- Synthesis and characterization of a brush-like copolymer of polylactide grafted onto chitosan
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A brush-like poly(DL)-lactide grafted onto chitosan as the backbone was investigated. The graft copolymerization was carried out with triethylaluminum as catalyst in toluene at 70°C. It was found that a greater lactide content in the feeding ratio results in a higher grafting percentage. FTIR spectrometry, 1H NMR, DSC scanning, and wide-angle X-ray scattering, respectively, are used to characterize these branch copolymers. A copolymer has a definite melting point when the molar feeding ratio of lactide to chitosan is more than 10:1, and the ΔH of the copolymers increases with the feed ratio of lactide to chitosan in feeding.
- Liu,Tian,Hu
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- From meso-Lactide to Isotactic Polylactide: Epimerization by B/N Lewis Pairs and Kinetic Resolution by Organic Catalysts
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B/N Lewis pairs have been discovered to catalyze rapid epimerization of meso-lactide (LA) or LA diastereomers quantitatively into rac-LA. The obtained rac-LA is kinetically polymerized into poly(l-lactide) and optically resolved d-LA, with a high stereoselectivity kL/kD of 53 and an ee of 91% at 50.6% monomer conversion, by newly designed bifunctional chiral catalyst 4 that incorporates three key elements (β-isocupreidine core, thiourea functionality, and chiral BINAM) into a single organic molecule. The epimerization and enantioselective polymerization can be coupled into a one-pot process for transforming meso-LA directly into poly(l-lactide) and d-LA.
- Zhu, Jian-Bo,Chen, Eugene Y.-X.
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- Chemical Recycling of End-of-Life Poly(lactide) via Zinc-Catalyzed Depolymerization and Polymerization
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The chemical recycling of poly(lactide) was investigated based on depolymerization and polymerization processes. Using methanol as depolymerization reagent and zinc salts as catalyst, poly(lactide) was depolymerized to methyl lactate applying microwave heating. An excellent performance was observed for zinc(II) acetate with turnover frequencies of up to 45000 h?1. In a second step the monomer methyl lactate was converted to (pre)poly(lactide) in the presence of catalytic amounts of zinc salts. Here zinc(II) triflate revealed excellent performance for the polymerization process (yield: 91 %, Mn ~8970 g/mol). Moreover, the (pre)poly(lactide) was depolymerized to lactide, the industrial relevant molecule for accessing high molecular weight poly(lactide), using zinc(II) acetate as catalyst.
- Cheung, Even,Alberti, Christoph,Enthaler, Stephan
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- In Vitro Characterization and Evaluation of the Cytotoxicity Effects of Nisin and Nisin-Loaded PLA-PEG-PLA Nanoparticles on Gastrointestinal (AGS and KYSE-30), Hepatic (HepG2) and Blood (K562) Cancer Cell Lines
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The aim of this study was an in vitro evaluation and comparison of the cytotoxic effects of free nisin and nisin-loaded PLA-PEG-PLA nanoparticles on gastrointestinal (AGS and KYSE-30), hepatic (HepG2), and blood (K562) cancer cell lines. To create this novel anti-cancer drug delivery system, the nanoparticles were synthesized and then loaded with nisin. Subsequently, their biocompatibility, ability to enter cells, and physicochemical properties, including formation, size, and shape, were studied using hemolysis, fluorescein isothiocyanate (FITC), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM), respectively. Then, its loading efficiency and release kinetics were examined to assess the potential impact of this formulation for the nanoparticle carrier candidacy. The cytotoxicities of nisin and nisin-loaded nanoparticles were evaluated by using the MTT and Neutral Red (NR) uptake assays. Detections of the apoptotic cells were done via Ethidium Bromide (EB)/Acridine Orange (AO) staining. The FTIR spectra, SEM images, and DLS graph confirmed the formations of the nanoparticles and nisin-loaded nanoparticles with spherical, distinct, and smooth surfaces and average sizes of 100 and 200?nm, respectively. The loading efficiency of the latter nanoparticles was about 85–90%. The hemolysis test represented their non-cytotoxicities and the FITC images indicated their entrance inside the cells. An increase in the percentage of apoptotic cells was observed through EB/AO staining. These results demonstrated that nisin had a cytotoxic effect on AGS, KYSE-30, HepG2, and K562 cancer cell lines, while the cytotoxicity of nisin-loaded nanoparticles was more than that of the free nisin.
- Goudarzi, Fariba,Asadi, Asadollah,Afsharpour, Maryam,Jamadi, Robab Hassanvand
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- A study on highly concentrated lactic acid and the synthesis of lactide from its solution
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Lactic acid is an important platform compound used as raw material for the production of lactide and polylactic acid. However, its concentration and composition distribution are not as simple as those of common compounds. In this work, the mass concentration distribution of highly concentrated lactic acid is determined by back titration. The components of highly concentrated lactic acid, crude lactide, and polymer after the reaction are analyzed by HPLC. Different concentrations of lactic acid solution were prepared for the synthesis of lactide and its content in the product was determined by 1H NMR analysis. We found that lactide is more easily produced from high-concentration lactic acid solution with which the condensed water is easier to release. Hence, the removal of condensed water is crucial to the formation of lactide, although it is not directly formed by esterification of two molecules of lactic acid.
- Liu, Lijuan,Xu, Xiaolong
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- Synthesis of new substituted 2,3-dihydro-1,4-dioxin-2-ones and 1,4-dioxan-2-ones
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3-Alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones reacted with acetyl chloride in the presence of zinc(II) chloride to give the corresponding 3-alkyl-5-acetyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones. Oxidation of the latter with hydrogen peroxide in formic acid, followed by treatment with magnesium bromide, afforded 3-alkyl-6-methyl-1,4-dioxane-2,5-diones. Successive chlorination and dechlorination of 6-hydroxymethy 1-1,4-dioxan-2-ones yielded 6-methylene-1,4-dioxan-2-ones.
