Formation Of Glycidol Research Articles

Effect of dough improvers on 3-monochloropropane-1,2-diol and glycidol formation in white bread

Effect of dough improvers on 3-monochloropropane-1,2-diol and glycidol formation in white bread

Factors Influencing the Formation of Chemical-Hemoglobin Adducts.

Hemoglobin (Hb) adducts have been used as biomarkers for the internal exposure to chemicals. Simultaneous exposure to chemicals that bond with the N-terminal valine of Hb to form adducts, such as glycidol, acrylamide, and glucose, may affect the formation of the individual Hb adducts. In this study, various factors influencing the formation of chemical–Hb adducts were analyzed using in vitro and in vivo systems. In the in vitro assays, the formation of glycidol– and acrylamide–Hb adducts was altered in the presence of glucose, serum albumin, and other chemicals. In contrast, in the in vivo experiments, glycidol– and acrylamide–Hb adduct formation was unchanged in mice exposed to glycidol and acrylamide. The interaction between glycidol and acrylamide with residues other than the N-terminal valine of Hb was analyzed using the protein thermal shift assay. Glycidol and acrylamide also interacted with amino acid residues other than the N-terminal valine of Hb. The presence of other blood components, such as amino acids, may affect the formation of chemical–Hb adducts. Further research is expected to elucidate the remaining unknown factors that affect the formation of chemical–Hb adducts.

Effect of sodium chloride on the solubility and hydrolysis of epichlorohydrin in water

The mutual solubility of the components in the epichlorhydrin–water–sodium chloride system was studied in the temperature range of 20–90 °С. It was found that epichlorohydrin is salted out as the concentration of NaCl increases. The Sechenov coefficient was determined to be equal to 0.29. It was found that epichlorohydrin reacts with an aqueous solution of sodium chloride to form glycerol dichlorohydrins. Alkali formed during this reaction catalyzes the hydrolysis of epichlorohydrin to glycerol monochlorohydrin, acts as a reagent in the glycidol formation and accelerates its subsequent conversion to glycerol.

Mechanism of Allyl Alcohol Epoxidation with Hydrogen Peroxide at Titanium Catalyst (Ts-1)

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Transesterification of biodiesel byproduct glycerol and dimethyl carbonate over porous biochar derived from pyrolysis of fishery waste

Glycerol carbonate (GC), an oxygenated fuel additive was synthesized from oversupplied glycerol in transesterification with dimethyl carbonate (DMC) over fishmeal biochar. Fishmeal was carbonized at various temperatures (550–750 °C). The most suitable carbonization temperature based on GC yield was utilized in transesterification. Biochar was characterized to investigate textural and basic properties and surface functional groups. Thermal treatment, methanol washing, and solvent addition techniques were adopted to investigate biochar reusability after each reuse. At the most suitable reaction conditions of 85 °C, 2 wt% catalyst dosage, and DMC-to-glycerol molar ratio of 2, 99.5% GC yield and complete conversion of glycerol were attained over biochar carbonized at 650 °C. Strong basicity of biochar initiated decarboxylation reaction, which resulted in formation of glycidol (0.5%). Addition of methanol without catalyst treatment after each reuse sustained GC yield of 93% at the end of fifth reuse.

Tandem Synthesis of Glycidol via Transesterification of Glycerol with DMC over Ba-Mixed Metal Oxide Catalysts

Glycerol carbonate (GC) and glycidol (GD) are commercial products possible from glycerol transformation, which has become a subject of great importance. Among several basic catalysts screened in this work, BaO showed the highest glycerol conversion of 71% with almost complete selectivity to GC. A tandem synthesis of GD with a selectivity as high as 80% with 98% glycerol conversion could be achieved with mixed oxides of Ba and lanthanides (La and Ce) prepared by the coprecipitation method. Although BaO alone showed the highest basicity as measured by CO2 TPD, tuning of basicity by incorporation of CeO2 resulted in the formation of GD. Incorporation of Ba into the ceria matrix induced oxygen vacancies in the cerium oxide material. The presence of u″/v″ doublets at 888.7 and 903.2 eV, respectively, in XPS of the Ba–Ce sample also confirmed the oxygen vacancies in the lattice. In this tandem approach to GD, the subsequent decarboxylation of initially formed GC was due to the presence of a CeO2 lattice with de...

