- Biomolecule-derived supported cobalt nanoparticles for hydrogenation of industrial olefins, natural oils and more in water
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Catalytic hydrogenation of olefins using noble metal catalysts or pyrophoric RANEY nickel is of high importance in the chemical industry. From the point of view of green and sustainable chemistry, design and development of Earth-abundant, less toxic, and more environmentally friendly catalysts are highly desirable. Herein, we report the convenient preparation of active cobalt catalysts and their application in hydrogenations of a wide range of terminal and internal carbon-carbon double bonds in water under mild conditions. Catalysts are prepared on multi-gram scale by pyrolysis of cobalt acetate and uracil, guanine, adenine or l-tryptophan. The most active material Co-Ura/C-600 showed good productivity in industrially relevant hydrogenation of diisobutene to isooctane and in natural oil hardening.
- Pews-Davtyan, Anahit,Scharnagl, Florian Korbinian,Hertrich, Maximilian Franz,Kreyenschulte, Carsten,Bartling, Stephan,Lund, Henrik,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 5104 - 5112
(2019/09/30)
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- Synthesis of glycerol monostearate over K2CO3/γ-Al2O3 catalyst
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The synthesis of glycerol monostearate by transesterification of methyl stearate with glycerol can be carried out in the presence of basic catalyst. The absence of solvent in the reaction system would result in a low conversion of methyl stearate as a consequence of low miscibility between reactants. The addition N,N′-dimethyl formamide as solvent improved the activity of the catalyst and selectivity to glycerol monostearate. Different K2CO3-containing γ-Al2O3 catalysts were made and used in the reaction. The results showed that catalyst with higher basicity could lead to better reactant's conversion but poorer selectivity to glycerol monostearate and the optimal load of K2CO3 inducing the highest yield to glycerol monostearate was 20 % mass fraction of γ-Al2O3 supporter. At a glycerol/methyl stearate ratio of 6:1, 165°C, 2 wt. % catalyst amount, a yield of 82.21 % of glycerol monostearate was achieved after 5h.
- Zhou, Lu,Gu, Yi,Hong, Mei,Xiao, Guomin
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p. 458 - 462
(2015/01/30)
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- Preparation of low calorie structured lipids catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene(TBD)-functionalized mesoporous SBA-15 silica in a heterogeneous manner
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1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD, a strong bicyclic guanidine base) functionalized SBA-15 material has been found to be an efficient solid catalyst for the interesterification between tributyrin and methyl stearate in a solvent-free system for the production of low-calorie structured lipid (LCSL). The solid base catalyst was characterized by using small-angle X-ray scattering, Fourier transform infrared spectra, thermo gravimetric analysis, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and elemental analysis techniques. The obtained LCSL was analyzed by reverse-phase high-performance liquid chromatography for triacylglycerol composition. The influence of various reaction parameters, such as the substrate ratio, reaction temperature, and reaction time, on the interesterification reaction was investigated systematically. More than 90% LCSL was obtained at 80°C within 1 h when the methyl stearate/tributyrin molar ratio of 2:1 was employed. The obtained solid catalyst could be recovered easily and reused for several recycles with a negligible loss of activity. By using the solid base catalyst, an eco-friendly more benign process for the interesterification reaction in a heterogeneous manner was developed.
