Epoxidation Of Α-pinene Research Articles

Kinetics of the isomerization of α-pinene epoxide over Fe supported MCM-41 and SBA-15 materials

A kinetic study for the isomerization of α-pinene epoxide over Fe/SBA-15 and Fe/MCM-41 catalysts was developed using a pseudo-homogeneous (polynomial law) and heterogeneous (LHHW formalism with one and two actives sites) models. TEM analysis of Fe/SBA-15 and Fe/MCM-41 showed that the materials have the typical hexagonal organization; FTIR adsorption–desorption of pyridine revealed the presence of Lewis acidity in both Fe/SBA-15 and Fe/MCM-41 catalysts. The presence of Fe3+ and Fe2+ species was concluded from XPS analysis; however, active site for α-pinene epoxide isomerization was attributed to Fe3+. With toluene as solvent, it was found that in both catalysts, the more adequate kinetic model was the unimolecular LHHW model with two active sites of the same type. Apparently, α-pinene epoxide isomerization is much faster over Fe/MCM-41 (5.78 L h−1 gFe−1) than over Fe/SBA-15 (1.14 L h−1 gFe−1). The activation energy for both Fe catalysts was evaluated using solvents of different polarity. In the case of Fe/MCM-41, the less energetic barrier was observed with toluene (30.99 kJ mol−1), while tert-butanol (13.76 kJ mol−1) was more favorable in the case of Fe/SBA-15 catalyst. Fe/MCM-41 is a very robust catalyst because it can be used up to four times without a significant loss of catalytic activity in comparison with Fe/SBA-15 that only can be used two times. Finally, a reaction mechanism was proposed for the isomerization of α-pinene epoxide over both Fe/SBA-15 and Fe/MCM-41 catalysts.

Isomerization of α- and β- pinene epoxides over Fe or Cu supported MCM-41 and SBA-15 materials

Fe and Cu based heterogeneous catalysts were evaluated in the isomerization reaction of α- and β-pinene epoxides. The metals were incorporated on SBA-15 and MCM-41 using incipient wetness impregnation procedure and the materials were characterized by XRD, Raman spectroscopy, BET analysis, NH3-TPD, TEM and XPS. 1.4/Fe-MCM-41 was the catalyst with the highest TON value (364) and α-pinene epoxide conversion (73%) with a campholenic aldehyde selectivity of 59%, while from β-pinene epoxide 1.4/Fe-SBA-15 was the material with the highest TON (299) and selectivity (100%) to myrtanal with a substrate conversion of 60%. Cu based materials presented lowest TON value for the rearrangement of β-pinene epoxide than using α-pinene epoxide as substrate. Besides, it was elucidated that the formation of campholenic aldehyde and myrtanal is function of the presence of metal oxides, mean particle diameter and the strength of acidity; moreover, the most active catalysts did not present leaching under the reaction conditions. 1.4/Fe-MCM-41 can be used until five times without loss of catalytic activity with α pinene epoxide. Based on the characterization and different products synthetized, a reaction mechanism for the rearrangement reaction of α-pinene epoxide is proposed. This is the first report of Cu heterogenized on mesoporous materials for the isomerization reaction of monoterpenes epoxides.

Enhanced activity of microwave-activated CoOx/MOR catalyst for the epoxidation of α-pinene with air

CoOx species is firstly introduced onto MOR (Mordenite) by impregnation with microwave heating to catalyze the epoxidation of α-pinene with air. The obtained samples have been characterized by X-ray diffraction, FTIR, SEM, TEM, BET surface area, porosity by N2 adsorption. 7%CoOx/MOR catalyst exhibits remarkably higher activity and selectivity in the epoxidation of α-pinene than that prepared by traditional heating impregnation. The epoxidation conversion of α-pinene over 7%CoOx/MOR prepared by microwave heating reaches 92.7 mol% in 4 h at 90 °C, which is nearly 1.5 times that of the catalyst by traditional impregnation. This is due to the fact that CoOx nanoparticles are produced by microwave heating and uniformly dispersed on MOR.

