Substrate Molar Ratio Research Articles

Synthesis of glyceryl monocaffeate using ionic liquids as catalysts

Glyceryl monocaffeate (GMC) is the hydrophilic derivative of caffeic acid (CA), which can be used in cosmetic and food industries. In this paper, GMC was prepared by the reaction of glycerol with different caffeoyl donors (CA, or ethyl caffeic (EC)). Seven functionalized ionic liquids ([PSO3HMIM]HSO4, [BSO3HMIM]TS, [BSO3HMIM]OTF, [BSO3HMIM]HSO4, [AAMIM]HSO4, [BSO3HMIM]HPO4 and [HMIM]HSO4) were used as catalysts. Effects of reaction variables (reaction temperature, time, pressure, catalyst load and molar ratio of substrates) on CA conversion and GMC yield were investigated. For the esterification of glycerol with CA, high CA conversion (95.6±2.1%) and GMC yield (93.8±3.2%) were achieved using [BSO3HMIM]TS as catalyst under the following conditions: 90°C, CA/glycerol 1:10 (mol/mol), catalyst load 10% (relative to the weight of all substrates), 2h. Activation energies (Ea) of CA conversion and GMC formation were 84.53kJ/mol and 86.67kJ/mol, respectively, which were lower than those (111.79, 116.24kJ/mol) of EC as caffeoyl donor.

A STATISTICAL APPROACH FOR OPTIMIZING THE HIGH YIELD GREEN PRODUCTION OF THE FLAVOR ESTER BUTYL BUTYRATE

Being the prevailing approach for producing esters such as butyl butyrate, the use of chemical route has been linked to numerous disadvantages. Hence, a green alternative method for higher yield production of butyl butyrate by esterification reaction utilizing Novozyme 435 as biocatalysts in a solvent-less system may prove useful. Such approach can be further improved by optimizing the relevant reaction parameters using the Response Surface Methodology by the Box-Benkhen Design attempted in this present study. The reaction parameters evaluated were: substrate molar ratio, time and temperature, and the response of each parameter was measured as percentage conversion yield. Using the Design Expert 7.1.6 optimization functions, the two sets of optimum conditions selected viz. [i] molar ratio butyric acid:butanol 1:3.93, 9.93 h at 56.09°C and [ii] molar ratio butyric acid:butanol 1:3.35, 9.79 h at 53.90°C had afforded the highest yield of butyl butyrate i.e. 99.62% and 99.55%, respectively. The ester product obtained from the reaction were confirmed as butyl butyrate by FTIR and GC. Therefore, the results substantiated the applicability of the RSM prediction technique as well as efficacy of Novozyme 435 as biocatalysts in the high yield solvent-less synthesis of butyl butyrate, adhering to the philosophy of Green Chemistry.

Lipase-Catalyzed Transesterification of Egg-Yolk Phophatidylcholine with Concentrate of n-3 Polyunsaturated Fatty Acids from Cod Liver Oil.

Phospholipids containing PUFAs are important vehicles for their delivering to the targeted tissues. In our research project we established enzymatic methods for the enrichment of natural egg-yolk PC with n-3 PUFAs. Instead of synthetic PUFA ethyl esters, the new strategy was developed using polyunsaturated fatty acids enriched fraction (PUFA-EF) from cod liver oil as the natural acyl donors. PUFA-EF was produced by urea-complexation and contained 86.9% PUFA including 8.5% stearidonic acid (SDA; 18:4(n-3)), 26.7% EPA, and 45.2% DHA. The transesterification of PC with PUFA was catalyzed by lipases. After screening of enzymes the effect of reaction medium; molar ratio of substrates and etc. was investigated. The highest incorporation of PUFA was 45.6%; including 36.8% DHA and 5.8% EPA at the following reaction conditions: hexane; 55 °C; PUFA-EF/PC acyl ratio of 10; 48 h of reaction time and lipase B from Candida antarctica as a biocatalyst (20% of enzyme load).

