group at the 3-position with (benzo)thiophenes in the presence of p-toluenesulfonic acid gave 3-(benzo)thienylmethyl-chlorins regioselectively. The α-position of unsubstituted thiophene was more reactive toward the acid-assisted dehydration reaction than the β-position. Electron-donating substituents at the β-position in thiophene were acceptable for the production of the α-adducts, but electron-withdrawing substitution on the thiophene core proved ineffective. The electron-rich α,α′-dimethylthiophene could not be substituted at the β-position with the (chlorin-3-yl)methyl group. The reaction with benzothiophene exclusively afforded the β-substituted adduct. The reverse regioselectivity was consistent with the conventional electrophilic substitutions of (benzo)thiophenes. Under the aforementioned Friedel–Crafts reaction conditions, the α-methylation of benzothiophene led to the β-adduct as expected, whereas its β-methylation resulted in the successful preparation of the α-adduct. The fusion of a benzo moiety on thiophene largely affected the reactivity and regioselectivity toward the production of the chlorophyll–thiophene conjugates.

Small Molecule π-π Stacking Promotes Efficient Photoelectrocatalytic Splitting of Aqueous Hydrogen Production from Polyaniline.

Photoelectrocatalysis efficiency depends on light absorption and the effective use of photogenerated carriers but is often limited by inefficient charge transfer and catalytic surface reactivity. In this study, π-π stacking of polar small molecules on aromatic ring-rich polyaniline (PANI) was carried out to improve its photoelectrocatalytic splitting of water for hydrogen production. Detailed photoelectrochemical experiments and density-functional theory (DFT) calculations show that small molecules of p-aminobenzoic acid (PABA) and PANI have the best π-π stacking (compared to p-toluenesulfonic acid (PTA)), which promotes the separation of carriers on the PANI surface. In addition, the polar effect of the small molecules also improves the reactivity of the PANI surface and also reduces the potential barrier for H2 evolution. The current density of PANI-PABA reached -0.12 mA/cm2 (1.23 V vs. RHE) 2.53 times higher than that of pure PANI in linear voltammetric scanning tests under light. This strategy of introducing polar small molecules into organocatalysts via π-π stacking will provide new ideas for the preparation of efficient organic photoelectrocatalysis.

Implementing efficient and sustainable pretreatment of Sorghum stalks for delignification and xylan separation with a ternary deep eutectic solvent under mild conditions.

Acidic deep eutectic solvent (DES) has garnered significant attention in biomass pretreatment due to its effectiveness. Octadecyl trimethyl ammonium chloride (OTAC) is a highly efficient surfactant, which is expected to create new DES with additional pretreatment functions. Accordingly, a new ternary deep eutectic solvent (TDES) was synthesized from OTAC, propionic acid (PA), and p-toluene sulfonic acid (p-TsOH) for pretreating sorghum stalk under the relatively mild condition to enhance enzymatic saccharification of sorghum stalks. Through the treatment with OTAC:PA:p-TsOH (1:2:0.1) at 80 °C for 30 min, 71.1 % of lignin was removed and 75.7 % of xylan was separated, and the enzymolysis efficiency of sorghum stalks was increased to 69.3 %. The accessibility of sorghum stalk to cellulose was increased to 414.3 mg dye/g cellulose while the surface area of lignin decreased to 517 m2/g. Along with the altered cellulose crystal structure and surface properties, the pretreatment mechanism for improving enzymatic hydrolysis capacity was proposed. Overall, this research implemented an efficient pretreatment using TDES OTAC:PA:p-TsOH for the valorization of sorghum stalk, providing a novel approach for the depolymerization and value-added utilization of lignocellulosic biomass in biorefining technology.

An integrated strategy for corncob pretreatment and coproduction of furfural and monosaccharides based on p-toluenesulfonic acid and deep eutectic solvent system

An integrated strategy for corncob pretreatment and coproduction of furfural and monosaccharides based on p-toluenesulfonic acid and deep eutectic solvent system

Valorization of wheat straw through enhancement of cellulose accessibility, xylan elimination and lignin removal by choline chloride:p-toluenesulfonic acid pretreatment.