Synthesis of Fencholenic Aldehyde from α-pinene Epoxide on Modified Clays

The conditions for isomerization of α-pinene epoxide (2,3-epoxypinane) on modified clays that gave comparatively high contents (33.0%) of fencholenic (iso-campholenic) aldehyde in the product mixture were determined. An effective method for isolating it was proposed. The structure of iso-campholenic aldehyde was confirmed by analyzing 2D NOESY and HMBC NMR spectra.

Optimización de la síntesis de aldehído canfolénico a partir del epóxido de α-pineno con Cu/MCM-41

Se sintetizó el catalizador Cu/MCM-41 mediante impregnación húmeda incipiente y se caracterizó por DRX, XPS, TPD-NH3 y adsorción-desorción de N2. Se evaluó el efecto de diferentes condiciones de reacción (temperatura, tiempo, tipo de solvente y cantidad de catalizador) en la isomerización del epóxido de α-pineno para la obtención de aldehído canfolénico con el catalizador Cu/MCM-41, que no había sido reportado previamente para este tipo de reacción. Se partió de un diseño experimental central compuesto mediante análisis de superficie de respuesta. Se encontró que la mejor selectividad fue de 85% (5 mg de catalizador; 70 °C; 0,5 h y el uso de acetato de etilo como solvente). Adicionalmente, se determinaron los principales factores y sus combinaciones que tenían mayor significancia en la síntesis del aldehído ajustado a un modelo polinomial de segundo grado. Se encontró que los factores que tienen mayor influencia en la conversión son la cantidad de catalizador, tiempo de reacción, el tipo de solvente y el factor combinado entre la cantidad de catalizador y el tipo de solvente. En el caso de la selectividad hacia el producto deseado no se encontró ningún factor significativo.

Ultrasonic and Catalyst-Free Epoxidation of Limonene and Other Terpenes Using Dimethyl Dioxirane in Semibatch Conditions

Limonene dioxide is a key intermediate molecule for the development of biobased polycarbonates or nonisocyanate polyurethanes. In this work the epoxidation of limonene to limonene dioxide using in-situ-generated dimethyl dioxirane as the oxidizing agent under both conventional agitation and ultrasound has been compared. The time required to completely convert limonene to limonene dioxide with 100% yield using ultrasound was only 4.5 min at room temperature. In comparison, when conventional agitation using a magnetic stirrer is used, the required time to reach a 97% yield of limonene dioxide was 1.5 h. The epoxidation of α-pinene has also been studied using both agitation techniques. Epoxidation of α-pinene to α-pinene oxide under ultrasound required only 4 min with an obtained yield of 100%, while in comparison with the conventional method the reaction time was 60 min. As for other terpenes, β-pinene was converted to β-pinene oxide in only 4 min whereas farnesol yielded 100% of the triepoxide in 8 min. Ca...

Dynamic modeling of the chemo-enzymatic epoxidation of α-pinene and prediction of continuous process performance

For the first time, a valid and reliable deterministic model for the description and prediction of the reaction dynamics of the chemo-enzymatic epoxidation in a continuous stirred tank reactor (CSTR) is presented. The model covers the different steps of the reaction cascade and all kinetic constants were found to be uniquely identifiable, which is a prerequisite for trustworthy model predictions. The chemo-enzymatic epoxidation is a multistep reaction, which consists of two consecutive reactions: the lipase-catalyzed peracid formation followed by a Prilezhaev epoxidation, wherein numerous factors govern the product formation. This makes the design of an optimal process particularly challenging and modeling mandatory. To obtain the model structure, the goodness of fit and (practical) parameter identifiability were taken into account. Different mass action kinetics, as well as mechanistic approaches, were investigated. Kinetic constants were fitted to experimental data using a multi-experiment fitting, and the practical identifiability of the estimated constants was shown. The developed CSTR process model, which describes the dynamics of the multistep chemo-enzymatic epoxidation of α-pinene, matched the experimental data very accurately. Moreover, it was successfully verified and validated over a broad range of operating conditions.

