Enzyme-mediated epoxidation of methyl oleate supported by imidazolium-based ionic liquids

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

The High ‘Lipolytic Jump’ of Immobilized Amano A Lipase from Aspergillus niger in Developed ‘ESS Catalytic Triangles’ Containing Natural Origin Substrates

Lipase Amano A from Aspergillus niger (AA-ANL) is among the most commonly applied enzymes in biocatalysis processes, making it a significant scientific subject in the pharmaceutical and medical disciplines. In this study, we investigated the lipolytic activity of AA-ANL immobilized onto polyacrylic support IB-150A in 23 oils of natural origin containing various amounts of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs). The created systems were expressed as an ‘ESS catalytic triangle’. A distinct ‘jump’ (up to 2400%) of lipolytic activity of immobilized AA-ANL compared to free lipase and hyperactivation in mostly tested substrates was observed. There was a ‘cutoff limit’ in a quantitative mutual ratio of ω-PUFAs/MUFAs, for which there was an increase or decrease in the activity of the immobilized AA-ANL. In addition, we observed the beneficial effect of immobilization using three polyacrylic supports (IB-150A, IB-D152, and IB-EC1) characterized by different intramolecular interactions. The developed substrate systems demonstrated considerable hyperactivation of immobilized AA-ANL. Moreover, a ‘lipolytic jump’ in the full range of tested temperature and pH was also observed. The considerable activity of AA-ANL-IB-150A after four reuse cycles was demonstrated. On the other hand, we observed an essential decrease in stability of immobilized lipase after 168 h of storage in a climate chamber. The tested kinetic profile of immobilized AA-ANL confirmed the increased affinity to the substrate relative to lipase in the free form.

Biocatalytic Epoxidation of Cyclooctene to 1,2-Epoxycyclooctane by a Newly Immobilized Aspergillus niger Lipase

A newly immobilized Aspergillus niger lipase (ANL@ZnGlu-MNPs) was employed for the preparation of 1,2-epoxycyclooctane by oxidation of cyclooctene. The chosen variables, including substrate concentration, reaction temperature, immobilized enzyme dose, and H2O2 dose, were optimized in the reaction system of ethyl acetate. The yield and the enantiomeric excess of the product were achieved at 56.8% and 84.1%, respectively, under the following optimum reaction conditions: the concentration of substrate (cyclooctene) was 150 mM, the dosages of immobilized enzyme (ANL@ZnGlu-MNPs) and hydrogen peroxide were respectively 100 mg and 4.4 mmol, and the reaction was carried out in the system of 4 mL ethyl acetate at 40 °C. Further study on the operational stability of ANL@ZnGlu-MNPs showed that more than 51.6% of product yield was obtained after reusing for ten batches. A novel immobilized lipase was prepared and applied to synthesize 1,2-epoxycyclooctane from cyclooctene. Although ANL@ZnGlu-MNPs performs well in operational stability and the reaction can achieve high enantiomeric purity of the product, the yield of the catalytic reaction needs to be further improved.

Epoxidación enzimática de metil ésteres de ácidos grasos de origen vegetal y sus aplicaciones como alternativa para sustituir a los derivados del petróleo

Recientemente, la modificación de aceites vegetales para obtener ésteres metílicos de ácidos grasos (FAMEs) o biodiesel ha emergido como una alternativa para la sustitución de los derivados del petróleo, esto debido a los problemas ambientales y de salud que genera su uso. Debido a su estructura química es posible epoxidar estas moléculas y usarlas directamente para producir plastificantes o lubricantes. Sin embargo, éstas también pueden ser sujetas a modificaciones para mejorar sus propiedades y el de servir como intermediarias para la síntesis de poliuretanos. Puesto que los métodos convencionales para la producción de epóxidos también son una fuente potencial de contaminación, se ha sugerido el uso de catalizadores enzimáticos como una alternativa sostenible o “Verde” para su preparación, ya que permiten obtener productos con alta pureza y mejores rendimientos. Este artículo presenta una revisión de la literatura disponible centrándose en la epoxidación enzimática de los FAMEs, así como sus principales aplicaciones.

Applications of Liquid/Liquid Biphasic Oxidations by Hydrogen Peroxide with Ionic Liquids or Deep Eutectic Solvents

This Minireview focuses on recent applications of ionic liquids (ILs) and deep eutectic solvents (DESs) in biphasic oxidations in which the oxidizing agent corresponds to hydrogen peroxide. Biphasic reactions are accomplished when the substrate presents low or moderate solubility in aqueous (polar) systems and/or when separation of products and byproduct is an issue. The properties of the IL and DES allows the reaction activity to be intensified. On the other hand, the high chemical stability of the ionic solvents allows the use of hydrogen peroxide to minimize solvent degradation and unwanted byproducts. The experimental evidence presented herein shows that ILs and DESs can be used as cocatalysts, catalysts, and solvents to achieve enhanced yields and conversions. The process advantages, in terms of a reduction of volatile solvents, improve the safety and use of the oxidizing agent, which implies the possibility of developing new process improvements in the future.