Aspergillus niger whole-cell catalyzed synthesis of caffeic acid phenethyl ester in ionic liquids.

Synthesis of caffeic acid ester essentially requires an efficient esterification process to produce various kinds of medicinally important ester derivatives. In the present study, a comprehensive and comparative analysis of whole-cell catalyzed caffeic acid esters production in ionic liquids (ILs) media was performed. Olive oil induced mycelial mass of halotolerant Aspergillus niger (A.niger) EXF 4321 was freeze dried and used as a catalyst. To ensure maximum solubilization of caffeic acid for highest substrate loading several ILs were screened and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N]) was found to have the maximum solubility and favoured for enzymatic activity of freeze dried mycelia. The whole-cell catalyzed synthesis of caffeic acid phenethyl ester (CAPE) conditions were optimized and bioconversion up to 84% was achieved at a substrate molar ratio of 1:20 (caffeic acid:2-phenyl ethanol), 30°C for 12h. Results obtained during this study were encouraging and helpful to design a bioreactor system to produce caffeic acid derived esters.

Highly Efficient Deacidification of High-Acid Rice Bran Oil Using Methanol as a Novel Acyl Acceptor.

A highly efficient process for reducing the fatty acid (FA) content of high-acid rice bran oil (RBO) was developed by immobilized partial glycerides-selective lipase SMG1-F278N-catalyzed esterification/transesterification using methanol as a novel acyl acceptor. Molecular docking simulation indicated that methanol was much closer to the catalytic serine (Ser-171) compared with ethanol and glycerol, which might be one of the reasons for its high efficiency in the deacidification of high-acid RBO. Additionally, the reaction parameters were optimized to minimize the FA content of high-acid RBO. Under the optimal conditions (substrate molar ratio of methanol to FAs of 1.8:1, enzyme loading of 40U/g, and at 30°C), FA content decreased from 25.14 to 0.03% after 6h of reaction. Immobilized SMG1-F278N exhibited excellent methanol tolerance and retained almost 100% of its initial activity after being used for ten batches. After purification by molecular distillation, the final product contained 97.86% triacylglycerol, 2.10% diacylglycerol, and 0.04% FA. The acid value of the final product was 0.09mg KOH/g, which reached the grade one standard of edible oil. Overall, methanol was a superior acyl acceptor for the deacidification of high-acid RBO and the high reusability of immobilized SMG1-F278N indicates an economically attractive process.

Enzymatic esterification of eugenol and benzoic acid by a novel chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase: Process optimization and kinetic assessments.

A biotechnological route via enzymatic esterification was proposed as an alternative way to synthesize the problematic anti-oxidant eugenyl benzoate. The new method overcomes the well-known drawbacks of the chemical route in favor of a more sustainable reaction process. The present work reports a Box-Behnken design (BBD) optimization process to synthesize eugenyl benzoate by esterification of eugenol and benzoic acid catalyzed by the chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase (RML-CS/CNWs). Effects of four reaction parameters: reaction time, temperature, substrate molar ratio of eugenol: benzoic acid and enzyme loading were assessed. Under optimum conditions, a maximum conversion yield as high as 66% at 50°C in 5h using 3mg/mL of RML-CS/CNWs, and a substrate molar ratio (eugenol: benzoic acid) of 3:1. Kinetic assessments revealed the RML-CS/CNWs catalyzed the reaction via a ping-pong bi-bi mechanism with eugenol inhibition, characterized by a Vmax of 3.83mMmin-1. The Michaelis-Menten constants for benzoic acid (Km,A) and eugenol (Km,B) were 34.04 and 138.28mM, respectively. The inhibition constant for eugenol (Ki,B) was 438.6mM while the turnover number (kcat) for the RML-CS/CNWs-catalyzed esterification reaction was 40.39min-1. RML-CS/CNWs were reusable up to 8 esterification cycles and showed higher thermal stability than free RML.