Highly efficient epoxidation of α-pinene with O2 photocatalyzed by dioxoMo(VI) complex anchored on TiO2 nanotubes

The effect of different surface OH's groups on the amount of anchored Mo complex: Mo(VI)Cl2O2Bipy (Bipy = 4,4′-dicaboxylato-2,2′-bipyridine) grafted on TiO2 (Mo(VI)Cl2O2Bipy/TiO2) and its effect on the photocatalytic Oxygen Atom Transfer (OAT) activity to α-pinene with O2 was studied. The amount of supported complex on TiO2 nanotubes is 5 times the amount of the grafted complex on TiO2 P-25 and OAT activity increase of 25%, may be associated to the physicochemical properties of TiO2 nanotubes. High selectivity was preserved toward the epoxide formation (>90%). The amount of Mo complex covalently anchored on TiO2 depends on the concentration, distribution and accessibility of the Ti-OH surface groups, which depend on the TiO2 preparation method. The different OH's groups, namely: Bridged, geminal and isolated were identified by FT-IR Photoacoustic Spectroscopy. Surface OH's concentration was determined by TGA methods, silylation reactions and XPS analysis.

An organic-single-phase CSTR process for the chemo-enzymatic epoxidation of α-pinene enables high selectivity and productivity

The aim of this work was to develop a new process strategy for the in-situ lipase-mediated synthesis of α-pinene oxide. To minimize the limitation of enzyme deactivation encountered in these reaction cascades, an organic-single-phase continuous stirred tank reactor (ospCSTR) process was developed. Considering the numerous degrees of freedom of this continuous multistep reaction which due to enzyme deactivation additionally has no steady-state, the process development is a challenging task. Therefore, the influence of operating parameters on the efficiency was studied in detail. Due to the avoidance of harsh conditions, at optimized parameters α-pinene oxide was produced selectively (95%), and with high space-time yields (880gPOL−1d−1). The catalytic productivity (118gPOg−1CalB) was significantly higher than previously reported. To counterbalance the reduced but still present deactivation, the opsCSTR was enhanced with intermittent enzyme dosing which, for the first time, enabled long-term operation, high catalytic productivity, and high space-time yield. With the ospCSTR augmented by enzyme dosing, we report an economical process for a chemo-enzymatic epoxidation of sensitive terpenes like e.g., α-pinene.

Cis-dioxo-Mo(VI) salophen complex supported on Fe3O4@SiO2 nanoparticles as an efficient magnetically separable and reusable nanocatalyst for selective epoxidation of olefins

In this work, paramagnetic Fe3O4/SiO2 nanoparticles were synthesized, characterized and functionalized with dioxo-Mo(VI) tetradentate Schiff base complex and characterized using IR spectroscopy, X-ray powder diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, diffuse reflectance spectroscopy and atomic absorption spectroscopy. Catalyst was used for the selective epoxidation of cyclooctene, cyclohexene, styrene, indene, α-pinene, 1-hepten, 1-octene, 1-dodecen and trans-stilbene using tert-butyl hydroperoxide as oxidant in 1,2-dichloroethane. This catalyst is efficient for oxidation of cyclooctene with a 100% selectivity for epoxidation with 100% conversion in 1 h. After the reaction, the magnetic nanocatalyst was easily separated by simply applying an external magnetic field and was used at least five successive times without significant decrease in conversion.

Biocatalytic epoxidation of α-pinene to oxy-derivatives over cross-linked lipase aggregates

Lipase-based cross-linked aggregates were investigated for a non-specific reaction, i.e. the epoxidation of α-pinene to its oxygenated derivatives. The activity of the biocatalysts has been evaluated in a green context, i.e. ethyl acetate as both acetate-supplier and organic solvent with H2O2/UHP/TBHP as oxidant. Screening of the lipase sources indicated Aspergillus niger lipase as the most efficient biocatalyst for this reaction. Different immobilization protocols ((i) cross-linked enzyme aggregates (CLEA), (ii) cross-linked enzyme aggregates onto magnetic particles (CLEMPA) and (iii) covalent immobilized enzyme (CIE) onto magnetic particles (MP)) were evaluated considering the activity as main parameter. Thus, CLEA and CLEMPA afforded better epoxidation yields of α-pinene towards CIE. The investigated biocatalytic systems allowed to transform α-pinene into oxigenated derivatives with industrial and commercial applications (e.g. α-pinene oxide, camphene, pinanediol and camphonelic aldehyde). FTIR investigations on the biocatalysts revealed the effects of the immobilization protocol on the enzyme secondary-structure. Additionally, textural characterizations were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) analysis.

