- Supramolecular behavior of fluorous polyglycerol dendrons and polyglycerol dendrimers with perfluorinated shells in water
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In this article, we describe the synthesis of a perfluoro-tagged polyglycerol dendron and its aggregation behavior in the presence of polyglycerol dendrimers with perfluorinated shells in water. The perfluoro-alkyl-perfluoro-alkyl interactions between the perfluorinated shells of the dendrimers and the perfluorinated tags of the dendrons lead to highly stable supramolecular architectures, due to self-assembly of the perfluorinated moieties. Furthermore, we show that the size of the resulting supramolecular complexes can be tuned by simple variation of the dendrimer-dendron ratio. Complexes at various ratios are characterized by optical microscopy, DLS, and TEM. In general, the results presented herein demonstrate that perfluoro-alkyl-perfluoro-alkyl interactions are applicable for the formation of stable supramolecular structures in water and thus provide a new tool for the design of supramolecular architectures in addition to traditional non-covalent interactions.
- Zieringer, Maximilian,Wyszogrodzka, Monika,Biskup, Karina,Haag, Rainer
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- Newer Non-ionic A2B2-Type Enzyme-Responsive Amphiphiles for Drug Delivery
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A new series of nonionic gemini amphiphiles have been synthesized in a multi-step chemoenzymatic approach by using a novel A2B2-type central core consisting of conjugating glycerol and propargyl bromide on 5-hydroxy isophthalic acid. A pair of hydrophilic monomethoxy poly(ethylene glycol) (mPEG) and hydrophobic linear alkyl chains (C12/C15) were then added to the core to obtain amphiphilic architectures. The aggregation tendency in aqueous media was studied by dynamic light scattering, fluorescence spectroscopy and cryogenic transmission electron microscopy. The nanotransport potential of the amphiphiles was studied for model hydrophobic guests, that is, the dye Nile Red and the drug Nimodipine by using UV/Vis and fluorescence spectroscopy. Evaluation of the viability of amphiphile-treated A549 cells showed them to be well tolerated up to the concentrations studied. Being ester based, these amphiphiles exhibit stimuli-responsive sensitivity towards esterases, and a rupture of amphiphilic architecture was observed in the presence of immobilized Candida antarctica lipase (Novozym 435), thus facilitating release of the encapsulated guest from the aggregate.
- Achazi, Katharina,B?ttcher, Christoph,Haag, Rainer,Krishna,Parshad, Badri,Sharma, Sunil K.
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- A Kinetic Investigation of Triacetin Methanolysis and Assessment of the Stability of a Sulfated Zirconium Oxide Catalyst
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In this work, the activity and stability of a sulfated zirconium catalyst in transesterification reactions of triacetin, a model molecule, were investigated. This catalyst has Lewis and Br?nsted acid sites and has shown to be highly active in reactions converting triacetin into methyl esters. This catalyst was synthesized using the impregnation method, and systematically characterized using the techniques of x-rays diffraction (XRD), scanning electron microscopy, Fourier transform-infrared spectroscopy (FT-IR), Brunauer, Emmett, and Teller, and thermal gravimetry analysis (TGA). Kinetic studies were carried out to determine the activation energy as well as the reaction order. The effects of the main reaction parameters, such as temperature, the molar ratio, and the catalyst content, were evaluated. The reuse and possible leaching of the catalyst were also investigated. The highest efficiency (ca. 99% of methyl esters) was achieved in the sulfated zirconium oxide-catalyzed transesterification reaction.
- Temóteo, Rafael L.,da Silva, Marcio J.,de ávila Rodrigues, Fabio,da Silva, Wagner F.,de Jesus Silva, Deusanilde,Oliveira, Cesar M.
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- Design and Synthesis of Novel Triazolyl Benzoxazine Derivatives and Evaluation of Their Antiproliferative and Antibacterial Activity
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A series of novel triazolyl benzoxazine derivatives have been synthesized via Cu(I)-catalyzed ‘Click’ cycloaddition. All of the compounds were fully characterized from their spectral data, and their antiproliferative activity was evaluated against three selected human cancer cell lines: cervical cancer cells (HeLa), colorectal adenocarcinoma (HT-29), and ovarian adenocarcinoma (SKOV-3). A few representative compounds have also been evaluated for their antibacterial potential against two bacterial strains Pseudomonas aeruginosa and Bacillus subtilis.
- Khan, Abdullah,Prasad, Suchita,Parmar, Virinder S.,Sharma, Sunil K.
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- Non-ionic dendronized multiamphiphilic polymers as nanocarriers for biomedical applications
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A new class of non-ionic dendronized multiamphiphilic polymers is prepared from a biodegradable (AB)n-type diblock polymer synthesized from 2-azido-1,3-propanediol (azido glycerol) and polyethylene glycol (PEG)-600 diethylester using Novozym-43
- Gupta, Shilpi,Schade, Boris,Kumar, Sumit,Boettcher, Christoph,Sharma, Sunil K.,Haag, Rainer
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- Aggregation Behavior of Non-ionic Twinned Amphiphiles and Their Application as Biomedical Nanocarriers
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A new class of twinned amphiphiles was developed by conjugating a pair of hydrophilic head groups from mPEG chains (Mn: 350 or 1000) and a pair of hydrophobic segments from linear alkyl chains (C11 or C18) through a novel spacer synthesized from glycerol and p-hydroxybenzoic acid. The aggregation phenomena of the amphiphiles were proven by DLS and fluorescence experiments, whereas size and morphology of the aggregates were evaluated by cryo-TEM. The measurements proved the formation of globular, thread-like or rod-like micelles as well as planar double-layer assemblies, depending on the amphiphile's molecular structure. The applicability of these non-ionic amphiphilic systems as nanocarriers for hydrophobic guest molecules was demonstrated by encapsulating a hydrophobic dye, Nile Red, and a hydrophobic drug, Nimodipine. The transport capacity results for both Nimodipine and Nile Red prove them as a promising candidate for drug delivery.
- Singh, Abhishek K.,Thota, Bala N. S.,Schade, Boris,Achazi, Katharina,Khan, Abdullah,B?ttcher, Christoph,Sharma, Sunil K.,Haag, Rainer
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- NO donors. Part 18: Bioactive metabolites of GTN and PETN-Synthesis and vasorelaxant properties
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The vasodilators glyceryl trinitrate (GTN) and pentaerythrityl tetranitrate (PETN) are supposed to be degraded in vivo to the lower nitrates PETriN, PEDN, PEMN, 1,2-GDN, 1,3-GDN, 1-GMN, and 2-GMN. We synthesized these bioactive metabolites as reference compounds for pharmacokinetic studies. The use of HPLC-methods for monitoring the stepwise reduction of PETN to lower nitrates and the syntheses of the glyceryl dinitrates proved advantageous. Furthermore, we measured the vasorelaxant properties of all metabolites by performing organ bath experiments with porcine pulmonary arteries. In general, the vasodilator potency increases with the number of nitrate moieties in the compound.