Intensification of acid catalyzed synthesis of tricaprylin using ultrasound pretreatment

Intensified synthesis of tricaprylin from caprylic acid and glycerol has been investigated based on novel approach of using ultrasound only in initial stages of the esterification under solvent free conditions. The effect of ultrasonic conditions such as time and power during the pretreatment as well as the reaction conditions such as substrate molar ratio, reaction time and catalyst loading during the conventional reaction on the yield of tricaprylin has been investigated. It was observed that the optimum pretreatment conditions were irradiation time of 60min with 240W supplied power and 60% duty cycle. The optimum reaction conditions were 4:1 molar ratio of caprylic acid to glycerol, catalyst loading as 1% and operating temperature of 170°C. Three different catalysts as sulphuric acid, hydrochloric acid and para-toluene sulphonic acid (PTSA) have been used to investigate the effect of type of catalyst and also the effect of the presence of adsorbent as silica gel was investigated. The obtained results confirmed that the activity of H2SO4 was higher as compared to HCL and PTSA. It was conclusively established that ultrasound pretreatment based approach greatly influenced the rate of reaction in comparison to the conventional approach and resulted in a green processing approach with maximum tricaprylin yield of 96.6% achieved in 9h of reaction time compared to 24h with conventional approach.

Kinetics of lipase-catalysed methyl gallate production in the presence of deep eutectic solvent

Production of methyl gallate (MG), which is an important phenolic acid ester for pharmaceutical industry, was carried out by Novozym 435-catalysed transesterification of propyl gallate (PG) with methanol in a deep eutectic solvent. Reaction parameters governing substrate molar ratio, enzyme concentration, temperature and agitation rate were investigated batch-wise in choline chloride:glycerol-water binary mixture. The results were evaluated in terms of conversion of PG, yield of MG and hydrolysis of PG to gallic acid. 10% (w/w) of water was found to be favourable in the reaction medium for low hydrolysis percent. The highest conversion (17.4%) and yield (60.4%) but the lowest hydrolysis (2%) after 120 h of transesterification were found at PG/methanol molar ratio of 1:6, enzyme concentration of 40 g/L, 50 °C and 200 rpm. A kinetic model based on the Ping-Pong Bi–Bi mechanism for transesterification of PG was proposed with the assumption that there were no internal and external mass transfer resistances.

Application of Transgalactosylation Activity of \u03b2-Galactosidase from Kluyveromyces lactis for the Synthesis of Ascorbic Acid Galactoside

In view of a commonly known beneficial role and low stability of ascorbic acid, many efforts are constantly undertaken to produce its improved derivatives. This paper presents results on the synthesis of ascorbic acid galactoside using transgalactosylation properties of β-galactosidase from Kluyveromyces lactis and lactose as a donor of galactosyl moiety. The purpose of this study was to determine the influence of selected factors (concentration and molar ratio of substrates, amount of the enzyme preparation, pH of the solution, presence of different ions) on the course of transgalactosylation reaction. Research has shown that approx. 2.5% dry matter (d.m.; 12.7 g/L) of ascorbic acid galactoside is formed under favourable conditions (50% (w/v) substrates, sodium ascorbate and lactose at the molar ratio of 1.9:1, enzyme dose of 28,600 U/100 g lactose, pH = 7.0). The addition of Mg2+ or K+ ions to the reaction medium caused an increase in the final product content (even up to approx. 3.4% d.m., 17.2 g/L), while Na+ or Mn2+ had an adverse impact on the yield. The gathered data may be valuable for cosmetic or food industry.