Bifunctional carbohydrate biopolymers entrapped lipase as catalyst for the two consecutive conversions of α-pinene to oxy-derivatives

Bifunctional catalysts designed as carbohydrate biopolymers entrapping lipase have been investigated for the biotransformation of a natural compound (α-pinene) to oxy-derivatives. Lipases assisted the epoxidation of α-pinene using H2O2 as oxidation reagent and ethyl acetate as both acetate-supplier and solvent affording α-pinene oxide as the main product. Further, the biopolymer promoted the isomerization of α-pinene oxide to campholenic aldehyde and trans-carenol. In this case, the biopolymers played double roles of the support and also active part of the bifunctional catalyst. Screening of enzymes and their entrapping in a biopolymeric matrix (e.g. Ca-alginate and κ-carrageenan) indicated the lipase extracted from Aspergillus niger as the most efficient. In addition, the presence of biopolymers enhanced the catalytic activity of the immobilized lipase (i.e. 13.39×103, 19.76×103and 26.46×103 for the free lipase, lipase-carrageenan and lipase-alginate, respectively). The catalysts stability and reusability were confirmed in eight consecutively reaction runs.

Kinetic study of α-pinene allylic oxidation over FePcCl16-NH2-SiO2 catalyst

The kinetic of α-pinene oxidation over an iron hexadecachlorinated phthalocyanine immobilized on modified silica (FePcCl16-NH2-SiO2) with t-butyl hydroperoxide (TBHP) as oxidant is proposed. Reaction rates were calculated by the initial reaction rate method from the data obtained in a batch reactor, and compared with kinetic expressions proposed from mechanisms based on Langmuir Hinshelwood Hougen Watson (LHHW) and power-rate law models. The kinetic parameters were estimated from the experimental data by optimization using the Genetic Algorithm. A kinetic expression based on LHHW model with the adsorption of α-pinene, TBHP and the main reaction products (verbenone, α-pinene epoxide and verbenol) on the surface of the catalyst predicted the experimental data with good accuracy (R2=0.986). The apparent activation energy of α-pinene allylic oxidation over FePcCl16-NH2-SiO2/TBHP was 40.08kJ/mol. α-Pinene conversion of 83.7% was obtained after 23h with a selectivity to verbenone of 23%. Under the reaction conditions leaching of the active species was not observed; however, the effect of radicals in the bulk liquid phase was demonstrated, confirming that the reaction involves a combination of both heterogeneous and homogeneous pathways. The catalyst can be used at least in seven cycles without loss of α-pinene conversion nor verbenone selectivity.

Synthesis of campholenic aldehyde from α-pinene using bi-functional PrAlPO-5 molecular sieves

Praseodymium incorporated AlPO-5 was synthesized hydrothermally in fluoride medium using triethylamine as template. PrAlPO-5 could be bi-functional in nature since the isolated praseodymium sites acted both as redox and acid sites. The framework incorporation of praseodymium in AlPO-5, and the absence of separate praseodymium oxide phase were confirmed by laser Raman and fluorescence studies. The chemisorbed oxygen on praseodymium sites were identified by ESR. The ex-situ pyridine adsorbed IR spectrum confirmed the presence of Lewis acid sites. The catalytic activity of PrAlPO-5 was evaluated in the synthesis of campholenic aldehyde from α-pinene. The epoxidation of α-pinene through chemisorbed oxygen followed by isomerisation of α-pinene oxide over Lewis acid sites on PrAlPO-5 yielded campholenic aldehyde selectively. PrAlPO-5 was proved to be an active, selective and reusable catalyst.

Selectively catalytic epoxidation of α-pinene with dry air over the composite catalysts of Co–MOR(L) with Schiff-base ligands

Twelve bi-/tridentate Schiff-base ligands (L1–L12) have been designed, synthesized and coordinated with ion-exchanged Co–MOR (Mordenite) forming a series of Co–MOR(L) composite catalysts, for which various analyzes and characterizations are conducted. Selectively catalytic epoxidation of α-pinene with dry air over Co–MOR(L) catalysts has been carried out, where uses TBHP in small amounts as the initiator. Among these Co–MOR(L) catalysts, Co–MOR(L8) exhibits the best activity for the titled reaction to obtain 85.8mol% conversion and 90.8% selectivity of epoxide. Some factors such as the structure of ligands, the oxidants, the solvents, the catalyst amount, the reaction temperature and time play important roles in controlling the epoxidation. The recyclable stability of the Co–MOR(L8) catalyst is confirmed. The studies on the electrochemical behaviors of Co species in Co–MOR(L8) reveal the importance of reversible change between Co oxidation states for the epoxidation.