- Akopyan,Khachatryan
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- Effect of block lengths on the association behavior of poly(l-lactic acid)/poly(ethylene glycol) (PLA-PEG-PLA) micelles in aqueous solution
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A series of poly(l-lactic acid)/poly(ethylene glycol) triblock copolymers with a PLA-PEG-PLA architecture were synthesized by a ring-opening polymerization (ROP) process. The copolymers were characterized by 1H NMR and GPC. The total number average molecular weights were in the range of 4,700-50,000, whereas the degrees of polymerization of the PLA and PEG blocks varied from 15 to 359 and from 68 to 136, respectively. The self-association of these copolymers in aqueous environment was studied by emission fluorescence spectroscopy of anilinonaphthalene probe and the critical association concentration (CAC) of the copolymers was measured. It was found that the micellization process of these copolymers was mainly determined by the length of the hydrophobic LA block, while the length of the hydrophilic PEG block had little effect. Furthermore, the low CAC values of the copolymers suggest that the copolymers form stable supramolecular structures in aqueous solutions.
- Pourhosseini, Pouneh S.,Amani, Reza,Saboury, Ali A.,Najafi, Farhood,Imani, Mohammad
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- Progress toward reaction monitoring at variable temperatures: a new stopped-flow NMR probe design
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A stopped-flow NMR probe is described that enables fast flow rates, short transfer times, and equilibration of the reactant magnetization and temperature prior to reaction. The capabilities of the probe are demonstrated by monitoring the polymerization of lactide as catalyzed by the air-sensitive catalyst 1,3-dimesitylimidazol-2-ylidene (IMes) over the temperature range of ?30 to 40 °C. The incorporation of stopped-flow capabilities into an NMR probe permits the rich information content of NMR to be accessed during the first few seconds of a fast reaction. Copyright
- Dunn, Anna L.,Landis, Clark R.
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- Synthesis of lactide from lactic acid and its esters in the presence of rare-earth compounds
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A procedure is described for the synthesis of lactide by dehydration of L-lactic acid and subsequent depolymerization of its oligomer mixture in the presence of yttrium(III) and praseodymium(III) oxides, as well as of cerium(III) chloride heptahydrate. The catalytic activity of yttrium and praseodymium sesquioxides was determined at different temperatures at the oligomerization and deoligomerization stages. Ethyl lactate was prepared in the presence of Purolite C100 MB cation exchange resin and subjected to oligomerization followed by thermal decomposition of oligoester and oligolactic acid mixture in the presence of yttrium(III) and praseodymium(III) oxides and aqueous cerium(III) chloride.
- Poryvaeva,Egiazaryan,Makarov,Moskalev,Razborov,Fedyushkin
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- Design of a heterogeneous catalytic process for the continuous and direct synthesis of lactide from lactic acid
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We present a continuous one-step reaction pathway for optically pure lactide under atmospheric conditions based on a novel SnO2-SiO2 nanocomposite catalyst. The new heterogeneous catalytic system gave a record high lactide yield of 94% with almost 100% enantioselectivity and long-term stability (>2500 h) from l-lactic acid.
- Upare, Pravin P.,Yoon, Ji Woong,Hwang, Dong Won,Lee, U-Hwang,Hwang, Young Kyu,Hong, Do-Young,Kim, Jin Chul,Lee, Jeong Hyeon,Kwak, Sang Kyu,Shin, Hyeyoung,Kim, Hyungjun,Chang, Jong-San
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- Synthesis of New Substituted 2,3-Dihydro-1,4-dioxin-2-ones and 1,4-Dioxan-2-ones
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3-Alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones reacted with acetyl chloride in the presence of zinc(II) chloride to give 5-acetyl-3-alkyl-6-methyl- 2,3-dihydro-l,4-dioxin-2-ones. Oxidation of the latter with hydrogen peroxide in formic acid, followed by treatment with magnesium bromide, afforded 3-alkyl-6-methyl-1,4-dioxane-2,5-diones. Chlorination of 6-hydroxymethyl-1,4- dioxan-2-ones with thionyl chloride and subsequent dehydrochlorination led to formation of 6-methylene-1,4-dioxan-2-ones.
- Akopyan,Khachatryan
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- Catalytic Gas-Phase Cyclization of Glycolate Esters: A Novel Route Toward Glycolide-Based Bioplastics
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A catalytic process to produce glycolide, the cyclic dimer of glycolic acid (GA), is proposed. Glycolide is the key building block of the biodegradable plastic polyglycolic acid. Instead of the current industrial two-step route, which involves the polycondensation of GA and a subsequent backbiting reaction, a new route based on the gas-phase transesterification of methyl glycolate (MGA) over a fixed catalyst bed is presented. With specific supported TiO2 catalysts, a high glycolide selectivity of 75–78 % can be achieved at the thermodynamically-limited equilibrium conversion of MGA (54 % at 300 °C, 5.6 vol% MGA, 1 atm). The absence of solvent and the continuous nature of the process should allow for easy product separation and recycling of unconverted esters, while the few side-products, i. e. linear alkyl glycolate dimers and trimers seem recoverable via methanolysis. The reaction is compared to the cyclization of other α-hydroxy esters, such as methyl lactate to lactide, over the same catalysts, in terms of kinetics and thermodynamics. The absence of a methyl substitution on the α-carbon seems to lead to faster cyclization kinetics of MGA when compared to methyl lactate or the double-substituted methyl-2-hydroxy-isobutyrate. Contrarily, glycolide production is less favored thermodynamically compared to lactide. The absence of glycolide decomposition at temperatures up to 300 °C however allows to increase equilibrium conversion by taking the endergonic reaction to higher temperatures.