- Lange, Kathrin,Koenig, Andreas,Roegler, Carolin,Seeling, Andreas,Lehmann, Jochen
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- Synthesis of non-ionic bolaamphiphiles and study of their self-assembly and transport behaviour for drug delivery applications
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A series of four bolaamphiphiles with different hydrophilic units has been synthesised. All the amphiphiles were well characterised from their physiochemical data. The aggregation tendency of newly synthesised amphiphiles was studied using fluorescence spectroscopy, dynamic light scattering (DLS), and cryogenic electron microscopy (cryo-TEM). Furthermore, their application as nanocarriers for hydrophobic guests was demonstrated by using two established standards, i.e. the dye Nile red and the drug nimodipine. A cytotoxicity and cellular uptake study has been carried out using A549 cells. Due to the presence of an ester linkage in PEG based bolaamphiphiles, a drug release study was performed in the presence of an immobilized enzyme Novozym-435 (a lipase).
- Rashmi,Singh, Abhishek K.,Achazi, Katharina,Schade, Boris,B?ttcher, Christoph,Haag, Rainer,Sharma, Sunil K.
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- Transesterification of triacetin and castor oil with methanol catalyzed by supported polyaniline-sulfate. A role of polymer morphology
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Polyaniline-sulfate deposited on three different carriers was studied for transesterification of triacetin and castor oil with methanol at mild reaction conditions (temperature of 55 °C). Multi-wall carbon nanotubes (CNT), carbon and silica were coated with polyaniline sulfate (ca. 20 wt%) during polymerization of aniline. Because of different textural and hydrophobic properties of the carriers, the polymer coatings of various morphologies were obtained as evidenced by the electron microscopy technique. A uniform coating of CNT with polymer resulted in the most extended polymer structure. Nanorods of polymer forming branched dendritic structures appeared in the other two carbon and silica carriers. The acid capacity and the strength of acid sites were similar in all studied catalysts. All the samples were found to be active solid acid catalysts in methanolysis of both studied triglycerides and CNT-coated polyaniline sulfate exhibited the highest activity. The course of reaction during methanolysis of triacetin on CNT-containing catalyst was similar to that in the presence of soluble sulfuric acid. On the other hand, a partial blockage of active sites was observed in carbon and silica coated with polyaniline sulfate. A blockage effect was ascribed to strong interaction of acid sites with more polar reagents among them diacetin and glycerol. These interactions were facilitated by aggregated fibriral morphology of the polymer coating resulting in locally high density of acid sites.
- Drelinkiewicz,Kalemba-Jaje,Lalik,Zi?ba,Mucha,Konyushenko,Stejskal
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- A highly active and stable organic-inorganic combined solid acid for the transesterification of glycerol under mild conditions
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Solid acid catalyst plays a crucial role in the petroleum refinery industry and bio-refinery technology. In this work, p-phenolsulfonic acid (PSA) was successfully grafted onto the surface of KH560-modified zirconium phosphate (K-ZrP) in a facile routine. The structure and property of this organic-inorganic combined solid acid PSA/K-ZrP-x were characterized via XRD, FTIR, 13C solid-state NMR, TG, N2 adsorption-desorption, SEM, pyridine-adsorption FTIR and XPS technologies. The characterization results showed that KH560 can bond with ZrP and promote the grafting of PSA on the surface of K-ZrP via the condensation reaction between its epoxy ring and the phenolic hydroxyl group in PSA. Consequently, PSA/K-ZrP-2 exhibited excellent performance and stability in the transesterification between glycerol and methyl acetate among the tested H3PW12O40, Amberlyst-45, HBEA, HZSM-5, ZrP, AlCl3 and FeCl3 catalysts. The calculated conversion of glycerol reached 81.3% with a 97.9% selectivity for monoacetin (MAG) and diacetin (DAG) with a 2.2% dosage of [H+] at 100 °C for 4 h. The highest specific activity of PSA/K-ZrP-2 reached 24028.2 mg-glycerol/g-cat/h in a short reaction time (at 0.17 h), and it could be recycled five times without obvious deactivation.
- Hou, Zhaoyin,Jiang, Yuanyuan,Long, Yihua,Wang, Zhengbao,Ye, Boyong,Zhao, Huaiyuan,Zhou, Ruru
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p. 1772 - 1781
(2021/06/28)
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- Lanthanum nanocluster/ZIF-8 for boosting catalytic CO2/glycerol conversion using MgCO3as a dehydrating agent
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A lanthanum-modified zeolitic imidazolate framework (La/ZIF-8) was developed to produce glycerol carbonate using CO2and glycerol as raw materials. La/ZIF-8 provides a high catalytic glycerol conversion efficiency owing to its surface-attached nanoclusters of La2O3, which can be viewed as La3+-O2?pairs that strengthen the Lewis basicity and acidity, and the large specific surface area of ZIF-8. The catalytic glycerol conversion and the yield of glycerol carbonate were 46.5% and 35.3%, respectively, using CH3CN as a dehydrating agent. With increase in the amount of CH3CN, the water molecules could react with CH3CN to reduce the selectivity. When an inorganic dehydrating agent, MgCO3, was used to physically adsorb and remove water molecules in the reaction, the selectivity of the reaction could be increased to over 95%, which is the highest ever reported. Reaction kinetics analysis also revealed that the activation energy of using MgCO3(5.4 kJ mol?1) as a dehydrating agent is lower than that using CH3CN (7.8 kJ mol?1). Moreover, the La/ZIF-8 could be recycled and reused at least three times with high catalytic performance. This study provides an effective material with dual Lewis basicity and acidity for CO2/glycerol conversion and significantly improves the catalytic performance using an inorganic dehydrating agent.