Baeyer‐Villiger oxidation of cyclopentanone over zeolite Y entrapped transition metal‐Schiff base complexes

Transition metal [M = VO (IV) and/or Cu (II)] complexes with Schiff base ligand, (Z)‐2‐((2‐hydroxybenzylideneamino)phenol (H2L) have been entrapped in the super cages of zeolite‐Y by Flexible Ligand Method. Synthesized materials have been characterized by preferential physico‐chemical techniques such as inductively coupled plasma optical emission spectroscopy (ICP‐OES), elemental analyses (CHN), fourier transmission infrared spectroscopy (FTIR), electronic and UV‐reflectance spectra, Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron micrographs (SEMs), X‐ray diffraction patterns (XRD) and thermogravimetric analysis (TGA). The catalytic competence of zeolite‐Y entrapped transition metal complexes was examined in Baeyer‐Villiger (BV) oxidation of cyclopentanone using 30% H2O2 as an oxidant beside neat complexes to check the aptitude of heterogeneous catalysis over the homogeneous system. The effect of experimental variables such as mole ratio of substrate to an oxidant, amount of catalyst, reaction time, varying oxidants and solvents on the conversion of cyclopentanone was also tested. Under the optimized reaction conditions, one of the zeolite‐Y entrapped transition metal complex viz. [VO(L)H2O]‐Y [where L = (Z)‐2‐((2‐hydroxybenzylideneamino)phenol] was found to be a potential contender by providing 80.22% conversion of cyclopentanone (TON: 10479.42), and the selectivity towards δ‐valerolactone was 83.56%.

Production of structured lipid with a low omega-6/omega-3 fatty acids ratio by enzymatic interesterification

A structured lipid (SL) constituting omega fatty acids was synthesized by using linseed and grape seed oils as substrates via a lipase-catalyzed reaction. Lipozyme® TL IM was used as a biocatalyst. Good quadratic models predicting the incorporation of omega fatty acids were achieved via the Response surface methodology (RSM). The optimal conditions for targeted omega-6/omega-3 fatty acid ratio (2:1) were obtained at a substrate molar ratio 1.4, time 8.4 h, and enzyme amount 6.4%. The SL contained linoleic acid (43 g 100g-1), which was mainly located in the sn-2 position (40 g 100g-1). ?-Linoleic acid, and α-linolenic acid at the sn-2 position were 22 g 100g-1, and 11 g 100g-1, respectively. The oxidative stability of the SL, and SL with antioxidants was also investigated. The produced SL may be proposed as a source of a balanced intake of omega fatty acids and an ingredient in functional food formulations.

Continuous Microflow Synthesis of Fuel Precursors from Platform Molecules Catalyzed by 1,5,7-Triazabicyclo[4.4.0]dec-5-ene

The first continuous flow synthesis of C8–C16 alkane fuel precursors from biobased platform molecules is reported. TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene) was found to be a recyclable and highly efficient organic base catalyst for the aldol condensation of furfural with carbonyl compounds, and the selectivity of mono- or difuryl product can be easily regulated by adjusting the molar ratio of substrates. By means of flow technique, a shorter reaction time, satisfactory output, and continuous preparation are achieved under the present procedure, representing a significant advance over the corresponding batch reaction conditions.

Synthesis and evaluation of novel ascorbyl cinnamates as potential anti-oxidant and antimicrobial agents

An efficient preparation procedure has been proposed for the synthesis of 5,6-di-O-cinnamyl-l-ascorbic acid ester (5,6-CA–AA) and 2-O-cinnamyl-l-ascorbic acid ester (2-CA–AA) via ascorbic acid (AA) and cinnamic acid (CA), and their anti-oxidant and antibacterial activities were also investigated. Among the factors affecting the synthesis efficiency of 5,6-CA–AA and 2-CA–AA, reaction solvent and substrate molar ratio were very important, resulting in 76 and 54% total yield, respectively. Further studies indicated that 5,6-CA–AA maintained the inherent inhibitory ability of AA in α, α-diphenyl-β-picrylhydrazyl radical scavenging assay. Also, it had stronger scavenging activity against hydroxyl radicals than that of standard tert-butylhydroquinone (EC50: 7.84 vs. 8.38 mM). In addition, 5,6-CA–AA and 2-CA–AA possessed comparable antibacterial activity to that of CA. Significantly, the application of ascorbyl cinnamate could retard the lipid oxidation of peanut oil and pork, and the corresponding perioxide value and thiobarbituric acid reactive substance content decreased by 32.0 and 56.5%, respectively. Moreover, the microbial reproduction of the pork treated with mixed ascorbyl cinnamate was attenuated to some extent. These investigations will pave the way for designing more efficient bifunctional derivatives of AA and CA.

