Epoxidation Of Limonene Research Articles

Limonene epoxidation by molecular sieves zincophosphates and zincochromates

Conversion of limonene in its derivatives has been an interesting process due to its high value for cosmetic, pharmaceutical and food industries. The use of molecular sieves based on transition metals in heterogeneous catalysis, and specifically in oxidative processes, has shown good results. Oxidation of limonene has been studied using zinc based catalyst, hydrogen peroxide as oxidative agent and t-butanol or tetrahydrofurane as solvents at different reaction times and temperatures. 1,2-Epoxi-limonene, carvone, carveol and limonene-1,2-diol were obtained as main products.

Catalytic asymmetric epoxidation of limonene using manganese Schiff-base complexes immobilized in ionic liquids

Abstract The asymmetric epoxidation of limonene has been performed using Jacobsen’s catalyst dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI · BF4) ionic liquid and with hydrogen peroxide oxidant giving high stereoselectivity. Limonene was selectively converted into 1,2-epoxi-p-ment-8-enes with a diastereoisomeric excess of 74% and conversions up to 70%. Chirality of limonene was found to play an important role in stereochemical formation of new chiral centers because the synthesis occurs with double asymmetric induction. Download : Download full-size image

Epoxidation of Limonene by Tert-butyl Hydroperoxide Catalyzed by Polybenzimidazole-supported Mo(VI) Complex

A polybenzimidazole supported Mo (VI) (PBI.Mo) catalyst has been prepared and characterised. The catalytic activities of the PBI.Mo catalyst in epoxidation of limonene with tent-butyl hydroperoxide (TBHP) as oxidant have been studied under different reaction conditions in a batch reactor. The batch experimental data provided useful information for conducting continuous experiments in a reactive distillation column (RDC) .

Alkene epoxidation by homogeneous and heterogenised manganese(II) catalysts with hydrogen peroxide

Three Schiff base ligands derived from three different 1,3-diones and diethylenetriamine have been synthesized and subsequently grafted on a silica surface via covalent bonds. The organic ligands as well as the heterogenised ligands reacted with manganese(II) ions leading to the formation of the corresponding metal complexes. Supported and non-supported manganese complexes have been evaluated as catalysts for alkene epoxidation with hydrogen peroxide in the presence of ammonium acetate as an additive. Both homogeneous and heterogeneous systems are able to activate hydrogen peroxide towards epoxide formation presenting remarkable catalytic properties. This catalytic ability of the immobilised manganese complexes is further highlighted, since they present efficient systems overcoming competitive H 2O 2 dismutation, in conjunction with advantages of the heterogeneous catalysts. In this context, they gave high yields for limonene epoxidation, significantly higher than the corresponding homogeneous catalysts.

Alumina as heterogeneous catalyst for the regioselective epoxidation of terpenic diolefins with hydrogen peroxide

The epoxidation of several terpenic diolefins (carvone, limonene, terpinolene, α-terpinene and γ-terpinene) in anhydrous conditions using alumina as a heterogeneous catalyst and hydrogen peroxide as the oxidant agent is studied in this work. Several kinds of chromatographic aluminas have been employed (acidic, basic and neutral), in order to study the effect of the surface acidity on the reaction. The reusability of the catalyst has also been addressed. Basic alumina was the catalyst that gave better activity and selectivity. The reactivity of the substrate increases with the nucleophilic character of its double bonds, and the regioselectivity to some monoepoxides is also related to this nucleophilic character. The epoxidation rate of carvone, limonene and terpinolene increased with the alumina/terpene molar ratio. The selectivity to epoxides increased for carvone, and it passed through a maximum for limonene and terpinolene with this variable. From the comparison between experiments performed removing the catalyst, without removing it, and without catalyst, it was deduced that alumina is responsible for the high activity and selectivity obtained when it is added to the reaction medium, and that a heterogeneous epoxidation occurs on alumina surface. The study of the reusability of alumina in the epoxidation of limonene and terpinolene shows negligible changes on selectivity after several cycles, whereas the decrease of activity in successive cycles is significant for the long reaction times used in limonene epoxidation.