- Hu, Chechia,Chang, Chien-Wei,Yoshida, Masaaki,Wang, Ke-Hsuan
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p. 7048 - 7058
(2021/03/29)
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- Biodiesel Glycerin Valorization into Oxygenated Fuel Additives
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Current industrial methods of biodiesel production lead to an excess of crude glycerin which requires costly purification before commercialization. Production of oxygenated fuel additives is a potential route for glycerin valorization. Glycerin acetylation was carried out over heterogeneous acid catalysts (15%, glycerol weight basis) using glacial acetic acid (molar ratio = 9). The catalysts, containing different amounts of phosphate species (P/Si from 10 to 20 atomic ratio), were prepared by wet impregnation of commercial silica with aqueous solutions of diammonium phosphate and ortho-phosphoric acid. X-ray diffraction patterns of calcined solids presented amorphous patterns like raw silica. The prepared catalysts presented, at 120?°C, glycerol conversion higher than 89.5% after 1?h of reaction, been diacetin the major product, with triacetin selectivities lower than 26.1%. Diacetin selectivity was found to be almost invariant with catalyst acidity thus underlining the relevance of catalyst porosity due to the large acetins molecules sizes. The slow rate of triacetin diffusion in narrow pores of catalyst might be responsible for the relatively low yield obtained. Surface phosphate species showed a slow rate of leaching in the reaction medium showing high catalyst stability. Graphical Abstract: [Figure not available: see fulltext.]
- Catarino, Mónica,Gomes Fonseca, Frederico,Gomes, Jo?o,Soares Dias, Ana Paula
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- 4'-ETHYNYL-2'-DEOXYADENOSINE DERIVATIVES AND THEIR USE IN HIV THERAPY
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The invention relates to compounds of Formulae (I)-(II), salts thereof, pharmaceutical compositions thereof, as well as methods of treating or preventing HIV in subjects.
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Page/Page column 71
(2021/03/05)
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- Metabolic engineering of: Escherichia coli for production of non-natural acetins from glycerol
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Mono-, di- and triacetin are three glycerol esters which are usually synthesized via costly and environmentally unfriendly chemical synthesis methods. Here, Escherichia coli is metabolically engineered for the production of mono-, di- and triacetin using glycerol as a substrate. First, a novel biosynthetic route of mono- and diacetin is established by overexpression of a native enzyme, maltose O-acetyltransferase (MAA). Next, the biosynthetic pathway is extended to produce a mixture of mono-, di- and triacetin by overexpression of chloramphenicol-O-acetyltransferase (CAT). By successive strategies, including heterologous gene expression, metabolic engineering, and culture optimization, a recombinant E. coli is enabled to produce more than 27 g L-1 of a mixture of mono-, di- and triacetin in shake flask cultures, which is a >650-fold increase over the initial production of 0.04 g L-1. In vitro studies confirm the acetylation of glycerol to mono- and diacetin by MAA, and the additional acetylation to triacetin by CAT. When crude glycerol is used as a substrate, the engineered strain produced a total of 25.9 g L-1 of the acetin mixture, about the same as that achieved from pure glycerol. To our knowledge, this is the first successful report of microbial production of the artificial chemicals, acetins.
- Jeong, Seong-Hee,Joo, Seongjoon,Kim, Kyung-Jin,Kim, Seon-Won,Seo, Hogyun,Sohn, Jung-Hoon,Tseten, Tenzin,Wang, Chonglong,Zada, Bakht
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supporting information
p. 7788 - 7802
(2020/12/01)
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- A transesterification-acetalization catalytic tandem process for the functionalization of glycerol: The pivotal role of isopropenyl acetate
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At 30 °C, in the presence of Amberlyst-15 as a catalyst, a tandem sequence was implemented by which a pool of innocuous reactants (isopropenyl acetate, acetic acid and acetone) allowed upgrading of glycerol through selective acetylation and acetalization processes. The study provided evidence for the occurrence of multiple concomitant reactions. Isopropenyl acetate acted as a transesterification agent to provide glyceryl esters, and it was concurrently subjected to an acidolysis reaction promoted by AcOH. Both these transformations co-generated acetone which converted glycerol into the corresponding acetals, while acidolysis sourced also acetic anhydride that acted as an acetylation reactant. However, tuning of conditions, mostly by changing the reactant molar ratio and optimizing the reaction time, was successful to steer the set of all reactions towards the synthesis of either a 1?:?1 mixture of acetal acetates (97% of which was solketal acetate) and triacetin, or acetal acetates in up to 91% yield, at complete conversion of glycerol. To the best of our knowledge, a one-pot protocol with such a degree of control on the functionalization of glycerol via transesterification and acetalization reactions has not been previously reported. The procedure was also easily reproduced on a gram scale, thereby proving its efficiency for preparative purposes. Finally, the design of experiments with isotopically labelled reagents, particularly d4-acetic acid and d6-acetone, helped to estimate the contribution of different reaction partners (iPAc/AcOH/acetone) to the formation of final products. This journal is
- Calmanti, Roberto,Perosa, Alvise,Rigo, Davide,Selva, Maurizio
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p. 5487 - 5496
(2020/09/23)
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- Single-pot template-free synthesis of a glycerol-derived C-Si-Zr mesoporous composite catalyst for fuel additive production
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Synthesis of a highly ordered mesoporous acid- as well as metal-functionalized carbon (-SO3H/C-Si-Zr) material is achieved for the first time from a simple single-pot template-free carbonization of low-value bio-derived glycerol. Addition of TEOS to glycerol right before the carbonization was observed to facilitate molecular-level interactions between them to establish C-Si bonding, which eventually leads to the formation of a high surface area mesoporous -SO3H/C-Si composite material. Unlike this, the addition of ZrO(NO3)2·xH2O to glycerol could not have such an effect, but when Zr is used in the presence of TEOS the mixture could successfully produce the -SO3H/C-Si-Zr composite possessing mesoporosity and uniform acidity suitable for bulky tri-acetin production useful for fuel applications. Here TEOS is observed to play two roles, (1) as a surface area and porosity improver of graphitic carbon by its C-Si interaction and (2) as a mediator to involve Zr in the carbon composite structure through its Si-OH group. Thus, the combined inclusion of Zr and Si sources in the glycerol-derived carbon structure could successfully introduce the positive aspects of porosity improvement (by Si) and acidity improvement (by zirconia) in the mixed composite -SO3H/C-Si-Zr to produce the highest ever selectivity of tri-acetin (～94 wt%) from the same low-value bio-derived glycerol by an acetylation reaction. The sustainability of the process lies in the utilization of waste glycerol as a source of the carbon composite, which in turn catalyzes selective low-value glycerol conversion to industrially important fuel additives.