- De Clercq, Rik,Makshina, Ekaterina,Sels, Bert F.,Dusselier, Michiel
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- Melt Chain Dimensions of Polylactide
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Melt chain dimensions of two polylactide samples were measured using small-angle neutron scattering, Three polylactides were synthesized: a deuterated polylactide containing 26% R-stereocenters (d-PLA-26), a hydrogenous polylactide with an R-content similar to the deuterated polylactide (PLA-28), and a hydrogenous polylactide that contained no R-stereocenters (PLA-0). The hydrogenous polylactides were each solution blended with the d-PLA-26 at a volume fraction of 0.2 for the deuterated polymer, and the melt chain dimensions of these polymers were determined. Small-angle neutron scattering experiments were performed at 30°C for the d-PLA-26/PLA-28 blend and at 200°C for both the d-PLA-26/PLA-28 and d-PLA-26/PLA-0 blends. Using three analysis methods, the average values for the statistical segment lengths, based on a C6 repeat unit, were found to be 10.0 ± 0.2 A for the PLA-28 at 30°C, 8.9 ± 0.2 A for the PLA-28 at 200°C, and 9.9 ± 0.4 A for the PLA-0 at 200°C.
- Anderson, Kelly S.,Hillmyer, Marc A.
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- Investigation into the Anticancer Activity and Apoptosis Induction of Brevinin-2R and Brevinin-2R-Conjugated PLA–PEG–PLA Nanoparticles and Strong Cell Cycle Arrest in AGS, HepG2 and KYSE-30 Cell Lines
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Our study aims to establish a biocompatible nanostructure for the improved delivery of anticancer peptide, Brevinin-2R, to treat human gastric adenocarcinoma (AGS), human liver hepatocellular carcinoma (HepG2) and human squamous cell carcinoma (KYSE-30) cells. Poly(l-lactide)–poly(ethylene glycol)–poly(l-lactide) (PLA–PEG–PLA) nanoparticles were synthesized, obtained by a solvent evaporation method and characterized using scanning electron microscopy (SEM), FTIR and DLS; chemically-synthesized Brevinin-2R was encapsulated in micelles. In vitro release and cell uptake assay were conducted before cytotoxicity tests. Cell cycle analysis and apoptosis study were performed through flow cytometry and Annexin-V-FlOUS cell staining. PLA–PEG–PLA nanoparticles showed a narrow-size distribution with a zeta potential of ? 26.63 and a high cell internalization. Brevinin-2R-conjugated nanoparticles were spherical in shape with an increased surface charge of ? 21.90. For the first time, viability tests showed that Brevinin-2R-conjugated nanoparticles were more efficient than Brevinin-2R against cancer cells causing higher rates of cell cycle arrest and apoptosis induction. Our new findings demonstrate the potential of PLA–PEG–PLA nanoparticles to boost the anticancer effect and improve the delivery of Brevinin-2R. The study of Brevinin-2R-loaded nanoparticles indicated noticeable results in terms of novel cancer therapy. PLA–PEG–PLA nanoparticles can act as a biocompatible delivery platform to take the advantage of Brevinin-2R toward cancer cells. This is a novel study as the Brevinin-2R-conjugated nanoparticles and applied approaches have not been already reported.
- Hassanvand Jamadi, Robab,Asadi, Asadollah,Yaghoubi, Hashem,Goudarzi, Fariba
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- SYNTHESIS METHOD AND DEVICE FOR RAPIDLY PRODUCING LACTIDE AT HIGH YIELD
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The invention discloses a synthesis method and device for rapidly producing lactide at high yield. The method comprises: adding a single component of lactic acid or two components of lactic acid and catalyst, passing the mixture through a mixer to enter an oligomer preparation system, increasing a residence time through bottom circulation, synthesizing oligomeric lactic acid, and passing a gas-phase component through a rectification system. With the adoption of the device, the lactide is capable of being efficiently synthesized, crude lactide with a yield of 94% to 98% is capable of being obtained.
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Paragraph 0050-0114
(2021/06/26)
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- Method for catalytically synthesizing lactide
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The invention discloses a method for catalytically synthesizing lactide. According to the method, a mixture of stannous lactate and a urea substance is used as a composite catalyst, L-lactic acid (orD-lactic acid) with the lactic acid content of 90% is used as a raw material, and a reduced pressure distillation technology is adopted to synthesize the L-lactide (or D-lactide). Compared with independent use of onecatalyst, by adopting the composite catalyst, the yield can be effectively increased, under the same experimental conditions, the crude yields of lactide synthesized by independently using stannous lactate or urea catalysts are 69%-72% and 23%-30% respectively, and the yield can be increased to 90% or above by using the composite catalyst of the two. Compared with a traditional tincatalyst or zinc catalyst and other composite catalytic components, the composite catalytic reaction system is low in reaction temperature (150-180 DEG C), short in reaction time (0.5-2 h), high in lactide yield (90% or above), capable of saving more energy and increasing the yield and beneficial to industrial production.
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Paragraph 0056-0076; 0081-0084; 0095-0096; 0099-0100
(2021/01/29)
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- Method for synthesizing rod-like long L-lactide crystal with high optical purity
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The invention discloses a method for synthesizing a rod-like long L-lactide crystal with high optical purity, namely the method for synthesizing the rod-like long L-lactide crystal with the high optical purity by utilizing a decompression method with lactic acid as a raw material. A synthesis technology of the rod-like long L-lactide crystal with the high optical purity comprises the following conditions: the amount of a certain amount of the lactic acid is 10-50mL, the volume of a proper amount of catalyst stannous octoate is 1-10mL, the gradually rising temperature range from 90 to 190 DEG C, and the pressure of a reduced pressure distillation reaction is minus 0.10MPa to 0.10MPa, and a certain time is 1-10h. A synthesis method of the rod-like long L-lactide crystal with the high opticalpurity comprises the following steps: 1), taking a certain amount of the lactic acid, adding into a three-necked bottle of 250mL, then adding a proper amount of stannous octoate, gradually heating, and performing a reduced pressure distillation reaction for a certain time to obtain a white lactic acid oligomer; 2), gradually heating the white lactic acid oligomer in a device, and performing the reduced pressure distillation reaction for a certain time until no obvious distillate appears, and collecting the distillate, that is a lactide product, wherein the product is a mixture of D-type lactide and L-type lactide.
