- Enzymatic synthesis of ascorbyl palmitate in ultrasound-assisted system: Process optimization and kinetic evaluation
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This work is focused on the optimization of reaction parameters for the synthesis of ascorbyl palmitate catalyzed by Candida antarctica lipase in different organic solvents under ultrasound irradiation. The sequential strategy of experimental design proved to be useful in determining the optimal conditions for reaction conversion in tert-butanol system using Novozym 435 as catalyst. The optimum production was achieved at 70°C, ascorbic acid to palmitic acid molar ratio of 1:9, enzyme concentration of 5 wt% at 3 h of reaction, resulting in an ascorbyl palmitate conversion of about 27%. Reaction kinetics for ascorbyl palmitate production in ultrasound device showed that satisfactory reaction conversions (～26%) could be achieved in short reaction times (2 h). The empirical kinetic model proposed is able to satisfactorily represent and predict the experimental data.
- Lerin, Lindomar A.,Feiten, Miriam C.,Richetti, Aline,Toniazzo, Geciane,Treichel, Helen,Mazutti, Marcio A.,Vladimir Oliveira,Oestreicher, Enrique G.,De Oliveira, Débora
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- Effect of the alkyl chains and of the headgroups on the thermal behavior of ascorbic acid surfactants mixtures
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The role of the alkyl chain length and of the headgroup on the thermal behavior of mixtures of ASC8 (ascorbyl octanoate) and ASC16 (ascorbyl hexadecanoate) was investigated through differential scanning calorimetry, small- and wide-angle X-ray scattering, and Fourier transform infrared spectroscopy experiments. The formation of two eutectics and of a peritectic point was found from the phase diagram, and their structural properties were studied. The results were compared by investigating the thermal behavior of mixtures of octanoic acid and hexadecanoic acid. The findings provide insights into the role of the ascorbyl headgroups on the intermolecular interactions that determine the phase behavior of the two ascorbic acid based surfactants in the solid state. ? 2014 American Chemical Society.
- Venturini, Chiara,Pomposi, Cristina,Ambrosi, Moira,Carretti, Emiliano,Fratini, Emiliano,Lo Nostro, Pierandrea,Baglioni, Piero
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- Lipase catalyzed ascorbyl palmitate synthesis under microwave irradiation
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The production of ascorbyl palmitate from palmitic acid and ascorbic acid through the esterification catalyzed by Novozym 435 was performed under microwave irradiation. The effects of different reaction parameters were evaluated. The reactions were carried out in organic solvent (acetone, tert-amyl alcohol, cyclohexane, acetonitrile) and the results show that tert-amyl alcohol was the best solvent for this reaction. Parameters as temperature, molar ratio and enzyme loading were evaluated through a central composite design (CCD). In the optimized conditions, 15% (w/w in relation of ascorbic acid weight) of enzyme, 70 C and molar ratio 1:5, 71% yield of ascorbyl palmitate could be achieved after 1 h.
- Costa, Ingrid C.R.,Sutili, Felipe K.,Da Silva, Gabriela V.V.,Leite, Selma G.F.,Miranda, Leandro S.M.,De Souza, Rodrigo O.M.A.
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- Antioxidative properties and enzymatic synthesis of ascorbyl FA esters
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Efficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants in t-amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl-activated acyl donors (71, 80, and 86% yields of esters with FA excesses of 1:1, 1:1.5, and 1:2, respectively). As very low water activity is needed to achieve sufficiently high yields of product, molecular sieves were used to improve the ascorbyl ester yields. Ascorbyl oleate is more amorphous and has a much lower m.p. and lower enthalpy of fusion than ascorbyl palmitate. This leads to a higher solubility of ascorbyl oleate in oil, resulting in an increased antioxidant effect compared to that of the palmitate. In an accelerated storage test using deodorized rapeseed oil, samples incubated with ascorbyl palmitate showed noticeable oxidation after 1 wk of storage, whereas samples incubated with ascorbyl oleate displayed negligible oxidation for 9 and 4 wk at 30 and 40°C, respectively.
- Viklund, Fredrik,Alander, Jari,Hult, Karl
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- High yields of ascorbyl palmitate by thermostable lipase-mediated esterification
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High yields of ascorbyl palmitate (6-O-palmitoyl L-ascorbic acid) were obtained by lipase-mediated esterification using Bacillus stearothermophilus SB 1 lipase. The final yield was greatly influenced by the initial water content of the system, quantity of enzyme, and molar ratio of palmitic acid to L-ascorbic acid. Reaction rates increased directly with temperature from 40 to 100 °C. Maximum conversion (97%) was achieved after 30 min at 100 °C (solvent-free), 1 h at 80 °C (solvent-free), and 2 h at 60 °C (solvent/hexane). The synthesis was scaled up to 1-L volume with 95% conversion using 50 mmoles of ascorbic acid and 250 mmoles of palmitic acid in hexane. Similar yields of ester were obtained in five repetitive cycles using 5 g enzyme immobilized on Accurel. The present B. stearothermophilus SB 1 lipase was a more efficient catalyst for the synthesis of ascorbyl palmitate than other commercial lipases.
