K10 Clay Research Articles

ChemInform Abstract: A Green Route for the Synthesis of 2‐Substituted Benzoxazole Derivatives Catalyzed by Al3+‐Exchanged K10 Clay.

AbstractA simple and efficient protocol using the title heterogeneous catalyst allows the synthesis of a wide range of benzoxazole and oxazolopyridine derivatives.

Synthesis of long alkyl chain ethers through etherification of ethylene glycol with 1-octene using heteropolyacid supported on K-10 clay

Transesterification of vegetable oil with lower alcohols leads to biodiesel formation which is accompanied by ∼10wt% glycerol as the co-product. Since biodiesel production is going on massive scale across the world, huge quantity of surplus glycerol will be available. Bioglycerol ought to be converted into valuable chemicals and fuels to enable biodiesel to be cost competitive with reference to petro-diesel. Depending on reaction conditions and catalysts, the hydrogenolysis/hydrogenation of glycerol can produce 1,2-propylene glycol, 1,3-propylene glycol, and ethylene glycol; all of which can be further converted into valuable chemicals. The objective of the current work was to convert ethylene glycol to value added etherified products by reaction with 1-octene to 2-(octan-2-yloxy) ethanol (C8 ether) and 1,2-bis(octan-2-yloxy) ethane (C16 ether). Several heterogeneous solid acid catalysts were used such as 20% (w/w) dodecatungstophosphoric acid (DTP) supported on K10 clay (DTP/K10), 20% (w/w) Cs2.5H0.5PW12O40/K10 (Cs-DTP/K10), 20% (w/w) DTP/ZrO2, and Amberlyst-35. Among them 20% (w/w) DTP/K10 was found to be the most efficient catalyst with 72% conversion of ethylene glycol and 80% of selectivity toward 2-(octan-2-yloxy) ethanol (C8 ether). The optimum reaction conditions were as follows: ethylene glycol to 1-octene mole ratio 1:3, catalyst loading 0.03g/cm3, temperature 140°C, pressure 1.5MPa, reaction time 5h. The effects of different process parameters such as speed of agitation, catalyst loading, mole ratio, temperature, and reusability of the catalyst were studied to examine the efficacy of 20% (w/w) DTP/K10. The process is solvent less, green and clean. Other substrates were also used to enhance the scope of this work.

One-pot synthesis of 2-substituted quinoxalines using K10-montmorillonite as heterogeneous catalyst

An efficient one-pot synthesis of 2-substituted quinoxalines from 1,2-diamines and phenacyl bromides is developed using K10-montmorillonite (K10 clay) as a catalyst at 50°C in acetonitrile medium. This method offers an easy route for the synthesis of substituted quinoxalines in high yields. A plausible mechanism is proposed in which quinoxalines are formed via dehydration–dehydrohalogenation–cyclization sequence. Further, the K10 clay catalyst is recovered by simple filtration and reused six times without any loss in its catalytic activity.

Synthesis, Quantum Chemical Calculations and Properties of Nonionic and Nonionic–Anionic Surfactants Based on Fatty Alkyl Succinate

AbstractTwo surfactants based on maleic anhydride were synthesized by esterification with fatty alcohols C10, C12 and C14 to produce half esters [I–III]. Nonionic surfactant monoesters [I–III]a–c synthesized by ethoxylation of [I–III] with different moles of ethylene oxide [6, 8 and 10] in the presence of K10 clay as an untraditionally catalyst. The later products were sulfonated to produce nonionic–anionic surfactants [IV–VI]a–c. The structures of synthesized surfactant were elucidated by FTIR and 1H‐NMR data. Their surface activity and biodegradability were determined. All the synthesized surfactants showed good surface activity and biodegradability, but anionic‐nonionic type has better effect than nonionic one. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the highest occupied molecular orbital–lowest unoccupied molecular orbital, ionization potential energy and ESP mapping of these compounds. Also, the absorption, distribution, metabolism, elimination and toxic properties were studied to gain a clear view of the oral bioavailability of these compounds.

ChemInform Abstract: Multicomponent Reactions Leading to Symmetric and Asymmetric Multi‐Substituted 1,4‐Dihydropyridines on Montmorillonite.

AbstractThe use of montmorillonite K10 clay as promoter for the synthesis of 1,4‐dihydropyridines (IV) is described.

