Epoxide Ring-opening Reaction Research Articles

How Lewis Acids Catalyze Ring-Openings of Cyclohexene Oxide.

We have quantum chemically studied the Lewis acid-catalyzed epoxide ring-opening reaction of cyclohexene epoxide by MeZH (Z = O, S, and NH) using relativistic dispersion-corrected density functional theory. We found that the reaction barrier of the Lewis acid-catalyzed epoxide ring-opening reactions decreases upon ascending in group 1 along the series Cs+ > Rb+ > K+ > Na+ > Li+ > H+. Our activation strain and Kohn–Sham molecular orbital analyses reveal that the enhanced reactivity of the Lewis acid-catalyzed ring-opening reaction is caused by the reduced steric (Pauli) repulsion between the filled orbitals of the epoxide and the nucleophile, as the Lewis acid polarizes the filled orbitals of the epoxide more efficiently away from the incoming nucleophile. Furthermore, we established that the regioselectivity of these ring-opening reactions is, aside from the “classical” strain control, also dictated by a hitherto unknown mechanism, namely, the steric (Pauli) repulsion between the nucleophile and the substrate, which could be traced back to the asymmetric orbital density on the epoxide. In all, this work again demonstrates that the concept of Pauli-lowering catalysis is a general phenomenon.

Facile microwave-assisted synthesis and antitubercular evaluation of novel aziridine derivatives

Novel 2-(aryloxymethyl)aziridines and 2-((3-aryl-1-phenylallyloxy)methyl)aziridine derivatives were prepared via ring-opening reaction of epoxides. The synthesized derivatives were characterized by using elemental analysis (EA), FT-IR, 13C NMR, and 1H NMR. The in vitro antitubercular activities of the synthesized compounds were evaluated against Mycobacterium tuberculosis H37Rv (MTB H37Rv) strain using MTT-MABA assay. All the aziridine derivatives exhibited improved persuasive antitubercular activity against MTB H37Rv in comparison with standard drugs. Among the tested compounds, 2-(naphthalene-1-yloxy) methyl aziridine (5b), 2-(naphthalene-2-yloxy)methylaziridine (5c), 2-(m-tolyloxymethyl)aziridine (5e), 2-(3-(4-methoxyphenyl)-1-phenylalloxy)methylaziridine (12b) and 2-(3-(2-chlorophenyl)-1-phenylallyloxy)methylaziridine (12c) revealed promising activity against MTB H37Rv. Specifically, compound 5b and 12 b showed three-times more active (MIC = 0.5 µg/mL) than the standard drugs ethambutol (MIC = 1.56 µg/mL) and ciprofloxacin (MIC = 1.56 µg/mL).

Ring Opening of Epoxides and Aziridines with Benzotriazoles Using Magnetically Retrievable Graphene Based (CoFe@rGO) Nanohybrid

Reduced Graphene oxide (rGO) behaves as an excellent heterogeneous catalyst because of its remarkable characteristics such as large specific surface area and high thermal stability. In this regards, Graphene oxide was converted to magnetic nanohybrid (CoFe@rGO) and utilized as an efficient heterogeneous catalyst for the ring opening reactions and act as Lewis acid to promote the reaction. Developed a new facile, environmentally benign and green methodology for the synthesis of β-hydroxytriazoles and β- N -tosylsulfonamidetriazoles derivatives via ring opening reaction of epoxides and aziridines respectively in the presence of CoFe@rGO nanohybrid as catalyst in good to excellent yields under solvent free reaction conditions. Catalyst was separated from the reaction mixture by an external magnet, recycled and reused up to six catalytic runs without significant loss of catalytic activity. Environmentally benign conditions, cheap starting materials, shorter reaction times, easy work-up and purification of the products, high regioselectivity, high yields, recyclability and reusability of catalyst are the main advantages of our protocol.

Optimisation of Epoxide Ring-Opening Reaction for the Synthesis of Bio-Polyol from Palm Oil Derivative Using Response Surface Methodology.

