Stearic Acid Methyl Ester Research Articles

Selective glycerol transesterification over mesoporous basic catalysts

The preparation of monoglycerides from fatty methyl esters and glycerol can be carried out in the presence of acid or basic catalysts. Moreover, the use of porous and basic solid catalysts could induce a shape selectivity modifying the monoglyceride selectivity. Lauric (C12), myristic (C14) and stearic (C18) acid methyl esters were used in the reaction with several MCM-41 magnesium-containing catalysts. Over an Mg-MCM-41 catalyst (interreticular distance d 100 of 3.4 nm), glycerol monolaurate was obtained with selectivity and yield of about 80%. To cite this article: J. Barrault et al., C. R. Chimie 7 (2004).

FS12.1 Allergic contact dermatitis from plastic gloves

Plastic gloves are made of polymers including polyvinylchloride, polyvinylalcohol, polyethylene and polyvinylacetate. Additives such as plasticizers, stabilizers, UV light absorbers, fungicides, bactericides, flame retardants and colourants are added to the polymer, and these are potential allergens. Contact allergy to plastic gloves is rare. The allergen responsible for the sensitization usually remains unknown. An organic pigment, Irgalite Orange F2G, and bisphenol A have both caused contact allergy from household‐type PVC gloves. 1 patient with allergic contact dermatitis from his PVC gloves reacted also to tricresyl phosphate and triphenyl phosphate, chemicals known to be used as plasticizers in PVC. A plasticizer, di(2‐ethylhexyl) phthalate (DOP), caused 1 case of contact urticaria from the vinyl chloride slip guard of cotton gloves. 1 patient with contact urticaria from his polyethylene gloves reacted to 3 antioxidants, octadecanoic acid methyl ester and di‐tertiary butyl phenol of the gloves on scratch testing. We report 3 additional cases of allergic contact dermatitis from PVC gloves due to bisphenol A. 2 of the patients reacted also to para‐tertiary butyl catechol, a polymerization inhibitor in PVC. In chemical analysis, the connection between sensitization to para‐tertiary butyl catechol and the use of vinyl gloves could not be proven. We analysed 16 brands of disposable PVC gloves for medical use, covering at least 80% of the Finnish market. We found a very small amount of bisphenol A in 1 brand, and no para‐tertiary butyl catechol in any of the gloves. However, bisphenol A should be remembered as a possible allergen in PVC gloves.

MODIFICATION OF FISH OIL BY LIPOZYME TL IM TO PRODUCE STRUCTURED LIPID

ABSTRACTStearic acid methyl esters was enzymatically interesterified with fish oil (EPAX 5500) containing 44.5 and 32.6 mol% eicosapentaenoic acid (EPA, C20:5n‐3) and docosahexaenoic acid (DHA, C22:6n‐3), respectively. Lipozyme TL IM from Thermomyces lanuginosus was used to produce structured lipids (SL) that may be suitable for margarine or shortening application. Interesteri‐fication was performed in hexane. Fish oil: stearic acid methyl ester levels ranging from 1 to 5 mole ratio was used. The effect of incubation time, substrate ratio and incubation temperature were also studied. Generally, as incubation time and substrate ratio increased, so did the mol % incorporation of stearic acid. After 24 h incubation in hexane, there was a 49.4 mol% incorporation of stearic acid into fish oil, while the mol% of EPA and DHA were reduced to 15.0 and 13.0 mol%, respectively. Time course studies also indicated that the highest stearic acid incorporation occurred at 72 h while 1:Sjish oil to stearic acid mole ratio gave the highest stearic acid incorporation. The data suggests that Lipozyme Ti5 IM could be used to produce SL.

Fatty acid composition of seeds of Satureja thymbra and S. cuneifolia.