Enzymatic Hydrolytic Resolution of Racemic Ibuprofen Ethyl Ester Using an Ionic Liquid as Cosolvent

The aim of this study was to develop an ionic liquid (IL) system for the enzymatic resolution of racemic ibuprofen ethyl ester to produce (S)-ibuprofen. Nineteen ILs were selected for use in buffer systems to investigate the effects of ILs as cosolvents for the production of (S)-ibuprofen using thermostable esterase (EST10) from Thermotoga maritima. Analysis of the catalytic efficiency and conformation of EST10 showed that [OmPy][BF₄] was the best medium for the EST10-catalyzed production of (S)-ibuprofen. The maximum degree of conversion degree (47.4%), enantiomeric excess of (S)-ibuprofen (96.6%) and enantiomeric ratio of EST10 (177.0) were achieved with an EST10 concentration of 15 mg/mL, racemic ibuprofen ethyl ester concentration of 150 mM, at 75 °C , with a reaction time of 10 h. The reaction time needed to achieve the highest yield of (S)-ibuprofen was decreased from 24 h to 10 h. These results are relevant to the proposed application of ILs as solvents for the EST10-catalyzed production of (S)-ibuprofen.

Combination of deep eutectic solvent and ionic liquid to improve biocatalytic reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cell

The efficient anti-Prelog asymmetric reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cells was successfully performed in a biphasic system consisting of deep eutectic solvent (DES) and water-immiscible ionic liquid (IL). Various DESs exerted different effects on the synthesis of (R)-2-octanol. Choline chloride/ethylene glycol (ChCl/EG) exhibited good biocompatibility and could moderately increase the cell membrane permeability thus leading to the better results. Adding ChCl/EG increased the optimal substrate concentration from 40 mM to 60 mM and the product e.e. kept above 99.9%. To further improve the reaction efficiency, water-immiscible ILs were introduced to the reaction system and an enhanced substrate concentration (1.5 M) was observed with C₄MIM·PF₆. Additionally, the cells manifested good operational stability in the reaction system. Thus, the efficient biocatalytic process with ChCl/EG and C₄MIM·PF₆ was promising for efficient synthesis of (R)-2-octanol.

Nanoparticle supported, magnetically separable manganese porphyrin as an efficient retrievable nanocatalyst in hydrocarbon oxidation reactions

Magnetically separable manganese porphyrin was prepared by immobilizing on functionalized magnetic nanoparticles via the amino propyl linkage and used as an efficient retrievable nanocatalyst in hydrocarbon oxidation reactions.

Technological Aspects of Chemoenzymatic Epoxidation of Fatty Acids, Fatty Acid Esters and Vegetable Oils: A Review

The general subject of the review is analysis of the effect of technological parameters on the chemoenzymatic epoxidation processes of vegetable oils, fatty acids and alkyl esters of fatty acids. The technological parameters considered include temperature, concentration, amount of hydrogen peroxide relative to the number of unsaturated bonds, the amounts of enzyme catalysts, presence of solvent and amount of free fatty acids. Also chemical reactions accompanying the technological processes are discussed together with different technological options and significance of the products obtained.

Amphiphilic polyoxometalate-paired polymer coated Fe₃O₄: magnetically recyclable catalyst for epoxidation of bio-derived olefins with H₂O₂

An amphiphilic composite with magnetic Fe3O4 core and dodecylamine-modified polyoxometalate-paired poly(ionic liquid) shell was synthesized and characterized by (1)H NMR, thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectroscopy, X-ray diffraction (XRD), and digital microscopy. Catalytic tests for H2O2-based epoxidation of bioderived olefins, along with comparisons to various counterparts, demonstrate well that this newly designed catalyst exhibits high activity and selectivity, coupled with convenient magnetic recovery, and effective regeneration. The unique amphiphilic catalyst structure and the intramolecular charge transfer between amino groups and heteropolyanions are revealed to be responsible for the catalyst's excellent performances in epoxidation reactions.