Different molar ratio of choline chloride (ChCl) and p-toluenesulfonic acid (p-TsOH) (2: 1, 1: 1 and 1: 2, mol: mol) were used to prepare deep eutectic solvents (ChCl: p-TsOH) for pretreating cellulose fibers to elevate cellulose accessibility, enhance xylan elimination, increase lignin removal and promote enzymatic digestion. ChCl: p-TsOH (1: 1, mol: mol) could effectually destroy the dense layout of wheat straw (WS) at 80 °C for 60 min. Cellulose crystallinity declined from 43.4 % to 25.5 %, and the lignin surface area and hydrophobicity were reduced to 182.6 m2/g and 3.2 L/g, respectively. While cellulose accessibility in WS was significantly improved to 523.9 mg/g. The delignification and xylan removal reached 72.4 % and 90.5 %, respectively. The enzymatic digestibility reached 89.3 %. Furthermore, molecular dynamics simulation and quantum chemistry calculation were conducted on the lignocellulose model. The van der Waals interaction between ChCl:p-TsOH and lignin and the dispersion interaction between ChCl and lignin were identified. Accordingly, the interaction between biomass and ChCl:p-TsOH was elucidated at the molecular level. It provides a comprehensive understanding of lignocellulosic biomass valorization through the highly efficient pretreatment by ChCl:p-TsOH.

The effect of toluene sulfonic acid remimazolam on postoperative delirium in elderly patients undergoing painless bronchoscopy

Toluene sulfonic acid remimazolam is a novel benzodiazepine that differs from traditional benzodiazepines (BZDs) due to its rapid onset, swift metabolism, and lack of hepatic or renal metabolism, as well as its reduced effects on cardiac and cerebral functions. Despite its potential advantages, clinical experience with this agent remains limited. This study investigated the effect of remizolam on postoperative delirium in elderly patients undergoing painless bronchoscopy. Among elderly patients undergoing routine painless bronchoscopy examinations, 50 cases were included in the remimazolam group, while the other 50 cases were selected as the propofol group. The primary outcome measured was the incidence of delirium on the first, second, third, fifth, and seventh postoperative days. The secondary outcome was the occurrence of adverse events, including hypotension, hypoxia, physical activity, agitation during recovery, dizziness, and nausea/vomiting during the procedure.This study confirmed that no cases of delirium in the remimazolam group, which also demonstrated a significantly lower incidence of adverse events compared to the propofol group (20% vs. 50%, P < 0.05). The results indicated remimazolam provides effective sedation with minimal adverse reactions and is associated with a lack of complications such as postoperative delirium in elderly patients undergoing painless bronchoscopy.

Achieving High Solid-Liquid Ratio through Competitive Coordination towards Efficient Recovery of Metals from Spent Batteries.

The recycling of critical metals from spent lithium-ion batteries represents a significant step towards meeting the enhancing resource requirements in the new energy industry. Nevertheless, achieving effective leaching of metals from the stable metal-oxygen (MO6) structure of spent ternary cathodes and separation of metal products simultaneously still remained a huge challenge towards industrial applications. Herein, a competitive coordination strategy was proposed to design a novel deep eutectic solvent (DESs), which improved both leaching and selective metal recycling capacity even at high solid-liquid ratio (1:10). The results demonstrated that the number of hydrogen bonds in designed ternary DESs was 16.5% higher compared to those in the binary DESs, resulting in efficient reaction kinetics to break the metals-oxygen bond. More importantly, the competing-ligand (p-toluenesulfonic acid) could preferentially enter into the first nanostructure sheath and reduce the proportion of solvated oxalic acid (OxA) from 28.36% to 17.76% within the nanostructure, which enable OxA molecules to enhance the coordination interaction with metal for precipitating NiC2O4·2H2O product (~ 95.7% purity) from spent cathodes. This work achieved impressive profitability ($16.05 per kg feedstock) and effectively reduction of GHG emissions during the recycling process, making it applicable to critical sustainability initiatives.