The development of bio-polyol from vegetable oil and its derivatives is gaining much interest from polyurethane industries and academia. In view of this, the availability of methyl oleate derived from palm oil, which is aimed at biodiesel production, provides an excellent feedstock to produce bio-polyol for polyurethane applications. In this recent study, response surface methodology (RSM) with a combination of central composite rotatable design (CCRD) was used to optimise the reaction parameters in order to obtain a maximised hydroxyl value (OHV). Three reaction parameters were selected, namely the mole ratio of epoxidised methyl oleate (EMO) to glycerol (1:5–1:10), the amount of catalyst loading (0.15–0.55%) and reaction temperature (90–150 °C) on a response variable as the hydroxyl value (OHV). The analysis of variance (ANOVA) indicated that the quadratic model was significant at 98% confidence level with (p-value > 0.0001) with an insignificant lack of fit and the regression coefficient (R2) was 0.9897. The optimum reaction conditions established by the predicted model were: 1:10 mole ratio of EMO to glycerol, 0.18% of catalyst and 120 °C reaction temperature, giving a hydroxyl value (OHV) of 306.190 mg KOH/g for the experimental value and 301.248 mg KOH/g for the predicted value. This result proves that the RSM model is capable of forecasting the relevant response. FTIR analysis was employed to monitor the changes of functional group for each synthesis and the confirmation of this finding was analysed by NMR analysis. The viscosity and average molecular weight (MW) were 513.48 mPa and 491 Da, respectively.

Post-synthetic amine functionalized SAPO-5 & SAPO-34 molecular sieves for epoxide ring opening reactions

SAPO-5 and SAPO-34 molecular sieves were synthesized by hydrothermal method and modified via post-synthetic amine functionalization using aminopropyltriethoxysilane (APTES). Functionalized materials were thoroughly characterized using powder XRD, N 2 adsorption, FT-IR, FE-SEM, TGA and 13 C-CP MAS NMR. Syntheses of β-phenoxy and β-amino alcohols were studied via the ring opening of epoxide with nitrogen containing (amines) or oxygen containing (alcohols) nucleophiles, respectively. Amine functionalized SAPO-5 and SAPO-34 molecular sieves were found to be active in epoxide ring opening reaction of propylene oxide with phenol for the major production of 1-phenoxy-2-propanol. Reaction conditions were optimized to achieve higher conversion and selectivity. SAPO-5-NH 2 was also found to be efficient with higher selectivity and conversion for other ring opening reactions using various epoxides and amines for the synthesis of β-amino alcohols. The experimental studies were compared with and complemented by the theoretical parameters.

Polyoxometalate-modified reduced graphene oxide foam as a monolith reactor for efficient flow catalysis of epoxide ring-opening reactions

A POM@rGO monolith reactor was constructed using a facile and broad-spectrum hydrothermal approach and it effectively catalyzes epoxide ring-opening reactions with 99% conversion and over 90% selectivity, reaching a turnover number (TON) of around 28 044 after 38 h catalysis.

Remarkable improvement of epoxide ring-opening reaction efficiency and selectivity with water as a green regulator

As a fully green regulator, water improves the product selectivity by regulating the transformation routes of the reaction intermediate.

Model-free cure kinetics of tetra-functional epoxy reinforced with GO and p-Phenylenediamine modified GO