Synthesis of 2-substituted 3-ethyl-3H-imidazo[4,5-b]pyridines catalyzed by Al3+-exchanged K10 clay as solid acids

A series of imidazopyridine derivatives have been synthesized efficiently via intramolecular cyclization in excellent yields using Al3+-exchanged on K10 montmorillonite clay (Al3+-K10 clay) as a reusable heterogeneous catalyst. To the best of our knowledge, this is the first report to utilize Al3+-K10 as a catalyst for imidazopyridine synthesis. Many functional groups are tolerated during the synthesis of targeted compounds. The catalyst is reused at least five times with a slight decrease in the yield. This catalyst is environmentally benign, cost-effective, and also provides other advantages such as nontoxicity, operational/experimental simplicity, and mild reaction conditions.

Advantageous delivery of nifedipine from inorganic materials showing increased solubility and biocompatibility

Nifedipine, a potent calcium-channel blocking agent, widely used for treating hypertension has been immobilized inside inorganic matrix materials. The drug was intercalated in Montmorillonite K10 clay by cation exchange, and loaded by an adsorption method inside the channels of mesoporous MCM-41. Spectroscopic evidence (FTIR, powder X-ray diffraction (XRD)) as well as elemental analysis thermal analysis and electron microscopy revealed the preparation of the drug-loaded materials. Release profiling in a simulated body fluid from MCM-41 is fast, indicating that a concentration peak is reached in a short period of time, while the release profile from K10 is much slower. The release profile from MCM-41 leads to higher drug solubility compared even with neat drug solubility, which is advantageous in a drug known for its low solubility (ca. 20μgmL–1). The same is true for K10 clay although its slow release kinetics leave it behind. Spectroscopic data supports this fact by showing that intermolecular host–guest interactions occur thus leading to the observed kinetic effects in the release experiments. In addition it is found that nifedipine inside the host materials is more resistant to photodegradation than in its pure form thus showing another important feature of the hybrid organic/inorganic formulation, as evidenced by GC data.

A green route for the synthesis of 2-substituted benzoxazole derivatives catalyzed by Al3+-exchanged K10 clay

A new, simple, and efficient protocol is developed for the synthesis of 2-substituted benzoxazole derivatives through N–C–O bond formation using Al3+-exchanged K10 clay (Al3+-K10) as catalyst. A wide range of benzoxazole derivatives are synthesized in high yields without affecting many functional groups. Hot filtration experiments showed the absence of metal leaching and catalyst can be reused for five times with only a slight decrease in yield.

ChemInform Abstract: Montmorillonite K10 Clay Catalyzed Synthesis of 4‐Aryltetrahydropyrans: A One‐Pot, Multicomponent, Environmentally Friendly Prins—Friedel—Crafts‐Type Reaction.

AbstractThe methodology represents a more environmentally and logistically friendly route to 4‐aryltetrahydropyrans and gives higher yields with ketones compared to previously reported strategies.

Regioselective ring opening reaction of epichlorohydrin with acetic acid to 3-chloro-2-hydroxypropyl acetate over cesium modified heteropolyacid on clay support

3-Chloro-2-hydroxypropyl acetate has wide applications in production of various epoxy resins, reactive polymers used for coating metal, leather, paper and wood. Regioselective ring opening reaction of epichlorohydrin with acetic acid to synthesize 3-chloro-2-hydroxypropyl acetate was studied using various solid acid catalysts such as 20% dodecatungstophosphoric acid (DTP)/K-10 clay, 20% (w/w) Cs2.5H0.5PW12O40/K-10, sulphated zirconia (SO4/ZrO2) and tungstated zirconia (WO3/ZrO2). Among the various screened catalysts, Cs2.5H0.5PW12O40 (Cs-DTP) supported on K-10 clay was found to be highly active and selective for regioselective ring opening of epichlorohydrin. The selectivity was >98%. The incorporation of Cs-DTP salt on K10 clay was found to increase acidity of catalyst as well showed change in structural properties which ultimately increased the selectivity of catalyst toward 3-chloro-2-hydroxypropyl acetate. Various parameters affecting the conversion and initial rates of reaction were optimized and a kinetic model was developed. The proposed kinetic model matches the experimental data very well.