Synthesis of Hollowed Polyoxometalate with a Flipped VO5 Unit by the Elimination of a Centered Organic Molecule.

Mechanistic understanding of the formation of clusters plays a role in designing the structure-dependent properties. Based on the fact that anions act as templates to form spherical polyoxovanadates, various structures were reported by changing anions in the synthetic solution. In this work, another factor in the formation of spherical polyoxometalates was demonstrated. By the reaction of [V10O26]4- in acetonitrile with a reductant to increase the number of tetravalent V4+ and p-toluene sulfonic acid to convert tetrahedral VO4 units to square-pyramidal VO5, acetonitrile-containing polyoxovanadate [V24O60(CH3CN)]6- (ICH3CN) was synthesized. The bulky and hydrophobic aromatic rings prevented the formed anions from acting as a template. By changing the synthetic solvent, encapsulated moieties were controlled. Nitromethane was also encapsulated to afford [V24O60(CH3NO2)]6- (ICH3NO2). When acetone was used as the solvent, the contaminated water was encapsulated to form [V24O60(H2O)]6- (IH2O). The encapsulated acetonitrile molecule was eliminated by heating ICH3CN up to 230 °C under N2 flow conditions to give hollowed polyoxovanadate [V24O60]6- (II), even though ICH3CN possesses no pores for acetonitrile to pass. From the X-ray crystallographic analysis of II, one of the 24 VO5 units was flipped. The electrochemical properties and catalytic performances between ICH3CN and II were also investigated.

Influence of sulfonic acid doping during polypyrrole electrodeposition on the corrosion protection for AA2024-T3

The electrodeposition of polypyrrole on AA2024-T3 was prepared by applying a constant potential via three different dopants including sulfuric acid (SA), p-toluenesulfonic acid (pTSA), and 2-naphthalenesulfonic acid (2NS). The polypyrrole coating was characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The anti-corrosion behavior was examined by Tafel curves to find the optimized concentration and deposition time for each dopant. Polypyrrole was successfully electrodeposited on AA2024-T3 with pTSA and 2NS dopants, which exhibited better corrosion protection compared with bare AA2024-T3. In addition, a conventional coating was applied with spray paint considered as a topcoat to further investigate the protection efficiency of the polypyrrole. The 2NS-doped polypyrrole exhibited a good protection efficiency of 99.99%. The results demonstrated that the chemical structure of the dopant influences the corrosion protection where the corrosion potential has positively increased with the extended electrodeposition time. Topcoat with spray paint working as a surface barrier can protect the polypyrrole coating and enlarge the protection time.

The Effect of p-Toluenesulfonic Acid and Phosphoric Acid (V) Content on the Heat Resistance and Thermal Properties of Phenol Resin and Phenol-Carbon Composite.

This work presents the results of research on the influence of the amount of p-toluenesulfonic acid and phosphoric acid (V) added to the phenol-formaldehyde resin (pH 7.3-7.8) on its thermal properties and on the phenol-formaldehyde-carbon composite produced on its basis. This material undergoes pyrolysis under high temperature. The addition of a catalyst to the phenol-formaldehyde resin affects its curing rate and degree of cross-linking, but how it affects the thermal properties of the resin depending on the temperature is the subject of this work. This article presents the results of thermal tests for phenol-formaldehyde resin and phenol-formaldehyde-carbon composite. It was examined how the content of the catalyst used during the production process affects the individual thermal parameters of the mentioned materials. The results include experimental tests of thermal diffusivity with uncertainty (±3%), specific heat capacity (±2.5%), thermal expansion with resolution 2 nm analyzed in the temperature range -40-115 °C and thermogravimetric TG/DTA analysis with resolution 0.03 µg in the temperature range from room temperature (RT = 23 °C) to 550 °C. Individual thermal tests showed changes in the thermal properties caused by changes in the catalyst content of the tested materials and the influence of the addition of carbon fibers on the properties of the composite compared to the pure phenol-formaldehyde resin. It was found that there is a certain maximum level of catalyst weight fraction at which the greatest decrease in thermal diffusivity occurs. In the case of phenolic-formaldehyde-carbon composite at -40 °C, an increase in catalyst weight fraction from 2 to 4 wt% caused a decrease in thermal diffusivity by 18.2%, and for phenol-formaldehyde resin, it was 2.8% with an increase in catalyst fraction from 4 to 10 wt%.