Kinetics of Enzymatic Synthesis of Cinnamyl Butyrate by Immobilized Lipase.

This work illustrates the enzymatic synthesis of cinnamyl butyrate by esterification of butyric acid and cinnamyl alcohol. Experiments were performed to study the various operating parameters such as molar ratio, enzyme concentration, temperature, and speed of agitation. Also, the suitable kinetic model for esterification reaction was predicted and the various kinetic parameters were determined. It has been observed that the experimental results agree well with the simulated results obtained by following the ping-pong bi-bi mechanism with dead-end inhibition by both the substrate acid and alcohol. The highest 90% conversion of butyric acid was observed after 12h at the following reaction conditions: substrate molar ratio 1:2 (butyric acid/cinnamyl alcohol), temperature 50°C, enzyme loading 2% (with respect to the weight of the substrates), and agitation speed 250rpm. Diffusional mass transfer limitations between substrate and enzyme surface do not show significant effect on reaction kinetics. Enzyme reusability study reveals that it retains 85% of its catalytic activity after five consecutive cycles.

Factors screening to statistical experimental design of racemic atenolol kinetic resolution via transesterification reaction in organic solvent using free Pseudomonas fluorescens lipase.

As the (R)-enantiomer of racemic atenolol has no β-blocking activity and no lack of side effects, switching from the racemate to the (S)-atenolol is more favorable. Transesterification of racemic atenolol using free enzymes investigated as a resource to resolve the racemate via this method is limited. Screenings of enzyme, medium, and acetyl donor were conducted first to give Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate. A statistical design of the experiment was then developed using Central Composite Design on some operational factors, which resulted in the conversions of 11.70-61.91% and substrate enantiomeric excess (ee) of 7.31-100%. The quadratic models are acceptable with R2 of 95.13% (conversion) and 89.63% (ee). The predicted values match the observed values reasonably well. Temperature, agitation speed, and substrate molar ratio factor have low effects on conversion and ee, but enzyme loading affects the responses highly. The interaction of temperature-agitation speed and temperature-substrate molar ratio show significant effects on conversion, while temperature-agitation speed, temperature-substrate molar ratio, and agitation speed-substrate molar ratio affect ee highly. Optimum conditions for the use of Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate were found at 45°C, 175rpm, 2000U, and 1:3.6 substrate molar ratio.

Synthesis of eugenyl acetate by immobilized lipase in a packed bed reactor and evaluation of its larvicidal activity

Abstract Eugenol esters, including eugenyl acetate, has been intensively investigated because of its beneficial antioxidant, antimicrobial, antitumor and potential larvicidal properties. Recent studies verified that small amounts of eugenol esters are effective against the development of larvae of Aedes egytpti . Packed bed reactors (PBR) have been employed for the synthesis of a variety of esters, as it is essential to assess some process parameters such as molar ratio of substrates, operating temperature and reaction residence time. Based on these aspects, the objective of this study was to evaluate the effect of molar ratio of eugenol and acetic anhydride, reaction temperature and substrates flow rate on the synthesis of eugenyl acetate esters in a packed bed reactor, using Lipozyme TL IM lipase as catalyst, and to determine the larvicidal activity of the obtained ester against larvae of A. aegypti . The optimal condition was obtained with flow rate of 0.1 mL min −1 , 55 °C and 1:5.82 (eugenol:acetic anhydride) molar ratio, affording a conversion value of about 93%. Further, the potential toxicity of A. aegypti larvae increased under the effect of eugenyl acetate, presenting a LC 50 of 0.102 mg mL −1 , which demonstrates its usability as a natural compound that can be employed in commercial larvicidal formulations.