Lipase-Mediated Formation of Peroxyoctanoic Acid Used in Catalytic Epoxidation of α-Pinene from Turpentine Oil

Lipase-Mediated Formation of Peroxyoctanoic Acid Used in Catalytic Epoxidation of α-Pinene from Turpentine Oil

Sodium Alginate Intercalated Zinc-Containing Layered Double Hydroxides for the Catalytic α-Pinene Oxidation

In this paper, the sodium alginate (SA) intercalated into a series of binary Mg-Al、Cu-Al, Zn-Al flaky layered double hydroxides (FLDH/SA) were fleetly prepared by the technology of the microwave-crystallization and low saturated state of coprecipitation. The purposed sample was characterized by XRD, IR and SEM. The result shows that the sample synthesized Zn-FLDH/SA with the flexible slice has the structure of LDHs, indicating the preparations are successful under microwave irradiation. The three types of CFLDH/SA were the calcined products of the three FLDH/SA under 673K for 4h, which were then applied to the catalytic α-pinene oxidation using 30 wt% hydrogen peroxide as oxidant. The effects of reaction time, catalyst type, reaction medium and so on were also investigated in details. The results show the Zn-CFLDH/SA is the best catalyst, α-pinene conversion and the selectivity of α-pinene epoxide , verbenol, verbenone can reach 69.6% and 29.1%, 39.6%, 12.0%, respectively, under optimized reaction conditions of acetone: water = 1:1 as reaction solvent, catalyst concentration of 0.431 g/L, reaction temperature 60 oC and reaction time 3 hours, Zn-CFLDH/SA as catalyst.

Synthesis and catalytic properties of titanium containing extra-large pore zeolite CIT-5

Titanium containing extra-large pore zeolite CIT-5 (IZA code: CFI) was successfully prepared by direct synthesis using Cab-O-Sil M5 and titanium(IV) butoxide in the presence of LiOH. N-Methylsparteinium hydroxide was used as a structure directing agent. The product crystallized into thin plate crystals with an approximate size of 20×5×0.2μm. The lowest achieved Si/Ti ratio was 23. The necessary duration of hydrothermal synthesis increased with increasing concentration of Ti in the reaction mixture from 11 days (Si/Ti=63 in product) to 17 days (Si/Ti=36) at 155°C. Prepared Ti-CFI samples exhibit BET surface areas in the range of 308–346m2/g and micropore volumes of 0.094–0.097cm3/g. CFI possesses extra-large pores (14-ring, 7.2×7.5Å) accessible for bulky molecules, therefore, Ti-CFI is a useful catalyst for epoxidation of double bonds in bulky molecules used in perfumery and pharmacy. The Ti-CFI samples proved to be catalytically active in epoxidation of 1-octene, cyclooctene, α-pinene, and norbornene with hydrogen peroxide as oxidation agent.

Effect of solvents on the rate of epoxidation of α-pinene and Δ3-carene with peroxydecanoic acid

Reaction of epoxidation of α-pinene and Δ3-carene with peroxydecanoic acid in various organic solvents was studied. Effective activation energies of oxidation of α-pinene and Δ3-carene with peroxydecanoic acid in various media are evaluated. It is shown that reaction medium significantly affects the rate of the process. Correlation dependences connecting the rate of epoxidation with main parameters of solvents are found.

Co2 +-exchanged MOR and 5A zeolites as efficient solid catalysts for the epoxidation of styrene with air

Selective oxidation of alkenes with air to corresponding epoxides was performed over simple ion-exchanged Co-MOR and Co-5A. Among all transition metal ions-exchanged M-zeolites, both Co-MOR and Co-5A exhibited the highest activity at 363K. Notably, for the epoxidation of styrene, α-pinene, α-methyl styrene and cyclooctene, Co-MOR obtained higher conversions than Co-5A, in agreement with the difference of pore sizes of both zeolitic materials. Recycling and control tests showed high durability of Co-MOR as a heterogeneous catalyst in our catalytic system.