The chemical composition of fatty acid methyl esters (FAMEs) from seeds of S. thymbra and S. cuneifolia were analyzed by GC/MS. 7 FAMEs were identified from the seeds of S. thymbra mainly as 9-octadecenoic acid methyl ester (43.9%), hexadecanoic acid methyl ester (11.4%), 9,12,15-octadecatrienoic acid methyl ester (Z,Z,Z) (30.2%), and octadecanoic acid methyl ester (14.1%), while from the seed of S. cuneifolia 10 FAMEs were obtained with the main components, similar to S. thymbra. These were identified as 9-octadecenoic acid methyl ester (10.1%), hexadecanoic acid methyl ester (methyl palmitate, 34.6%), 9,12,15-octadecatrienoic acid methyl ester (Z,Z,Z) (6.3%) and octadecanoic acid methyl ester (1.8%).

Spectroscopic evidence for a preferential location of lidocaine inside phospholipid bilayers

We examined the effect of uncharged lidocaine on the structure and dynamics of egg phosphatidylcholine (EPC) membranes at pH 10.5 in order to assess the location of this local anesthetic in the bilayer. Changes in the organization of small unilamellar vesicles were monitored either by electron paramagnetic resonance (EPR)—in the spectra of doxyl derivatives of stearic acid methyl esters labeled at different positions in the acyl chain (5-, 7-, 12- and 16-MeSL)—or by fluorescence, with pyrene fatty-acid (4-, 6-, 10- and 16-Py) probes. The largest effects were observed with labels located at the upper positions of the fatty-acid acyl-chain. Dynamic information was obtained by 1H-NMR. Lidocaine protons presented shorter longitudinal relaxation times ( T 1) values due to their binding, and consequent immobilization to the membrane. In the presence of lidocaine the mobility of all glycerol protons of EPC decreased, while the choline protons revealed a higher degree of mobility, indicating a reduced participation in lipid–lipid interactions. Two-dimensional Nuclear Overhauser Effect experiments detected contacts between aromatic lidocaine protons and the phospholipid-choline methyl group. Fourier-transform infrared spectroscopy spectra revealed that lidocaine changes the access of water to the glycerol region of the bilayer. A ‘transient site’ model for lidocaine preferential location in EPC bilayers is proposed. The model is based on the consideration that insertion of the bulky aromatic ring of the anesthetic into the glycerol backbone region causes a decrease in the mobility of that EPC region ( T 1 data) and an increased mobility of the acyl chains (EPR and fluorescence data).

Communication ecology of webbing clothes moth: 4. Identification of male- and female-produced pheromones

We investigated the hypothesis that aggregation signals produced by male webbing clothes moths (WCM), Tineola bisselliella (Hum.) (Lepidoptera: Tineidae), and close-range male attractant signals produced by females have a pheromonal basis, at least in part. Gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of bioactive methanolic extracts of male WCM disclosed three candidate pheromone components: hexadecanoic acid methyl ester (16:Ester), (Z)-9-hexadecenoic acid methyl ester (Z9—16:Ester), and octadecanoic acid methyl ester (18:Ester). In bioassay experiments in a large Plexiglas™ arena, a blend of synthetic 16:Ester plus Z9—16:Ester was attractive to male and virgin (but not mated) female WCM; the 18:Ester was inactive. GC-EAD analyses of pheromone gland extracts from female WCM revealed (E,Z)-2,13-octadecadienal (E2Z13—18:Ald) and (E,Z)-2,13-octadecadienol (E2Z13—18:OH) as candidate sex pheromone components. In arena bioassay experiments, 1—5 female equivalents of synthetic E2Z13—18:Ald (0.2 ng) and E2Z13—18:OH (0.1 ng) were more attractive to male WCM than were two virgin female WCM. We anticipate that the combination of aggregation and sex pheromones, male-produced sonic aggregation signals, and habitat-derived semiochemicals will be highly effective in attracting male and female WCM to commercial traps.

Photoinitiated cationic oligomerization of terminal and internal epoxides

The iodonium salt-catalyzed, photoinduced cationic oligomerization of terminal and internal monoepoxides from oleochemical as well as the petrochemical origin was studied. The ring-opening of terminal epoxides (1,2-octene oxide, phenyl glycidyl ether, 9,10-epoxy decanoic acid methyl ester and 10,11-epoxy undecanoic acid methyl ester) predominantly led to macrocyclic oligoethers (Mn = 650—1,100 g/mol) via backbiting in quantitative yields. Mixtures of cyclic and bishydroxy-terminated oligoethers (Mn = 1,050—1,500 g/mol) were achieved by the conversion of internal epoxides (7,8-tetradecene oxide and cis-9,10-epoxy octadecanoic acid methyl ester) in yields of 80—95%. Macrocyclization was completely suppressed by addition of 20 mol-% water or ethylene glycol receiving diol-oligoethers for potential application as soft segments for polyurethanes with molecular weights of approximately 1,300 g/mol.