Limonene Epoxidation: Diffusion and Reaction over PW-Amberlite in a Triphasic System

The effect of several reaction parameters on limonene epoxidation and hydrogen peroxide decomposition over PW-Amberlite was studied. Parameters evaluated were as follows: amount of catalyst (8−28 g/L), average particle diameter (110−720 μm), and concentrations of acetonitrile (7.4−15.7 mol/L), limonene (0.27−1.04 mol/L), hydrogen peroxide (0.73−1.92 mol/L), water (5.84−7.39 mol/L), and limonene epoxide (0−0.17 mol/L). The initial limonene reaction rate exhibits a maximum at 71 wt % acetonitrile (18 wt % hydrogen peroxide), 6.5 times higher than that obtained under biphasic conditions. According to Weisz−Prater criterion, mass transfer limitations were insignificant for catalyst particle sizes smaller than 425 μm. External mass transfer limitations were avoided by using a stirring speed of 1000 rpm. The apparent activation energy of limonene epoxidation was 25 kJ/mol, three times lower than that previously found in a biphasic system. Empirical reaction rates of limonene epoxidation and hydrogen peroxide d...

Application of complex heteropolytungstates in limonene epoxidation by H 2O 2 in biphasic medium

The synthesis of potassium salts of Cu heteropolytungstate was carried out by reaction in aqueous solution of Na 8H[ΔPW 9O 34]·19H 2O lacunary precursor with Cu nitrate in KCl excess. The product is a mixture of two isomers related to Keggin structure, having a composition K 5.5Na 1.5[PW 10O 38Cu 2(H 2O) 2]·13H 2O, which are the main phases, while the tetra-nuclear copper cluster with formula: [K 10(PW 9O 34) 2Cu 4(H 2O) 2]·20H 2O was the minority phase. The characterization was carried out by means of X-ray powder diffraction analysis (XRD) and vibrational FT-IR and Raman spectroscopy. The Cu-phase mixture was used as catalyst for the epoxidation of limonene in biphasic (water–organic) reaction media using hydrogen peroxide (35% aqueous H 2O 2) as the oxygen donor. It was able to oxidize selectively limonene towards the epoxide at very high turnover numbers. In addition, similar studies were performed with both the structural related ([K 10(PW 9O 34) 2Co 4(H 2O) 2]·20H 2O) and the lacunary precursor for comparative purposes. Some comments about the stability of copper and cobalt tetra-nuclear phases were made on the basis of topological and electronic considerations and the distortion of the metal environments was related to the catalytic behavior.

Ti-MCM-41 silylation: Development of a simple methodology for its estimation: Silylation effect on the activity and selectivity in the limonene oxidation with H 2O 2

Ti-MCM-41 was prepared and characterized. The isomorphical substitution of Si 4+ by Ti 4+ and the presence of mesoporous hexagonal structure were verified. The solid was silylated with increasing quantities of hexamethyldisilazane. This process did not change the structural properties of the solid. Using themogravimetric analysis, the optimal quantity of the silylant agent to neutralize the superficial silanols was evaluated. The non-silylated and the silylated solids (with the optimal quantity) were tested in the limonene oxidation with hydrogen peroxide. The silylated solid showed a greater hydrogen peroxide efficiency and a higher activity and selectivity in the limonene epoxidation, compared with the non-silylated one. These effects are attributed to the higher hydrophobic character of the solid surface, produced by the silanols neutralization.

Polymer-supported manganese porphyrin catalysts—peptide-linker promoted chemoselectivity

Manganese porphyrin catalysts were tethered to polymer-supports via peptide linkers. The reactivity and chemoselectivity of the catalysts were assessed in the epoxidation of limonene. It was found that the inclusion of a peptide linker incorporating a donor heteroatom which could act as an axial ligand led to a supported manganese porphyrin catalyst with unprecedented selectivity and stability.

Oxidations by the system “hydrogen peroxide–dinuclear manganese(IV) complex–carboxylic acid”

