Epoxy Acid Research Articles

Characterization of polysorbate 80 with liquid chromatography mass spectrometry and nuclear magnetic resonance spectroscopy: Specific determination of oxidation products of thermally oxidized polysorbate 80

The polysorbate species in polysorbate 80 (PS 80) have been characterized with 1H NMR, LC–UV/MS and MS/MS. The MS was operated with both negative and positive electrospray ionization (ESI). PS 80 was found to contain mono- and di-fatty acid esters of polyoxyethylene (POE) sorbitan, POE isosorbide and of POE. In addition, the same species were also present without fatty acid esters. The polysorbate species were esterified with C12:0, C14:0, C16:1, C16:0, C18:2, C18:1 and C18:0 fatty acids. The main species were polysorbate esters of C18:1. The C18:2 polysorbate species were shown, by 1H NMR, to have a large component of fatty acids with a conjugated double bond of ZE and/or EZ configuration. The positive ESI mass spectra of the polysorbate species displayed a specific in-source fatty acid fragment for each fatty acid ester. The mass chromatograms of the in-source fatty acid fragments were used to determine the degradation of specific polysorbate species in PS 80. The C18:2 polysorbate species were completely degraded after 8 weeks at 40°C under an atmosphere of air, while the main C18:1 polysorbate species were reduced to ca. 80–86% accompanied by an increase of short-chain POE C18:1 species. Polysorbate species esterified with C18:1–OH, C18:1 keto and C18:0 epoxy acids were found as degradation products of PS 80 stored at 40°C for 8 weeks under air. C18:1–OH, C18:1 keto and C18:0 epoxy acids were believed to be oxidation products of C18:1. With the present conditions, the positive ESI mass spectra of C18:1–OH and C18:0 epoxy polysorbate species displayed identical ions to the C18:2 polysorbate species due to a facile in-source loss of H2O from the protonated molecules. The presence of polysorbate esters of C18:1–OH and C18:0 epoxy acids were established using negative ESI MS. The presence of oxidized fatty acids in degraded PS 80 was also confirmed by saponification and extraction followed by negative ESI LC–MS analysis of the free fatty acids.

Analysis of streptolydigin degradation and conversion in cultural supernatants of Streptomyces lydicus AS 4.2501

AbstractA variety of structural analogues of streptolydigin exists in the cultural supernatants of Streptomyces lydicus AS 4.2501. The degradation of streptolydigin in cultural supernatants with different pH values kept at 25°C in a thermostatic bath was investigated using LC-MS/MS detection. Analysis of the alkaline supernatants (pH 9.50) provides evidence of degradation and conversion between streptolydigin and its structural analogues. Interestingly, a new streptolydigin analogue was detected by LC-MS and photo-diode array (PDA) detection in the process of alkaline degradation. After 48 h in a thermostatic bath, the degradation of streptolydigin and its two analogues at pH 9.50 approached pseudo-first order kinetics. Comparatively, the degradation of streptolydigin was much more rapid in the cultural supernatants with pH 3.05, only requiring 2 hours. Qualitative analysis of the degradation products by LC-MS/MS and PDA indicated that hydrolysis of the epoxy ether bond and acid amide bond was the major mechanism of degradation in acidic cultural supernatants. Two degradation products in the acid supernatant were assumed.

Multiwalled carbon nantoubes-reinforced poly(hydroxyaminoether) prepared by one pot graft-from method

Multiwalled carbon nanotubes (MWNTs)-reinforced poly(hydroxyaminoether) (PHAE) was fabricated via one pot graft-from method. The modification of MWNTs and in situ polymerization of PHAE were combined in one reaction pot without interruption for the purification of modified carbon nanotubes. Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, and Raman spectra clearly indicated that PHAE was successfully attached to the surface of MWNTs via esterification reaction between epoxy and carboxylic acid from MWNTs. Tensile tests showed that the tensile strength and modulus of PHAE/MWNTs composites were improved compared with that of pristine PHAE. Moreover, the reinforcing effect of one pot graft-from method was found to be better than that of graft-to method. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Quantitative determination of epoxy acids, keto acids and hydroxy acids formed in fats and oils at frying temperatures

A method based on derivatization to fatty acid methyl esters and GC is proposed for the quantitative analysis of hydroxy acids, keto acids and epoxy acids in fats and oils. Isolation of the analytes by solid-phase extraction is proposed to prevent analytical interferences caused by non-altered fatty acids naturally occurring in oils. In addition, hydrogenation is required before the GC analysis to improve repeatability. The analytical method was applied to thermoxidized samples of high linoleic sunflower oil, high oleic sunflower oil and high palmitic sunflower oil. Results showed total levels of these compounds in the order of mg/g of oil in samples with contents of polar compounds ranging from 6.7 to 25.7%. The compounds analyzed constituted major fractions of the oxidized fatty acids.