- Al-Muhtaseb, Ala'A H.,Diwakar, Jitendra,Kumar, Saurabh,Saxena, Sandeep K.,Selvamani, Arumugam,Viswanadham, Nagabhatla
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supporting information
p. 8254 - 8263
(2020/06/10)
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- A comparative study on porous solid acid oxides as catalysts in the esterification of glycerol with acetic acid
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Acid catalysts comprising of porous SiAl, as well as molybdophosphoric heteropolyacid, supported SiAl nanotubes were synthesized. The characterizations were through scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), termoprogrammed ammonia desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR). Esterification of glycerol into acetins reaction was evaluated over two series of SiAl-based solids. Both series displayed very good activity as well as selectivity towards the acetins within a short reaction time. However, porous SiAl deactivated due to acid sites leaching in long-term catalytic runs. The tuning of the loadings of the molybdophosphoric amount on SiAl halloysite nanotubes leads to an increase in the selectivity towards the mono, di, and triacetins. These catalysts were also recycled up to three times, and a 17 percent of conversion and 100 percent of selectivity for triacetin were obtained due to the combination of acidity, stable structure and porosity of the molybdophosphoric supported SiAl nanotubes.
- Araujo, Jesuina C. S.,Campos, Adriana F.,Filho, Josué M.,Freire, Paulo T. C.,Lang, Rossano,Neto, Antonio B. S.,Oliveira, Alcineia C.,Rodriguez-Castellón, Enrique,Sousa, Francisco F. F.
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- Application of SO4/WOZrO2 catalyst to preparation of diacetin from glycerol through catalytic conversion
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The invention discloses a purpose of an SO4/WOZrO2 catalyst to preparation of diacetin from glycerol through catalytic conversion. The catalyst has the specific surface area of 10 to 40m.g, the hole volume being 0.002 to 0.1cm.g, the hole diameter being 3 to 20nm, and the mol ratio of tungsten to zirconium is (1:3)-(3:1). Experiment results prove that the SO4/WOZrO2 catalyst shows excellent catalytic activity in preparation of the diacetin from the glycerol; the glycerol conversion rate can reach 100 percent; the yield of the diacetine can reach 50 percent or higher; products and catalysts can be easily separated; the recovery catalysts can be repeatedly used; the circulation stability is high.
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Paragraph 0013; 0019-0020
(2018/09/13)
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- Acetylation of Glycerol over Highly Stable and Active Sulfated Alumina Catalyst: Reaction Mechanism, Kinetic Modeling and Estimation of Kinetic Parameters
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The Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetic model was developed for acetylation of glycerol over highly stable and active 2 M SO4 2?/γ-Al2O3 catalyst. The apparent reaction rate constants were determin
- Pankajakshan, Arun,Pudi, Satyanarayana Murty,Biswas, Prakash
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- Method for preparing 2-amino-6-chloro-9-(4-acetoxy-3-acetoxymethylbutyl)purine
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The invention relates to a method for preparing 2-amino-6-chloro-9-(4-acetoxy-3-acetoxymethylbutyl)purine. The method comprises the following steps: reacting 1,3-dichloro-2-propanol with acetic acid to obtain 1,3-diacetoxy-2-propanol, brominating the 1,3-diacetoxy-2-propanol to obtain 1,3-diacetoxy-2-bromopropane, and reacting the 1,3-diacetoxy-2-bromopropane with zinc powder to obtain 1,3-diacetoxy-2-propylzinc bromide, and then performing a Negishi Coupling reaction on the 1,3-diacetoxy-2-propylzinc bromide and chloro-9-bromoethylpurine to obtain 2-amino-6-chloro-9-(4-acetoxy-3-acetoxymethylbutyl)purine. The obtained 2-amino-6-chloro-9-(4-acetoxy-3-acetoxymethylbutyl)purine has an HPLC purity of 99.5% or more, and can be used for producing famciclovir and penciclovir.
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Paragraph 0019; 0035
(2018/08/03)
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- The effect of an electron-withdrawing group in the imidazolium cation: The case of nitro-functionalized imidazolium salts as acidic catalysts for the acetylation of glycerol
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The acetylation of glycerol was achieved with high conversion and selectivity towards triacetin at low temperatures and short reaction times by using acidic imidazolium salts as catalysts. Moreover, the addition of a nitro group to the imidazolium cation affords a much more competent catalyst, indicating a significant effect provided by the simple electronic change in the imidazolium cation. Theoretical calculations revealed increased polarization of the acidic hydrogen bond on the nitrated salts, which may be related to their superior catalytic behavior when compared to the non-functionalized salts. Combining the preliminary experimental and theoretical results, it is possible to suppose that the catalytic activity of acidic imidazolium salts may be better comprehended by its Br?nsted acidities, but other parameters such as hardness, electronegativity, electrophilicity and ion-pair binding energy were also evaluated in order to investigate their effects in the acetylation of glycerol promoted by these acidic imidazolium salts.
- Morais, Eduardo M.,Grillo, Igor B.,Stassen, Hubert K.,Seferin, Marcus,Scholten, Jackson D.
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p. 10774 - 10783
(2018/07/05)
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- POSS-derived solid acid catalysts with excellent hydrophobicity for highly efficient transformations of glycerol
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Novel excellent hydrophobic POSS-derived solid acid catalysts were successfully synthesized through free radical copolymerization of polyhedral oligomeric vinylsilsesquioxanes (POSS) with sodium p-styrene sulfonate (POSS-x-SO3H), and characterized by several physicochemical methods. Green routes toward valorization of glycerol via acetalization with benzaldehyde and esterification of glycerol with acetic acid have been proposed. The as-prepared catalysts showed very high activities and selectivities toward glycerol derivatives within a short reaction time, which were even higher than that of homogeneous H2SO4. The POSS-2-SO3H catalyst was recycled up to five times without any significant loss of activity. The excellent performance of these solid acid catalysts is mostly attributed to the combination of superior hydrophobicity and large specific surface area.
