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The increasing worries by the inadequate use of energy and the preservation of nature are promoting an increasing interest in the production of biolubricants. After discussing the necessity of producing biolubricants, this review focuses on the production of these interesting molecules through the use of lipases, discussing the different possibilities (esterification of free fatty acids, hydroesterification or transesterification of oils and fats, transesterification of biodiesel with more adequate alcohols, estolides production, modification of fatty acids). The utilization of discarded substrates has special interest due to the double positive ecological impact (e.g., oil distillated, overused oils). Pros and cons of all these possibilities, together with general considerations to optimize the different processes will be outlined. Some possibilities to overcome some of the problems detected in the production of these interesting compounds will be also discussed.

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Epoxidation of castor oil in synthetic and enzymatic routes was carried out in order to promote a system with less environmental impact. The epoxidation reactions of castor oil compounds upon addition of lipase enzyme with and without acrylic immobilization and with reaction times of 24 and 6 h, as well as the synthetic compounds upon addition of Amberlite resin and formic acid, were investigated using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance in hydrogen molecules (1H-NMR). The analysis indicated that the enzymatic reactions (6 h) and synthetic reactions provided a conversion from 50 to 96% and epoxidation from 25 to 48%, resulting from peak stretching and signal disintegration in the hydroxyl region due to the appearance of H2O in the interaction of peracid with catalyst. In systems without toluene, a dehydration event with a peak absorbance of 0.02 AU, indicating a possible vinyl group at 2355 cm-1 in enzymatic reactions without acrylic immobilization, was observed and resulted in a selectivity of 2%. In the absence of a solid catalyst, an unsaturation conversion of castor oil above 90% was achieved; however, this catalyst is necessary for the epoxidation to take place, whereas the lipase enzyme becomes able of epoxidizing and dehydrating the castor oil upon changing the time or reaction system. The conversation from 28 to 48% of solid catalysts (Amberlite and lipase enzyme) displays their importance to the instauration conversion of castor oil into oxirane rings.

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In this study, sulfated tin (IV) oxide solid acid catalyst was prepared for the epoxidation of Argemone mexicana oil (AMO) with peroxyacetic acid formed in-situ. The catalyst was synthesized using the chemical co-precipitation method and characterized. The effects of various epoxidation parameters on ethylenic double bond conversion (%) and oxygen ring content were analyzed. The maximum ethylenic double bond conversion of 95.5% and epoxy oxygen content of 6.25 was found at the molar ratio of AMO to 30% of H2O2 = 1:2.5, molar ratio of AMO to acetic acid = 1:1.5, catalyst concentration = 12.5%, and reaction temperature = 70 °C at reaction time = 6 h. The kinetic and thermodynamic features of the epoxidation of AMO were also analyzed with appropriate models. The results of the kinetic study of the epoxidation reaction followed pseudo first order with the activation energy = 0.47.03 kJ/mol. Moreover, the thermodynamic constants of epoxidation of AMO were found as ΔH = 44.18 kJ/mol, ΔS = -137.91 Jmol-1k-1) and ΔG = 91.12 kJ/mol. The epoxidized product of AMO was further analyzed using FTIR, 1H NMR, and 13C NMR. The results of these analyses confirmed the successful conversion of the ethylenic double bond in the AMO to EAMO.

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Monoterpenes, such as beta-pinene, are secondary metabolites widely used in the flavors and fragrance industries and can have their structure altered to enhance their applicability, such as producing epoxides, which are used as intermediaries for pharmaceuticals. Epoxides are commonly synthesized by the use of inorganic acids as catalysts, although the acid medium induces epoxide degradation. To overcome these limitations biocatalysis is shown as an alternative. Related to, this work aimed to perform the synthesis of ß-Pinene epoxide using Pseudozyma antarctica lipase B (Novozym®435) as a biocatalyst, while determining the independent variables that influence the reaction using experimental design tools. Different solvent systems were evaluated (cyclohexane, acetonitrile, ethyl acetate, and dichloromethane) until 72 h reaction time, from which ethyl acetate showed higher conversion into the epoxidized product (40% in 24 h). Under the other solvents systems, several oxidized by-products were obtained, such as ketones and aldehydes. Moreover, applying metrics of green chemistry, ethyl acetate was also corroborated as the most promising solvent, with a higher atom economy (66.8%) in comparison to the others (41.3%), and a smaller E-value (1.19). Ethyl acetate was the solvent/acyl donor of choice and had the molar ratio and percentage of biocatalyst increased, which resulted in 80% of the product after 3 h of reaction. To obtain an optimized model, four independent variables (temperature, stirring, molar ratio, percentage of biocatalyst) were evaluated using experimental design tools, Fractional Factorial Design and Central Composite Rotatable Design, with conversions ranging from 23 to 95% after 3 h. All the independent variables were statistically significant (p < 0.05) and had different degrees of impact on the conversion. Kinetic parameters of the reaction were determined using the Lineweaver-Burk model (results under 30.1 mmol for Km and 10.7 mmol.min-1 for Vmax). In conclusion, the combination of two different tools of experimental design provided the development of an optimized model for beta-Pinene epoxidation, achieving high conversion to the epoxidized product after 3 h.