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Paragraph 0017-0035
(2019/01/17)
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- METHOD FOR SYNTHESIZING LACTIDE BY MEANS OF CATALYSIS OF LACTID ACID
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The present invention relates to a method for the catalytic synthesis of lactide from lactic acid. The method relates to the synthesis of lactide from lactic acid under the catalysis of a zinc oxide nanoparticle aqueous dispersion as a catalyst. The present invention has four technical characteristics: I. the zinc oxide nanoparticle aqueous dispersion catalyst has a sufficient surface area, and the size of nanoparticles is merely 30-40 nm, providing a sufficient contact area between the substrate (lactic acid) and the catalyst; II. the new catalyst has a milder catalytic effect on polymerization, allowing the molecular weight distribution of a prepolymer within a range of 400-1500 g/mol, which is advantageous for depolymerization to proceed; III. the new catalyst is stable, thus avoiding oxidation or carbonization in a high temperature reaction; and IV. the new catalyst has a low toxicity and a small threat to human health.
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Paragraph 0028-0040
(2019/02/24)
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- Continuous lactide synthesis process and apparatus
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Lock taken bath used for energy intensive processes the synthesis polylactic acid number are disclosed. In the present invention newly developed SnO2 - SiO2 Nano composite catalyst effect using won - based substrate. The catalyst is fast reaction rates (20 ms) and enabling a 94% yield (highest yield temporal) are used to lock taken number tank. Process of the present invention is rapid kinetics and high yield as well as, the commonly used contrast process has numerous advantages. In addition, the fast reaction rates, its processing amount significantly maxims. In addition, the process of the present invention carried out in atmospheric conditions, the high vacuum conditions (20 mmHg) is operated in a more energy efficient during processes currently used are disclosed. Thus, the process of the present invention can reduce costs associated with polylactic acid number tub. (by machine translation)
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Paragraph 0096; 0097; 0104; 0107; 0112
(2018/10/24)
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- PROCESS FOR PREPARING A CYCLIC DIESTER OR A CYCLIC DIAMIDE BY REACTING A HYDROXYCARBOXYLIC ACID OR AMIDE WITH AN ACIDIC BEA-TYPE (H-BETA POLYMORPH A) ZEOLITE
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A process for preparing a cyclic diester or a cyclic diamide by reacting a hydroxycarboxylic acid or amide with an acidic BEA (H-beta polymorph A) type zeolite. The process is characterised in that the total amount of acid sites is in the range of from 0.25 to 1.0 mmol/g and the amount of medium acid sites is at least 40% of the total amount of acid sites. The total amount of acid sites and the amount of medium acid sites are determined by NH3-TPD (temperature-programmed desorption of ammonia). Preferably, the process refers to the preparation of lactide from lactic acid. The framework structure of the zeolitic material comprises Si, Al, O, and H.
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Page/Page column 32-33
(2018/10/19)
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- TRANSFORMATIONS OF MESO-LACTIDE
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B/N Lewis pairs have been discovered to catalyze rapid epimerization of meso-lactide (LA) or LA diastereomers quantitatively into rac-LA. The obtained rac-LA can be kinetically polymerized into poly(L-lactide) and optically resolved D-LA, with a high stereoselectivity factor kL/kD of 53 and an ee value of 91% at 50.6% monomer conversion, by a bifunctional chiral catalyst. The epimerization and enantioselective polymerization can be coupled into a one-pot process for transforming meso-LA directly into poly(L-lactide) and D-LA.
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Paragraph 0096
(2018/09/18)
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- Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates
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A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO2/SiO2 catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates. The catalytic activity of TiO2/SiO2 catalysts was strongly correlated to their optical properties by DR UV/Vis spectroscopy. Catalysts with high band-gap energy of the supported TiO2 phase, indicative of a high surface spreading of isolated Ti centers, show the highest turnover frequency per Ti site.
- De Clercq, Rik,Dusselier, Michiel,Makshina, Ekaterina,Sels, Bert F.
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supporting information
p. 3074 - 3078
(2018/03/13)
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- Production of lactide
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Disclosed is a method for producing a lactide using a pyridinium-based catalyst, the method involving esterifying the carboxyl group of a lactic acid oligomer by means of a specific primary alcohol and heating the esterified product thus obtained under reduced pressure.