Atom Economical Green Synthesis of Chloromethyl-1,3-dioxolanes from Epichlorohydrin Using Supported Heteropolyacids

Bioglycerol can be valorized to different products, among which epichlorohydrin is an important intermediate used in a variety of industries. Chloromethyl-1,3-dioxolane is one of the important pharmaceutical intermediates, which is obtained by cycloaddition reactions of epichlorohydrin with ketones. Chloromethyldioxolane derivatives are used as tranquilizers, as plasticizers, as a new class of adrenoceptor antagonists, and also as potential monomers for polymerization and ploycondensation. In the present work, study of the cycloaddition reaction of epichlorohydrin with acetone using 20% (w/w) cesium-substituted dodecatungstophosporic acid (Cs2.5H0.5PW12O40, Cs-DTP) supported on K10 clay has been done. Different catalysts such as K10 clay, 20% (w/w) dodecatungstophosporic acid (DTP)/K10, 20% (w/w) Cs2.5H0.5PW12O40/K10, and 20% (w/w) Cs2.5H0.5PW12O40/HMS were synthesized, and their efficacies were studied. The 20% (w/w) Cs2.5H0.5PW12O40 (Cs-DTP)/K10 clay was found to be highly active. The catalyst was well characterized by different techniques, viz., FTIR, XRD, SEM, and NH3-TPD. A temperature of 70 °C and mole ratio of epichlorohydrin to acetone of 1:8 should be used. The reaction is 100% atom economical and green. The catalyst is reusable. A kinetic model for the cycloaddition reaction has been developed. The reaction mechanism is of the Langmuir–Hinshelwood–Hougen–Watson (LHHW) type with very weak adsorption of both reactants in the absence of any diffusion resistance. The energy of activation is 15.77 kcal/mol.

Montmorillonite K10 Clay Catalyzed Synthesis of 4-Aryltetrahydropyrans: A One-Pot, Multicomponent, Environmentally Friendly Prins-Friedel-Crafts-Type Reaction

The Montmorillonite K10 clay catalyzed synthesis of 4-aryltetrahydropyrans is presented as a one-pot, multicomponent, environmentally friendly Prins–Friedel–Crafts-type reaction.

Catalytic Upgrading of Bio-Oil by Reacting with Olefins and Alcohols over Solid Acids: Reaction Paths via Model Compound Studies

Catalytic refining of bio-oil by reacting with olefin/alcohol over solid acids can convert bio-oil to oxygen-containing fuels. Reactivities of groups of compounds typically present in bio-oil with 1-octene (or 1-butanol) were studied at 120 °C/3 h over Dowex50WX2, Amberlyst15, Amberlyst36, silica sulfuric acid (SSA) and Cs2.5H0.5PW12O40 supported on K10 clay (Cs2.5/K10, 30 wt. %). These compounds include phenol, water, acetic acid, acetaldehyde, hydroxyacetone, d-glucose and 2-hydroxymethylfuran. Mechanisms for the overall conversions were proposed. Other olefins (1,7-octadiene, cyclohexene, and 2,4,4-trimethylpentene) and alcohols (iso-butanol) with different activities were also investigated. All the olefins and alcohols used were effective but produced varying product selectivities. A complex model bio-oil, synthesized by mixing all the above-stated model compounds, was refined under similar conditions to test the catalyst’s activity. SSA shows the highest hydrothermal stability. Cs2.5/K10 lost most of its activity. A global reaction pathway is outlined. Simultaneous and competing esterification, etherfication, acetal formation, hydration, isomerization and other equilibria were involved. Synergistic interactions among reactants and products were determined. Acid-catalyzed olefin hydration removed water and drove the esterification and acetal formation equilibria toward ester and acetal products.

Montmorillonite K10 Clay Catalyzed One Pot Synthesis of 2,4,6-Tri Substituted Pyridine under Solvent Free Condition

Montmorillonite K10 catalyzed synthesis of 2,4,6 triaryl pyridine under solvent free condition is described. Montmorillonite effectively catalyzed the reaction in good to excellent yields. Using this solid catalyst, the reactions could be carried out in a short period of time with very good yield of triaryl pyridines, up to 97% under solvent free condition. This catalyst could be recycled very easily, which makes this methodology environmentally benign. The catalyst is active over three cycles.

Montmorillonite clay catalyzed synthesis of functionalized pyrroles through domino four-component coupling of amines, aldehydes, 1,3-dicarbonyl compounds and nitroalkanes

An efficient and eco-friendly synthesis of functionalized pyrroles using recyclable montmorillonite clay K10 and KSF catalysts has been described. The clay-catalyzed domino four-component coupling (4CC) of amines, aldehydes, 1,3-dicarbonyl compounds and nitroalkanes produced functionalized pyrroles in good yields. The developed methods offers advantages such as operational simplicity, economical, simple workup, use of commercial recyclable catalyst and excellent functional group compatibility to synthesize structurally diverse pyrroles. This is the first report on the use of heterogeneous catalyst for this 4CC.