- Leng, Yan,Zhao, Jiwei,Jiang, Pingping,Lu, Dan
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p. 875 - 881
(2016/02/18)
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- Understanding the role of Keggin type heteropolyacid catalysts for glycerol acetylation using toluene as an entrainer
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The heterogeneously catalyzed esterification (acetylation) of glycerol toward triacetin in batch mode in presence of toluene as entrainer was studied. Silicotungstic acid, tungstophosphoric acid and phosphomolybdic acid as heteropolyacids (HPAs) supported on silica, alumina or silica-alumina were used as catalysts. The course of the reaction was found to be very sensitive to the nature of the HPA as well as the support. Solid characterization by Raman spectroscopy, XRD, and pyridine-FTIR revealed that only combinations of tungsten-based HPAs and silica support were able to preserve the structure of active component throughout the preparation process, which was essential to obtain active and selective catalysts. The interaction between HPA and support was decisive for stability and dispersion of the catalytically active species. With the best performing catalyst H4SiW12O40/SiO2, selectivity to triacetin reached 71% at complete conversion within 24?h. The high selectivity to triacetin is attributed the Br?nsted acidic sites originated from stabilized Keggin structure and continuous removal of water during course of reaction. Toluene is able to form azeotropic mixtures with water and acetic acid and keeps the reaction temperature below the boiling point of acetic acid. Thus, water-free reaction conditions can be established. The catalyst was reusable; however, the activity and selectivity towards triacetin slightly decreased in a repetition run due to loss of active sites.
- Kale,Armbruster,Eckelt,Bentrup,Umbarkar,Dongare,Martin
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- Volume accessibility of acid sites in modified montmorillonite and triacetin selectivity in acetylation of glycerol
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Organic acid treatment enhances the acidity and surface characteristics of montmorillonite clay by dealumination. Dealuminated and Al-clays were used for acetylation of glycerol with acetic acid. All clays used had comparable acidity but pore characteristics were different. Though glycerol conversions were similar but triacetin selectivity was different. Al-clay and acid treated clays showed poor and improved selectivity, respectively. This was attributed to increased pore volume around the acid sites, which facilitates the multiple acetylation of glycerol. The generated space around acid centers, termed as 'volume accessibility', helps glycerol to interact with acylium ions formed on the acid sites more effectively leading to formation of triacetin. Correlations were made between the changed characteristics of clays and triacetin yield. Among the different correlations, triacetin selectivity correlates well with the volume accessibility. The latter is quite useful in predicting the catalytic performance.
- Venkatesha,Bhat,Prakash, B. S. Jai
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p. 45819 - 45828
(2016/06/06)
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- Fe4(SiW12O40)3-catalyzed glycerol acetylation: Synthesis of bioadditives by using highly active Lewis acid catalyst
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In order to investigate the effect of Lewis acidic metals on the acid properties of Keggin heteropolyacids catalysts, a set of metal-exchanged HPAs (i.e. M3/nPW12O40, M3/nPMo12O40 and M4/nSiW12O40 (M?=?Cu, Co and Mn, n?=?2; M?=?Fe, n?=?3) were synthesized and their activity on glycerol esterification with acetic acid was evaluated. This procedure avoids the use of corrosive Br?nsted acid catalysts. Regardless of the heteropoly anion, the activity of catalysts in terms of metal cations followed the sequence: Fe3+>?Cu2+>?Mn2+>?Co2+. It has been found that among the HPAs, only H4SiW12O40 has the acidic protons that can be successfully exchanged with Fe3+ cations, resulting in Fe4(SiW12O40)3 salt, the most active and selective catalyst. The highest conversion (ca.99.9%) was achieved in Fe4(SiW12O40)3-catalyzed esterification reactions, along with the highest selectivity for di and triacetyl glycerol (ca.55 and 42%, respectively). Effects of temperature, stoichiometry of reactants, concentration and nature of catalysts were assessed. A kinetic study of Fe4(SiW12O40)3 or H4SiW12O40-catalyzed reactions was conducted and the activation energy determined.
- Da Silva, Márcio José,Liberto, Natalia Aparecida,De Andrade Leles, Lorena Cristina,Pereira, Ulisses Alves
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- An efficient and sustainable production of triacetin from the acetylation of glycerol using magnetic solid acid catalysts under mild conditions
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The efficient and selective acetylation of glycerol to produce triacetin is achieved using magnetic solid acids as catalysts. The Fe-based materials including Fe-Sn-Ti (OH)x, Fe-Sn-Ti(SO42-) and Fe-Sn-Ti(SO42-)-t (t represents the temperature for the heating treatment) were successfully prepared and employed in the acetylation of glycerol, respectively. As a result, 100% conversion and 99.0% selectivity for triacetin was obtained in the presence of a catalytic amount of Fe-Sn-Ti(SO42-)-400 at 80 °C for 30 min, which exhibits higher catalytic activity than those of some molecular sieves. The magnetic catalytic materials were respectively characterized by XRD, IR, TG-DTG, BET and NH3-TPD techniques. Moreover, the effects of reaction temperature and reaction time in the glycerol acetylation are investigated in detail. Finally, based on the experimental results and reaction phenomena, a possible mechanism for the catalytic reaction is proposed.
- Sun, Jinyan,Tong, Xinli,Yu, Linhao,Wan, Jun
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p. 115 - 122
(2016/03/19)
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- Selective formation of triacetin by glycerol acetylation using acidic ion-exchange resins as catalyst and toluene as an entrainer
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Esterification of glycerol with acetic acid in the presence of toluene as an entrainer was performed over acidic Amberlyst ion-exchange resins in a batch reactor. Toluene continuously removed the reaction water, thus the chemical equilibrium was effectively shifted; the selectivity for the most desired product triacetin was dramatically increased. The influence of reaction conditions such as reaction time, acetic acid: glycerol molar ratio and catalyst amount were investigated. More than 95% selectivity to triacetin at complete glycerol conversion was obtained. The ion-exchange resin catalysts were reusable in subsequent runs, but due to some deactivation the triacetin yields deteriorated.
- Kale,Umbarkar,Dongare,Eckelt,Armbruster,Martin
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- Biobased catalyst in biorefinery processes: Sulphonated hydrothermal carbon for glycerol esterification
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Sulphonated hydrothermal carbon (SHTC), obtained from d-glucose by mild hydrothermal carbonisation and subsequent sulphonation with sulphuric acid, is able to catalyse the esterification of glycerol with different carboxylic acids, namely, acetic, butyric and caprylic acids. Product selectivity can be tuned by simply controlling the reaction conditions. On the one hand, SHTC provides one of the best selectivity towards monoacetins described up to now without the need for an excess of glycerol. On the other hand, excellent selectivity towards triacylglycerides (TAG) can be obtained, beyond those described with other solid catalysts, including well-known sulphonic resins. Recovery of the catalyst showed partial deactivation of the solid. The formation of sulphonate esters on the surface, confirmed by solid state NMR, was the cause of this behaviour. Acid treatment of the used catalyst, with subsequent hydrolysis of the surface sulphonate esters, allows SHTC to recover its activity. The higher selectivity towards mono- and triesters and its renewable origin makes SHTC an attractive catalyst in biorefinery processes.
