Base Catalyst Research Articles

Effect of montmorillonite K-10 catalyst on the synthesis of (E)-1-phenyl-3-(2-methoxyphenyl)-2-propen-1-one using the microwave irradiation method

Background: A research investigation was conducted to examine how the utilisation of the montmorillonite K-10 catalyst impacts the production of (E)-1-phenyl-3-(2-methoxyphenyl)-2-propen-1-one (PMPP) using the microwave irradiation method since the conventional method has not been successful. Objective: The aim of this research was to investigate the impact of employing the montmorillonite K-10 catalyst in the synthesis of PMPP using the microwave irradiation method. Method: The compound was created using the Claisen-Schmidt condensation technique through a nucleophilic addition reaction. Results: The result of the synthesis was a yellowish powder. The percentage of synthesis of PMPP using the microwave irradiation method was 4.98%, with a melting point of 53-54oC. The synthesised compounds were identified by UV-Vis, Infrared and H-NMR spectroscopy. Conclusion: Synthesis of PMPP with montmorillonite K-10 catalyst can be carried out using microwave irradiation. The synthesis using the montmorillonite K-10 catalyst gave a relatively small yield of (E)-1-phenyl-3-(2-methoxyphenyl)-2-propen-1-one compared to a strong base catalyst.

High performance of a base catalyst from Moringa leaves ash for biodiesel conversion of low-grade Bali Malapari oil

High performance of a base catalyst from Moringa leaves ash for biodiesel conversion of low-grade Bali Malapari oil

Preparation of Co/SiC catalyst and its catalytic activity for ammonia decomposition to produce hydrogen

SiC was first synthesized using the sol-gel method and subsequent carbothermal reduction method, then xCo/SiC-700 and 30%Co/SiC-T catalysts were prepared by hydrothermal method and thermal treatment. The structure of the catalysts was characterized by XRD, SEM/TEM, XPS, H2-TPR, CO2-TPD, etc. Their catalytic activities for ammonia decomposition to produce hydrogen were investigated in a fixed-bed reactor. The results showed that the synthesized SiC had a high specific surface area and could evenly disperse Co3O4 nanoparticles, which increased the exposure of active sites and improved the adsorption capacity on the catalyst surface. N2-TPD indicates that 30%Co/SiC-700 has a high N2 adsorption capacity, effectively preventing hydrogen reduction of Co3O4 nanoparticles in the catalyst during ammonia decomposition. CO-TPD shows that Co has the best dispersion on 30%Co/SiC-700 catalyst. CO2-TPD shows the higher the catalyst's basicity, the stronger ammonia's decomposition ability. Among the synthesized catalysts, 30% Co/SiC-700 showed the best catalytic activity for ammonia decomposition, with the ammonia conversion of 78.3% and hydrogen production of 25.0 mmol H2 gcat−1 min−1 at 550 °C under 30,000 mL gcat−1 h−1.

Innovative Application of Polyether Amine as a Recyclable Catalyst in Aerobic Thiophenol Oxidation

Polyether amines are versatile compounds characterized by a flexible structure, consisting of polyoxypropylene and polyoxyethylene as the backbone, with amine groups at each end. They have widespread applications in various industrial processes and daily life. Despite their versatility, the utilization of polyether amines as base catalysts is rare. In this study, one kind of three-arm polyether amine 1 was employed as an environmentally friendly, cost-effective catalyst for the aerobic oxidation of thiophenols, leading to the synthesis of disulfides. The oxidative coupling of thiols serves as a fundamental pathway for the production of disulfides, which are vital in both chemical and biological processes. In contrast to known methods for thiol oxidation, this polyether amine-based catalytic process eliminates the need for expensive stoichiometric oxidants and minimizes the formation of over-oxidized by-products. Using a mere 0.5 mol % of the polyether amine 1 as the catalyst, a remarkable > 96% yield was achieved for all 16 tested substrates, encompassing a diverse range of functional groups, under the catalytic aerobic oxidation conditions. Furthermore, it is noteworthy that over 90% of the polyether amine catalyst can be efficiently recovered for reuse without loss of activity, making this a sustainable and cost-effective catalytic approach.