Tetra-functional epoxy was reinforced with graphene oxide (GO) and p-Phenylenediamine functionalized graphene oxide (fGO). FTIR and XPS analysis of fGO confirmed the attachment of amine groups on its surface. Data obtained from nonisothermal DSC scans of neat epoxy and epoxy modified with 0.1 and 0.5 wt.% GO and fGO was studied to evaluate the effect of filler content and chemistry on the curing behavior of epoxy. Cure analysis was performed quantitatively using the integral isoconversional method to identify the dependence of activation energy (Eα) on conversion. Eα for neat epoxy increased with increase in conversion, possibly because at higher conversions, reactions such as etherification and homo-polymerization controlled the reaction kinetics. The addition of GO and fGO both displayed a lower activation energy in the conversion range α = 0.5−0.9 as compared to neat epoxy. The activation energy of fGO reinforced epoxy remained almost constant with change in conversion. This behavior was attributable to the amine groups attached to the surface of the filler, which acted as a secondary hardener and triggered the epoxide ring opening reaction. This fact was supported by the comparative XPS analysis of fGO and curing agent which clearly indicated the compositional similarities between the two. Further the autocatalytic model was used to determine reaction parameters. The overall order of the curing reaction was more than unity throughout, indicative of a complex reaction mechanism.

Tuning the nucleophilic attack and the reductive action of glycine on graphene oxide under basic medium

Amino acids are important compounds for GO functionalization because they can improve GO properties for many applications ranging from biomedicine to depollution. However, amino acids can act as nucleophiles or as reducing agents for GO functionalization or reduction, respectively. Hence, we systematically studied the GO functionalization/reduction using glycine as a model amino acid under basic conditions at room temperature. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the modified GO with glycine. We found that low glycine concentrations produced an epoxide ring opening reaction, whereas an increase in glycine concentration led to GO reduction. The basic medium allowed to conserve the carboxylic acid groups, whereas the GO reduction mechanism was governed by the partial hydrolysis of epoxide groups and the subsequent reduction of carboxylic acids to carbonyls. This article opens up the opportunity to study and control the conditions in which different amino acids could be used for either GO functionalization or GO reduction.

Conformational Landscapes of Halohydrin Dehalogenases and Their Accessible Active Site Tunnels

Halohydrin dehalogenases (HHDH) are industrially relevant biocatalysts exhibiting a promiscuous epoxide-ring opening reactivity in the presence of small nucleophiles, thus giving access to novel carbon–carbon, carbon–oxygen, carbon–nitrogen, and carbon–sulfur bonds. Recently, the repertoire of HHDH has been expanded, providing access to some novel HHDH subclasses exhibiting a broader epoxide substrate scope. In this work, we develop a computational approach based on the application of linear and non-linear dimensionality reduction techniques to long time-scale Molecular Dynamics (MD) simulations to study the HHDH conformational landscapes. We couple the analysis of the conformational landscapes to CAVER calculations to assess their impact on the active site tunnels and potential ability towards bulky epoxide ring opening reaction. Our study indicates that the analyzed HHDHs subclasses share a common breathing motion of the halide binding pocket, but present large deviations in the loops adjacent to the active site pocket and N-terminal regions. Such conformational differences affect the available tunnels for epoxide binding to the active site. The superior activity of the HHDH G subclass towards bulkier substrates is explained by the additional structural elements delimiting the active site region, its rich conformational heterogeneity, and the substantially wider and frequently observed active site tunnels. This study therefore provides key information for HHDH promiscuity and engineering.

Phosphorus-Containing Silsesquioxane Derivatives as Additive or Reactive Components of Epoxy Resins.

Two phosphorus-containing cage-like silsesquioxane derivatives were synthesized as reactive or additive flame retardants for epoxy resin. The silsesquioxanes were obtained via an epoxide ring-opening reaction using a 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPA). In one derivative containing in its structure 4 glycidoxypropyl and 4 phosphate groups, denoted as 4P4GS, only half of the epoxy rings was reacted with phosphate to obtain a reactive additive, while in the second derivative containing 8 phosphate groups, denoted as 8PS, all epoxy groups were converted, thus an additive modifier was obtained. The silsesquioxanes containing phosphorus atoms and the reactive phosphorus-free silsesquioxane derivative (octakis[(3-glycidoxypropyl)dimethylsiloxy]octasilsesquioxane (8GS)) were used to prepare hybrid materials based on epoxy resin. To compare the impact of the structure of silsesquioxane derivatives on the properties of hybrid materials, a number of samples containing 1, 5, and 10% of the modifiers making a series of epoxy materials containing additive or reactive modifiers, were obtained. The modified epoxies were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), nanoindentation, water contact angle, and cone calorimetry tests to assess the effects of the modifier structure on the physicochemical properties of the investigated materials.