Chemoenzymatic epoxidation of alkenes and reusability study of the phenylacetic acid

Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The immobilised Candida antarctica lipase B, Novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide (H₂O₂) and phenylacetic acid. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. A variety of alkenes were oxidised with this system, resulting in 75–99% yield of the respective epoxides. On the other hand, the phenylacetic acid was recovered from the reaction media and reused for more epoxidation. Interestingly, the waste phenylacetic acid had the ability to be reused for epoxidation of the 1-nonene to 1-nonene oxide, giving an excellent yield of 90%.

Application of ionic liquids in liquid chromatography and electrodriven separation

Ionic liquids (ILs) are salts in the liquid state at ambient temperature, which are nonvolatile, nonflammable with high thermal stability and dissolve easily for a wide range of inorganic and organic materials. As a kind of potential green solvent, they show high efficiency and selectivity in the field of separation research, especially in instrumental analysis. Thus far, ILs have been successfully applied by many related researchers in high-performance liquid chromatography and capillary electrophoresis as chromatographic stationary phases, mobile phase additives or electroosmotic flow modifiers. This paper provides a detailed review of these applications in the study of natural products, foods, drugs and other fine chemicals. Furthermore, the prospects of ILs in liquid chromatographic and electrodriven techniques are discussed.

The Biginelli reaction with an imidazolium-tagged recyclable iron catalyst: kinetics, mechanism, and antitumoral activity

The present work describes the synthesis, characterization, and application of a new ion-tagged iron catalyst. The catalyst was employed in the Biginelli reaction with impressive performance. High yields have been achieved when the reaction was carried out in imidazolium-based ionic liquids (BMI⋅PF6, BMI⋅NTf2, and BMI⋅BF4), thus showing that the ionic-liquid effects play a role in the reaction. Moreover, the ion-tagged catalyst could be recovered and reused up to eight times without any noticeable loss in activity. Mechanistic studies performed by using high-resolution electrospray-ionization quadrupole-time-of-flight mass (HR-EI-QTOF) spectrometry and kinetic experiments indicate only one reaction pathway and rule out the other two possibilities under the development conditions. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. Finally, the 37 dihydropyrimidinone derivatives, products of the Biginelli reaction, had their cytotoxicity evaluated in assays against MCF-7 cancer cell linages with encouraging results of some derivatives, which were virtually non-toxic against healthy cell linages (fibroblasts).

Iron complex with ionic tag-catalyzed olefin reduction under oxidative conditions--a different reaction for iron

An iron(III) complex with ionic tags was applied to the reduction of alkenes in imidazolium-based ionic liquids (ILs) under oxidative conditions. The catalyst is very efficient to promote reactions of biomass derivatives. At least ten recycling reactions were performed without any loss of catalytic activity. Some important mechanistic insights for this new reaction are also provided based mostly on electrospray ionization quadrupole-time of flight mass spectrometry (ESI-QTOF-MS).

Optimization of lipase-mediated synthesis of 1-nonene oxide using phenylacetic acid and hydrogen peroxide

Herein, an efficient epoxidation of 1-nonene is described. In a simple epoxidation system, commercially available Novozym 435, an immobilized Candida antarctica lipase B, and hydrogen peroxide (H₂O₂) were utilized to facilitate the in situ oxidation of phenylacetic acid to the corresponding peroxy acid which then reacted with 1-nonene to give 1-nonene oxide with high yield and selectivity. The aliphatic terminal alkene was epoxidised efficiently in chloroform to give an excellent yield (97%–99%) under the optimum reaction conditions, including temperature (35 °C), initial H₂O₂ concentration (30%), H₂O₂ amount (4.4 mmol), H₂O₂ addition rate (one step), acid amount (8.8 mmol), and stirring speed (250 rpm). Interestingly, the enzyme was stable under the single-step addition of H₂O₂ with a catalytic activity of 190.0 Ug⁻¹. The entire epoxidation process was carried out within 12 h using a conventional water bath shaker.

Biodiesel synthesis and conformation of lipase from Burkholderia cepacia in room temperature ionic liquids and organic solvents

Biodiesel synthesis and conformation of Burkholderia cepacia lipase (BCL) were studied in 19 different room temperature ionic liquids (RTLLs) with a range of cation and anion structures. Overall, anion selection had a greater influence on biodiesel conversion than cation choice. RTILs containing Tf2N- and PF6- anions were suitable reaction media, while RTIL of [OmPy][BF4] was the best reaction medium with a biodiesel yield of 82.2±1.2%. RTILs with strong water miscible properties showed very low biodiesel yields. Conformational analysis by FT-IR revealed that higher biodiesel conversion in RTILs was correlated with a low tendency in α-helix content of BCL. An ultrasound-assisted biocatalysis process in RTILs was used to improve mass transfer rate, leading to 83% reduction of the reaction time for biodiesel production.