Neutral lipids from seeds of Asteraceae plants

Lipids from seeds of three plants of the Asteraceae family, Cousinia franchetii, Arctium leiospermum, and Rhaponticum integrifolium, were studied. The principal constituents of lipids from the three plants were shown to be acylglycerides of ordinary fatty acids and oxygenated fatty acids using chemical and chromatographic analyses. The composition of the ordinary unoxidized and epoxy acids was determined by GC.

Synthesis, characterization, and properties of novel organic/inorganic epoxy hybrids containing nitrogen/silicon via the sol-gel method

Organic–inorganic hybrids were prepared with a diglycidyl ether of bisphenol A (DGEBA) type epoxy and silane-modified isocyanuric acid triglycidyl ester via the sol–gel process. The DGEBA-type epoxy was modified by a coupling agent to improve the compatibility of the organic and inorganic phases. The sol–gel technique was used successfully to incorporate silicon and nitrogen into the network of hybrids, increasing the thermal stability. Fourier transform infrared and 29Si-NMR were used to characterize the structures of the hybrids. The results revealed that trisubstituted siloxane bonds (T3) was the major environment forming a network structure. The morphology of the ceramer was examined with scanning electron microscopy, Si mapping, and transmission electron microscopy. The particle sizes were less than 100 nm. The hybrids were nanocomposites. The ultraviolet–visible spectra of the epoxy hybrid showed no obvious absorbance over a range of 400–800 nm. This phenomenon revealed that the hybrids were transparent. The thermogravimetric analysis revealed that the char yields of the hybrids increased with the contents of the inorganic components. The integral procedure decomposition temperatures of the hybrids were higher than that of the pure epoxy. The thermal stability of the hybrids increased with the contents of the inorganic components. The inorganic components could improve the thermal stability of the pure epoxy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

An Efficient and Practical System for the Catalytic Oxidation of Alcohols, Aldehydes, and α,β-Unsaturated Carboxylic Acids

Upon exposure to commercial bleach (approximately 5% aqueous sodium hypochlorite), nickel(II) chloride or nickel(II) acetate is transformed quantitatively into an insoluble nickel species, nickel oxide hydroxide. This material consists of high surface area nanoparticles (ca. 4 nm) and is a useful heterogeneous catalyst for the oxidation of many organic compounds. The oxidation of primary alcohols to carboxylic acids, secondary alcohols to ketones, aldehydes to carboxylic acids, and alpha, beta-unsaturated carboxylic acids to epoxy acids is demonstrated using 2.5 mol % of nickel catalyst and commercial bleach as the terminal oxidant. We demonstrate the controlled and selective oxidation of several organic substrates using this system affording 70-95% isolated yields and 90-100% purity. In most cases, the oxidations can be performed without an organic solvent, making this approach attractive as a "greener" alternative to conventional oxidations.

Sources and composition of hydrolysable aliphatic lipids and phenols in soils from western Canada

The hydrolyzable lipid composition of grassland and forest soils, and their overlying vegetation (i.e., prairie grasses, aspen, and pine) were analyzed by alkaline hydrolysis and gas chromatography–mass spectrometry (GC–MS). Prior to hydrolysis, samples were pre-extracted with organic solvents to remove free lipids. The hydrolysis products from soils and plants consisted of series of aliphatic lipids (alkanoic acids, alkanols, alkanedioic acids, ω-hydroxyalkanoic acids, α-hydroxyalkanoic acids, mid-chain-substituted hydroxy and epoxy acids), benzyls and phenols. Cutin, suberin and plant waxes are believed to be the major sources for the detected lipids. The composition of cutin and suberin monomers in the soils is similar to the patterns observed in the corresponding vegetation reflecting the preservation of plant biomolecules such as cutin and suberin. The long-chain ω-hydroxyalkanoic and α,ω-alkanedioic acids (>C 16) as observed in the grass roots are typical biomarkers for suberin and indicate a major input of root biomass to the soils. Mid-chain-substituted hydroxy and epoxy acids (C 14–C 18) derived from the cutin of leaves were detected in the soils but in low abundance, indicating only a minor input of leaf material. A parameter to estimate the input of leaf vs. root organic matter is developed and applied based on the pattern and distribution of observed cutin and suberin biomarkers. The cutin/suberin ratios decrease from plant material to the mineral horizons likely due to the steady input of fresh root material in the soil horizons rather than the preferential degradation of cutin. The decrease of total hydrolysis products from the overlying vegetation to the soil is consistent with the degradation of hydrolysable biomarkers. Long-chain ω-hydroxyalkanoic and α,ω-alkanedioic acids derived from suberin are observed to decompose without preference of specific constituents. In contrast, mid-chain-substituted hydroxy and epoxy acids appear to be preferentially degraded in soils compared to other cutin and suberin monomers such as ω-hydroxyalkanoic acids. However, the steady input of roots which are rich in ω-hydroxyalkanoic acids and low in mid-chain-substituted acids may in part influence the degradation parameters resulting in an apparent higher rate of degradation.