Brønsted-Acid Catalyzed Diastereo- and Enantioselective Synthesis of Spiroisoindolinones from Enamides.

A highly stereoselective Brønsted-acid catalyzed synthesis of densely substituted spiroisoindolinones from enamides and 3-hydroxy-isoindolinones is described. With simple Brønsted-acids, such as para-toluene sulfonic acid, spiroisoindolinones with three contiguous stereogenic centers are formed in high yields (up to 97 %) and diastereoselectivities (up to >98 : <2 : 0 : 0 dr) under mild reaction conditions. With the use of a chiral phosphoric acid catalyst, a diastereo- and enantioselective synthesis of the corresponding spiroisoindolinones was achieved. Mechanistic investigations indicate a step-wise mechanism via an initial addition of the enamide to an electrophilic N-acylimine species followed by an intramolecular aza-Friedel-Crafts reaction. Addition of a strong Lewis acid can be used to facilitate the second step for less reactive substrates.

Production of dehydrated lignin-blending carboxylated nanocellulose with superior redispersion behavior and reinforcement effect for PVA nanocomposite films.

This study aims to explore the redispersibility of dehydrated nanocellulose with p-toluenesulfonic acid (p-TsOH) fractionated lignin as an eco-friendly and cost-effective capping agent, to cope with the challenge of irreversible agglomeration and thus loss of nanoscale of nanocellulose upon dehydration. The intermixing of nanocellulose and p-TsOH fractionated lignin was achieved using an aqueous ethanol solution as the medium and films of lignin-blending cellulose nanofibers (L+CNF) with excellent redispersing properties were obtained after facile air-drying. With 0.02% ammonia as the dispersing solution, the dehydrated L+CNF film was able to achieve nearly 100% redispersion yield after 30min of mechanical agitation. If necessary, lignin in redispersed L+CNF can be removed by simple ethanol washing and centrifugation. In addition, redispersed L+CNF can be hybridized with poly(vinyl alcohol) (PVA) in a simple process to prepare PVA nanocomposite films with excellent hydrophobic, thermally stable, antibacterial, and mechanical properties. This study provided a sustainable and cost-effective solution to the dehydration/redispersion challenges of nanocellulose.

Study on high efficiency separation of low condensation lignin and its dissolution mechanism by 1, 4 butanediol combined with p-toluene sulfonic acid pretreatment system

Study on high efficiency separation of low condensation lignin and its dissolution mechanism by 1, 4 butanediol combined with p-toluene sulfonic acid pretreatment system

Green extraction of natural indigoid from Baphicacanthus cusia (Nees) Bremek using hydrophilic and hydrophobic deep eutectic solvent technology

This study focused on the development of an alternative and more environmentally friendly extraction solvent, a deep eutectic system (DES), for extracting indigoid pigments, specifically indigo and indirubin, from Baphicacanthus cusia (BC). BC is recognized in the textile industry as a natural vat dye and in traditional Chinese medicine as "Qing-Dai". It is known for treating inflammatory diseases such as psoriasis. In this study, 46 DES systems were compared with conventional methods. The hydrophobic DES, a terpenoid and fatty acid system comprising thymol:decanoic acid (DES40), and the hydrophilic DES, a choline chloride-based system comprising choline chloride: p-toluenesulfonic acid (DES19), showed significant extraction improvements. DES40 and DES19 achieved approximately 26-fold higher indigo content compared to classical ethanol and outperformed the harsh organic solvent dichloromethane. The green extraction process was optimized using a Box–Behnken design, considering parameters such as temperature, time and co-solvent. DES19 maximized indigo and indirubin content to 270.91±14.38 and 5.70±0.11mg/g, respectively, while DES40 yielded 108.28 ± 3.9 and 0.16 ± 0.00mg/mg/g, respectively. Safety evaluations using a cell-based MTT model with human skin cells in keratinocytes and fibroblasts showed that both DES19 and DES40 were safe at all concentrations tested. These results indicate that a more environmentally friendly solvent technology for the extraction of indigoids from BC using the DES is an efficient and potential application in the textile and pharmaceutical industries.