Efficient approach for exploring the multiple-channel bimolecular interactions of conformationally flexible reagents. Epoxide ring opening reaction

Algorithm for generation and assessment of probability of possible reaction pathways for multiple-channel bimolecular interactions is presented. The proposed algorithm comprises a combination of few steps. They include conformational search for reaction intermediate using the molecular mechanics (MMX) approach, based on the obtained conformation construction of structures of transition states and pre-reaction complexes, and calculation activation energies to further determine the probable reaction pathways. The proposed algorithm could be adopted for investigation of chemical and biochemical reactions of different types. Here, we have considered the reaction of bicyclo[2.2.1]hept-5-en-endo-2-ylmethylamine (1) with glycidyl ether (2) in a neutral environment that proceeds through SN2-like mechanism forming bipolar ion (3) which is a good starting point for identification of the reaction channels. Conformational properties of intermediate (3) have been investigated using stochastic conformational search. From the 95 localized conformations within 10 kcal/mol of global minimum that have been obtained, 63 unique transition state conformations were generated and optimized by using the PM7 and M062X/6-31G(d) methods for accurate estimation of overall rate constant of reaction. The most energetically favorable pathways have been investigated at the M062X/6-31G(d) level of theory taking into account the influence of solvent.

Tetranuclear Zn complex covalently immobilized on sulfopropylsilylated mesoporous silica: An efficient catalyst for ring opening reaction of epoxide with amine

Tetranuclear Zn complex, [Zn4(L)2(LH)2((CH3)2SO)2]·2CH3OH·(CH3)2SO·H2O (1) [where LH3 = 3-(E)-(2-hydroxyphenylimino)methyl-4-hydroxy-5-hydroxymethylphenyl (LH3)] was prepared and characterized by single-crystal X-ray analysis. Then, it was incorporated to the sulfopropylsilylated MCM-48, MCM-41 and SBA-15 mesoporous silica materials. The prepared materials were thoroughly characterized by XRD, FT-IR, N2 adsorption/desorption analysis, NH3-TPD, TGA, SEM-EDX and ICP-OES measurements. These catalysts were successfully used for the ring opening reaction of propylene oxide with morpholine producing the corresponding β-aminoalcohols. An abrupt increase in catalytic activities was observed after anchoring of the tetranuclear Zn complex onto the inner surface of sulfopropylsilylated mesoporous materials. Among all the catalysts, the tetranuclear Zn complex incorporated MCM-48 was found to be most active in this reaction system and gave maximum 95% conversion. Catalysis by the tetranuclear Zn complex immobilized on MCM-48 was totally heterogeneous and the catalyst was recyclable up to 4 times without leaching.

Epoxide Syntheses and Ring-Opening Reactions in Drug Development

This review concentrates on success stories from the synthesis of approved medicines and drug candidates using epoxide chemistry in the development of robust and efficient syntheses at large scale. The focus is on those parts of each synthesis related to the substrate-controlled/diastereoselective and catalytic asymmetric synthesis of epoxide intermediates and their subsequent ring-opening reactions with various nucleophiles. These are described in the form of case studies of high profile pharmaceuticals spanning a diverse range of indications and molecular scaffolds such as heterocycles, terpenes, steroids, peptidomimetics, alkaloids and main stream small molecules. Representative examples include, but are not limited to the antihypertensive diltiazem, the antidepressant reboxetine, the HIV protease inhibitors atazanavir and indinavir, efinaconazole and related triazole antifungals, tasimelteon for sleep disorders, the anticancer agent carfilzomib, the anticoagulant rivaroxaban the antibiotic linezolid and the antiviral oseltamivir. Emphasis is given on aspects of catalytic asymmetric epoxidation employing metals with chiral ligands particularly with the Sharpless and Jacobsen–Katsuki methods as well as organocatalysts such as the chiral ketones of Shi and Yang, Pages’s chiral iminium salts and typical chiral phase transfer agents.