- De La Calle, Carlos,Fraile, José M.,García-Bordejé, Enrique,Pires, Elísabet,Roldán, Laura
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p. 2897 - 2903
(2015/05/13)
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- Graphene oxide as a facile solid acid catalyst for the production of bioadditives from glycerol esterification
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Graphene oxide (GO) has proved to be a highly active and reusable solid acid catalyst for glycerol esterification with acetic acid in the synthesis of bioadditives diacylglycerol (DAG) and triacylglycerol (TAG). The effects of reaction temperature, molar ratio of acetic acid to glycerol, catalyst amount and reaction time were investigated. A 90.2% combined selectivity of DAG and TAG with complete glycerol conversion was achieved at 120 °C for 6 h over GO. Final characterization shows that the active site of GO is the remaining SO3H group.
- Gao, Xiaoqing,Zhu, Shanhui,Li, Yongwang
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- Regioselective acetylation of diols and polyols by acetate catalysis: Mechanism and application
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We propose a principle for H-bonding activation in acylation of hydroxyl groups, where the acylation is activated by the formation of hydrogen bonds between hydroxyl groups and anions. With the guidance of this principle, we demonstrate a method for the selective acylation of carbohydrates. By this method, diols and polyols are regioselectively acetylated in high yields under mild conditions using catalytic amounts of acetate. In comparison to other methods involving reagents such as organotin, organoboron, organosilicon, organobase, and metal salts, this method is more environmentally friendly, convenient, and efficient and is also associated with higher regioselectivity. We have performed a thorough quantum chemical study to decipher the mechanism, which suggests that acetate first forms a dual H-bond complex with a diol, which enables subsequent monoacylation by acetic anhydride under mild conditions. The regioselectivity appears to originate from the inherent structure of the diols and polyols and their specific interactions with the coordinating acetate catalyst.
- Ren, Bo,Rahm, Martin,Zhang, Xiaoling,Zhou, Yixuan,Dong, Hai
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p. 8134 - 8142
(2015/03/18)
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- Heteropolyacid-based ionic liquids as efficient homogeneous catalysts for acetylation of glycerol
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A series of homogeneous catalysts consisting of pyridinium propyl sulfobetaine (PPS), tungstophosphoric acid (TPA), and acetic acid (HOAc) have been synthesized and exploited for catalytic acetylation of glycerol (GL). Their acid properties were characterized by 31P NMR of trimethylphosphine oxide (TMPO) as the probe molecule, and the effects of acidic strength, PPS/TPA, TPA/GL, and HOAc/GL ratios as well as reaction temperature on catalytic performances during acetylation reaction were investigated. These water-tolerable PPS-TPA-HOAc catalysts, which tend to segregate from glycerol acetate products to form distinct biphasic liquid layers spontaneously after the reaction, were found to be highly efficient and durable for acetylation reaction under continuous operation conditions. Typically, a complete GL conversion may be achieved with a superior glycerol triacetate (GTA) selectivity of 86-99%. Moreover, the unique self-separation biphasic characteristics of the catalyst system facilitate facile separation of products and recycling of catalyst, rendering practical industrial applications in acetylation of alcohol.
- Huang, Ming-Yu,Han, Xiao-Xiang,Hung, Chin-Te,Lin, Jann-Chen,Wu, Pei-Hao,Wu, Jung-Chung,Liu, Shang-Bin
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- Heteropolyacid-based ionic liquids as efficient homogeneous catalysts for acetylation of glycerol
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A series of homogeneous catalysts consisting of pyridinium propyl sulfobetaine (PPS), tungstophosphoric acid (TPA), and acetic acid (HOAc) have been synthesized and exploited for catalytic acetylation of glycerol (GL). Their acid properties were characterized by 31P NMR of trimethylphosphine oxide (TMPO) as the probe molecule, and the effects of acidic strength, PPS/TPA, TPA/GL, and HOAc/GL ratios as well as reaction temperature on catalytic performances during acetylation reaction were investigated. These water-tolerable PPS-TPA-HOAc catalysts, which tend to segregate from glycerol acetate products to form distinct biphasic liquid layers spontaneously after the reaction, were found to be highly efficient and durable for acetylation reaction under continuous operation conditions. Typically, a complete GL conversion may be achieved with a superior glycerol triacetate (GTA) selectivity of 86-99%. Moreover, the unique self-separation biphasic characteristics of the catalyst system facilitate facile separation of products and recycling of catalyst, rendering practical industrial applications in acetylation of alcohol.
- Huang, Ming-Yu,Han, Xiao-Xiang,Hung, Chin-Te,Lin, Jann-Chen,Wu, Pei-Hao,Wu, Jung-Chung,Liu, Shang-Bin
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- Pheromone synthesis. Part 255: Synthesis and GC-MS analysis of pheromonal triacylglycerols of male Drosophila fruit flies
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Pheromonal triacylglycerols and their analogs, 1A, 1B, 2A, 2B, 3A, 3B, and 3C, of male Drosophila fruit flies were synthesized and analyzed by GC-MS. Their GC retention times were found to be a reliable measure to analyze and identify these triacylglycerols with acetyl, oleoyl and tigloyl groups, although the stereo- and regioisomers of 1 (1A and 1B), 2 (2A and 2B), and 3 (3A, 3B, and 3C) could not be distinguished from each other by MS alone.
- Mori, Kenji
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p. 5752 - 5762
(2015/03/30)
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- Design of a highly active silver-exchanged phosphotungstic acid catalyst for glycerol esterification with acetic acid
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A series of highly active, selective, and stable silver-exchanged phosphotungstic acid (AgPW) catalysts were prepared, characterized, and evaluated for bio-derived glycerol esterification with acetic acid to produce valuable biofuel additives. The structures, morphologies, acidities, and water tolerance of these samples were determined by FTIR, Raman, XRD, SEM-EDX, FT-IR of pyridine adsorption, and H2O-TPD. Several typical acidic catalysts were also performed for comparison. Among them, partially silver-exchanged phosphotungstic acid (Ag1PW) presented exceptionally high activity, with 96.8% conversion within just 15 min of reaction time and remarkable stability, due to the unique Keggin structure, high acidity as well as outstanding water-tolerance property. A plausible reaction mechanism was also proposed. In addition, this Ag1PW catalyst exhibited universal significance for esterification, holding great potential for a wide range of other acid-catalyzed reactions.