Development of a New Salt of Piperine with Toluene Sulfonic Acid and Its Anti-Inflammation Effect In Vivo.

Piperine (PPN) is a natural compound with an anti-inflammation effect and low solubility. Hence, some molecular modifications have improved its solid-state character, including cocrystal formation. However, the salt structure has yet to be widely studied. In this research, PPN was reacted with toluene sulfonic acid (TSA), which was expected to increase its solubility and anti-inflammatory effects. This experiment used solid-state reactions and analysis, including thermal analysis, infrared spectroscopy, and powder X-ray diffractometry, to characterize the new multicomponent solid phase. Next, single crystal R-ray diffractometry was used to determine the final three-dimensional conformation structure. After that, the salt, which can be reproduced by wet grinding, was tested for improved stability and anti-inflammatory effects. As a result, the PPN-TSA multicomponent solid was confirmed as a solid salt with monoclinic packing, exhibiting better solubility and anti-inflammation effects. Thus, this new organic salt has the potential for further phytochemical compound development.

Facile fractionation of poplar by a novel ternary deep eutectic solvent (DES) for cellulosic ethanol production under mild pretreatment conditions

The efficient fractionation of lignocellulosic biomass using deep eutectic solvent (DES) is emerging as an innovative and eco-friendly approach. In this study, a novel ternary DES composed of triethylbenzyl ammonium chloride (TEBAC), p-toluene sulfonic acid (TsOH), and ethylene glycol (EG) was employed for the pretreatment of poplar wood to enhance cellulosic ethanol production. Key pretreatment parameters, including temperature, DES molar ratios, and reaction time, were systematically optimized. Under optimal conditions (90 ºC, 60 min, TEBAC/TsOH/EG ratio of 1:1.5:3) lignin removal reached 90.64±1.28 % and xylan removal achieved 85.56±1.34 %, significantly improving cellulose digestibility. The improvement might be attributed to the removal of hemicellulose and lignin, which exposed cellulose and enhanced the accessibility of cellulase to cellulose. Additionally, optimized enzymatic hydrolysis yielded a glucose concentration of 65.98±0.97 g/L using an enzyme loading of 15 FPU/g poplar and a solid loading of 13.33 %. Furthermore, during pre-hydrolysis combined with simultaneous saccharification and fermentation (PSSF), an ethanol concentration of 37.58±0.23 g/L was achieved. Overall, this study demonstrates a novel ternary DES pretreatment method that effectively facilitates the fractionation and conversion of woody biomass into cellulosic ethanol.

Steering Acid-Base Site Distribution and Hydrophobicity of Bioresourced Bifunctional Hybrid Materials for Direct Synthesis of γ-Valerolactone from Biomass-Based Furfural.

