137-66-6Relevant articles and documents
Enzymatic synthesis of ascorbyl palmitate in ultrasound-assisted system: Process optimization and kinetic evaluation
Lerin, Lindomar A.,Feiten, Miriam C.,Richetti, Aline,Toniazzo, Geciane,Treichel, Helen,Mazutti, Marcio A.,Vladimir Oliveira,Oestreicher, Enrique G.,De Oliveira, Débora
, p. 988 - 996 (2011)
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.
Lipase catalyzed ascorbyl palmitate synthesis under microwave irradiation
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.
, p. 127 - 131 (2014)
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.
High yields of ascorbyl palmitate by thermostable lipase-mediated esterification
Bradoo,Saxena,Gupta
, p. 1291 - 1295 (1999)
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.
Coagels from alkanoyl-6-O-ascorbic acid derivatives as drug carriers: Structure and rheology
Palma, Santiago,Jimenez-Kairuz, Alvaro,Fratoni, Laura,Lo Nostro, Pierandrea,Manzo, Ruben,Allemandi, Daniel
, p. 1271 - 1276 (2003)
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.
Preparation method of L-ascorbic acid-6-palmitate
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Paragraph 0047-0050, (2017/03/14)
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.