- Zhu, Shanhui,Gao, Xiaoqing,Dong, Fang,Zhu, Yulei,Zheng, Hongyan,Li, Yongwang
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p. 155 - 163
(2013/09/02)
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- Yttrium-grafted mesostructured SBA-3 catalyst for the transesterification of glycerol with methyl acetate to synthesize fuel oxygenates
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The synthesis of di- and triacetyl glycerol (DAG and TAG) via the transesterification of glycerol with methyl acetate was investigated over series of solid acid catalysts prepared by grafting yttrium, 1-3.5 wt.%, into the framework of SBA-3 support. The p
- Khayoon,Hameed
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- Synthesis of bio-additives: Transesterification of ethyl acetate with glycerol using homogeneous or heterogeneous acid catalysts
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A new catalytic route with potential practical interest to sustainable production of bioadditives from glycerol is described. Ethyl acetate was transesterified with glycerol, in the ratio glycerol:EtOAc 1:10, at 25 or 90 °C using 0.1 equiv. of H2SO4 or TsOH, as homogeneous catalysts. H2SO4 led to the total glycerol consumption in 2 h. In the equilibrium, attained in 9 h, 100percent yield of a diacetin:triacetin (55:45) mixture was formed. Using Amberlyst? 15 dry and Amberlyst? 16 wet in 1:30 glycerol:EtOAc ratio and reflux at 90 °C the total glycerol consumption was achieved in 2 and 10h, respectively. The lower reactivity of Amberlyst-16 wet was explained in terms of deactivation of acid sites and decrease in glycerol diffusion to the inner resin pores, both factors caused by adsorbed water. The kinetics of glycerol transformation and product distribution in the equilibrium in relation to the H2SO 4, Amberlyst-15 (dry) and Amberlyst-16 (wet) catalyzed reactions were measured.
- Meireles, Bruno A.,Pereira, Vera Lu?cia P.
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- The preparation of trisubstituted alkenyl nucleoside phosphonates under ultrasound-assisted olefin cross-metathesis
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Intermolecular ultrasound-assisted olefin cross-metathesis is reported. This approach allows an easy access to challenging trisubstituted alkenyl nucleoside phosphonates. Regioselective chemoenzymatic deacetylation and Mitsunobu coupling are also describe
- Sari, Ozkan,Hamada, Manabu,Roy, Vincent,Nolan, Steven P.,Agrofoglio, Luigi A.
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supporting information
p. 4390 - 4393
(2013/09/24)
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- Development of niobium containing acidic catalysts for glycerol esterification
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Mesoporous silicate and niobiosilicate materials of SBA-15 type were prepared and post-synthesis modified with MPTMS, i.e. (3-mercaptopropyl) trimethoxysilane, followed by oxidation of thiol species. The samples obtained were characterised by different techniques (N2 adsorption/desorption, XRD, elemental and thermal analyses) and applied as catalysts in glycerol esterification with acetic acid. The focus was on the comparison of the role of niobium in the formation of sulphonic species and its stability in the post-synthesis modified materials (prepared within this work) with those, already published, prepared by one-pot synthesis method. The most important finding is that the presence of niobium in the SBA-15 structure improves the efficiency of -SH oxidation by hydrogen peroxide towards sulphonic species like in case of one-pot synthesised samples. However, contrary to the latter samples the presence of niobium does not increase the stability of the modifier (oxidized MPTMS). This has an impact on faster deactivation of samples prepared. Samples prepared with post-synthesis modification exhibit much higher activity in glycerol esterification.
- Trejda, MacIej,Stawicka, Katarzyna,Dubinska, Anna,Ziolek, Maria
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experimental part
p. 129 - 134
(2012/08/13)
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- The role of Nb in the formation of sulphonic species in SBA-15 and MCF functionalised with MPTMS
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Mesoporous silica and niobiosilicate materials of SBA-15 and MCF types were prepared in the presence of MPTMS, i.e. (3-mercaptopropyl)trimethoxysilane and hydrogen peroxide. The samples obtained were characterised by different techniques (N2 adsorption/desorption, XRD, elemental and thermal analyses) and applied as catalysts in glycerol esterification with acetic acid. The role of niobium species on the formation of sulphonic species and stability of organosilane modifier was explored. The most important finding is that the addition of niobium to the synthesis gel improves the efficiency of -SH oxidation by hydrogen peroxide towards sulphonic species. This behaviour is not dependent on the type of structure of mesoporous materials (SBA-15 or MCF). However, the kind of mesoporous solid influences the efficiency of Nb incorporation and on the esterification process. MCF matrix improves the catalytic performance of the MPTMS modified catalyst.
- Trejda, Maciej,Stawicka, Katarzyna,Ziolek, Maria
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p. 130 - 135
(2013/01/13)
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- A simple and convenient chemoenzymatic approach for the synthesis of valuable triacylglycerol-based dendritic building blocks
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Dendritic macromolecules have a significant impact in the field of material sciences and are one of the major starting points for nanotechnology as a result of the numerous modifications that can be conducted, either on the surface or within their molecular infrastructure. Thus taking advantage of their unique architectural, structural, and functional features, a highly efficient three-step convergent chemoenzymatic approach for the synthesis of dendritic polyester/polyamido-ester building block structures using structured triacylglycerols as acylating agent has been designed and developed. This convergent approach is remarkable, because of the simplicity and convenience to synthesize star shaped and linear dendritic building block scaffolds, as it requires no purification other than a simple solvent extraction. Different core molecules have been used to generate a series of novel star shaped and linear dendritic building blocks without requiring any chromatographic separation.
- Gupta, Shilpi,Jalal, Sarah,Kumar, Sumit,Haag, Rainer,Sharma, Sunil K.
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p. 1376 - 1387
(2012/11/07)
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- Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin
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The present invention concerns an optimized process to obtain a mixture of lower carboxylic acid mono, di and triesters, from raw glycerin, a by-product of the process to obtain biodiesel, a transesterification of vegetable raw material with lower alcohols. The invention particularly refers to an optimized process to obtain triacetin or a mixture of mono-, di- and triacetin from that raw glycerin, without prior purification.
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Page/Page column 9-10
(2011/02/17)
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- PROCESS TO OBTAIN A MIXTURE OF LOWER CARBOXYLIC MONO, DI AND TRIESTERS FROM RAW GLYCERIN
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The present invention concerns an optimized process to obtain a mixture of lower carboxylic acid mono, di and triesters, from raw glycerin, a by-product of the process to obtain biodiesel, a transesterification of vegetable raw material with lower alcohols. The invention particularly refers to an optimized process to obtain triacetin or a mixture of mono-, di- and triacetin from that raw glycerin, without prior purification.
