Super acid catalyzed dimerization of fatty acids derived from safflower oil and dehydrated castor oil

Dimerization of fatty acids derived from dehydrated castor oil and safflower oil was carried out on the recently described sulphate-treated zirconia catalyst and trifluoromethane sulphonic acid (triflic acid) under autogeneous pressure in the temperature range of 160–240 C. Triflic acid was observed to be highly active; however, the product obtained was deeply colored. Zirconia exhibited high activity for the reaction. The important features of this catalyst were the high selectivity for dimer (low yields of trimer) and no significant coloration of the products. The zirconia catalyst shows promise for industrial use.     

The role of safflower oil in edible oil applications

Safflower oil has been used as an edible oil in numerous countries for many years. In the US, commercial use of safflower oil as an edible product was noted in the 1950's and the use continues at progressively higher levels each year. One use of safflower oil in “dressing” type products is related to the natural cold resistance of the oil. Other applications include oil, margarine and some imitation dairy products. Additional development work has been done on other food products so that the scope of usage could be broadened if there should be increased demands for safflower oil. The susceptibility of safflower oil to oxidation has been minimized by improved processing and packaging. Further use of safflower oil appears to be dependent upon availability, pricing, good cold resistance and the role of polyunsaturates in the diet.     

Effect of amino acids on the autoxidation of safflower oil in emulsions

Oxygen absorption rates were measured on liquid emulsions containing safflower oil and various amino acids. The antioxidant effects of the several amino acids were quite variable depending on the type of emulsifier used, the pH of the system and the presence of added sugar. Preliminary tests with Maillard reaction products obtained by heating dextrose with lysine showed little stabilizing effect. In freeze-dried emulsions, methionine, threonine, lysine and histidine all exhibited antioxidant activity. With sodium caseinate as the matrix, methionine was much better than any of the other amino acids. The inclusion of sugar enhanced the rate of oxidation. Porosity measurements on the freeze-dried powders revealed that oxygen diffusion was not rate-determining. When xanthan gum was used to replace caseinate in these dried emulsions, oxidation rates increased.     

Effect of sugars and sugar alcohols on autoxidation of safflower oil in emulsions

Oxygen absorption rates were measured on liquid emulsions containing safflower oil and glycerol, sugars or sugar alcohols. Stability to oxidation improved as the level of added compound was increased. Emulsion viscosities were higher, and resistance to creaming was better at the higher concentrations of additives. It is suggested that diffusion of oxygen through the oil-water interface is the rate determining step which is probably slower at high viscosity and in the absence of creaming. Freezedried emulsions containing safflower oil, protein, polyols and anionic surfactant oxidized more rapidly than did those samples in which either polyol or surfactant was omitted. The differences in oxidation rate could be accounted for on the basis of degree of oil dispersion and porosity of the dried particles. No evidence has been found for any true antioxidant or pro-oxidant effect of these compounds.     

High-oleic safflower oil. Stability and chemical modification

High-oleic acid safflower oil has been shown to have high-temperature oxidative stability comparable with that of hydrogenated vegetable oils. This stability, added to the ease of handling at low temperatures, should make the oil attractive as a commercial cooking oil. Epoxidation of the new safflower oil led to a product similar to epoxidized olive oil but lighter in color.     

Quantitative analysis of polymerized fatty acids using gel permeation chromatography

The acid clay catalyzed dimerization of tall oil fatty acids and oleic acid yields commercial products which are complex mixtures of monomers, dimers, trimers, and higher polymers of various structures. Analyses for monomer, dimer, and trimer concentrations are important to ensure good quality control and reproducible end use performance. Techniques for direct determination of monomer, dimer, and trimer acids by gel permeation chromatography are presented. The components are separated using Bio Beads SX-2 gel. Heptanoic acid is used as an internal standard. The standard deviations for determination of dimer, trimer, and monomer are 1.0, 0.4, and 0.2% respectively. Calibration was accomplished using dimer and trimer fractions isolated from a preparative scale chromatographic system. It is suggested that a measure of higher polymeric acids can be obtained by difference after correction for neutral materials.     