- Xie, Wenlei,Qi, Cong
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p. 3348 - 3355
(2014/05/06)
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- 13C NMR quantification of mono and diacylglycerols obtained through the solvent-free lipase-catalyzed esterification of saturated fatty acids
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In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent-free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) and different reaction conditions were evaluated. Under the optimal reaction conditions, esterifications catalyzed by Lipozyme RM IM resulted in a mixture of MAG and DAG at high conversion rates for all of the substrates. In addition, except for the reaction of industrial residue at atmospheric pressure, all of these products met the World Health Organization and European Union directives for acylglycerol mixtures for use in food applications. The products were quantified by 13C NMR, with the aid of an external reference signal which was generated from a sealed coaxial tube filled with acetonitrile-d3. After calibrating the area of this signal using the classical external reference method, the same coaxial tube was used repeatedly to quantify the reaction products. Copyright
- Fernandes, Jane Luiza Nogueira,De Souza, Rodrigo Octavio Mendonca Alves,De Vasconcellos Azeredo, Rodrigo Bagueira
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experimental part
p. 424 - 428
(2012/08/14)
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- MALLEABLE, BIODEGRADABLE HEMOSTATIC AGENT
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A malleable, biodegradable hemostatic agent is provided that can be used for mechanical sealing of bleeding bone tissue, as well as a method for forming a malleable, biodegradable hemostatic agent of this type, and a medical implant having a coating that includes a malleable, biodegradable hemostatic agent of this type. The malleable, biodegradable hemostatic agent contains (a) at least one saturated glycerol-1,2,3-tri-fatty acid ester having a melting temperature above 37° C., (b) at least one filling agent present in particulate form, at least in part, and having a melting temperature above 37° C., and (c) at least one compound having a melting temperature not above 37° C. and a solubility at a temperature of 25° C. of less than 50 grams per liter of water.
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- Synthesis and analysis of symmetrical and nonsymmetrical disaturated/monounsaturated triacylglycerols
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Symmetrical disaturated triacylglycerols of the structure SUS, where S is stearic acid (18:0) and U is an unsaturated fatty acid, either oleic (O; 9cis-18:1), linoleic (L; 9cis, 12cis-18:2), or linolenic (Ln; 9cis, 12cis, 15cis-18:3), are important components providing functionality to interesterified fat blends and structurally modified oils. Nonsymmetrical triacylglycerols of the structure SSU can significantly change melting point and solid fat content profiles. To characterize the physical properties of pure and symmetrical and nonsymmetrical triacylglycerol mixtures, the same reaction sequence has been used to prepare multigram quantities of triacylglycerols SUS and SSU. Tristearin was converted to a mixture of mono-, di-, and triacylglycerols, and the 1,3- and 1,2-diacylglycerol fraction was isolated by silica column chromatography. The 1,3-diacylglycerols were removed by crystallization from acetone and esterified with the appropriate fatty acid to form the symmetrical triacylglycerols with >99% SUS structure. The more difficult to obtain 1,2-diacylglycerols were prepared by esterification of the enriched 1,2-diacylglycerol fraction (80-86% 1,2-diacylglycerols) remaining after removal of much of the 1,3-isomer by crystallization, but silver resin or silver nitrate impregnated silica gel chromatography was required to isolate the nonsymmetrical triacylglycerols. SSL and SSLn were prepared in purities of >98% by this procedure, but not SSO. Silver ion HPLC was found to be as accurate as, and more rapid than, lipolysis/gas chromatography for the determination of the isomeric purities of the synthesized triacylglycerols.
- Adlof, Richard O.,List, Gary R.
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p. 2096 - 2099
(2007/10/03)
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- Chemoenzymatic synthesis of structured triacylglycerols containing eicosapentaenoic and docosahexaenoic acids
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There are indications in the recent literature that the location of polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in triacylglycerols (TAG) may influence their oxidative stability. To address that question, two types of structured lipids were designed and synthesized: firstly, a TAG molecule possessing pure EPA or DHA at the mid-position with stearic acid at the outer positions; and secondly, a TAG molecule possessing pure EPA or DHA located at one of the outer positions with stearic acid at the mid-position and the remaining end position. The former adduct was synthesized in two steps by a chemoenzymatic approach. In the first step 1,3-distearoylglycerol was afforded in good yield (74%) by esterifying glycerol with two equivalents of stearic acid in ether in the presence of silica gel using LipozymeTM as a biocatalyst. This was followed by a subsequent chemical esterification with pure EPA or DHA using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as a coupling agent in the presence of 4-dimethylaminopyridine in dichloro-methane in excellent yields (94 and 91%, respectively). The latter adduct was synthesized in two enzymatic steps. In the first step tristearoylglycerol was prepared in very high yield (88%) by esterifying glycerol with a stoichiometric amount of stearic acid under vacuum at 70-75 °C using an immobilized Candida antarctica lipase without a solvent. That adduct was subsequently treated in an acidolysis reaction with two equivalents of EPA or DHA without solvent at 70-75 °C or in toluene at 40 °C in the presence of Lipozyme to afford the desired product in moderate yields (44 and 29%, respectively).