Study of dichlophenac polymeric derivative with 12-DOXYL spin probe

Continuous wave (CW) electron paramagnetic resonance (EPR) studies of the 12-doxylmethyl stearic acid methyl ester (12-DOXYL) spin probe were made in the solutions of a triblock copolymer of acrylamide, vinylchloroethyl ether and an ester of the vinylchloroethyl ether with 2-[(2,6-dichlorophenyl)amino] benzene acetic acid, “dichlophenac” (DPH). Light scattering experiments show that the hydrophobic DPH group influences the clustering of the polymer in solution. The EPR evidence suggests that when the polymer is dissolved in buffer solutions of 12-DOXYL, the spin probe undergoes a partitioning between the solution, the polymer clusters and a minor third environment. The rate of the 12-DOXYL partitioning from the solution into the polymer cluster is fast compared with the time scale of the changes observed in light scattering and exhibits a dependence on the concentration of the polymer in solution and the pH. The 12-DOXYL environment in the polymer cluster is characterized as restricting 12-DOXYL to slow molecular motion with rotational correlation time τ=1.3×10 −8 s/rad and permitting relatively infrequent collisions between the 12-DOXYL molecules. The solution spectrum of the 12-DOXYL is dominated by the spin exchange narrowing expected for concentrated assemblies of the 12-DOXYL molecules, such as a micelle or bilayer. Partitioning of a hydrophobic spin probe in an aqueous solution is shown to be a sensitive measure of the presence of stabilizing hydrophobic regions in a polymer aggregate.

Enzymatic transesterification of triolein and stearic acid and solid fat content of their products

AbstractTwo systems were investigated and compared as models for making margarine‐type fats. Two immobilized lipases, IM60 from Rhizomucor miehei and SP435 from Candida antarctica, were used to catalyze the transesterification of triolein with stearic acid and stearic acid methyl ester, respectively, in n‐hexane. The optimal reaction temperature for both enzymes was 55°C at a mole ratio of triolein to acyl donor of 1:2. Equilibria were reached at 18 h for IM60 and 24 h for SP435. Analysis of the overall yield and incorporation of fatty acid at the sn‐2 position indicated that the triacylglycerol products contained 38.4 and 16.2% 18:0 for acidolysis and 34.2 and 11.3% for interesterification reactions, respectively, at the 2‐position. With SP435, the softest fat was produced after 18 h of incubation, and the hardest after 30 h. For IM60 system, 18 h of incubation gave the most plastic fat.

Metastable McLafferty rearrangement reaction in the electron impact ionization of stearic acid methyl ester

The metastable peaks for the McLafferty rearrangement and double hydrogen rearrangement reactions have been observed in the stearic acid methyl ester system under electron impact ionization. The metastable ion spectrum of the M +. ion gave peaks corresponding to the ions at m/z 74, 75, 87 and 88, whereas the collision-induced dissociation spectrum showed low intensity ions at m/z 75 and 88 which come from double hydrogen rearrangement reactions of M +. ions. The kinetics for the change of the molecular ions to different structures before fragmentation have been discussed.