EPOXIDATION OF ALLYL ALCOHOL TO GLYCIDOL WITH HYDROGEN PEROXIDE AT TITANIUM SILICALITE

It was studied the epoxidation mechanism of allyl alcohol using titanosilicate zeolite (TS-1) at 40°C by means of procedures for the nomination and discrimination of mechanism hypotheses. The hypotheses was carried out using the literature data and the preliminary experiment results. Discrimination hypothetical mechanisms implemented on the basis of the univariate results of the kinetic experiment, varying concentrations of allyl alcohol, hydrogen peroxide and glycidol. The most probable mechanism involves the hydrogen peroxide and allyl alcohol adsorption at the catalyst active centers and the glycidol formation at a reversible stage in the interaction of the adsorbed molecules of the reactants. Considered hypotheses include a different sequence of interaction of the reactants with active catalyst centre. In addition, hypotheses take into account the formation of intermediate compounds as well as inactive products of the interaction of substances present in the reaction system, with the active centers on the silicalite surface. For each hypothesis, it was formulated the corresponding system of differential equations and carried out the estimation of the rate constants. The quality of the experimental data description was judged by the residual sums of squared deviations and correlation coefficients. The best results are obtained for the hypothesis involving the hydrogen peroxide and allyl alcohol adsorption at the two active catalyst centers with subsequent interaction of the resultant intermediates between them, with the formation of glycidol adsorbed on one center, free catalyst centre and molecule of water. Formation of free glycidol occurs at a reversible stage. A significant part of the active centers of the catalyst increasing the concentration of glycidol is associated with it. This is the main reason for the decrease of the reaction rate, apart from reducing the concentration of the reactants.

Effects of 3-monochloropropane-1,2-diol (3-MCPD) and its metabolites on DNA damage and repair under in vitro conditions

3-monochloropropane-1,2-diol (3-MCPD) is a food contaminant that occurs during industrial production processes and can be found mainly in fat and salt containing products. 3-MCPD has exhibited mutagenic activity in vitro but not in vivo, however, a genotoxic mechanism for the occurrence of kidney tumors has not so far been excluded. The main pathway of mammalian 3-MCPD metabolism is via the formation of β – chlorolactatic acid and formation of glycidol has been demonstrated in bacterial metabolism. The aim of this study was to investigate genotoxic and oxidative DNA damaging effects of 3-MCPD and its metabolites, and to provide a better understanding of their roles in DNA repair processes. DNA damage was assessed by alkaline comet assay in target rat kidney epithelial cell lines (NRK-52E) and human embryonic kidney cells (HEK-293). Purine and pyrimidine base damage, H2O2 sensitivity and DNA repair capacity were assessed via modified comet assay. The results revealed in vitro evidence for increased genotoxicity and H2O2 sensitivity. No association was found between oxidative DNA damage and DNA repair capacity with the exception of glycidol treatment at 20 μg/mL. These findings provide further insights into the mechanisms underlying the in vitro genotoxic potential of 3-MCPD and metabolites.

Transesterification of glycerol with dimethyl carbonate for the synthesis of glycerol carbonate over Mg/Zr/Sr mixed oxide base catalysts

A series of Mg/Zr/Sr based mixed oxide catalysts with varying molar ratios were prepared by a co-precipitation method. The X-ray diffraction and temperature programmed desorption of CO2 were used to derive the characteristics of the catalysts. These catalysts were evaluated for the synthesis of glycerol carbonate by the transesterification of glycerol with dimethyl carbonate. The transesterification activity depended on the molar ratio of the Mg/Zr/Sr and the pre-treatment temperature of the catalysts. The catalysts basicity was influenced by the molar ratio of the mixed oxides and calcinations temperature. The catalyst with a Mg/Zr/Sr molar ratio of 3 : 1 : 1, calcined at 650 °C, showed the highest glycerol conversion and selectivity to glycerol carbonate. During this reaction, the formation of glycidol by the decarbonylation of glycerol carbonate was observed over the catalysts with a high basic strength. The reaction parameters also influence the glycerol conversion and selectivity to glycerol carbonate.

A Revisited Picture of the Mechanism of Glycerol Dehydration

The dehydration mechanism of neutral glycerol in the gas phase was investigated by means of metadynamics simulations. Structures, vibrational frequencies, Gibbs free energy barriers, and rate constants at 800 K were computed for the different steps involved in the pyrolytic process. In this article, we provide a novel mechanism for the dehydration of neutral glycerol, proceeding via formation of glycidol with a barrier of 66.8 kcal/mol. The formation of glycidol is the rate limiting step of the overall decomposition process. Once formed, glycidol converts into 3-hydroxypropanal with a barrier of 49.5 kcal/mol. 3-Hydroxypropanal can decompose further into acrolein or into formaldehyde and vinyl-alcohol with barriers of 53.9 and 35.3 kcal/mol, respectively. These findings offer new insights to available experimental data based on glycerol pyrolysis studies performed with isotopic labeling and on the interpretation of the chemistry of glycerol and sugars in pyrolytic conditions.