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Paragraph 0080-0082
(2017/08/02)
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- PREPARATION METHOD FOR LACTIDE
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The present invention relates to a method for producing lactide, which comprises the following steps: a first temperature rising and depressurization step for depressurization after raising a temperature of lactic acid up to 160-180anddeg;C; a second temperature rising and depressurization step for adding a reaction catalyst into a product obtained in the first temperature rising and depressurization step, raising the temperature up to 180-210anddeg;C at the rate of 1-10 anddeg;C/min, and depressurizing down to 0.001-1 torr at the rate of 5-20 torr/min; and a lactide extraction step for inserting the product obtained in the second temperature rising and depressurization step into a falling film reactor.COPYRIGHT KIPO 2017
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Paragraph 0043-0047; 0071
(2017/10/20)
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- TECHNOLOGICAL METHOD FOR SYNTHESIS OF OPTICALLY PURE L-/D-LACTIDE CATALYZED BY BIOGENIC GUANIDINE
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A technological method for synthesizing optically pure L-/D-lactide by using a biogenic guanidine catalysis method. The method of the present invention comprises: by using biogenic guanidine creatinine (CR) as a catalyst and L-/D-lactic acid (90% of mass content) as a raw material, synthesizing optically pure L-/D-lactide by using a reactive reduced pressure distillation catalysis method. The method of the present invention has advantages that the used catalyst is biogenic guanidine creatinine and free of toxicity, metal, and cytotoxicity; the synthesized lactide is high in optical purity (the specific rotation of the L-lactide [α]25 D=?276??280, and the specific rotation of the D-lactide [α]25 D=280), and does not contain any metal; the amount of the catalyst used in reaction is low, the technological process is simplified (a process for rectifying and purifying a crude lactide product by using a conventional method is avoided); and the technological method is simple and convenient to operate and easy in industrial implementation.
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Paragraph 0019-0021
(2016/03/26)
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- PREPARATION METHOD FOR LACTIDE
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The present invention refers to, after depressurization step at elevated temperature and elevated temperature until one of lactic acid 160 °C to 180 °C a pressures number 1; number 1 in the range from 1 °C/a pressures obtained resist reaction catalyst at elevated temperature and adding 210 °C temperature up to 180 °C 10 °C/min. after one rate, 20 torr/min. to about 5 torr/rate 0. 001 torr to 1 torr including number 2 to the depressurization step at elevated temperature and a pressures step; and said number 2 in water at elevated temperature and process of 0 °C to 40 °C a pressures obtained contact cleaning step; including a, number of bath method taken to lock are disclosed.
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Paragraph 0042-0045
(2017/05/20)
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- METHOD FOR MANUFACTURING LACTIDE
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The invention pertains to a method for producing lactide comprising the steps of - providing a solution of lactic acid in a volatile organic solvent, - subjecting the solution to an evaporation step to remove volatile organic solvent and water, resulting in the formation of a composition comprising lactic acid oligomer, - adding catalyst to the composition comprising lactic acid oligomer, and bringing the mixture to reaction conditions, to form lactide. It has been found that the process according to the invention results in the efficient production of lactide with a high production rate and a good product quality.
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Page/Page column 22; 23
(2016/09/22)
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- Utilizing the catalytic synthesis mode of the method of preparing lactide
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Utilizing the catalytic synthesis mode of the method of preparing lactide to a process for the preparation of lactide. The invention provides an environmental friendly, convenient operation by utilizing catalytic synthesis mode of the method of preparing lactide. Utilizing the catalytic synthesis mode of the method of preparing lactide, characterized in that comprises a lower step. Utilizing the catalytic synthesis mode of the method of preparing lactide, characterized in that comprises a lower step. (1) the D, L-lactic acid heating and dewatering. (2) lactic acid oligosynthetic oligomer. According to the quality than add a certain amount of catalyst, under reduced pressure (13.3KPa) re-under slow heating to 140 °C. (3) adding catalyst latter settles 10 minutes, stirring with water and again heated to 90 degree Celsius to maintain 3 to 5 hours after cooling. (4) low tetramer depolymerises ring. Replace the receiving device, re-started to rise quickly. (5) extraction separation: the resulting solution for 10 minutes later, extraction by adding extracting agent, after extraction to obtain solution, vested.
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Paragraph 0015-0021
(2017/03/22)
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- PREPARATION METHOD FOR LACTIDE
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The lactic acid 160 °C to 180 °C a pressures after depressurization step at elevated temperature and elevated temperature until one number 1; and number 1 in the range from 1 °C/a pressures obtained resist reaction catalyst at elevated temperature and adding 10 °C/min. 180 °C to 210 °C temperature rate until after one, 20 torr/min. to about 5 torr/rate 0. 001 torr to 1 torr a pressures step including number 2 to the depressurization step at elevated temperature and; including a, number of bath method taken to lock are disclosed.
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Paragraph 0041-0052
(2017/06/09)
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- Preparing method of lactide stereisomer mixture
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The invention provides a preparing method of a lactide stereisomer mixture, which comprises: taking an alkali metal compound as a catalyst, performing stereoisomerism reaction on a raw material lactide under a condition of 120-250 DEG C to obtain the stereisomer mixture containing D-, L- and meso- lactide, wherein the catalyst is selected from one or more from hydride, boron hydrogen compound, amide, chloride, bromide, monoiodide, sulfide, chlorate, bromate, iodate, chlorite, hypobromite, perchlorate, perbromate, periodate, sulfite, hydrosulphite, nitrate and nitrite of alkali metal. The specific alkali metal compound is taken as the catalyst for lactide isomerization reaction, the inversion of configuration of the lactide can be efficiently realized in an economic and environment-friendly manner, and the stereisomer mixture containing D-, L- and meso- lactide is prepared.
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- METHOD FOR PRODUCING LACTIDE DIRECTLY FROM LACTIC ACID AND A CATALYST USED THEREIN
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The present invention provides a method for directly producing lactide by subjecting lactic acid to a dehydration reaction in the presence of a catalyst comprising a tin compound, preferably, a tin (IV) compound, wherein lactide can be produced directly or by one step from lactic acid, without going through the step of producing or separating lactic acid oligomer. The method of the present invention has advantages of causing no loss of lactic acid, having a high conversion ratio to lactic acid and a high selectivity to optically pure lactide, and maintaining a long life time of the catalyst. Further, since lactic acid oligomer is not or hardly generated and the selectivity of meso-lactide is low, the method also has an advantage that the cost for removing or purifying this can be saved.