Custard apple seed oil-based polyesteramide polyol- a precursor for layered double hydroxide (LDH)-modified polyurethane coatings

Polyesteramide polyol was synthesized by employing aminolysis with a base catalyst with custard apple seed oil as source material. It was afterward esterified with phthalic anhydride to form polyesteramide polyol. Polyurethane coatings are produced by combining polyesteramide polyols, which are synthesized, with hexamethylene diisocyanate trimer (HDI). The co-precipitation technique was used to synthesize a nickel-aluminum layered double hydroxide (Ni-Al LDH). Subsequently, the synthesized Ni-Al LDH was further modified by incorporating the corrosion inhibitor 2-mercaptobenzothiazole (MBT) into its interlayer space by the in-situ method. The synthesized Ni-Al LDH and Ni-Al-MBT LDH are then incorporated into the polyesteramide polyol to enhance the anti-corrosive properties of the polyurethane coatings. The synthesized diethanolamide, polyesteramide polyol, and LDH have been characterized using FTIR whereas SEM and XRD are specific to LDH analysis. EIS, DSC, TGA, salt spray, contact angle, and mechanical testing such as thickness, adhesion flexibility, scratch hardness, impact resistance, and pencil hardness are focused on coating evaluation. The incorporation of LDH led to a substantial enhancement in the coating's corrosion resistance, as evidenced by a decrease in corrosion. Incorporating LDH and MBT-LDH improved the scratch resistance of the coating by 1.5 kg compared to plain PU coating, whereas hardness properties also improved slightly. In anticorrosive analysis, it is observed that LDH and MBT-LDH show better anticorrosive performance as compared to plain PU coating.

Triton B Catalyzed Rapid and Mild Synthetic Protocol for both Henry Reaction of Isatin and Michael Reaction of Chalcone with Nitroalkane

AbstractA highly efficient and general synthetic protocol for both Henry and Michael reactions was developed using metal-free catalyst Triton B (benzyltrimethylammonium hydroxide) and isatins and chalcones, respectively. This methodology is inexpensive, the reagents are easy to handle, and the approach offers wide functional group tolerance of isatins and chalcones. The base catalyst Triton B is less toxic, recyclable, and reusable. This efficient method reduces reaction times, minimizes reagent excess, avoids chromatography, and is aligned with sustainable chemistry principles, offering eco-friendly applications in diverse industries.

Synthesis and characterization of new heterocycles containing the 1,2,3-triazole ring system

The unexpected (E)-1,4-bis(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)but‑2-ene-1,4‑dione was produced in 89 % yield from the reaction of 2‑bromo-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one and sodium benzenesulfinate dihydrate in boiling ethanol. The reaction of the synthesized symmetrical 2-butene-1,4‑dione and 1,2-phenylenediamine in acetic acid afforded 2-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)-1H-benzo[d]imidazole in 68 % yield. 2,3-Dibromopropan-1-one was synthesized in 82 % from bromination of the corresponding chalcone under acidic conditions. Treatment of dibromoketone and benzylamine or phosphonic dihydrazide in ethanol in the presence of a basic catalyst unexpectedly afforded 2‑bromo-3-ethoxyketone in reasonable yield. The reactivity of hydrazonoyl chloride towards 5-methyl- and 5‑chloro-1,2,3-triazol-4-carbohydrazides was also investigated to afford the corresponding bis-hydrazone and the unanticipated tris-hydrazone.

Fine-Tuning Electron-Donor Capability in the Basic Anion of Poly(ionic liquid) Frameworks for Revolutionizing Catalytic Synthesis of Ethyl Methyl Carbonate with Both Ultrahigh Catalytic Activity and Selectivity.