Autocatalytic Acylation of Phospholipase-like Myotoxins

Several snake venoms contain a phospholipase A2 in which position 49 in the active site is occupied by a lysine or a serine instead of the aspartate residue normally found. Although these proteins do not bind Ca2+ and are devoid of catalytic activity, they are still highly specific myotoxins and have recently been shown to induce membrane leakage by a new type of cytolytic mechanism. Three of these toxins, myotoxin II from Bothrops asper, ammodytin L from Vipera ammodytes, and the K49 protein from Agkistrodon piscivorus piscivorus, were examined for their interaction with fatty acids and were found to bind long-chain fatty acids covalently by a rapid, spontaneous, autocatalytic process. The fatty acids could be released by treatment with 1 M NH2OH or NaOH, but not with 1 M NaCl or by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Electron spin resonance studies using spin-labeled fatty acids showed that only the carboxyl headgroup of the fatty acid was linked to protein amino acid, the carbon chain had free mobility and did not bind tightly to the protein surface. Stearic acid methyl esters and short-chain fatty acids did not bind to the toxins. Acylated myotoxins bound to the surface of liposomes and isolated muscle membranes, with the fatty acid moiety inserted into the lipid bilayer and possibly acting as an anchor. The phospholipase-like myotoxins represent the first group of proteins able to undergo acylation by spontaneous reaction with free fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of fatty acid methyl esters by thermal analysis

The thermal stability of selected straight-chain (C6-C14) esters of fatty acids has been studied by TG-DTG and DTA analysis. In DTG, a peak is detected between 84° and 125° C followed by a main effect in the range 105°–215°C, whereas in DTA only an exothermic peak appears in the range of 126.5° to 187°C (onset temperatures). The temperatures of these effects have been related with ignition points, molecular weights and boiling points. The characteristics of melting and recrystallization of the above fatty acid methyl esters and those with carbon numbers between C14 and C24 have been established by DSC along the melting range between −83° and 50°C. Polymorphism appears in caproic, heptanoic, palmitic and stearic acid methyl esters.

Interaction between Thiaminetetrahydrofurfuryl Disulfide with Fatty Acid in 1,2-Dichloroethane.

The interaction between thiamine tetrahydrofurfuryl disulfide (TTFD) and saturated fatty acid (FA) in 1, 2-dichloroethane at 25°C was studied by phase solubility analysis using FA with various carbon numbers (14, 16, and 18), stearyl alcohol, and stearic acid methyl ester. The solubility of TTFD increased with the addition of FA. The solubility of TTFD also increased with the addition of stearyl alcohol, while its solubility decreased when stearic acid methyl ester was added.It was found that the solubility of stearic acid also increased with the addition of TTFD, and that TTFD cannot form a crystalline complex with stearic acid.These results are compared with those obtained for thiamine disulfide (TDS) and cycotiamine. The mode of the solubilization of TDS by FA in 1, 2-dichloroethane, and its relation to the crystallization of the complex between TDS and FA was discussed.

Solubilization of Thiamine Disulfide by Fatty Acid or Its Analog in 1,2-Dichloroethane.

The solubility change of thiamine disulfide (TDS) in 1, 2-dichloroethane by the addition of fatty acid (FA), fatty alcohol or fatty acid methyl ester was determined by phase solubility analysis at 25°C. The solubility of TDS increased linearly with added concentrations of stearic acid, palmitic acid or myristic acid, but the diagram did not exhibit a plateau due to the appearance of a solid complex. The dependency of the FA slope values on the number of carbon atoms in FA was very little. The solubility of TDS also incerased linearly with added concentrations of stearyl alcohol, while the value for the slope was smaller than FA. On the other hand, the solubility of TDS decreased by the addition of stearic acid methyl ester. The results agreed well with those for the solubilization of cycotiamine, a thiamine derivative, by FA and FA analogs in 1, 2-dichloroethane.

Long-chain chloroalkane utilization by a marine protozoan

Summary: A long-chain chloroalkane, 1-chlorooctadecane, was biotransformed by a marine amoeba, Trichosphaerium 1–7, and utilized by this organism as a carbon source. Haloalkane metabolism was accompanied by marked cell darkening which may represent xenobiotic-induced melanin biosynthesis. Radiolabelled carbon atoms derived from 1-chloro[1-14C]octadecane were incorporated into cellular proteins and organic intermediates, including fatty acids. Gas chromatography and mass spectrometry analyses of the fatty acid methyl ester derivatives, however, showed that they were not chlorinated. [1-14C]Octadecanoic acid methyl ester was detected by mass spectrometry, but hexadecanoic acid methyl ester did not contain detectable 14C. These data suggest that the amoebae convert the chloroalkane to the corresponding fatty acid by oxidative dehalogenation.