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Paragraph 0070; 0071
(2015/09/23)
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- Synthesis of (R)-lactic acid and (2R,5R)-2-tert-Butyl-5-methyl-1,3-dioxolan-4-one
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Abstract A convenient procedure for the synthesis of very expensive (R)-lactic acid from relatively inexpensive (R)-alanine is described. Its subsequent conversion into a chiral dioxolanone can be carried out by using an inexpensive pivalaldehyde-tert-butanol mixture.
- Aitken, R. Alan,Meehan, Anna,Power, Lynn A.
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p. 1557 - 1559
(2015/06/02)
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- PROCESS FOR PREPARING CYCLIC ESTERS AND CYCLIC AMIDES
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The invention relates to a process for preparing a cyclic ester or a cyclic amide, comprising the step of: contacting at least one hydroxycarboxylic acid and/or at least one amino-carboxylic acid; or an ester, or salt thereof; wherein said hydroxycarboxylic acid is a 2-hydroxycarboxylic acid,or a 6–hydroxycarboxylic acid; and wherein said amino carboxylic acid is a 2-amino-carboxylic acid or a 6-amino-carboxylic acid; with at least one acidic zeolite comprising: - two or three interconnected and non-parallel channel systems, wherein at least one of said channel systems comprises 10-or more-membered ring channels; and a framework Si/X2 ratio of at least 24 as measured by NMR; or - three interconnected and non-parallel channel systems, wherein at least two of said channel systems comprise 10-or more-membered ring channels; and a framework Si/X2 ratio of at least 6 as measured by NMR; wherein each X is Al or B, and wherein the process is performed at a pressure between 0.5 and 20 bar.
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Page/Page column 25-30
(2014/08/20)
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- Gas phase dehydration of lactic acid to acrylic acid over alkaline-earth phosphates catalysts
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A series of alkaline-earth phosphates were prepared by co-precipitation method using sodium free or sodium containing precursors and evaluated for gas phase dehydration of lactic acid. The catalysts were characterized by BET measurements, X-ray diffraction, chemical analysis, XPS spectroscopy and both NH3 and CO2-TPD. After checking the stability of catalysts under feed, it was shown that selectivity to acrylic acid strongly depended on reaction temperature but not on contact time. At temperature of 380 C, values ranging from 19 to 49% were measured for the different prepared catalysts. The highest value was reached with Ba3(PO4)2 (55% for C3 products) but selectivities rather close were obtained with different other phosphates suggesting kinetic limitation. Acid-base properties measurements revealed that alkaline-earth phosphates exhibited high proportion of acidic and basic sites with same weak strength. Furthermore, correlation between acrylic selectivity of alkaline earth phosphates and the acid-base balance were clearly established for the first time: selectivity was 50% for balance close to 1 and decreased by factor two increasing this parameter to 2. Finally, FTIR spectra of spent catalysts showed alkaline-earth lactates adsorbed over the catalysts which could be reaction intermediates for dehydration of lactic acid.
- Blanco,Delichere,Millet,Loridant
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p. 185 - 191
(2014/03/21)
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- Process For The Preparation Of L-Lactide Of High Chemical Yield And Optical Purity
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A process for the synthesis of 100% optically pure L(+)-lactide catalyzed by zinc and tin metal catalysts of less than 150 micron particle size is disclosed. The L-lactide obtained was further purified to obtain lactide of 100% optical purity and acid impurities less than 10 meq/kg.
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Paragraph 0064; 0065; 0066; 0067
(2013/03/26)
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- Method for obtaining lactide
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Processes for producing lactide from lactic acid oligomers are described herein. The processes generally include heating a lactic acid oligomer in the presence of a catalyst at a temperature of between 150° C. and 300° C. under a pressure of less than 0.01 MPa to form a lactide; distilling the lactide; and condensing and recovering the lactide, wherein the catalyst is a metal salt of the phosphite anion PO33? in which the metal is selected from the group consisting of tin, aluminum, zinc, titanium and zirconium.
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Page/Page column 3; 4; 5
(2013/12/03)
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- Reactions of hydrogen peroxide with acetylacetone and 2- acetylcyclopentanone
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A reaction of acetylacetone with equimolar amount of concentrated aqueous H2O2 in both organic solvents (ButOH, AcOH) and water at various temperatures gave the corresponding 3,5-dihydroxy-1,2- dioxolanes with different configuration of stereogenic centers. In the pres-ence of an excess of H2O2, 3,5-dihydroxy-1,2-dioxolanes were converted to a mixture of 5-hydroperoxy-3-hydroxy-1,2-dioxolanes and further to a mixture of dimeric 1,2-dioxolan-3-ylperoxides. All the peroxides formed exist in solutions as equilibrium mixtures with the starting reagents. A prolonged reflux of solutions of 3,5-dihydroxy-1,2-dioxolanes in ButOH in the presence of a large excess of H2O2 led to the skeletal rearrangements of the substrates to a mixture of propionic acid and hydroxyacetone, which underwent further oxidative transfor-mations. Unlike acetylacetone, 2-acetylcyclopentanone reacted with H2O2 in aqueous phase or in solutions in ButOH under thermodynamic or kinetic control with the formation of the corresponding 5-hydroperoxy-3-hydroxy- 1,2-dioxolanes, rather than 3,5-dihydroxy-1,2-di-oxolanes. Thermodynamically controlled process in solution in AcOH gave a mixture of all four possible hydroperoxyhydroxy-1,2-dioxolanes. These cyclic peroxides in solutions in ButOH or AcOH readily converted to a mixture of AcOH, glutaric, α-methyladipic, and α-hydroxy-α-methyladipic acids. An active α-hydroxylation of the substrate was observed upon reflux of a solution of 2-acetylcyclopentanone and H2O2 in AcOH.