Microwave-assisted synthesis of polyglycerol from glycerol carbonate

Microwave irradiation of glycerol carbonate allows formation of glycidol, which readily polymerizes to form polyglycerol under mild conditions comparatively to the classical polyetherification reaction involving high temperature and basic conditions. Analysis of the crude reactional mixture indicated the presence of low-molecular weight oligomers constituted mainly of di, tri, and tetraglycerols with small quantities of higher molecular weights oligomers. Molecular size distribution was relatively similar to that of polyglycerols obtained under basic condition, even if these latter contained slightly higher amounts of high-molecular weight oligomers. Structure of oligomers differs slightly according to the conditions of polymerization, and polyglycerols are obtained under microwave activation containing higher contents of cyclic isomers, whereas polyglycerols obtained under basic conditions contain more ramified isomers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Solvent‐free synthesis of glycerol carbonate and glycidol from 3‐chloro‐1,2‐propanediol and potassium (hydrogen) carbonate

AbstractBACKGROUND: 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. Copyright © 2010 Society of Chemical Industry

Functionalization of poly(vinyl alcohol) by addition of methacryloyl groups: characterization by FTIR and NMR and optimization of reaction conditions by RSM

AbstractThe modification of poly(vinyl alcohol) (PVA) with glycidyl methacrylate (GMA) in DMSO catalyzed by TEMED is reported in this paper. PVA was dissolved in DMSO and reacted with GMA at 30 ºC in a closed vessel under N2 gas bubbling for 24 hours. The reaction was characterized by FTIR and NMR (1H, 13C/DEPT and HETCOR) spectroscopies. The reaction occurs by transesterification through the insertion of methacryloyl groups into PVA chains and probably with the formation of glycidol as a by-product. The degree of substitution (DS) that represents the number of methacryloyl groups inserted was determined through 1H NMR spectra based on the ratio between the averaged area due to the vinyl hydrogen from methacryloyl groups at δ̣ 5.6 ppm and δ 6.0 ppm and the total area of the vinyl hydrogen and hydroxyl hydrogen of PVA. By use of response surface methodology the experimental conditions were optimized. The optimum conditions were 62 ºC with a reaction time of 6 hours. In these optimized conditions, the reactions using the molar ratios [-OH(PVA)/GMA] equal to 1/0.10, 1/0.25, 1/0.50, 1/0.75 and 1/1 were investigated. The response surface was based on the model DS= −19.70 + 6.09x10−1T +1.93 t − 3.89x10−3 T2 − 5.21x10−2t2 − 2.14x10−2 T * t, where T is the temperature (°C) and t the reaction time (hours). This model explained 99.20 % of the 99.64 % explainable statistical data. Using the optimized conditions, it is possible to produce a desired modified PVA, (or PVA-Ma), because DS raises linearly to the ratio [-OH(PVA)/GMA] up to 25 mol-% and the respective yield ranged from 83 to 92 %. It is difficult to obtain more than 50 mol-% substitution of PVA hydroxyl by methacryloyl groups even in these optimized conditions due to increased steric hindrance by the large number of the methacryloyl groups inserted into PVA.

Metabolic inactivation of 2-oxiranylmethyl 2-ethyl2,5-dimethylhexanoate (C10GE) in skin, lung and liver of human, rat and mouse

1. The inactivation of 2-oxiranylmethyl 2-ethyl-2,5-dimethylhexanoate (C10GE), one of the most abundant isomers of the epoxy-resin Cardura®E-10 glycidyl ester, was studied in subcellular fractions of human, C3H mouse and F344 rat liver, lung and skin. 2. C10GE is chemically very stable and resistant to aqueous hydrolysis, but it was rapidly metabolized in both cytosolic and microsomal fractions of all organs by epoxide hydrolase (EH)-catalysed hydrolysis of the epoxide moiety as well as carboxylesterase (CE)-catalysed hydrolysis of the ester bond. In cytosol the epoxide group was also efficiently conjugated with glutathione, catalysed by glutathione S-transferase (GST), but this conjugation was much less important than hydrolysis in human as well as rodent samples. Although CE-catalysed hydrolysis of C10GE would theoretically give rise to the formation of glycidol, a directly acting mutagen, it is highly unlikely that any significant level of glycidol would occur in vivo since reported rates of inactivation of glycidol exceed the total rate of hydrolysis of C10GE. 3. The overall rates of inactivation in vitro decreased in the following order: mouse > rat > human. Scaling of the data in vitro to clearances in vivo suggests that the detoxifying capacity in the rodents is similar and about an order of magnitude greater than in human. Nevertheless, the rate of inactivation is 2-3 orders of magnitude greater than for simple epoxides such as butadiene monoxide and about one order of magnitude higher than for the diglycidyl ether of bisphenol A (BADGE). 4. The transdermal penetration and metabolism of [14C]-C10GE was studied in fresh full-thickness mouse, and dermatomized human and rat skin. Of the total radioactivity applied on the skin, only 0.24±0.06 (SD), 1.8±0.2 and 6.8±0.6% penetrated through human, mouse and rat skin respectively. The corresponding apparent skin permeability constants were 0.81, 6.42 and 26.4X 10−6 cm/h. 5. During transdermal penetration, [14C]-C10GE was extensively hydrolysed to the corresponding diol and the free acid. Only 0.01, 0.11 and 0.21% of the applied dose was absorbed unchanged through the human, mouse and rat skin respectively.