- Haraldsson, Gudmundur G.,Halldorsson, Arnar,Kulas, Elin
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p. 1139 - 1145
(2007/10/03)
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- Preparation of monoglycerides by guanidine-catalyzed processes
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Glycerolysis of methyl stearate and tristearin has been carried out in the presence of alkylguanidines - strong nonionic bases - as catalysts. When applied at 10 mol%, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,2,3-tricyclohexylguanidine, and 1,3-dicyclohexyl-2-n-octylguanidine give monoglycerides in more than 90% selectivity, in a maximum of 6 h reaction time.
- Guimaraes Aguiar, Leila M.,Vargas, Rogerio Matheus
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p. 755 - 756
(2007/10/03)
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- 1H-Nuclear magnetic resonance spectroscopic studies of saturated, acetylenic and ethylenic triacylglycerols
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The 1H-NMR spectroscopic properties of 15 synthetic homologous saturated triacylglycerols of type AAA and 16 mixed saturated triacylglycerols of type ABA and AAB have been studied. Triacylglycerols containing short-chain fatty acids (2:0-6:0) are readily identified. Triacylglycerols containing medium- and long-chain fatty acid components are not differentiated. From the analysis of 19 acetylenic triacylglycerols of type AAA, ABA and AAB (containing positional isomers of acetylenic fatty acids), it is only possible to characterize triacylglycerols with acyl groups containing the acetylenic bond at the Δ2-Δ5 position. 1H-NMR analysis could not confirm the positions (α- or β-acyl) of the acetylenic acids in mixed triacylglycerols. In the study of 22 ethylenic triacylglycerols of type AAA containing positional isomers of (Z)- or (E)-ethylenic acids, molecules containing an ethylenic bond in the Δ2 position of the acyl chains were readily characterized, as the ethylenic protons in the α- and β-acyl chains were fully resolved. Triacylglycerols containing an unsaturated center at the position were characterized by the shifts of the 2-H protons. The spectra of the remaining triacylglycerol molecules were very similar and the position of the ethylenic system could not be determined by this technique.
- Lie Ken Jie, Marcel S.F.,Lam
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p. 155 - 171
(2007/10/03)
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- Fat Hydrolysis and Esterification by a Lipase from Humicola lanuginosa
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The hydrolysis and esterification by a thermostable lipase from Humicola lanuginosa No. 3 were investigated.Both reactions occurred readily at temperatures between 45-50 deg C.Esterification by the enzyme with glycerol was observed to be specific towards fatty acids with carbon numbers of C12-C18.Lauric acid esters with different alcohols such as primary alcohols, terpene alcohols, etc., were also synthesized readily.Esterification by the enzyme was adversely affected by the water content (optimum, ca. 7percent), however, the hydrolysis rate increased rapidly with increasing water content (optimum, ca. 60percent).The enzyme showed increased activity in organic solvent-aqueous reaction systems.Nevertheless, hydrolysis in complete organic phase reactions was found not to be feasible.Hydrolysis at a higher temperature (50 or 55 deg C) in a solvent free phase was almost the same as that in organic solvent-aqueous phase reactions.The components of glycerides varied considerably during hydrolysis, whereby esterification resulted in a higher quantity of mono- and diglycerides (about 40percent), compared to in the case of hydrolysis, for which the value was about 10-20percent.
- Omar, Ibrahim Che,Nishio, Naomichi,Nagai, Shiro
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p. 2153 - 2160
(2007/10/02)
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- Topical corticosteroid formulations
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This present invention relates to a solution for topical or local application comprising at least one corticosteroid; from about 1% to 4% by weight of solubilization agents consisting essentially of a combination of at least one glyceryl ester of a fatty acid of 6 to 22 carbon atoms and a betaine surfactant, from about 10% to 50% by weight of composition of an alkanol cosolvent, and from about 20% to 50% water.
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- Coal tar gel composition
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Compositions effective for topically treating skin conditions, especially psoriasis and eczema which contains as an essential ingredient coal tar in a gel base.
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