Synthesis and characterization of polyvinyl alcohol/corn starch/linseed polyol-based hydrogel loaded with biosynthesized silver nanoparticles

Nanocomposite hydrogel film was prepared from Polyvinyl alcohol [PVA], Corn Starch [CS], Linseed oil polyol [LP], and silver nanoparticles [NP]. LP was prepared by epoxidation and hydration of Linseed oil [LO]. IR and NMR supported the insertion of hydroxyl groups in LP by epoxide ring opening reaction at epoxidized LO. Silver NP were biosynthesized using aqueous leaves' extract from locally grown Ocimum forsskaolii Benth [LEO] plant. FTIR, XRD, UV and TEM confirmed the synthesis of NP (size 30 to 39 nm). Transparent and foldable hydrogel film resulted by blending the constituents (PVA, CS, LP and NP), crosslinking by glutaraldehyde, at room temperature, and showed expansion in water, different pH solutions, biodegradation and good antibacterial and antifungal activity against tested microbes. Linseed polyol influenced the structure, morphology, hydrophilicity, improved swelling ability and thermal stability and accelerated biodegradation of hydrogel films. NP were well adhered to LP globules that were embedded in PVA/CS matrix as strung set of beads (LP globules) decorated with black pearls (spherical NP). Silver NP conferred antimicrobial behavior to hydrogel film as observed by antimicrobial screening on different microbes. The results were encouraging and showed that such hydrogel films may find prospective applications in antimicrobial packaging.

Soybean Oil Epoxidation: Kinetics of the Epoxide Ring Opening Reactions

The epoxide ring opening reaction (ROR) can be considered as the most important side reaction occurring in the epoxidation of soybean oil reaction network. This reaction consistently reduces the selectivity to epoxidized soybean oil (ESBO). The reaction is also important for producing polyols and lubricants. In this work, the reaction was studied in different operative conditions to evaluate the effect on ROR rate respectively: (i) The Bronsted acidity of the mineral acid (H2SO4 or H3PO4), used as catalyst for promoting the oxidation with hydrogen peroxide of formic to performic acid, that is, the reactant in the epoxide formation; (ii) the concentration of the nucleophilic agents, normally present during the ESBO synthesis like HCOOH, HCOOOH, H2O, H2O2; (iii) the stirring rate that changes the oil–water interface area and affects the mass transfer rate; (iv) the adopted temperature. Many different kinetic runs were made in different operative conditions, starting from an already epoxidized soybean oil. On the basis of these runs two different reaction mechanisms were hypothesized, one promoted by the Bronsted acidity mainly occurring at the oil–water interface and one promoted by the nucleophilic agents, in particular by formic acid. As it will be seen, the kinetic laws corresponding to the two mentioned mechanisms are quite different and this explain the divergent data reported in the literature on this subject. All the kinetic runs were correctly interpreted with a new developed biphasic kinetic model.

Elimination of interfering molybdenum oxyanion with an anion-exchange monolithic spin tip (AXTip) for precise determination of cadmium in human urine by ICP-MS