Ethyl methyl carbonate (EMC) is a crucial solvent extensively utilized in lithium-ion battery electrolytes; the transesterification of dimethyl carbonate (DMC) with ethanol is a pivotal reaction for EMC production. However, this reaction faces challenges due to the trade-off between catalytic activity and selectivity from the basic catalysts. In this issue, we report an innovative strategy through fine-tuning the electron-donor capability of the basic phenolate anion ([PhO]) in a novel poly(ionic liquid) (PIL) framework, as synthesized via an alkylation reaction between 1,3,5-tris(bromomethyl)benzene, biphenyldiimidazole, and N,N'-carbonyldiimidazole (CDI) to trigger targeted basicity that can directionally catalyze the transesterification of DMC with ethanol, so as to achieve both ultrahigh catalytic activity and selectivity toward EMC. By varying the substituent groups with electron-withdrawing and electron-donating effects on the phenolate anion, the PILs show expected changes in the catalytic performance, following well with the trend of charge density on these substituted phenolate anions. The optimized catalyst [CPIL-CDI][MeOPhO], induced by p-methoxyphenolate anions, allows an extraordinary EMC yield of 72.19% and an EMC selectivity of 91.48% under mild conditions without any process intensifications, suppressing all of the reported catalysts reported to date. Outcomes and approaches shown in this work have the potential to expedite the systematic design of cations and anions within PILs for industrial-scale EMC production through environmentally friendly transesterification processes.

Efficient isomerization of glucose into fructose by MgO-doped lignin-derived ordered mesoporous carbon

The conversion of glucose into fructose can transform cellulose into high-value chemicals. This study introduces an innovative synthesis method for creating an MgO-based ordered mesoporous carbon (MgO@OMC) catalyst, aimed at the efficient isomerization of glucose into fructose. Throughout the synthesis process, lignin serves as the exclusive carbon precursor, while Mg2+ functions as both a crosslinking agent and a metallic active center. This enables a one-step synthesis of MgO@OMC via a solvent-induced evaporation self-assembly (EISA) method. The synthesized MgO@OMCs exhibit an impeccable 2D hexagonal ordered mesoporous structure, in addition to a substantial specific surface area (378.2 m2/g) and small MgO nanoparticles (1.52 nm). Furthermore, this catalyst was shown active, selective, and reusable in the isomerization of glucose to fructose. It yields 41 % fructose with a selectivity of up to 89.3 % at a significant glucose loading of 7 wt% in aqueous solution over MgO0.5@OMC-600. This performance closely rivals the current maximum glucose isomerization yield achieved with solid base catalysts. Additionally, the catalyst retains a fructose selectivity above 60 % even after 4 cycles, a feature attributable to its extended ordered mesoporous structure and the spatial confinement effect of the OMCs, bestowing it with high catalytic efficiency.

Highly Efficient and Reproducible Sonochemical Synthesis of ZnO Nanocrystals.

Sonochemical synthesis can be a facile, fast, efficient, versatile and economical way to prepare a large variety of conventional or novel nanostructured materials (metallic, magnetic, semiconducting, polymeric, etc.). In this work, zinc oxide nanocrystals were synthesized by irradiating and heating at 90 °C in a commercial ultrasonic bath a water solution of zinc nitrate hexahydrate and ammonia solution or hexamethylenetetramine as base catalysts. The evolution of the powder morphology and its crystalline structure were investigated at different times of ultrasonic irradiation (0-9 hours) and compared with those of samples obtained by only heating the solutions in a muffle furnace in order to enlighten the growth mechanism. It resulted that: i) the crystal morphology depends on the selected base, ii) for samples obtained by using ultrasounds, the homogeneity of the powders depends on the irradiation time, iii) by comparing all samples obtained at 7 hours of heating, the aspect ratio of the crystals is higher for those that also underwent to ultrasounds.