- Novikov,Shestak
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p. 2171 - 2190
(2014/11/07)
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- METHOD OF PREPARING LACTIDE FROM LACTATE
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The present invention provides a method of preparing lactide with a high yield from lactate obtained through a fermentation process. In certain embodiments, the invention provides a method of preparing high-purity lactide with a high yield, wherein the method comprises treating lactate with a specific solvent, using a catalyst, and phase-separating the resultant. In accordance with the invention, costs for manufacturing polylactic acid can be considerably reduced.
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Paragraph 0057-0059
(2013/10/22)
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- Racemization-free synthesis of lactide using an onium salt catalyst
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Synthesis of LL-lactide with high chemical, diastereomeric, and enantiomeric purities was achieved by depolymerization of oligo(lactic acid) in the presence of an onium salt catalyst.
- Ishijima, Yuuki,Maruta, Yasumi,Abiko, Atsushi
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supporting information
p. 1456 - 1458
(2013/01/16)
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- PROCESS FOR THE MANUFACTURE OF LACTIDE
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Process for the manufacture of lactide comprising heating lactic acid in the presence of at least one hygroscopic salt present in an amount of at least 1 mol per mol of lactic acid.
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Page/Page column 9-10
(2012/01/14)
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- Method for the production of a mixture of lactide derivatives
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A mixture of cyclic diesters derived from lactic acid and in cases a mixture of a racemate of dilactide may be produced in several different processes. In some instances, the process can thereby start from the corresponding alpha-hydroxycarboxylic acids, the corresponding cyclic diesters or oligomers of the corresponding alpha-hydroxycarboxylic acids.
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Page/Page column 7
(2012/06/18)
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- RECOVERY METHOD OF HIGHLY PURE LACTIC ACID AND ALKYL LACTATE
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A method for recovery of highly pure alkyl lactate and lactic acid is provided, which includes a step 1 for producing source liquid comprising lactic acid or ammonium lactate; a step 2 for dehydrating the source liquid product of step 1; a step 3 for producing liquid mixture by sequentially adding and stirring alcohol and acid solution to the dehydrated source liquid; a step 4 for separating and removing ammonium salt precipitation from the liquid mixture of step 3; a step 5 for producing alkyl lactate from ammonium salt-free liquid mixture by esterification reaction; and a step 6 for separating alcohol and alkyl lactate by distillation from the mixture of step 5.
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Page/Page column 6
(2012/06/16)
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- Studies on the epimerization of diastereomeric lactides
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The epimerization of chiral lactides was studied in the presence of various homogeneous and heterogeneous bases. Some solvent/base systems were found to promote epimerization at room temperature efficiently. Side reactions such as polymerization were not observed or occurred only slowly. This new protocol offers the opportunity of the transformation of meso-lactide into rac-lactide. Therefore it can reduce the overall manufacturing costs of polylactides, a problem which currently hampers the broad application of those environmentally friendly polymers in a large scale.
- Shuklov, Ivan A.,Jiao, Haijun,Schulze, Joachim,Tietz, Wolfgang,Kühlein, Klaus,B?rner, Armin
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experimental part
p. 1027 - 1030
(2011/03/20)
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- METHODS FOR PRODUCING LACTIDE WITH RECYCLE OF MESO-LACTIDE
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An S, S- and R,R-lactide stream suitable for polymerization is prepared by producing a low molecular weight poly(lactic acid), depolymerizing the low molecular weight poly(lactic acid) to form a mixture of S, S-, R,R- and meso- lactide, and separating meso-lactide from this mixture to form an S, S- and R,R- lactide stream. Meso-lactide is recycled into the process, and shifts the mole fractions of the lactides in the lactide mixture that is produced.
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Page/Page column 32-35
(2010/10/03)
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- RECOVERY OF LACTIC ACID VALUES FROM A MESO-LACTIDE STREAM
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Lactic acid equivalents are recovered from a starting lactide stream by catalytically racemizing a portion of the lactide in the stream at a temperature of 18O°C or below. This increases the proportion of two species of lactide (i.e., at least two of S, S-, R,R- or meso-lactide) at the expense of the third species. The racemized mixture so obtained can be separated to recover some or all of one or more of the lactide species from the remaining lactide species, by a process such as melt crystallization or distillation. Impurities in the starting lactide stream usually are retained mostly in the remaining meso-lactide, so a highly purified S, S- and/or R,R-lactide stream can be produced in this manner. Such a purified S, S- and R,R-lactide stream is suitable for polymerization to form a polylactide.
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Page/Page column 23; 24
(2010/10/03)
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- Catalyst for direct conversion of esters of lactic acid to lactide and the method for producing lactide using the same
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The present disclosure discloses a catalyst for directly producing a lactide which is a cyclic ester used as a monomer for polylactides, and a method for directly producing a lactide using the catalyst, the method including the transesterification reaction between two molecules of an ester of lactic acid or a mixture containing the ester of lactic acid with a small amount of lactic acid and oligomer of lactic acid under an inert environment in the presence of a titanium-based catalyst or a catalyst mixture containing the titanium-based catalyst so as to produce lactide while simultaneously removing an alcohol (ROH) generated as a by-product. As compared to a conventional commercialized process, since the method for producing a lactide in accordance with the present disclosure is a novel process capable of directly producing the lactide from the ester of lactic acid, energy consumption is low and the lactide can be produced through a simple process showing a high yield while maintaining optical property (D-form or L-form optical isomer).