A simple purification technique using an anion-exchange monolithic spin tip was described for the elimination of molybdenum oxyanion interfering with precise determination of cadmium in human urine samples by ICP-MS. The tip device named “anion-exchange tip-in monolith (AXTip)” was laboratory-prepared within the confines of a commercially available syringe filter tip by a two-step process: (1) in situ copolymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) and (2) its subsequent modification with trimethylamine (TMA), as a strong anion-exchange functional group, via ring-opening reaction of epoxide. The adsorption capacity of the AXTip was > 3.2 μmol/tip for molybdenum oxyanion. The performance of the AXTip was evaluated through an adsorption/non-adsorption experiment for molybdenum, cadmium and other metal and metalloid species, using a model solution and human urine samples to optimize the sample solution's pH and dilution factor for the AXTip treatment. In the case of urine sample analysis, 8 times dilution and pH adjustment to 4.0 prior to AXTip treatment were found to allow > 98% elimination of interfering molybdenum oxyanions and quantitative recovery (103 ± 7%) of cadmium. At the optimized conditions, the AXTip treatment reduces Mo/Cd ratio from ~400 in human urines to < 10, which is sufficient for conducting ICP-MS measurement of cadmium in no-gas mode (without collision/reaction cell technique). The proposed purification technique was validated through the analysis of an accuracy control material of human urine (Seronorm™ Trace Elements Urine L-1). Good agreement of the observed values with the reference values indicates that the proposed technique is practically applicable.

Star-shaped amino-functionalized poly(glycerol methacrylate)-stabilized gold nanoparticle composites with catalytic activity for reduction of 4-nitrophenol

Polymers containing amine moieties reduce Au(III) and stabilize gold nanoparticles (AuNPs). Such polymers can be used to synthesize AuNPs with controlled sizes and shapes, providing high stability to the colloidal solutions. A star amino-functionalized poly(glycidyl methacrylate) (PGMA) can quickly be prepared by epoxide ring-opening reactions. We functionalized the β-cyclodextrin-(PGMA)7 with diethanolamine (DEA) to create a star polymer (β-CD-(PGDEA)7) by atom transfer radical polymerization (ATRP), using β-cyclodextrin (β-CD) as macroinitiator. We determined the tertiary amine content (-NR2 = 0.63 mmol/g; R = -CH2-CH2-OH) on the star polymer by gravimetric analysis. The material β-CD-(PGDEA)7 reduces Au(III) and stabilize AuNPs, following a strategy in-situ. AuNPs (7.8 nm) were created by controlling the tertiary amine content/Au(III) molar ratio. The ratio 5 at pH 5.2 supports protonated -NR2H+ (that binds [AuCl4]−) and -NR2 (that stabilize AuNPs) on the star polymer structure, providing colloidal stability over 70 days at room temperature due to the high Zeta potential (+30 mV). The catalytic activity of the colloidal suspension containing the star polymer-capped AuNPs was investigated in the conversion of 4-nitrophenol to 4-aminophenol, using sodium borohydride as a hydrogen donor agent. A high catalyst activity (knor = 65.11 L/min μmol) was obtained at 0.0043 μmol/L AuNPs. The result is assigned to the excellent AuNPs stability imparted by star polymer coatings, showing that the star polymer does not influence the catalytic activity of the covered AuNPs.

Towards Thermally Reversible Networks Based on Furan-Functionalization of Jatropha Oil.

A novel biobased monomer for the preparation of thermally reversible networks based on the Diels-Alder reaction was synthesized from jatropha oil. The oil was epoxidized and subsequently reacted with furfurylamine to attach furan groups via an epoxide ring opening reaction. However, furfurylamine also reacted with the ester groups of the triglycerides via aminolysis, thus resulting in short-chain molecules that ultimately yielded brittle thermally reversible polymers upon cross-linking via a Diels-Alder reaction. A full-factorial experimental design was used in finding the optimum conditions to minimize ester aminolysis and to maximize the epoxide ring opening reaction as well as the number of furans attached to the modified oil. The optimum conditions were determined experimentally and were found to be 80 °C, 24 h, 1:1 molar ratio, with 50 mol % of LiBr with respect to the modified oil, resulting in 35% of ester conversion, 99% of epoxide conversion, and an average of 1.32 furans/triglyceride. Ultimately, further optimization by a statistical approach led to an average of 2.19 furans per triglyceride, which eventually yielded a flexible network upon cross-linking via a Diels-Alder reaction instead of the brittle one obtained when the furan-functionalization reaction was not optimized.

A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites

Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.