One-pot catalytic conversion of sugars to methyl lactate over acid-base bifunctional Sn/MgO catalysts

Alkyl lactates represent such green added-value chemicals that commonly used as biodegradable green solvents, detergents, pharmaceutical intermediates et al. Catalytic conversion of carbohydrates to methyl lactate (MLA) is a representative way for high-value utilization of biomass and the key lies in the development of highly efficient catalysts. In methanol, strong acid or alkaline catalysts are usually used under high temperature and high pressure, suffering from problems such as low selectivity, high cost or contamination of environment. This study aims to develop an acid-base bifunctional heterogeneous catalyst for the one-pot conversion of sugars to MLA under mild conditions. Sn/Mg composite oxides was synthesized by a coprecipitation method and further modified by poly (vinyl imidazole) ([PVIM]) to tune the hydrophilicity. Effect of polymer and Sn amount, calcination temperature, reaction temperature, catalyst dosage, and substrate concentration were investigated. The acid-base properties were characterized by NH3-TPD, pyridine-FTIR and CO2-TPD analysis. It was found that the presence of medium acid sites and medium base sites played an important role to the cascade reactions of carbohydrates to MLA. An optimum MLA yield of 55.4% was achieved over 10[PVIM]-5Sn/MgO (0.05 g) with complete conversion of glucose (28 mM) at 140 ℃, 2 MPa N2 for 10 h. The reaction conditions are mild and no strong acid or strong base catalyst is required. Furthermore, a possible reaction mechanism was proposed that the introduction of [PVIM] effectively regulated the local microenvironment of active sites and the acid base synergism greatly promoted the retro-aldol condensation, dehydration and hydrogen transfer reactions during the conversion of glucose to MLA.

Multiscale calculations reveal new insights into the reaction mechanism between KRASG12C and α, β-unsaturated carbonyl of covalent inhibitors

Utilizing α,β-unsaturated carbonyl group as Michael acceptors to react with thiols represents a successful strategy for developing KRASG12C inhibitors. Despite this, the precise reaction mechanism between KRASG12C and covalent inhibitors remains a subject of debate, primarily due to the absence of an appropriate residue capable of deprotonating the cysteine thiol as a base. To uncover this reaction mechanism, we first discussed the chemical reaction mechanism in solvent conditions via density functional theory (DFT) calculation. Based on this, we then proposed and validated the enzymatic reaction mechanism by employing quantum mechanics/molecular mechanics (QM/MM) calculation. Our QM/MM analysis suggests that, in biological conditions, proton transfer and nucleophilic addition may proceed through a concerted process to form an enolate intermediate, bypassing the need for a base catalyst. This proposed mechanism differs from previous findings. Following the formation of the enolate intermediate, solvent-assisted tautomerization results in the final product. Our calculations indicate that solvent-assisted tautomerization is the rate-limiting step in the catalytic cycle under biological conditions. On the basis of this reaction mechanism, the calculated kinact/ki for two inhibitors is consistent well with the experimental results. Our findings provide new insights into the reaction mechanism between the cysteine of KRASG12C and the covalent inhibitors and may provide valuable information for designing effective covalent inhibitors targeting KRASG12C and other similar targets.

Preparation and Characterization of Magnetic Material/Chitosan Composite Modified with Glycidyl-Trimethylammonium Chloride

Glycidyl-trimethylammonium chloride (GTMAC) containing quaternary ammonium (QA) groups is commonly used as a base catalyst for any organic reaction. This research prepared a novel composite of GTMAC attached to chitosan-coated magnetic material (MM/Chi/GTMAC) using a precipitation method. The effect of chitosan and GTMAC contents on MM/chi/GTMAC properties was studied, where the chitosan content varied from 0, 0.3, 0.5, 1.0, and 3.0 mol, and GTMAC varied from 0, 0.3, 0.8, 1.0, 1.5, and 3 mL with the constant mass of MM (0.4640 g). The physicochemical and morphological properties were characterized with FTIR, SEM-EDX, XRD, TGA, UV-vis, AAS, and zeta-sizer, and the magnetic strength was simply tested with an external magnet. The result showed that a mixture containing chitosan and GTMAC of 0.358 g and 1.5 mL was an optimum composition, in which MM/chi(0.5)/GTMAC(1.5) has high thermal stability, low chitosan and Fe solubility, and optimum content of QA (0.284 mol/g) without loss of magnetic strength. The higher the amount of chitosan, the lower the magnetic properties, and the higher the GTMAC did not increase the QA content. Therefore, the composite produced has the potential to be a novel heterogeneous base catalyst that is quickly recovered from any organic reaction media.