Dinuclear manganese(IV) complex [LMn(O) 3 MnL](PF 6 ) 2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) efficiently catalyzes epoxidation of sterically accessible olefins, including natural compounds by hydrogen peroxide in acetonitrile at room temperature if a small amount of a carboxylic acid (for example, oxalic acid) is present in the solution. . Dinuclear manganese(IV) complex [LMn(O) 3 MnL](PF 6 ) 2 ( 1 , L = 1,4,7-trimethyl-1,4,7-triazacyclononane) efficiently catalyzes epoxidation of sterically accessible olefins, including natural compounds by hydrogen peroxide in acetonitrile at room temperature if a small amount of a carboxylic acid is present in the solution. The kinetics of dec-1-ene epoxidation and accompanying dioxygen evolution (catalase activity) under the action of this system in the presence of acetic acid has been studied. The initial rates of both epoxidation and O 2 evolution are proportional to the catalyst initial concentration. First order has been found for catalyst 1 for both processes, whereas the rate dependences of the dec-1-ene epoxidation is first order and the O 2 evolution is second order for H 2 O 2 . The epoxidation rate increases and the O 2 evolution rate decreases with growing of acetic acid concentration. Zero order has been found for dec-1-ene in its epoxidation. The reaction proceeds with an induction period for a few minutes during which changes in the electronic spectra of the reaction solution are observed. It has been proposed that the processes of the alkane oxidation and dioxygen evolution on the one hand and of the olefin epoxidation on the other hand are induced by different intermediate species. An assumption has been made that the epoxidation occurs with participation of oxo-hydroxy Mn(V) derivative [LMn V ( O)(O) 2 (HO)Mn IV L] 2+ , whereas di(hydroperoxy) complex [LMn III (OOH)(O) 2 (HOO)Mn IV L] + is responsible for the alkane oxidation with simultaneous dioxygen evolution. The following equations for the initial rates were proposed for [CH 3 CO 2 H] = 0.25 mol dm −3 : d[epoxide]/d t = k eff (epoxide)[ 1 ][H 2 O 2 ] with k eff (epoxide) = 2.8–3.7 mol −1 dm 3 s −1 ; d[CyOOH]/d t = k eff (CyOOH)[ 1 ][H 2 O 2 ] 2 [CyH] with k eff (CyOOH) = 4.1–6.2 mol −3 dm 9 s −1 ; d[O 2 ]/d t = k eff (O 2 )[ 1 ][H 2 O 2 ] 2 with k eff (O 2 ) = 2.8–7.0 mol −2 dm 6 s −1 . Many different carboxylic acids were checked as cocatalysts and it has been found that oxalic acid acts with the highest efficiency in the epoxidation whereas the accompanying catalase activity of the system is very low in this case. It has been also demonstrated that complex 1 is unique catalyst because similar compounds containing only one Mn(IV) center ( 2 ) or dinuclear complex with bridging phenylboronic acid ( 3 ) are very poor catalysts in the olefin epoxidation. No epoxidation has been found when hydrogen peroxide was replaced by tert -butyl hydroperoxide. The system based on 1 , H 2 O 2 and acetic and/or oxalic acid was employed for the efficient epoxidation of terpenes limonene, citral, carvone and linalool, while other terpenes containing sterically hindered double bonds (citronellal, α- and β-isomers of pinene) were epoxidized only with <15% yield. Using limonene as example, it has been demonstrated that regioselectivity of the epoxidation (predominant formation of product with addition of the O atom either to internal ring or external double bond) can be controlled by replacing acetic acid by oxalic acid.

Oxidations by the system “hydrogen peroxide–dinuclear manganese(IV) complex–carboxylic acid”Part 5. Epoxidation of olefins including natural terpenes

Dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (1, L = 1,4,7-trimethyl-1,4,7-triazacyclononane) efficiently catalyzes epoxidation of sterically accessible olefins, including natural compounds by hydrogen peroxide in acetonitrile at room temperature if a small amount of a carboxylic acid is present in the solution. The kinetics of dec-1-ene epoxidation and accompanying dioxygen evolution (catalase activity) under the action of this system in the presence of acetic acid has been studied. The initial rates of both epoxidation and O 2 evolution are proportional to the catalyst initial concentration. First order has been found for catalyst 1 for both processes, whereas the rate dependences of the dec-1-ene epoxidation is first order and the O 2 evolution is second order for H2O2. The epoxidation rate increases and the O2 evolution rate decreases with growing of acetic acid concentration. Zero order has been found for dec-1-ene in its epoxidation. The reaction proceeds with an induction period for a few minutes during which changes in the electronic spectra of the reaction solution are observed. It has been proposed that the processes of the alkane oxidation and dioxygen evolution on the one hand and of the olefin epoxidation on the other hand are induced by different intermediate species. An assumption has been made that the epoxidation occurs with participation of oxo-hydroxy Mn(V) derivative [LMn V ( O)(O)2(HO)Mn IV L] 2+ , whereas di(hydroperoxy) complex [LMn III (OOH)(O)2(HOO)Mn IV L] + is responsible for the alkane oxidation with simultaneous dioxygen evolution. The following equations for the initial rates were proposed for [CH 3CO2H] = 0.25 mol dm −3 : d[epoxide]/dt = keff (epoxide)[1][H2O2] with keff (epoxide) = 2.8–3.7 mol −1 dm 3 s −1 ; d[CyOOH]/dt = keff (CyOOH)[1][H2O2] 2 [CyH] with keff (CyOOH) = 4.1–6.2 mol −3 dm 9 s −1 ; d[O2]/dt = keff (O2)[1][H2O2] 2 with keff (O2) = 2.8–7.0 mol −2 dm 6 s −1 . Many different carboxylic acids were checked as cocatalysts and it has been found that oxalic acid acts with the highest efficiency in the epoxidation whereas the accompanying catalase activity of the system is very low in this case. It has been also demonstrated that complex 1 is unique catalyst because similar compounds containing only one Mn(IV) center (2) or dinuclear complex with bridging phenylboronic acid (3) are very poor catalysts in the olefin epoxidation. No epoxidation has been found when hydrogen peroxide was replaced by tert-butyl hydroperoxide. The system based on 1 ,H 2O2 and acetic and/or oxalic acid was employed for the efficient epoxidation of terpenes limonene, citral, carvone and linalool, while other terpenes containing sterically hindered double bonds (citronellal, - and -isomers of pinene) were epoxidized only with <15% yield. Using limonene as example, it has been demonstrated that regioselectivity of the epoxidation (predominant formation of product with addition of the O atom either to internal ring or external double bond) can be controlled by replacing acetic acid by oxalic acid. © 2004 Elsevier B.V. All rights reserved.