The Behaviour of Phenolic Antioxidants,Synergists and their Mixtures in Two Vegetable Oils

Tertiary butylhydroquinone (TBHQ), hydroquinone (HQ), propyl gallate (PG), butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) had much higher antioxidant activity in crude safflower oil than in a commercial brand vegetable oil (Bint oil). The following active oxygen (AOM, hours at 97.8° C) and storage stability (days at 45° C) values for each antioxidant in safflower oil were; (27.9, 105.0), (21.2, 44.8), (15.3, 45.5), (9.8, 36.8) and (7.9, 33.5) respectively compared with (6.8, 31.5) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. The same values in Bint oil were: (9.0, 34.3), (9.0, 28.3), (9.4, 41.0), (7.3, 28.5) and (6.2, 2.5) respectively compared with (5.3, 23.3) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. AP was more effective and CA least effective in safflower oil, whereas the reverse was true in Bint oil. The five antioxidants were individually blended with the three synergists (0.01 % of each) and the 15 combinations added to each oil and compared with the antioxidant controls at 0.02 %. Safflower oil stability was greater with pure TBHQ, HQ and PG than with any of the synergist mixtures whereas the BHA, BHT-synergist mixtures were found equal or superior to that treated with BHA or BHT alone. Bint oil treated with CATBHQ or CA-HQ mixtures showed improved stability compared to oils treated with these antioxidants alone. However, the AOM method alone suggested CA-PG, CA-BHA and CA-BHT mixtures improved the stability compared to the oil-antioxidant controls. Chelation of metals by CA was assumed to be the primary cause of this synergism, whereas AP and AA behaved more like weak antioxidants.     

The antioxidant activity of amino acids in two vegetable oils

Of 27 amino acids studied, most had some antioxidant activity when added in aqueous solution to either safflower oil or a mixture of sunflower and cottonseed oil (active oxygen and storage methods). Cysteine-HCl, glutamic acid-HCl (in the mixture), and glutamic acid-HCl (in safflower oil) behaved as prooxidants. When added as a solid, most amino acids were ineffective. The protection factors of these amino acids were less than 1.3 in safflower oil with methionine, proline, lysine and cysteine providing the highest activ-ity. In the oil mixture (which had a higher metal content) lysine, arginine, glutamic acid, methionine, and hydroxyproline were anti-oxidant with protection factors of up to 1.85. Chelation of metals by amino acids was presumably responsible for the antioxidant activity. The increase in cysteine concentration up to 1% has more than doubled the protection factor in Bint oil (compared with the 0.01% level), whereas with some other amino acids the increase was either small or slight.     

微化工技术在防老剂TMQ合成中的应用

介绍微化工技术产生的背景,分析微化工技术在防老剂TMQ合成中的应用。与现有技术相比,通过使用微通道反应器制备防老剂TMQ,反应时间缩短,反应转化率提高,产品质量稳定,安全性好;设备损耗低,可以连续不间断反应;操作简单,对环境污染小,具有良好的工业应用前景;制备的防老剂TMQ转化率为85%~99%,防老剂TMQ的二、三、四聚体总含量达40%~75%。     

Sterol additives as polymerization inhibitors for frying oils

Addition of certain vegetable oil unsaponifiables to safflower oil protects it from oxidative polymerization during heating at frying temperature. The unsaponifiables isolated from olive, corn, wheat germ andVernonia anthelmintica oils were found to be effective. The fraction responsible for this effect is largely sterol in nature. Although the common plant sterols show no antioxidant activity, the 4-α-methyl sterols function well. The sterols fromVernonia oil, which contain no 4-α-methyl group, are also active. It appears that an isofucosterol side chain may be the structural feature required to obtain this protective effect.     