A convenient synthesis of trans -3-hydroxy-L-proline

A simple synthesis of cis-3-hydroxy-L-proline has been achieved starting from b -alanine making use of Sharpless asymmetric epoxidation as a key step in the synthesis. cis-3-Hydroxy-L-proline is a relatively rare b -hydroxy-a -amino acid, which has been found as a component of the antibiotic teleomycin.1 In connection with the synthesis of the natural product cyclothialidine2, we required to synthesize the optically pure cis-3-hydroxy-L-proline in good chemical yield. Several syntheses of cis-3-hydroxy-L-proline have been reported. Apart from the enzymatic resolution3 of cisand trans-3-hydroxy proline, a variety of approaches to the synthesis of this amino acid are reported in the literature with varying degree of success and limitations.4 Most of these utilized enzymatic methods or chiron approach to get the optically pure product. We decided to study a new approach to the asymmetric synthesis of cis-3-hydroxy-Lproline 1 using Sharpless asymmetric epoxidation as a key step in the synthetic strategy. A retrosynthetic analysis of this approach is depicted in scheme-1 Cis-3-hydroxy proline can be derived from trans-3-hydroxy proline which in turn can be formed by an intramolecular cyclisation of an amino epoxide. The chiral epoxide can be generated by Sharpless epoxidation of a suitable allylic alcohol. The allylic alcohol in turn can be derived from b alanine by straightforward synthetic manipulations. The synthetic route was started with the readily available and inexpensive b -alanine. A suitable protective group for the amino group was needed which will be stable to Sharpless epoxidation conditions later in the sequence. It is well documented in the literature5 that the Boc or Cbz protected amines usually lead to the formation of cyclic urethane derivatives under these conditions. Various type of N-protecting groups that would encourage cyclization through nitrogen namely N-tosyl, N-trityl, and even unprotected derivatives have been tried but in all the cases the reaction leads to a complex mixture of products. All the problems are taken care of when nitrogen is protected both with tosyl as well as benzyl group.6 The synthetic route adopted to achieve the synthesis of 1 is presented in scheme-2. The methyl ester of b -alanine was readily converted to the N-protected methylester 2 which on reduction with lithium aluminium hydride in ether (0oC) provided the alcohol 3 in quantitative yield. The alcohol 3 was then oxidized with Dess-Martin periodinane to afford the aldehyde 4 in 97% yield while the Swern oxidation of the same compound gave the product only in 69% yield. The aldehyde 4 was allowed to react with triethylphosphono acetate7 and the trans olefin 5 was obtained in 89% yield. Initially the reduction of the unsaturated ester 5 was tried with lithium aluminium hydride in ether but it led to a mixture of allylic alcohol 6 and the corresponding saturated alcohol. However when the reduction of 5 was carried out with AlH3, generated in situ, the allylic alcohol 6 was the only product obtained in quantitative yield. Now the stage is set for carrying out Sharpless asymmetric epoxidation. The allyl alcohol 6 was treated with titanium tetraisopropoxide, tert-butyl hydroperoxide, and L-(+)-diethyl tartarate8 and the epoxy alcohol 7 was obtained in 92% yield with 98% ee. The enantiomeric excess was estimated by NMR shift reagent [Eu(hfc)3] experiments. Initially the direct oxidation of the epoxy alcohol 7 to the epoxy acid 8 with RuCl3/NaIO4 was carried out but the yield obtained in this reaction was generally poor (45% of corresponding methyl ester). Therefore the epoxy alcohol 7 was first oxidized to the aldehyde with Dess-Martin periodinane followed by oxidation with Ag2O to get the epoxy carboxylic acid 8 (91%). Compound 8 was converted to its methyl ester 9 on treatment with diazomethane in high yield. NMR experiments with chiral shift reagent [Eu(hfc)3] revealed the product 9 to have optical purity of 98% ee.