Effect of reaction conditions on limonene epoxidation with H 2O 2 catalyzed by supported Keggin heteropolycompounds

Limonene epoxidation by hydrogen peroxide in the presence of Keggin-type heteropolycompound supported catalysts was studied. Catalysts containing molybdenum or tungsten heteropolycompounds were prepared by pore filling impregnation of carbon or alumina, and were characterized by diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) and potentiometric titration. During the reaction, limonene oxide, carvone, carveol, diols and limonene hydroperoxide were produced. Different reaction conditions have been studied, such as nitrogen atmosphere, absence of light, and radical scavenger addition. A catalytic process of oxygen transference could be assumed to occur when a lacunar tungstophosphate supported on carbon is used as catalyst, forming a peroxometalate intermediate. A free radical competitive mechanism was found in the presence of alumina-supported heteropolyacids.

Mechanistic studies on the Mukaiyama epoxidation.

A detailed mechanistic study on the Mukaiyama epoxidation of limonene with dioxygen as oxidant, bis(acetylacetonato)nickel(II) as catalyst, and an aldehyde as co-reagent is reported. All major products of the reaction have been quantitatively identified, both with isobutyraldehyde and 2-methylundecanal as co-reacting aldehydes. Limonene epoxide is formed in good yield. The main products evolving from the aldehyde are carboxylic acid, CO(2), CO, and lower molecular weight ketone and alcohol (K + A). A mechanism is proposed in which an acylperoxy radical formed by the autoxidation of the aldehyde is the epoxidizing species. The observation of carbon dioxide and (K + A) in a 1:1 molar ratio supports this mechanism. CO(2) and (K + A) are formed in molar amounts of 50-60% with respect to the amount of epoxide produced, indicating that epoxidation takes place not only via acylperoxy radicals but also via a peracid route. Cyclohexene epoxidation was also investigated with a number of different metal complexes as catalysts. Cyclohexene is very sensitive for allylic oxidation, which provides information about the action of the catalyst, e.g., metals that form strongly oxidizing stable high-valence complexes are more likely to induce allylic oxidation. Color changes in the reaction mixture indicate the presence of such high-valence species. In the case of nickel, it was found that low-valence compounds predominate during the reaction, which is in line with the fact that this metal displays the highest selectivity for epoxide. A mechanism that accounts for the observations is presented.

On the kinetics of epoxidation of olefins by cis and trans-[RuCl2(dppb)(2,2′-bipy)] complexes

Abstract The kinetics of the epoxidation of cis-cyclooctene, 2-norbornene and limonene catalyzed by cis-[RuCl2(dppb)(2,2′-bipy)] (1) or trans-[RuCl2(dppb)(2,2′-bipy)] (2) (where, dppb: 1,4-bis(diphenylphosphino)butane; 2,2′-bipy: 2,2′-bipyridine) in the presence of iodosylbenzene (PhIO) follow a Michaelis–Menten type mechanism. The performance of 1 and 2 in the epoxidation of cis-cyclooctene, 2-norbornene and limonene are respectively (1) Vmax=8.62, 11.6 and 4.98 mol l−1 min−1 and (2) Vmax=4.28, 7.55 and 5.66 mol l−1 min−1. The activation energies of the epoxidations catalyzed by 1 are 1.5–3.3 kcal mol−1 lower than those measured for 2.