Reduction of Free Fatty Acids in Acidic Nonedible Oils by Modified K10 Clay

AbstractBiodiesel is a biofuel obtained from vegetable oils. The oils used as raw materials are usually refined edible vegetable oils. Nonedible acidic oils are unsuitable for biodiesel production unless reduction of the high content in free fatty acids (FFA) of these materials had been achieved. Obtaining a good raw material from unprofitable oils becomes an important research field. Additionally clays have a long history in industrial sorption and catalysis, some being commercially available and with properties that can be modified. In this work we present the results of the use of the montmorillonite clay K10 and two acid modified clays K10(I) and K10(II), in the esterification of stearic acid with methanol and 95 % of methyl stearate was obtained with K10(II). These clays were then used for the first time to reduce the acidity of enhanced FFA sunflower oil and they show to be very effective. Reduction of FFA from 11 to 4 % was obtained with K10(II) mainly due to 94 % conversion of FFA into fatty acid methyl esters (FAME). These clays were also tested with two waste oils, one from domestic use and the other gathered from different restaurants, and showed their ability to lower the acidity of these oils. Reactions were followed by 1H NMR as well as quantitative determination of FFA and FAME. Clays were characterized by FTIR and XRD.

Gas sensor based on montmorillonite/polypyrrole composites prepared by in situ polymerization in aqueous medium

Abstract We have synthesized clay/polypyrrole composites via in situ polymerization in aqueous medium, with the anionic surfactant dodecylbenzenesulfonic acid sodium salt (DBSA) playing a dual role as a dopant. We submitted the commercial clay k10 montmorillonite to a previous organophilic treatment with hexadecyltrimethyl ammonium bromide (C 19 H 42 NBr). The lattice parameters, as determined by X-ray diffraction, were d = 1.35 nm, 1.9 nm and 4.2 nm, for the pure montmorillonite (MMTK10), organophilic MMT (MMTO), and MMTO/polypyrrole samples, respectively. Infrared absorption spectroscopy analysis confirmed the presence of vibration peaks associated to both C C and N H polypyrrole bonds and also to MMT characteristic groups. When tested as active materials in sensors of methanol, ethanol, hexane and benzene vapors, these composites have shown a significant sensitivity to the presence of both polar and nonpolar volatile organic compounds. In special, these hybrid (organophilic clay)/polypyrrole films have shown a better level of recognition towards nonpolar compounds than other doped PPY films previously examined.

ChemInform Abstract: Envirocat (K10‐MX)‐Catalyzed Regioselective Transformation of Alkenes into Iodohydrins and β‐Iodo Ethers and Further Conversion of Iodohydrins to Epoxides Using Al2O3—Na2CO3 under MWI.

AbstractEnvirocats, prepared by treating montmorillonite K10 clay with aqueous solutions of metal salts (MX), are found to be efficient catalysts for the regioselective formation of iodohydrins or related β‐iodo ethers from alkenes under microwave irradiations.

Preparation, characterisation and evaluation of brazilian clay-based catalysts for use in esterification reactions

Natural Brazilian clay-based catalysts were prepared, characterised, and their catalytic activity was assessed in esterification reactions. The natural clays were acid activated as received, without any previous treatment. Both natural and acid-activated clays were characterised by XRD, NH3-TPD, thermodesorption of n-butylamine, N2 adsorption analysis, FT-IR, TGA and DTA. The catalytic performance was investigated in the esterification of several carboxylic acids with different alcohols. The reactions were carried out in a 1:3 carboxylic acid/alcohol molar ratio at 100 ºC and atmospheric pressure for 3 h. The acid-activated clays provided good yields and better performance than commercial clay K10.

Envirocat (K10-MX)–Catalyzed Regioselective Transformation of Alkenes into Iodohydrins and β-Iodo Ethers and Further Conversion of Iodohydrins to Epoxides Using Al2O3-Na2CO3 Under MWI

Commercial K10 clay was converted to extremely efficient and environmentally friendly catalyst K10-MX for the preparation of iodohydrins and β-iodo ethers from alkenes (terminal as well as internal) using microwave irradiation. This method was further extended for the conversion of alkenes to epoxides via iodohydrin intermediate in a one-pot reaction system.