- Bradoo,Saxena,Gupta
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- Enzymatic synthesis and anti-oxidative activities of plant oil-based ascorbyl esters in 2-methyltetrahydrofuran-containing mixtures
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Ascorbyl fatty acid esters are commercially interesting fat-soluble antioxidants. In this work, enzymatic synthesis of ascorbyl esters from less expensive and readily available plant oils, and their anti-oxidative activities are described. Among the immob
- Hu, Ying-Dan,Zong, Min-Hua,Li, Ning
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- Coagels from alkanoyl-6-O-ascorbic acid derivatives as drug carriers: Structure and rheology
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6-O-Ascorbic acid alkanoates (ASCn, where n is the number of carbon atoms in the alkyl chain) behave as surfactants and form stable supramolecular assemblies in water, depending on chemical structure, concentration and temperature. In concentrated water dispersions, ASCn form liquid crystalline structures ('coagels'), below the critical micellar temperature (CMT), with a typical Krafft phenomenon. Such semisolid systems incorporate and stabilize drugs like anthralin, which is insoluble and unstable in aqueous media. The rheological behavior of coagels obtained from aqueous ASC8, ASC10, ASC11, ASC12, ASC14 and ASC16 was evaluated and related to the coagel structure. For ASC8, ASC12, ASC14 and ASC16 complex rheology was observed and spur values were determined. This behavior is indicative of a high three-dimensional structure. The spur value represents a sharp point of structural breakdown at low shear rate. At this point the semisolids acquire pseudoplastic flow with a very low viscosity. Instead, ASC10 and ASC11 coagels showed pseudoplastic flow and - in the case of ASC11 - thixotropy was observed. The ASCn coagel rheological behavior and their capability to load pharmacologically active compounds point to a potentially valuable capacity for such systems as drug carriers.
- Palma, Santiago,Jimenez-Kairuz, Alvaro,Fratoni, Laura,Lo Nostro, Pierandrea,Manzo, Ruben,Allemandi, Daniel
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- Green synthesis method of vitamin C higher fatty acid ester
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The invention discloses a green synthesis method of vitamin C higher fatty acid ester, and the method comprises the following steps: under the catalysis of an acylation reaction catalyst, carrying outesterification reaction on vitamin C and higher fatty acid anhydride under a solvent-free condition, and carrying out after-treatment to obtain the vitamin C higher fatty acid ester. The synthesis method is environmentally friendly, low in reaction temperature, low in energy consumption, low in cost, high in molecular utilization rate of raw materials and auxiliary materials and high in yield.
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Paragraph 0049-0063
(2021/03/13)
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- Preparation method of L-ascorbic acid-6-palmitate
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The invention discloses a preparation method of L-ascorbic acid-6-palmitate, which is characterized by comprising the following steps: (1) at a first temperature, performing a first contact reaction to palmitic acid and L-ascorbic acid in concentrated sulfuric acid; (2) at a second temperature, performing a second contact reaction to a mixture obtained in the first contact reaction and palmitic anhydride, wherein the first temperature is not more than 20 DEG C and the second temperature is higher than the first temperature by 5-10 DEG C. According to the method, the yield of the L-ascorbic acid-6-palmitate can reach 91% and the purity of the product reaches more than 98%. The method is free of addition of sulfur trioxide, phosphorus oxychloride and the like, thereby avoiding influence on products and device corrosion and environment pollution due to addition of the compounds. The preparation method is simple in operations and is suitable for industrial production.
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Paragraph 0047-0050
(2017/03/14)
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- A direct esterification method reaction solution from separation and purification method for vitamin C palmitate hydrochloride
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The invention relates to a method for separating and purifying vitamin C palmitate from reaction liquid of a direct esterification method, and the method applied to separation and purification fields of the reaction liquid. The separating and purifying method comprises the following steps of: reacting vitamin C with palmitic acid under catalysis of concentrated sulfuric acid, so as to obtain the reaction liquid of the vitamin C palmitate; slowly pouring the reaction liquid into ice-bath cooling water or trash ice, adding methylbenzene to carry out extraction, and carrying out standing and layering to separate out a lower-layer waste acid layer and leave a methylbenzene layer; adding water into the methylbenzene layer, carrying out crystallization and filtering so as to obtain a filter cake, and respectively washing the filter cake by utilizing proper amount of methylbenzene and water; adding the filter cake into the water and stirring for 0.5-3 hours, filtering, and carrying out water washing until the pH of the effluent water is 6-7, so as to obtain crude products of the vitamin C palmitate; and carrying out recrystallization on the crude products of the vitamin C palmitate by utilizing ethanol so as to obtain finished products of the vitamin C palmitate. The method for separating and purifying the vitamin C palmitate from the reaction liquid of the direct esterification method has the advantages that solvents are simply separated and purified, are low in toxin and can be recycled, the separation and purification cost is low, the product purity is high, the condition is mild and the operation is simple and convenient.