Kinetics of limonene epoxidation by hydrogen peroxide on PW-Amberlite

Selective limonene epoxidation was carried out over a heteropolyacid anchored on Amberlite IRA-900, using hydrogen peroxide as the oxidant. The effects of various parameters such as the concentration of catalyst, H 2O 2, limonene, and water on the rate of reaction have been studied. A mechanism similar to that proposed under the so-called Ishii–Venturello chemistry was used to develop a kinetic model based on the Langmuir–Hinshelwood formalism. This includes the adsorption of reactants and solvent on the catalyst. Although the kinetic model showed to be in agreement with the experimental results, water did not appear to adsorb on the catalytic sites. Furthermore, the influence of epoxide addition to the reaction mixture was examined. Epoxide deactivates the catalyst and the reaction practically stops when the amount of epoxide added is equivalent to about 160 turnovers. Notwithstanding, the catalyst is reactivated after being washed with acetone.

Selectivity in the Oxidation of Limonene by Amphiphilized Metalloporphyrins in Micellar Media

The weak interactions responsible for the aggregation and organization of micellar aggregates have been shown to control the regioselectivity of the epoxidation of limonene catalyzed by manganese porphyrins toward the endo double bond. The same reaction carried out in the presence of aggregates formed by sodium N-dodecanoyl-l-prolinate has shown the same regioselectivity, a selectivity toward the R enantiomer of limonene and a slight but significative stereoselectivity due to the organization of the molecular aggregates.

Alumina-catalyzed alkene epoxidation with hydrogen peroxide

Inexpensive Al 2O 3 can be used as a simple catalyst for alkene epoxidation, using anhydrous hydrogen peroxide as oxidant. This system is active and selective in the epoxidation of several alkenes. Besides the epoxidation of the terpenes limonene and α-pinene, we studied the epoxidation of cyclohexene and cyclooctene, as well as α-olefins, such as 1-octene and 1-decene. Productivities of up to 4.3 g products per gram catalyst were obtained and the catalyst was recycled without significant loss of activity.

Epoxidation of limonene over hydrotalcite-like compounds with hydrogen peroxide in the presence of nitriles

This paper reports the synthesis of an Mg/Al double layered hydroxide (LDH) by coprecipitation, and of its dodecylsulphate (DS) and dodecylbenzenesulphonate (DBS) intercalates by rehydration. The resulting LDHs, also known as hydrotalcite-like compounds, were characterized by using various instrumental techniques including X-ray diffraction (XRD), IR spectroscopy and solid-state NMR spectroscopy. The solids obtained were tested as catalysts in the epoxidation of limonene with hydrogen peroxide. Because the presence of a nitrile was found to be indispensable for the reaction to develop to an acceptable extent, the influence of various nitriles on catalytic activity was examined. The epoxidation reaction yielded limonene oxide.

Catalytic Epoxidation of Limonene

The epoxidation of limonene with hidrogen peroxide was studied over zeolite Tibeta (a large pore material) and heteropoly acids on carbono and alumina supported. PW11/C was catalyst the best tested.

Using inorganic silicate precursor/molybdenum peroxo complexes/onium salt interfaces in aqueous acidic media to design mesoporous silica with high molybdenum content and high dispersion

Mesoporous molybdosilicate, [Mo]-MCM-41, molecular sieves with variable amounts of molybdenum (VI) have been synthesized in acidic media from MoO 3, aqueous hydrogen peroxide and tetraethyl orthosilicate as the silicon source. This procedure avoids the formation of iso-(or hetero-)polyooxometalates and eliminates the need for careful control of the rate of hydrolysis of the metal precursors, e.g. alkoxides, sometimes involved in the syntheses of transition metal-containing mesoporous materials. The parent materials are calcined in air (60°C h −1, isothermal at 920 K for 4 h) to decompose the organic structure-directing agent. The materials have been characterized by chemical analysis, X-ray diffraction and EDS analysis, TEM, 29 Si MAS NMR, UV-visible diffuse reflectance spectroscopy and nitrogen sorption isotherms. In contrast to previous preparations, such syntheses give an increase in the Mo/Si (mol/mol) ratio of up to 0.04 and a greater dispersion of the surface species. For chemical characterization, ( R)-(+)-limonene epoxidation with anhydrous tert-butylhydroperoxide/decane/pentane mixtures was used as a test; high conversions and selectivities can be obtained at 20°C. Different leaching behaviors were observed as a consequence of the different catalyst preparation methods. A comparative IR spectroscopic study was performed to obtain evidence for the formation of [Mo]-OOt-Bu surface species.