Three-Component Reaction of Benzylamines, Diethyl Phosphite and Triethyl Orthoformate: Dependence of the Reaction Course on the Structural Features of the Substrates and Reaction Conditions.

The reaction between benzyl amines, triethyl orthoformate, and diethyl phosphite affords either bisphosphonic (compound 1) or N-benzylaminobenzylphosphonic (compound 2) acid depending on the reaction conditions. The final output of the reaction can be manipulated by the choice of reaction conditions, particularly the molar ratio of substrates.

The Response Surface Methodology as a tool to optimize the extraction and acid hydrolysis processes applied to babassu residues

Neste trabalho, a nova abordagem para obter extrativos, hemicelulose e lignina total a partir de típicos resíduos de biomassa brasileira é otimizada pela Metodologia de Superfície de Resposta (MSR). Os efeitos das variáveis reacionais, incluindo o tempo de reação e extração das hidrólises, assim como a razão molar do substrato álcool foram investigados. Foram usados modelos de regressão polinomiais quadráticos para analisar os dados experimentais. O coeficiente de determinação foi maior do que 0,85 e o modelo foi considerado adequado. Os dados obtidos demonstraram que as metodologias do Laboratório Nacional de Energia Renovável devem ser adequadas para cada tipo de biomassa. Além disso, com os resultados otimizados, estes dados podem ser empregados na produção de larga escala de combustíveis oriundos de biomassa.

Synthesis of 1,3-distearoyl-2-oleoylglycerol by enzymatic acidolysis in a solvent-free system.

1,3-Distearoyl-2-oleoylglycerol (SOS) is widely used as a cocoa butter improver and an anti-blooming agent in the chocolate industry. In this study, an effective process was developed to prepare SOS by enzymatic acidolysis. Under optimal reaction conditions (substrate molar ratio of 12, NS40086 loading of 10%, a solvent-free system, 75°C for 4h), a SOS yield of 70.2% was obtained. Subsequently, two-step purification was applied to purify the crude SOS product. Free fatty acids were completely removed after molecular distillation. After acetone fractionation, the purity of SOS reached 92.2% with an 85.1% recovery. Comparison of various physicochemical properties of purified SOS and a commercial cocoa butter improver showed their properties to be similar. This study provides an effective and sustainable process for the synthesis of SOS product, which is expected to be used as a high-quality cocoa butter improver or an anti-blooming agent in the chocolate industry.

Substrate temperature and molar ratio induced changes on the properties of nebulized spray deposited MnS films

Various properties of MnS thin films deposited on glass substrate by a simple and novel nebulized spray technique are described in this work. The thickness of MnS thin film increases linearly with increase in molar ratio and substrate temperature. From the X-ray diffraction study, the impact of molar ratio and substrate temperature is well pronounced in the formation of well crystalline MnS thin films. The SEM images showed more grains formation and well defined compact nature composed of single type densely packed grains. The AFM images exhibited that all the films show homogenous surface with pinhole free in nature. The decrease in average transmittance of films with increasing substrate temperature and molar ratio are due to the influence of grain growth induced by the enhancement in crystalline behavior of the films. It is observed that the energy band gaps of MnS thin films are decreased with increasing substrate temperature and molar ratio. The intensity of emission peaks increased with increasing solution concentration and substrate temperature owing to the change in surface area to volume ratio of MnS micro/nano-structures with molar ratio. All the Raman peaks showed the vibrations of Mn–S bonds. The magnetic study confirmed the ferromagnetic behavior of MnS films at 5 K, whereas the film exhibits paramagnetic behavior at 300 K.