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Page/Page column 16-17
(2011/02/24)
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- Esterification of glycerol with acetic acid using double SO 3H-functionalized ionic liquids as recoverable catalysts
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Esterification of glycerol with acetic acid was studied using a series of Bronsted acidic ionic liquids as catalysts. The results indicate that double SO3H-functionalized ionic liquids show high catalytic activity and fair reusability even at very low catalyst loadings, while the conventional non-functionalized ionic liquids show poor activity. The Bronsted acidity-catalytic activity relationships were also investigated and the results showed that the sequence of the catalytic activity observed in the transformation was in good agreement with the Bronsted acidity order determined by the Hammett method. The Royal Society of Chemistry.
- Liu, Xiumei,Ma, Huiyuan,Wu, Yue,Wang, Chang,Yang, Miao,Yan, Peifang,Welz-Biermann, Urs
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experimental part
p. 697 - 701
(2011/05/03)
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- Acetylation of glycerol over heteropolyacids supported on activated carbon
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The acetylation of glycerol was carried out over dodecatungstophosphoric acid (PW) supported on activated carbon, being the monoacetin, diacetin and triacetin the reaction products. A series of catalysts, with different heteropolyacid loading (from 3.5 to 6.5 wt.%), were prepared. It was observed that the catalytic activity increases with the amount of PW immobilized on the activated carbon, being the PW2-AC (with 4.9 wt.%) the most active sample. However, at high loading of heteropolyacid on the activated carbon, a decrease on the catalytic activity was observed, which can be probably explained due to some hindrance in the activated carbon porous system. All catalysts exhibited good values of selectivity to the diacetin. Catalytic stability of the PW2-AC was also studied by performing consecutives batch runs with the same catalyst sample. After the third batch, it was observed that the catalytic activity stabilized.
- Ferreira,Fonseca,Ramos,Vital,Castanheiro
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experimental part
p. 573 - 576
(2012/01/12)
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- A green method for selective acetylation of primary alcohols using ethyl acetate and solid potassium carbonate
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A simple and selective acetylation of primary alcohols in the presence of other reactive functionalities such as secondary alcohol, phenol, acetonide and amine is described using mild ethyl acetate as the acetyl-transfer agent and solid potassium carbonate as the catalyst.
- Mallesha,Rao, S. Prahlada,Suhas,Gowda, D. Channe
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experimental part
p. 536 - 539
(2011/11/30)
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- Selective esterification of glycerol to bioadditives over heteropoly tungstate supported on Cs-containing zirconia catalysts
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Esterification of glycerol with acetic acid was carried out over tungstophosphoric acid (TPA) supported on Cs-containing zirconia. The catalysts were prepared by impregnation method and characterized by FT-infrared spectroscopy, X-ray diffraction and temperature program desorption of NH 3. The catalysts exhibited more than 90% conversion within a short reaction time. The catalytic activity depends on the amount of exchangeable Cs with TPA on zirconia, which is in tern related to the acidity of the catalysts. The acidity of the catalysts varied with the presence of residual protons of TPA. The effects of various parameters, such as reaction temperature, catalyst concentration and molar ratio of glycerol to acetic acid, were studied and optimized reaction conditions are established.
- Jagadeeswaraiah,Balaraju,Prasad, P.S. Sai,Lingaiah
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experimental part
p. 166 - 170
(2011/01/03)
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- Chemoenzymatic synthesis of symmetrically structured triacylglycerols possessing short-chain fatty acids
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Synthesis of symmetrically structured triacylglycerols possessing bioactive n-3 polyunsaturated fatty acids (eicosapentaenoic acid or docosahexaenoic acid) at the 2-position and a short-chain fatty acid (C2, C4, C6) located at the end-positions by a highly efficient two-step chemoenzymatic process is described. Full regiocontrol devoid of any acyl-migration side reactions was obtained in both a lipase promoted step to introduce the short-chain fatty acids exclusively into the primary alcohol positions of glycerol using activated vinyl esters at low temperature and a subsequent coupling reaction involving free EPA and DHA using EDAC as a coupling agent.
- Magnusson, Carlos D.,Haraldsson, Gudmundur G.
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experimental part
p. 2728 - 2731
(2010/05/17)
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- Continuous synthesis of glycerol acetates in supercritical carbon dioxide using Amberlyst 15
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Continuous esterification of glycerol with acetic acid was investigated in supercritical carbon dioxide (scCO2) using Amberlyst 15 as a heterogeneous catalyst. The effect of pressure at (65-300) bar on the substrate conversion and the reaction yield and selectivity was studied. With increasing pressure, the percent of total yield and conversion remain almost unaffected and the selectivity of monoacetin synthesis increases while the selectivity for triacetin stays relatively unchanged. The effect of temperature on the yield, conversion, and the selectivity at (100-150) °C was also investigated. With increasing temperature from 100 to 140 °C, the selectivity for monoacetin decreases while for tri- and diacetin slightly increases. In contrast, with further increase in temperature, from 140 °C to 150 °C, the selectivity of monoacetin synthesis increases while that of diacetin decreases. By increasing the molar ratio of acetic acid to glycerol to 24, a selectivity of 100% was achieved for 2 h while the yield was 41% for the continuous triacetin synthesis in scCO2. When neat scCO2 as solvent with no catalyst was used, only monoacetin with 29% conversion was synthesized. The catalyst durability was also studied by monitoring the reaction for 25 h. The results show that the catalyst retains its activity even for 25 h but the selectivity for triacetin synthesis declines from 100% to about 60%.
- Rezayat, Marzieh,Ghaziaskar, Hassan S.
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experimental part
p. 710 - 715
(2010/04/23)
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- Therapeutic use of acyl glycerols and the nitrogen- and sulphur- containing analogues thereof
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The invention relates to the use of acyl glycerols and the nitrogen- and sulfur-containing analogues thereof in the therapeutic field, particularly in human health. The inventive compounds have advantageous pharmacological properties and are particularly of use for the prevention or treatment of neurodegenerative diseases.
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Page/Page column 30
(2008/06/13)
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- Therapeutic use of of acyglycerols and the nitrogen-and sulphur-containing analogues thereof
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The invention relates to the use of acylglycerols and the nitrogen- and sulfur-containing analogues thereof in therapy, particularly for the treatment of cerebral ischemia. The invention further relates to methods for preparing said derivatives, novel compounds, in particular acylglycerols, the nitrogen- and sulfur-containing analogues thereof and methods for preparing same.
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Page/Page column 14
(2010/11/24)
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