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Paragraph 0017-0022
(2017/03/08)
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- Synthesis and properties of ascorbyl esters catalyzed by lipozyme TL im using triglycerides as acyl donors
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Esters of l-ascorbic acid with long-chain fatty acids (E-304) are employed as antioxidants in foods rich in lipids. Although their enzymatic synthesis offers some advantages compared with the current chemical processes, most of the reported methods employ the immobilized lipase from Candida antarctica as biocatalyst and free fatty acids or activated esters as acyl donors. In order to diminish the cost of the process, we have investigated the synthesis of ascorbyl oleate and ascorbyl palmitate esters with the immobilized Thermomyces lanuginosus lipase Lipozyme TL IM-which is significantly less expensive than Novozym 435-and triglycerides as source of fatty acids. Lipozyme TL IM gave rise to a lower yield of 6-O-ascorbyl oleate than Novozym 435 when using triolein (64 vs. 84%) and olive oil (27 vs. 33%) as acyl donors. Both 6-O-ascorbyl oleate and 6-O-ascorbyl palmitate displayed excellent surfactant and antioxidant properties. The Trolox Equivalent Antioxidant Capability values for the oleate and palmitate were 71 and 84%, respectively, of those obtained with l-ascorbic acid; however, both derivatives were able to stabilize soybean oil towards peroxide formation.
- Reyes-Duarte,Lopez-Cortes,Torres,Comelles,Parra,Pena,Ugidos,Ballesteros,Plou
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scheme or table
p. 57 - 64
(2011/10/04)
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- Green enzymatic synthesis of L-ascorbyl fatty acid ester: An antioxidant
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In green chemistry, biocatalysis using microwaves is a very attractive tool for various regioselective syntheses. L-Ascorbyl fatty acid esters were synthesized by an immobilized lipase from Bulkholderia multivorans using microwaves, with a dynamically enh
- Kidwai, Mazaahir,Mothsra, Poonam,Gupta, Namita,Kumar, S. Suresh,Gupta, Rani
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experimental part
p. 1143 - 1151
(2009/09/25)
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- Novel 6-O-acylated vitamin C derivatives as hyaluronidase inhibitors with selectivity for bacterial lyases
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Previously, we identified ascorbic acid 6-O-hexadecanoate as an up to 1500 times more potent inhibitor of bacterial and bovine hyaluronidases than the parent compound, vitamin C, and determined a crystal structure of hyaluronidase from Streptococcus pneumoniae in complex with the inhibitor. As the alkanoyl chain interacts with a hydrophobic patch of the enzyme we synthesized other 6-O-acylated vitamin C derivatives bearing various lipophilic residues and investigated the inhibition of Streptococcus agalactiae strain 4755 hyaluronidase (SagHyal4755) and of bovine testicular hyaluronidases (BTH) in a turbidimetric assay. All compounds showed selectivity for the bacterial enzyme. Whereas vitamin C 6-O-hexanoate only weakly inhibited SagHyal4755, the inhibition of both enzymes increased with the length of the aliphatic chain. In the case of the 6-O-octadecanoate, IC50 values of 0.9 and 39 μM for SagHyal4755 and BTH, respectively, were determined. Partial replacement of the aliphatic chain with a phenyl, p-phenylene or p-biphenylyl group resulted in inhibitors with activity in the lower micromolar range, too. The title compounds are among the most potent inhibitors of both enzymes known to date.
- Spickenreither, Martin,Braun, Stephan,Bernhardt, Guenther,Dove, Stefan,Buschauer, Armin
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p. 5313 - 5316
(2007/10/03)
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- Vinyl carboxylate an acylating reagent for selective acylation of amines and diols
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Vinyl group of vinyl alkylate (C=2 or 16) and vinyl benzoate have been found to be a good leaving group in acylation of alcohols (40-50% yield) and amines (in 60-90% yield).
- Chen,Chen,Chen,Wang
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p. 3583 - 3584
(2007/10/02)
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- Palatable solid pesticidal compositions of ethylene and vinyl acetate copolymer
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The invention comprises compositions in solid form of ethylene/vinyl acetate copolymer with an effective amount of bioactive agent, a protein/carbohydrate-lipid source, 0 to 20% of an edible oil and optionally an attractant, dye, preservative, adversive agent and biomarker and the use, thereof, to control pests.
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- Long-acting pyrethrum/pyrethroid based pesticides with silicone stabilizers
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Pesticidal compositions based on nontoxic, naturally unstable insecticides (pyrethrum, synthetic pyrethroids and mixtures thereof) include a liquid alkyl aryl silicone polymer which stabilizes the insecticide to provide an extended effective killing life. The compositions additionally include a synergist to provide an immediate killing action and an antioxidant to protect the insecticide against destruction by oxygen. Ultraviolet protectants and insect repellents may also be included. Applications include control of insect pests to animals and plants and general purpose insect control. Exemplary formulations are given for compositions to be applied as sprays, dips, powdered or dusts, foggers and shampoos.
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