Preparation of nickel aluminate supported Ni nanocatalyst and its catalytic activity for ammonia decomposition to produce hydrogen

In this work, nickel aluminate (NiAl2O4) was synthesized through the co-precipitation, and then the Ni/NiAl2O4 catalysts were prepared by impregnation and the catalytic activity of the catalyst was evaluated. The results indicated that the synthesized NiAl2O4 had a large specific surface area, promoting the dispersion of Ni species and thus exposing more active sites. The strong metal-support interaction between Ni species and NiAl2O4 contributed significantly to the catalysts' high catalytic activity. Meanwhile, the strong basicity of catalyst could adjust the bond energy of Ni–N, which were conducive to desorption of the recombinant N2 from the metal surface. The Ni/NiAl2O4 catalyst with Ni loading of 50 wt% and calcination temperature of 700 oC exhibited the best catalytic activity with ammonia conversion of 95.3% at 550 oC under 30000 mL∙gcat-1∙h-1. This study offers a potential approach to developing a cost-effective and highly efficient catalyst for decomposing ammonia.

Liquid Hot Water (LHW) and Hydrothermal Carbonization (HTC) of Coffee Berry Waste: Kinetics, Catalysis, and Optimization for the Synthesis of Platform Chemicals

Colombia is the world’s leading producer of mildly washed arabica coffee and produces 12.6 million bags of green coffee, but at the same time, 784,000 tons of waste biomass are dumped in open fields, of which only 5% is recovered or used. The objective of this project was to evaluate the production of platform chemicals from these coffee wastes for sustainable resource management. To achieve this, biomass characterization was carried out using proximate analysis, ultimate analysis, and structural analysis. Hydrothermal valorization was carried out at a temperature range of 120–180 °C (LHW) and 180–260 °C (HTC) for one hour. The platform chemicals obtained were quantified by HPLC-RI and monitored by pH and conductivity, and the solid fraction was characterized by monitoring the functional groups in IR spectroscopy and elemental analysis. Hydrolysis processes were obtained at 150 °C, production of platform chemicals at 180 °C, and maximum concentration at 180 °C-4 h; over 200 °C, degradation of the products in the liquid fraction starts to take place. Homogeneous basic and acid catalysts were used to improve the yields of the reaction. The kinetics of the hydrolysis of lignocellulosic structures to sugars were also analyzed and described, and reaction orders of 1 (LHW), 3 (HTC), and their respective reaction rate equations were reported.

Synthesis of HNTs-Ca/Zn catalyst for biodiesel production from acidulated palm oil: Optimized by GA-BP

The development of heterogeneous base catalyst with acid resistance has become a major topic in the current research on the biodiesel production process. Halloysite nanotubes (HNTs) is supported with bimetallic of calcium and zinc for modification and labeled as HNTs-Ca/Zn to show both the acid and base characteristics. Further, this supported catalyst is used to produce biodiesel from the acidulated palm oil through catalyzing transesterification in one-step in this study. The HNTs-Ca/Zn catalyst, synthesized by the impregnation method, is characterized by TG-DTG, XRD, XPS, TEM, SEM-EDX, nitrogen adsorption-desorption, CO2/NH3-TPD, FTIR and Raman. The capability of the HNTs-Ca/Zn catalyst in catalyzing transesterification is investigated, where the maximum yield of 95.22% is achieved with the molar ratio of Zn to Ca of 1.5. The advantage of HNTs-Ca/Zn1.5 catalyst is prominent when the transesterification source oil is acidulated, where the biodiesel yield of 92.66% is obtained even at the acid value of 26.02 mg KOH g−1. Besides, reusability of the catalyst is acceptable, where the yield of 77.91% is maintained after the fourth reused cycle. Further, the Genetic Algorithm-Back Propagation (GA-BP) neural network is used to train and predict the transesterification parameters of the reaction temperature, catalyst amount and methanol to oil molar ratio. The prediction of the biodiesel yield is reasonable. At the predicted reaction parameters of 158 °C, catalyst amount of 7.1 wt.% and methanol to oil molar ratio of 15.5, the predicted biodiesel yield is 98.71%, where the experimental verification value is 98.60%. Therefore, the HNTs-Ca/Zn catalyst is considered to demonstrate exceptional catalytic performance and recyclability, offering the potential for biodiesel production.