橡胶防老剂RD生产现状与发展趋势

橡胶防老剂RD对热氧老化的防护非常有效,对金属的催化氧化也有极强的抑制作用,是防老剂甲和防老剂丁的理想替代品。1999年我国防老剂RD的消费量为7500t,预计2005年的消费量将超过1.4万t,2015年将达到2万t。提高防老剂RD中的二聚体含量、减少杂质、生产出高品质产品,扩大单套装置的生产能力,实现规模化经营,是防老剂RD的发展趋势。     

Canolol Dimer,a Biologically Active Phenolic Compound of Edible Rapeseed Oil

Rapeseed and its oil are the source of many biologically active substances. From crude rapeseed oil, canolol is isolated and from edible oil its dimer. Herein, we tested the biological activity of those two compounds isolated from the oils by determining their antioxidant capacity and in vitro cytotoxicity on human tumor cell lines. Canolol and its dimer showed antiproliferative activity on both cell lines with IC₅₀ values of 46.45 μM in HeLa, and 51.19 μM in MCF7 cells, respectively. Evaluation of cell death was also done, while the oxygen radical absorbance capacity method confirmed that the canolol dimer has higher antioxidant potential than canolol. Stability of canolol and its dimer under different storage conditions showed that for a longer period of time both compounds should be stored in a freezer, but also that the dimer is more stable against degradation than canolol. Presented results indicate possible applications of canolol and its dimer in the food and pharmaceutical industry as a natural antioxidant and an anticancer agent, respectively.     

Model studies and the ADMET polymerization of soybean oil

Grubbs' ruthenium catalyst 2 has been employed in model studies of the acyclic diene metathesis (ADMET) polymerization of soybean oil. In the presence of 0.1 mol% of catalyst 2, the ADMET polymerization of ethylene glycol dioleate afforded the isomerized (E)-dioleate (27%), dimer (18%), trimer (13%), tetramer (7%), pentamer (5%), hexamer (4%), heptamer (4%), and 9-octadecene (21%). Only a trace of any intramolecular cyclized product was formed. Under the same conditions, glycerol trioleate underwent ADMET polymerization to produce dimer, trimer, tetramer, pentamer, and monocyclic oligomers, with monocyclic oligomers predominating. The high number of repeat units in the monocyclic oligomers (n≅6, 10, and 21) in dicates that cross-linking occurs readily in this process. Based on our model system studies, we have examined the ADMET polymerization of soybean oil and succeeded in producing polymeric materials ranging from sticky oils to rubbers.     

Depolymerization of poly(ethylene terephthalate) resin under pressure

The process of depolymerization of PET resin by EG glycolysis under pressure is investigated. The kinetics of this pressurized depolymerization of PET resin is discussed. It was found that the rate of depolymerization is dependent of temperature, pressure, and concentration ratio of EG to PET. The rate of depolymerization is proportional to the square of EG concentration and faster than that under atmospheric pressure. Glycolyzed products under pressure consist of the PET monomer, BHET, and oligomers, mostly dimer and trimer. An equilibrium between BHET and oligomers is attained quickly soon after the depolymerization step is completed in the case of a higher ratio of EG/PET used. In the case of lower ratio of EG/PET, the final product now consists of higher molecular weight of oligomers rather than monomer, dimer, and trimer.     

Quenching of pyrolysis products of p-xylene in toluene-kinetic studies of acetone-soluble products

Pyrolysis of p-xylene was carried out in a tubular reactor at partial pressures varying from 0.184 kPa to 2.199 kPa with steam as a diluent. The product stream was quenched in toluene, and the solid products formed in quenching were shown to consist of p-cyclophane (acetone insoluble) and linear dimer, linear trimer and one immovable component (in TLC analysis) constituting the acetone-soluble part. Their rates of formation in the quencher were experimentally determined. The kinetic model which was used to explain the rate data of p-cyclophane formation⁽¹⁾ was extended to include the formation of linear dimer and trimer of p-xylene. The rate expressions derived from the kinetic model were shown to be consistent with experimental results.     