Phase and miscibility behavior of binary lipid systems

Differential scanning calorimetry was applied to study the phase diagrams of the following binary lipid systems: myristic acid (C13COOH) / pentadecanoic acid (C14COOH); palmitic acid methyl ester (C15COOMe) / heptadecanoic acid methyl ester (C16COOMe); palmitic acid methyl ester (C15COOMe) / stearic acid methyl ester (C17COOMe); palmitic acid methyl ester (C15COOMe) / arachidic acid methyl ester (C19COOMe). A distinct succession in the phase diagram types and phase regions was observed, according to the chemical structure of the mixing components.

Formation of a cycotiamine complex with fatty acid in dichloroethane.

The formation of complexes between cycotiamine (CCT) and fatty acids (FA) (tetradecanoic acid, hexadecanoic acid, and octadecanoic acid) in 1, 2-dichloroethane was studied by phase solubility analysis and ultraviolet absorption spectroscopy. The apparent stability constants of the equimolar complexes between CCT and FA were determined at 288, 298, and 310 k, and thermodynamically discussed. The complex formation ability of FA depended on the number of carbon atoms in FA, but the differences were small. The ability of 1-octadecanol was very small, and octadecanoic acid methyl ester had none. From these results CCT-FA were concluded to be hydrogen bonded complexes in which FA act as hydrogen donors. The complex formation reactions were exothermic anc enthalpically controlled.

Effect of pressure on the properties of a surfactant micelle and a lipid membrane studied by the spin-probe method

High-pressure e.s.r. spectra of a spin probe, 16-doxyl stearic acid methyl ester, in a surfactant micelle and in lipid bilayers have been measured up to ca. 300 atm. The spectra of the probe in a sodium dodecyl sulphate micelle altered little with pressure. The viscosity in the micelle, calculated from the rotational correlation time using the Stokes–Einstein equation, showed that it increases ca. 2.5 times under 3000 atm pressure. In an egg phosphatidylcholine bilayer, the effect of pressure was far larger than that in the micelle. The three-line spectrum under 1 atm became the rigid-limit one under 2900 atm, suggesting that the liquid-crystalline state changes into the gel state with an increase in pressure. The effect of pressure on the viscosities in the micelle and the lipid membrane has been discussed by comparison with those of water and dodecane. In a dilauroylphosphatidylcholine bilayer the spin probe as gradually segregated from the bilayer with increasing pressure, showing that phase separation takes place in the lipid bilayer with increasing pressure.

ＦＡＢＭＳにおける低極性有機化合物のための新しいマトリックス系の効果

A new matrix system m-NBA-DTDE (1:1) for FABMS of low-polar compounds, such as cholesterol (1) and stearic acid methyl ester (2), was prepared. The system, i.e., a 1:1 mixture of m-NBA (m-nitrobenzyl alcohol) to DTDE (2, 2′-dithiodiethanol or 2-hydroxyethyl disulfide), contributed to measuring the positive ion FAB mass spectra of above compounds and morusin permethyl ether (3), and it brought an effective result on the ion current lifetime and the reproducibility of their spectra. The positive ion FAB mass spectra of these low-polar compounds were compared with the corresponding positive ion EI and CI mass spectra.

Kinetic studies on the interesterification of oils and fats using dried cells of fungus

The kinetics of enzymatic interesterification of oils and fats, using acetone dried cells of Rhizopus chinensis as a lipase catalyst, have been investigated in a batch operation. To clarify the mechanism of this reaction, several models are discussed under various conditions in terms of the ratio of triglyceride (TG)/fatty acid (FA) and of the water content. First, in the reaction between olive oil and methyl stearate, the parameters involved in each model were determined by the trial-and-error method so as to make the calculated results fit with the experimental data. Then, the models were compared with the experimental data obtained from the reactions with a mixture of stearic and palmitic acid methyl esters, where the proportions of (TG)/(FA) and water content were varied. From the results, the model based on either first order kinetics or on the formation of the glyceride-enzyme complex was confirmed to fit best with the data under a wide range of reaction conditions. This suggests that the fatty acid moiety of TG seems to be exchanged through the glyceride-enzyme complex in the enzymatic interesterification of oils and fats.