Synthesis and Characterization of K2O/ACT Catalyst for Biodiesel Production from Beef Fat Waste

The increasing use of petroleum as fuel has depleted fuel, so alternative fuels such as biodiesel are needed because they are environmentally friendly and come from vegetable and animal sources. Therefore, this article presents biodiesel production from beef fat using a K2O/ACT heterogeneous base catalyst derived from egg shells. The Eggshell becomes a CaO catalyst after 3 hours of calcination at 900°C. The K2O/ACT catalyst was synthesized by impregnating CaO with KOH and characterized using XRD and BET. The K2O/ACT catalyst was compared to the CaO catalyst for transesterification activity under appropriate conditions (reaction temperature 65°C, catalyst loading 3% by weight, oil to methanol molar ratio 1:12, and reaction time 3 hours). The catalytic activity of the catalyst was determined to be 98.40% Fatty Acid Methyl Ester (FAME). The insertion of K2O into the CaO catalyst increases the basicity characteristics, thereby increasing the catalytic activity of transesterification.

Catalytic Cleavage of the 9-Fluorenylmethoxycarbonyl (Fmoc) Protecting Group under Neat Conditions.

This work reports the first solvent-free catalytic approach for the cleavage of the fluorenylmethoxycarbonyl (Fmoc) protecting group from amine and alcohol functionalities. Various saccharide, peptide, and glyco-amino acid substrates were efficiently deprotected by simple treatment with 20 mol % neat 4-dimethylaminopyridine (DMAP) (one of the effective base catalysts found), without any solvent or stoichiometric additives. Small model structures were finally assembled through one-pot, base-catalyzed, solvent-free multistep sequences combining the Fmoc cleavage with esterification, amidation, and/or glycosylation steps.

Catalytic dehydrogenation cracking characteristics of vacuum residue over solid basic catalyst

The basic calcium aluminate with appropriate catalytic cracking activity, excellent anti-coking performance, and hydrothermal stability is of great potential for the utilization of heavy oil. However, there is a lack of systematic research on the catalytic dehydrogenation cracking characteristics of vacuum residue (VR) over solid basic catalyst. Thus, by combining the TG and Py-GC/MS methods, the dehydrogenation cracking behavior of S-VR was investigated. The results indicated that S-VR cracking on calcium aluminate leads to less coking and higher olefin content in liquid products compared with FCC catalyst and quartz sand. Then, the activation energy Ea is computed from the catalytic dehydrogenation cracking of S-VR on calcium aluminate. The results show that the Ea values from Friedman and OFW methods range from 68 to 143 kJ∙mol−1 and 114 to 192 kJ∙mol−1, respectively. After that, the molecular-level carbon number distributions of the products obtained from cracking S-VR on different reaction conditions are investigated, and the optimal reaction temperature and the heating rate are 650 °C and 1000 °C/s, respectively. Finally, the free radical regulation theory was constructed to explain the catalytic dehydrogenation cracking mechanism of basic calcium aluminate catalyst.

Enantioselective Syntheses of 3,4-Dihydropyrans Employing Isochalcogenourea-Catalyzed Formal (4+2)-Cycloadditions of Allenoates.

We herein successfully demonstrate the use of chiral isochalcogenoureas as Lewis Base catalysts for a variety of (4+2)-cycloaddition reactions of allenoates and different Michael acceptors. In all cases the same structural key-motive, a dihydropyran with a (Z)-configurated exocyclic double bond could be accessed as the major regio- and diastereoisomer in an enantioselective manner. Furthermore, these chiral dihydropyrans were successfully engaged in different follow-up transformations.