Supercritical fluid fractionation of thermally oxidized canola oil

Supercritical fluid extraction procedures were developed to fractionate thermally oxidized canola oil. Canola oil was heated in a sealed glass ampoule for 72 h at 200°C in a forced-convection oven. After heating, the percentages of triacylglycerol (TAG) trimer, dimer, monomer and lowermolecular weight (LMW) compounds in the heated oil sample (as determined by high-performance size-exclusion chromatography) were 3.0, 8.4, 81.3 and 7.3%, respectively. The LMW compounds included diacylglycerols, monoacylglycerols and free fatty acids. Fractions of TAG monomer of approximately 98% purity were isolated after extraction at 408 atm for 45 min. After a second extraction at 442 atm for 45 min, a TAG dimer fraction of 95% purity was isolated. Recoveries of TAG monomer and dimer were 96 and 87%, respectively.     

Participation of sesamol in stability of sesame oil

Sesame oil is known to be the most resistant to oxidative rancidity. Constituents of sesame oil such as sesamolin, sesamol and sesamol dimer (a possible intermediate of oxidative degradation of sesamol) were determined by high performance liquid chromatography using a reverse-phase column. Sesamol was specifically determined in an alternative way by use of hydrogen peroxide/horseradish peroxidase. Sesamolin was relatively stable but sesamol and sesamol dimer were unstable when irradiated in benzene, and the final degradation products were identical. Whereas sesamolin was inactive, sesamol and sesamol dimer showed significant antioxidant activity in several kinds of fat and oils. Stability of Japan Pharmacopoeia sesame oil free from sesamol was relatively low; antioxidant activity of sesamol incorporated in the oil was unexpectedly low and was rapidly lost in the oil activated by oxygen. Edible sesame oil with intrinsic sesamol was highly stable. Activation of the edible oil gradually increased the sesamol content with concomitant decrease of sesamolin. High stability of edible sesame oil could not be ascribed to sesamol, but it could be explained by another powerful antioxidant(s) which might stabilize both the oil and unstable sesamol.     

Monohydroxylation of unsaturated oils: III. Use of halogen intermediates

Hydroxylation of safflower and linseed oils by routes involving halogen compounds is described. A product containing 20.5% Br was obtained by treatment of safflower oil in CCl₄ solution with N-bromosuccinimide (NBS) in presence of benzoyl peroxide and UV illumination. Bromine was totally removed using Ag₂O in 50% dioxan; the resulting hydroxyl value (HV) was only 100, against an expected HV of 180, perhaps because of dehydration and ether formation. Using other silver salts, bromine replacement with hydroxyl was always incomplete. Such residual bromine was totally replaced by hydrogen, without altering other characteristics, by treatment of the product with zinc amalgam in acetic acid. Linseed oil by similar NBS bromination (Br 22.2%) and Ag₂O treatment gave a product with Br 2.9%, HV 74, conj. diene 15% and conj. triene 4%. Halogenreplacement difficulties also attended the hydrobromination of these oils at the double bonds, followed by hydroxylation. Addition of hypochlorous or hypobromous acid to safflower oil, followed by total replacement of halogen with hydrogen using zinc amalgam, yielded products of HV 75 and 83 respectively. The degree of hydroxylation was only half of that expected from the loss of unsaturation.     

Synthesis and evaluation of polytriethanolamine monooleates for oil-based muds

New emulsifiers were developed by esterification of polytriethanolamine based on the dimerization and trimerization of triethanolamine. The dimer and trimer were esterified with oleic acid to prepare monoesters of di-triethanolamine and tri-triethanolamine. The synthesized esters were evaluated as water-in-oil emulsifiers in oil-based muds, which are the circulating fluids used in rotary drilling to perform various functions required in the drilling operation, such as control of density, flow, and filtration properties. The dimer and trimer of triethanolamine were also esterified with hydrolyzed cottonseed oil, and the resulting esters were evaluated as commercial emulsifiers for oil-base muds.