Browsing by Keyword "Glycerol"
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Item Solvent-free synthesis of glycerol carbonate and glycidol from 3-chloro-1,2-propanediol and potassium (hydrogen) carbonate(2010-12) Gómez-Jiménez-Aberasturi, Olga; Ochoa-Gómez, José R.; Pesquera-Rodríguez, Amaia; Ramírez-López, Camilo; Alonso-Vicario, Ainhoa; Torrecilla-Soria, Jesús; BIOECONOMÍA Y CO2; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER); SGBACKGROUND: An indirect solvent-free synthetic approach for obtaining glycerol carbonate and glycidol from glycerol and CO2 through their more reactive and easily synthesizable derivatives 3-chloro-1,2-propanediol (HAL) and potassium (hydrogen) carbonate has been studied. RESULTS: The reaction is fast with source of carbonation and temperature having a strong influence on the results. A yield of 80% glycerol carbonate together with a simultaneous substantial production of glycidol (0.56 mol mol-1 glycerol carbonate) are obtained using K2CO3 as the carbonation source at 80 °C, a reaction time of 30 min and a 3:1 HAL/K2CO3 molar ratio. A lower yield of glycerol carbonate (60%) is obtained from KHCO3 after 50 min with the other experimental conditions remaining unchanged. In this case, glycidol formation is zero or insignificant. Glycerol is also obtained in high yields, although in much lower amounts from KHCO3 (~0.59 mol mol-1 glycerol carbonate independent of operating conditions) than from K2CO3 (0.84-1.1 mol mol-1 glycerol carbonate, depending on experimental conditions). CONCLUSIONS: The proposed synthetic strategy overcomes the currently difficult direct reaction between glycerol and CO2, leading to the simultaneous synthesis of two valuable chemicals: glycerol carbonate and glycidol. However, glycerol is also obtained in substantial amounts thus decreasing the overall yield of the process. Thus, methods for preventing its formation must be developed for industrial feasibility.Item Synthesis of glycerol carbonate from 3-chloro-1,2-propanediol and carbon dioxide using triethylamine as both solvent and CO2 fixation-activation agent(2011-11-15) Ochoa-Gómez, José R.; Gómez-Jiménez-Aberasturi, Olga; Ramírez-López, Camilo A.; Nieto-Mestre, Javier; Maestro-Madurga, Belén; Belsué, Mikel; Tecnalia Research & Innovation; BIOECONOMÍA Y CO2; VALORIZACIÓN DE RESIDUOSThe synthesis of glycerol carbonate from 3-chloro-1,2-propanediol, a glycerol derivative easily obtained by reacting glycerol with HCl, and carbon dioxide using triethylamine as both solvent and CO2 fixation and activation agent is reported. The influence on conversions and yields of triethylamine/3-chloro-1,2-propanediol molar ratio, temperature, CO2 pressure and reaction time has been studied. A 3-chloro-1,2-propanediol conversion of 100% and a glycerol carbonate yield of 90% are obtained at 100°C, using a triethylamine/3-chloro-1,2-propanediol molar ratio of 1.5, a carbon dioxide pressure of 25bar and 60min. Glycerol was the only byproduct detected in 4-6% yields independently of experimental conditions. Above 100°C, glycerol carbonate yield decreases dramatically due to glycerol carbonate polymerization resulting in a polyglycerol mixture. The yield of glycerol carbonate is strongly and negatively influenced by the presence of water. A reaction mechanism is proposed in which the first step is the formation of a zwitterionic adduct between triethylamine and CO2 which reacts with 3-chloro-1,2-propanediol leading to an intermediate which evolves towards glycerol carbonate either directly or through the glycidol intermediate.Item Synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification: Catalyst screening and reaction optimization(2009-09-25) Ochoa-Gómez, José R.; Gómez-Jiménez-Aberasturi, Olga; Maestro-Madurga, Belén; Pesquera-Rodríguez, Amaia; Ramírez-López, Camilo; Lorenzo-Ibarreta, Leire; Torrecilla-Soria, Jesús; Villarán-Velasco, María C.; BIOECONOMÍA Y CO2; Centros PRE-FUSION TECNALIA - (FORMER); SG; Alimentación SostenibleThe synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification is reported. Firstly, a catalyst screening has been performed by studying the influence of different basic and acid homogeneous and heterogeneous catalysts on reaction results. Catalytic activity is extremely low for acidic catalysts indicating that reaction rate is very slow. On the contrary, high conversions and yields are obtained for basic catalysts. Catalytic activity increases with catalyst basic strength. The best heterogeneous catalyst is CaO. Calcination of CaO increases dramatically its activity due to calcium hydroxide removal from its surface. A reaction optimization study has been carried out with CaO as catalyst by using a factorial design of experiments leading to operation conditions for achieving a 100% conversion and a >95% yield at 1.5 h reaction time: 95 °C, catalyst/glycerol molar ratio = 0.06 and dimethyl carbonate/glycerol molar ratio = 3.5. Carbonate glycerol can be easily isolated by filtering the catalyst out and evaporating the filtrate at vacuum. Leaching of catalyst in reaction medium was lower than 0.34%. Catalyst recycling leads to a quick decrease in both conversions and yields probably due to a combination of catalyst deactivation by CaO exposure to air between catalytic runs, and a decrease in the catalyst surface area available for reaction due to particle agglomeration.Item Two-step oxidation of glycerol to glyceric acid catalyzed by the Phanerochaete chrysosporium glyoxal oxidase(2012-02-10) Roncal, Tomás; Muñoz, Carmen; Lorenzo, Leire; Maestro, Belén; Díaz de Guereñu, María del Mar; BIOECONOMÍA Y CO2; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSGlyoxal oxidase of P. chrysosporium is a radical copper oxidase that catalyzes oxidation of aldehydes to carboxylic acids coupled to dioxygen reduction to H 2O 2. In addition to known substrates, glycerol is also found to be a substrate for glyoxal oxidase. During enzyme turnover, glyoxal oxidase undergoes a reversible inactivation, probably caused by loss of the active site free radical, resulting in short-lasting enzyme activities and undetectable substrate conversions. Enzyme activity could be extended by including two additional enzymes, horseradish peroxidase and catalase, in addition to a redox chemical activator, such as Mn(III) (or Mn(II)+H 2O 2) or hexachloroiridate. Using this three-enzyme system glycerol was converted in glyceric acid in a two-step reaction, with glyceraldehyde as intermediate. A possible operation mechanism is proposed in which the three enzymes would work coordinately allowing to maintain a sustained glyoxal oxidase activity. In the course of its catalytic cycle, glyoxal oxidase alternates between two functional and interconvertible reduced and oxidized forms resulting from a two-electron transfer process. However, glyoxal oxidase can also undergo an one-electron reduction to a catalytically inactive form lacking the active site free radical. Horseradish peroxidase could use glyoxal oxidase-generated H 2O 2 to oxidize Mn(II) to Mn(III) which, in turn, would reoxidize and reactivate the inactive form of glyoxal oxidase. Catalase would remove the excess of H 2O 2 generated during the reaction. In spite of the improvement achieved using the three-enzyme system, glyoxal oxidase inactivation still occurred, which resulted in low substrate conversions. Possible causes of inactivation, including end-product inhibition, are discussed.