Changes occurring in vegetable oils composition due to microwave heating

The effect of microwave heating on three vegetable oils having different lipid compositions was studied. Sunflower, soybean and peanut oils in comparison with oil admixture of soybean and peanut oil (1:1, w/w), were selected for this study. Each oil was heated for 2, 4, 6, 8, 10, 12, 15 and 18 minutes in microwave oven. Peroxide value, free acidity and colour absorbance (at 420 nm) were proportionally increasing with the increase of heating period. Colour absorption threw light on the formation of browning products arising from phospholipids during microwave heating. Total tocopherol contents were determined by preparative thin layer chromatography, whereas the fatty acid compositions and formed epoxy acid were analyzed by capillary gas liquid chromatography. The formed conjugated dienes and trienes were determined by UV spectrophotometry. It was found that the total tocopherols of the microwave heated oils, decreased depending on the type of the predominating tocopherols. Also a relation of peroxide formation, during microwave heating, with changes in total tocopherol composition was discussed. It was found that polyunsaturated fatty acids generally decreased by increasing the heating period. The results obtained from the heated oil admixture helped interpret the results obtained from other heated individual oils.

Effect of the crosslinking degree on curing kinetics of an epoxy–acid copolymer system

AbstractThe hardening of a commercial epoxy resin (DGEBA) with the cure of high molecular weight acid copolymers was studied using differential scanning calorimetry (DSC). The systems were uncured and partially cured epoxy/poly(acrylic acid–styrene) (SAAS), at different contents of styrene. The conversion degree of the crosslinking of the systems, examined versus time, temperature of hardening, and styrene contents in the copolymers, were determined. The activation energies of the crosslinking reactions were calculated by the Freeman–Carrol relation and showed a dependence on the state of hardening. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2834–2839, 2003

Epoxidation catalysts

The major component of the cuticular hydroxyfatty acid polymer, cutin, of spinach leaf was identified as 18-hydroxy-cis-9,10-epoxystearic acid. A 3000g particulate fraction obtained from the homogenates of young spinach leaves catalyzed the epoxidation of 18-hydroxyoleic acid to 18-hydroxy-cis-9,10-epoxystearic acid. The epoxy acid was identified by thin-layer chromatography of the product of hydration of the oxirane function and subsequent reduction (octadecane-1,9,10,18-tetraol), on silica gel G and boric acid impregnated silica gel, and by radio gas-liquid chromatography of the periodate oxidation product of the tetraol derived from the epoxy acid. This enzymatic epoxidation required ATP, CoA, NADPH, and O2 for maximal activity. The pH optimum for epoxidation was 9.0, and the epoxidase activity was located mainly in the 3000g particulate fraction, which contained the cuticular membranes. The rate of epoxidation of the unsaturated acid was linear up to 2 h and up to a protein concentration of 1.5 mg/ml. The apparent Km and V of the enzyme was 7.5 × 10−5m and 180 nmol/1-h-mg protein, respectively. That the epoxidase has a stringent substrate specificity was indicated by the observation that 18-hydroxyelaidic acid, 18-acetoxyoleic acid, and oleic acid were not readily epoxidized by this enzyme preparation. Light reversible inhibition by CO suggested the involvement of cytochrome P-450 in the epoxidation. Chelators inhibited epoxidation, and this inhibition was reversed by FeSO4. The epoxidase was inhibited 30% by 0.5 mm NaCN, whereas the same concentration of NaN3 showed very little inhibition. The present epoxidase is unique in that it is associated with the 3000g particles which contain the cutin polymer and in that it requires activation of the carboxyl group distal to the epoxidation site. Enzyme preparations capable of epoxidizing 18-hydroxyoleic acid were also obtained from the skin of apple fruit and from the epidermis of Senecio odoris leaves. This is the first report on an enzyme involved in the biosynthesis of the C18 family of cutin monomer acids.

Determination of all pKa values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges

Determination of all pKa values of some di- and tri-carboxylic unsaturated and epoxy acids and their polylinear correlation with the carboxylic group atomic charges

Determination of all pKa Values of Some di- and Tri-Carboxylic Unsaturated and Epoxy Acids and Their Polylinear Correlation with the Carboxylic Group Atomic Charges

For a series of seven unsaturated and seven epoxy di- and tricarboxylic acids, p Kaa values were determined potentiometrically in aqueous media at 25 °C and an ionic strength of 0.1 M (NaCl). The thermodynamic p Kaa values were correlated with the atomic charges of carboxylic group calculated by the MNDO-PM3 semiempirical MO method.