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Epoxy resins made from vegetable oils are an alternative to synthesize epoxy resins from renewable sources. Tung oil is rich in α -eleostearic fatty acid, which contains three double bonds producing epoxy resins with up to three epoxy groups per fatty acid. This work studied the production of tung oil epoxy resin using hydrogen peroxide as an oxidizing agent and acetic and formic acid as percarboxylic acid precursors, applying low frequency high power ultrasound. This study evaluated the effects of ultrasound power density, hydrogen peroxide concentration, acetic acid concentration, and formic acid concentration on the yield into epoxy resin, selectivity, and by-products formation. Application of ultrasound was carried out using a 19 kHz probe ultrasound (horn ultrasound) with a 1.3 cm diameter titanium probe, 500 W nominal power, 2940 W L-1 maximum effective power density applied to the reaction mixture. Ultrasound technology yielded up to 85% of epoxy resin in 3 h of reaction. The use of formic acid resulted in a slightly lower oil conversion than acetic acid but with a much higher selectivity towards epoxidized tung oil. However, using acetic acid resulted in the production of high-value by-products, such as 2-heptenal and 2,4-nonadienal. The ultrasound-assisted epoxidation showed to be particularly efficient when applied to oils containing conjugated double-bonds.

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The objective of this research was to investigate the development of epoxides from Chlorella vulgaris lipids to obtain a novel bio-based resin. The process involved the production of fatty acid methyl esters (FAMEs) by in situ transesterification of microalgal biomass, followed by epoxidation of the FAMEs to obtain bioresin. During the FAME production process, an assessment was made of the main factors affecting the production of unsaturated fatty acid methyl esters (UFAMEs), such as catalyst dosage and methanol:hexane volume ratio. For step epoxidation, an evaluation of the catalyst concentration, temperature and formic acid:hydrogen peroxide ratio was made. From the results obtained, UFAME production was maximized using 20 wt% of catalyst dosage and a volume ratio of 1:2 (v/v, methanol:hexane). Then, in the epoxidation stage, a higher yield was obtained using 1 wt% of catalyst with a volume ratio of 1:1 and maintaining a temperature of 70 °C. The bioresin was blended with neat epoxy resin (DGEBA) and cured with tetraethylenepentamine (TEPA). Bio-based resin was characterized via Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) to evaluate this material as an alternative source for oleochemistry.

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A study of the reactivity of 25R and 25S 23E-benzylidene spirostanes that includes epoxidation, catalytic hydrogenation as well as Lewis or Brønsted acid-catalyzed rearrangements is described. Exhaustive NMR characterization of the obtained compounds is presented. Additionally the structures of some of the obtained compounds were confirmed by single crystal X-Ray Diffraction studies.

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Nowadays the industrial chemistry reactions rely on green technologies. Enzymes as lipases are increasing its use in diverse chemical processes. Epoxidized fatty acid methyl esters obtained from transesterification of vegetable oils have recently found applications as polymer plasticizer, agrochemical, cosmetics, pharmaceuticals and food additives. In this research article, grapeseed, avocado and olive oils naturally containing high percents of mono and poly unsaturations were used as starting materials for the production of unsaturated fatty acid methyl esters. The effect of lauric acid as an active oxygen carrier was studied on epoxidation reactions where unsaturated fatty acid methyl esters were converted to epoxy fatty acid methyl esters using immobilized Candida antarctica Lipase type B as catalyst and hydrogen peroxide as oxygen donor at mild temperature and pressure conditions. After this study it was confirmed by 1H NMR, 13C NMR and GC-MS that the addition of lauric acid to the enzymatic reaction is unnecessary to transform the alkenes in to epoxides. It was found that quantitative conversions were possible in despite of a carboxylic acid absence.

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This review presents the recent research in biocatalysis and biotransformation in Brazil. Several substrates were biotransformed by fungi, bacteria and plants. Biocatalytic deracemization of secondary alcohols, oxidation of sulfides, sp(3) CH hydroxylation and epoxidation of alkenes were described. Chemo-enzymatic resolution of racemic alcohols and amines were carried out with lipases using several substrates containing heteroatoms such as silicon, boron, selenium and tellurium. Biotransformation of nitriles by marine fungi, hydrolysis of epoxides by microorganisms of Brazilian origin and biooxidation of natural products were described. Enzymatic reactions under microwave irradiation, continuous flow, and enzymatic assays using fluorescent probes were reported.

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External flavoprotein monooxygenases comprise a group of flavin-dependent oxidoreductases that catalyze the insertion of one atom of molecular oxygen into an organic substrate and the second atom is reduced to water. These enzymes are involved in a great number of metabolic pathways both in prokaryotes and eukaryotes. Flavoprotein monooxygenases have attracted the attention of researchers for several decades and the advent of recombinant DNA technology caused a great progress in the field. These enzymes are subjected to detailed biochemical and structural characterization and some of them are also regarded as appealing oxidative biocatalysts for the production of fine chemicals and valuable intermediates toward active pharmaceutical ingredients due to their high chemo-, stereo-, and regioselectivity. Here, we review the most representative reactions catalyzed both in vivo and in vitro by prototype flavoprotein monooxygenases, highlighting the strategies employed to produce them recombinantly, to enhance the yield of soluble proteins, and to improve cofactor regeneration in order to obtain versatile biocatalysts. Although we describe the most outstanding features of flavoprotein monooxygenases, we mainly focus on enzymes that were cloned, expressed and used for biocatalysis during the last years.

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In this study HPLC-DAD-MS/MS was applied for the identification of compounds derived from (all-E)-ß-carotene following epoxidation and oxidative cleavage. The consequences on the CIELAB colour parameters and antioxidant capacity (AC) were also evaluated. Five apocarotenoids, three secocarotenoids, seven Z isomers and two epoxides were detected as a result of the oxidative cleavage. Four epoxides and three Z isomers were detected as a consequence of the epoxidation reaction. Some compounds were detected for the first time as a result of oxidation reactions. Both treatments led to a marked decrease in b(∗) and Cab(∗) values, indicating that these colour parameters can be used for the rapid assessment of ß-carotene oxidation. The oxidative cleavage of ß-carotene resulted in increased capacity to both scavenge ABTS(+) and quench singlet oxygen. These results suggest that the study of the AC of these oxidative derivatives and their possible usefulness as food ingredients deserves further attention.

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