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Page/Page column 8; 9
(2011/01/11)
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- Catalyst For Direct Conversion Of Esters Of Lactic Acid To Lactide And The Method For Producing Lactide Using The Same
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The present disclosure discloses a catalyst for directly producing a lactide which is a cyclic ester used as a monomer for polylactides, and a method for directly producing a lactide using the catalyst, the method including the transesterification reaction between two molecules of an ester of lactic acid or a mixture containing the ester of lactic acid with a small amount of lactic acid and oligomer of lactic acid under an inert environment in the presence of a titanium-based catalyst or a catalyst mixture containing the titanium-based catalyst so as to produce lactide while simultaneously removing an alcohol (ROH) generated as a by-product. As compared to a conventional commercialized process, since the method for producing a lactide in accordance with the present disclosure is a novel process capable of directly producing the lactide from the ester of lactic acid, energy consumption is low and the lactide can be produced through a simple process showing a high yield while maintaining optical property (D-form or L-form optical isomer).
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Page/Page column 6-7
(2010/12/29)
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- PROCESS FOR MANUFACTURING A CYCLIC DIESTER OF AN A-HYDROXY ACID
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Process for manufacturing a cyclic diester of an α-hydroxy acid comprising the following steps: a substantially anhydrous salt of a divalent metal and of an α-hydroxy acid is mixed with a strong acid, the pKa of which is less than that of the α-hydroxy acid and the salt of which with the divalent metal is hygroscopic; andthe mixture is left to react for a sufficient time in order to obtain the cyclic diester dispersed in the hygroscopic salt.
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Page/Page column 4
(2009/12/28)
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- A PROCESS FOR THE PRODUCTION OF CYCLIC DIESTERS OF ALPHA-HYDROXYACIDS
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Process for the synthesis of a cyclic diester of an alpha-hydroxyacid, comprising the following steps: an alkalino-earth salt of the corresponding alpha-hydroxyacid is mixed with said alpha-hydroxyacid and water; the mixture is treated by evaporation-crystallization, so that a hydrate of the alkalino-earth salt of the linear dimer of the corresponding alpha-hydroxiacid precipitates; the hydrated salt is dehydrated to give the corresponding anhydrous salt; and the anhydrous salt is pyrolyzed, releasing the cyclic diester of the corresponding alpha-hydroxyacid and leaving the alkalino-earth hydroxide as solid residue.
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Page/Page column 9-10
(2009/07/25)
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- METHOD AND APPARATUS FOR PRODUCING POLYHYDROXY CARBOXYLIC ACID
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The object is to provide a method and apparatus for producing a polyhydroxy carboxylic acid according to which an annular diner can be efficiently obtained in the production of polyhydroxy carboxylic acid which is small in distribution breadth of molecular weight in depolymerization and opening ring polymerization steps. There are provided a depolymerization device 11 which depolymerizes hydroxy carboxylic acid or a polycondensate thereof into an annular dimer, a upper distillation column 13 which condenses the annular dimer vaporized in the depolymerization device 11, and lower distillation column 12 which refluxes the annular dimer and is provided between the depolymerization device 11 and the upper distillation column 13, said depolymerization device 11 having a polycondensate feed opening 54 and an annular dimer discharge opening 55 which are provided at a casing 50, a liquid film being formed inside the casing 50 and heated by a heating part.
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Page/Page column 5-6
(2010/11/29)
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- A bifunctional monomer derived from lactide for toughening polylactide
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(6S)-3-Methylene-6-methyl-1,4-dioxane-2,5-dione was synthesized from l-lactide and used as the dienophile to prepare spiro[6-methyl-1,4-dioxane-2,5-dione-3,2′-bicyclo[2.2.1]hept[5]ene] via an exoselective and diastereofacial-selective Diels-Alder reaction. Polymerizations of this bifunctional lactide derivative were successfully carried out under ring-opening and ring-opening metathesis polymerization conditions to yield high molecular weight and high Tg polymers. We further demonstrated that by incorporating a small percentage of spiro[6-methyl-1,4-dioxane-2,5-dione-3,2-bicyclo[2.2.1]hept[5]ene] into poly(1,5-cyclooctadiene) and copolymerizing it with dl-lactide, novel polymeric alloys of PLA can be created that have tremendous improvements in toughness over PLA and the corresponding binary blend of PLA and poly(1,5-cyclooctadiene). Copyright
- Jing, Feng,Hillmyer, Marc A.
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supporting information; experimental part
p. 13826 - 13827
(2009/02/07)
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- Menthyl lactate process
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A simple, high-yield process for making menthyl lactate (ML) is disclosed. Menthol and lactic acid react to produce a mixture comprising menthyl lactate and one or more higher lactoyl esters of ML. Hydrolysis of the esterification mixture follows in the presence of aqueous base under conditions effective to convert the higher lactoyl esters to menthyl lactate. Coincidentally, the conditions minimize hydrolysis of menthyl lactate to menthol, thereby maximizing the overall yield of ML.
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Page/Page column 5-6
(2008/06/13)
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- METHOD OF RECOVERING LACTIDE FROM POLYLACTIC ACID OR DERIVATIVE THEREOF
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To provide an efficient method for recovering and producing lactide having high optical purity by depolymerizing a polylactic acid or derivative thereof in order to carry out chemical recycling of the polylactic acid or derivative thereof or of a resin composition comprising same, wherein a mixture of a polylactic acid or derivative thereof and aluminum hydroxide is thermally decomposed at a temperature in a range from at least the melting temperature of the polylactic acid or derivative thereof to no greater than 320°C, thus recovering lactide.
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Page/Page column 8
(2008/06/13)
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- Method for the productiion of polylactide from a solution of lactic acid or one of the derivatives thereof
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A process for the production of polylactide, the stages of which for the production and purification of lactide, starting from an aqueous solution of lactic acid or of its derivatives, includes evaporation of water with formation of oligomers, depolymerization to give lactide, condensation and then crystallization of the crude lactide product to give purified lactide, aqueous treatment of the residual fractions from the crystallization and polymerization of purified and/or prepurified lactide to give polylactide in an extruder and in the presence of catalysts. An alternative process includes carrying out the aqueous treatment before the crystallization.
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Page/Page column 9
(2010/02/15)
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