Two‐stage solvent extraction of seeds of Hibiscus abelmoschus linn: Lipid and FA compositions

AbstractThe lipid and FA compositions of TAG seed oil of ambrette (Hibiscus abelmoschus), contrary to earlier reports, were found to contain only a small amount of epoxy FA. Higher HBr absorption values were shown to be due to the presence of fragrance components of the seed coat in the oil derived from intact whole seeds. Cyclopropene/cyclopropane acids in the FAME were determined to be about 1.5% by GLC, while epoxy acids were less than 1% by two different methods. Based on the physicochemical characteristics and lipid and FA compositions of the fresh and methanol‐extracted seeds, ambrette TAG oil may be a candidate for edible use. The process of selective recovery of the expensive fragrant oily concentrate in higher yield in a first step and of an edible fatty oil in a second step makes it an attractive economic proposal.

Decomposition behavior of vinyl ester resins prepared in presence of tertiary amines

Vinyl ester resins V1, V2, and V3of acid value (∼6 mg KOH/g solid) were synthesized using bisphenol-A epoxy and acrylic acid in the presence of triethyl, tripropyl, and tributyl amines, respectively. The synthesized resins were characterized by Fourier transform infrared spectroscopy and a new peak at 2360 cm−1was observed due to attachment of amines to resin structure by a hydrogen bond. All the resins containing styrene (40% w/w) as reactive diluent were cured with benzoyl peroxide (2 phr) at 90°C for 1 hr. Decomposition behavior of the samples was studied by dynamic thermogravimetry at a heating rate of 10°C min−1under nitrogen atmosphere. For all the samples, the order of reaction was found to be 1. This was calculated using Coats and Redfern equation in accordance with best-fit analysis and was confirmed further by linear regression analysis. From this value of reaction order, activation energy (E) and pre-exponential factor (Z) were calculated. The activation energy increases from 25.90 to 30.72 kcal mol−1for V1to V3. The validity of data was checked by t-test statistical analysis.

Are changes of the cell membrane structure causally involved in the aging process?

Lipid peroxidation is recognized by proliferation, wounding, and aging. The connecting link between these different events is a change in cell wall structure, which activates membrane bound phospholipases. These cleave phospholipids. Thus liberated polyunsaturated fatty acids (PUFAs) are substrates for lipoxygenases, which accept equally well linoleic acid and arachidonic acid and generate lipid hydroperoxides (LOOHs). If the amount of free PUFAs exceeds a certain amount, lipoxygenases commit suicide. The consequence is liberation of free iron ions that react with LOOHs by formation of radicals. These start a chain reaction. LOO* radicals produced in the course of this process attack proteins, nucleic acids, and also double bonds of all unsaturated compounds by epoxidation. Morever LOOHs are decomposed to toxic epoxy acids and alphabetagammadelta-unsaturated aldehydes. Both species react with glutathione. The resulting products seem to induce apoptosis. Since the products generated by wounding or aging are formed by decomposition of LOOHs the investigation of the aging processes can be simplified by studying the physiological action of artificially generated lipid peroxidation products derived from pure PUFAs. Degradation products of LOOHs are generated by thermal decomposition of fat-containing PUFAs. These products are induced into the body by adsorption in the intestine. They are at least partly incorporated in low density lipoproteins (LDLs). Primarily investigations seem to indicate that an overload of a diet rich in PUFAs induces only after two days an increase in oxidized LDL/PUFAs for a factor up to two in young people and for a factor of more than two in old individuals.

Photocure Behavior of Highly Transparent and Thermally Stable Photosensitive Polymer

A new photosensitive prepolymer was designed and synthesized by esterification of an epoxy and methacrylic acid. Photopolymerization behavior of the prepolymer was quantitatively investigated by FT-IR spectroscopy. We also studied thermal stability by observing changes in the transmittance of the polymer film upon heating at 250 °C for a given period of time.

Photocure Behavior of Highly Transparent and Thermally Stable Photosensitive Polymer

A new photosensitive prepolymer was designed and synthesized by esterification of an epoxy and methacrylic acid. Photopolymerization behavior of the prepolymer was quantitatively investigated by FT-IR spectroscopy. We also studied thermal stability by observing changes in the transmittance of the polymer film upon heating at 250 °C for a given period of time.

Camphor-Based α-Bromo Ketones for the Asymmetric Darzens Reaction

(1R)-2-endo-Bromoacetyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol (endo-2-bromoacetylisoborneol) 4 and its trimethylsilyl ether 3 are presented as efficient reagents for the asymmetric Darzens reaction. From the alpha,beta-epoxy ketone adducts the chiral inductor camphor is removed, by treatment with ceric(IV) ammonium nitrate, to yield the corresponding epoxy acids which are isolated as their dicyclohexylammonium salts.