The direct production of value-added chemicals from biomass via multiple conversion processes with a sole renewable solid catalyst is promising for carbon-neutral development while challenging. Herein, a series of novel bioresourced organic-inorganic hybrid materials were synthesized from bio-based ascorbic acid (Vc), zirconium chloride (ZrCl4) and p-toluenesulfonic acid (p-TSA) through a facile solvothermal process. The as-prepared Zr-Vc-3 catalyst with Vc, ZrCl4, and p-TSA in the 1 : 1:0.5 molar ratio displayed outstanding performance in direct furfural-to-γ-valerolactone (GVL) transformation, giving an ultrahigh GVL yield of 76.2 %, with an ideal activation energy (55.46 kJ mol-1), outperforming state-of-the-art catalysts. The superior performance of Zr-Vc-3 could be ascribed to its good reusability, relatively large pore size, suitable amount of acid-base sites, and good hydrophobicity. Mechanistic studies unveiled that Lewis acid-base sites facilitate the conversion of furfural to furfuryl alcohol and isopropyl levulinate (IPL) to 4-hydroxypentanoate via transfer hydrogenation process, while Brønsted acid sites are instrumental in the ring-opening of furfuryl alcohol to IPL and the lactonization of 4-hydroxypentanoate to GVL, overall contributing to the multi-step conversion of furfural to GVL in a single pot. This work provides a valuable reference for precisely constructing bio-based OIHMs with tailored functionalities for the one-pot valorization of biomass feedstocks via tandem reactions.

Brønsted Acid-Catalyzed, Asymmetric Allenoate Claisen Reaction.

An auxiliary-based protocol is described for an asymmetric allenoate Claisen rearrangement. Silicated tosic acid (10 mol %) was used as an inexpensive, user-friendly catalyst. Stereochemical analysis revealed a preferential attack at the si face of prostereogenic olefin. The amine auxiliary was readily hydrolyzed and can be isolated from the reaction mixture (85-87% recovery). The resulting unsaturated β-keto esters were isolated in ≤99% yield and 98% ee. Diastereoselective examples provided a 96:4 syn:anti ratio of the resulting vicinal stereocenters.

Sustainable synthesis of Di-iso-octyl Maleate using 3-octanol extracted from Peppermint oil

Surfactants are vital in industries such as detergents, textiles, and cosmetics, and their synthesis from renewable or waste-derived feedstocks aligns with sustainability goals. This study explores the valorization of 3-octanol, a byproduct of peppermint oil extraction, into di-isooctyl maleate (DOM), a precursor to di-octyl sulphosuccinate (DOSS), a widely used surfactant. The synthesis of DOM was achieved via esterification of 3-octanol and maleic anhydride in the presence of para-toluene sulphonic acid (PTSA) as a catalyst. Reaction parameters, including catalyst concentration, reaction time, and temperature, were systematically optimized to maximize yield. The highest yield of 96.34% was obtained using 0.4 g of PTSA per 5 g of 3-octanol, with an optimal temperature of 80–85°C and a reaction time of 3 hours. Experimental data showed a decline in yield beyond this catalyst concentration and reaction duration, indicating the importance of precise parameter control. Alternate catalysts such as Amberlite and Indion 130 were tested. This study demonstrates a sustainable and scalable approach to converting waste-derived 3-octanol into value-added surfactants, providing an economically viable solution with minimal equipment and investment requirements.

Synthesis of Polyethylene Glycol Esters from Oleic, Stearic, and Palmitic Acids as a Pour Point Depressant (PPD)

Polyethylene glycol (PEG) ester is a non ionic surfactant compound that could use a pour point depressant (PPD) for crude oil. Synthesis of PEG-ester with reflux and mono wave-50 methods through esterification fatty acid such as oleic acid, stearic acid, and palmitic acid with adding p-toluene sulfonic acid (p-TSA) as a catalyst. The product of esterification could be a mixture of monoester and diester. Synthesized PEG ester by reflux method resulted in higher yield than by mono wave-50 method. IR spectra analysis of PEG400-oleate, PEG400-stearate, and PEG400-palmitate show the presence of an absorption band at a wavenumber of around 1100 cm-1 that indicates the stretching vibration of the C-O ester. (LC-MS/MS) analysis that shows the molecular weight of PEG400-oleate was 845.6154 g/mol and, PEG400-stearate was 785.5952 g/mol. Mean, while PEG400-palmitate produced three ester compounds with different molecular weights: 741.5669 g/mol, 685.5057 g/mol, and 734.5208 g/mol. The pour point measurement results show that the PEG-fatty acid product in the range of 0.1% to 1% has not been able to reduce the pour point of the crude oil sample. Keywords: Esterification, FTIR, LC-MS/MS, Surfactant