Electrolytic acetoxylation of methyl oleate

The electrolysis of methyl oleate in acetic acid solution with LiClO₄ as the supporting electrolyte was studied. Both stirred and pumped undivided cells were used with Pt electrodes. Constant current at 6, 8, 16 and 24 ma/cm² current densities was used. The amount of acetoxyl substitution appeared to be independent of the current density. With 4 Faradays of charge, about 1.1 acetoxy groups were introduced/mole at a current efficiency (i.e., net chemical reaction/net charge) of 50 to 60%. The acetoxylated octadecenoates exhibit thermal instability upon molecular distillation with the formation of conjugated unsaturation by loss of acetic acid. Catalytic hydrogenation of the acetoxylated product yielded distillable acetoxylated methyl octadecanoates. The unsaturated acetoxylated products gave 25–47% undistillable material upon molecular distillation, while the saturated acetoxy derivatives had as little as 1%. From the corresponding alcohols of the unsaturated acetoxy products,t-butyldimethylsilyl ethers were prepared and analyzed by mass spectrometry. This analysis supported the hypothesis that the principal points of acetoxyl substitution in the mono-acetoxylated esters were at C-8,9,10 and 11, while the acetoxylation in the poly-acetoxylated esters was more widely dispersed.     

Nitrosyl chloride adduct of methyl oleate

Nitrosyl chloride was added to methyl oleate on a preparative scale to give the adduct in essentially quantitative yield. The chlorine of the adduct was quite labile; was replaced by methoxyl, hydroxyl, acetoxyl, piperidino, and amino groups; and was eliminated to give the unsaturated nitroso compound. Under any conditions only 15–20% of the nitroso group of the adduct isomerized to oximino. Reduction with zinc and acetic acid gave the hydroxylamino derivative Presented at the AOCS meeting, Chicago, 1964. No. Utiliz. Res. and Dev. Div., ARS, USDA.     

油酸甲酯合成反应动力学研究

油酸甲酯是一种重要的化工原料,因现行生产工艺存在污染环境、腐蚀设备、反应转化率较低等问题,使其生产受到了一定制约,为此,提出了一种无催化"两步法"合成油酸甲酯的工艺路线。文中在"两步法"工艺路线的基础上进一步研究了油酸甲酯合成反应动力学。采用积分法分析了在293,298,303,308,313 K下的实验数据,结果表明二步反应均符合二级反应特征,反应遵循四面体机理,并得到了不同温度下的动力学方程式。根据得到的不同温度下的反应速率常数确定了二步反应的活化能分别为121.6 kJ/mol和115.2 kJ/mol,频率因子为2.76×1019和4.03×1018。在实验293—313 K温度范围内,通过实验对得到的动力学方程进行验证,得到的实验值与动力学方程计算值相符合,说明得到的动力学方程是可靠的,为"两步法"合成油酸甲酯的工业放大提供了理论依据。     

油酸甲酯合成反应的热力学性质分析

采用Joback基团贡献法、Yoneda基团贡献法及Tyagi方程估算了无催化两步法合成油酸甲酯反应体系中油酸、油酰氯、油酸甲酯等物质的热力学数据,并结合可查取的物性实验数据,得到了该反应体系反应焓变ΔrHm、反应熵变ΔrSm、反应吉布斯自由能变ΔrGm及反应平衡常数K。结果表明:标准状态下酰氯化为吸热反应,且单独存在时较难进行,醇解为放热反应,且反应可进行完全。通过分析各热力学函数数值特点,结合整个两步反应的始末态热力学数据,依据近似原则和勒夏特列原理平衡移动原理,可以得出酰氯化反应在适当条件下是可正常进行的,且实际实验现象对此进行了验证。     

Hydrocarbons in irradiated beef and methyl oleate

The presence of hydrocarbons among the volatile compounds in food products, particularly in irradiated meat, was first discovered by Merritt and his co-workers in 1959 (5,6). It is the purpose of this paper to focus wider attention on this significant discovery and to report briefly on new work which relates the formation of hydrocarbons in irradiated meat to lipids.     

The oxidation of methyl oleate I. The preparation,properties and reactions of methyl hydroperoxido oleate

Summary Low temperature fractional crystallization from acetone has been applied to the separation of methyl hydroperoxido oleate in 85 to 90 percent purity from partially oxidized methyl oleate. The hydroperoxido ester was subjected to hydrogenation, oxidative fission, and reduction with hydrogen iodide. Certain characteristics of the original hydroperoxide and its reaction products have been described. The results obtained lend definite support to the view that the first oxidation product of methyl oleate is a mixture of 8- and 11-hydroperoxido octadecenoic acids, at least under the conditions employed,i.e., oxidation under the influence of ultraviolet light or reaction temperatures up to 60° C. The spectral absorption of methyl hydroperoxido oleate and some derived products was determined. The hydroperoxide group was shown to have no characteristic absorption in the ultraviolet region. The reactions of the peroxide with alkali, hydroxylamine, lead tetraacetate, and α-tocopherol have been described and discussed. Presented before the 37th Annual Meeting of the American Oil Chemists' Society, New Orieans, Luisiana, May 15–17, 1946. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

The oxidation of methyl oleate. II. A reaction between methyl hydroperoxido oleate and oleic acid

Oleic acid is intermolecularly oxidized by methyl hydroperoxido leate at 90°C, through the addition of oxygen at the olefinic bond with the formation of opexy and dihydroxy compounds. Only the lowmelting isomeric form of dihydroxystearic acid could be isolated from the reaction mixture. The oxidation of olefinic linkages by hydroperoxides appears to account, at least in part, for the observed reduction of unsaturation in autoxidizing fats. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Epoxidation of methyl oleate with hydrogen peroxide

Summary Simple addition of hydrogen peroxide to a 10 molar excess of glacial acetic acid in the presence of sulfuric acid catalyst gave about 90% conversion to peracetic acid in the peracid preforming step. Improved hydrogen peroxide efficiency in the epoxidation step was obtained by using a 0.9:1 molar ratio of preformed peracetic acid to methyl oleate. Under these conditions most of the peracetic acid was used in forming the epoxide. Stainless Steels 304, 316, 321, 329, and 430 are satisfactory as materials of construction from the standpoint of both corrosion resistance and effect on the reaction. Presented at the 27th annual fall meeting, American Oil Chemists’ Society, Nov. 4–6, 1953, in Chicago, Ill.     

The elaidinization of methyl oleate with mercaptans

Methyl oleate is transformed into methyl elaidate by mercaptans. The equilibrium mixture, containing 77% elaidate, can be obtained from either isomer. A concomitant, although much slower reaction, is the addition of the sulfhydry group to the double bond of either ester. The effects of numerous reaction conditions on the extent and rate of the isomerization are given. The reaction is presented as an incipient addition of the mercaptan to the double bond, as a reversible thiyl radical attack on one of the unsaturated carbon atoms. Presented at the AOCS meeting in Minneapolis, 1963. Contribution No. 858 of the Agricultural Experiments Station, University of Arizona.     

Studies on the ozonization of methyl oleate

The ozonides of methyl 9-octadecenoate, 9-octadecene and methyl 9-octadecendioate (along with pelargonyl aldehyde, methyl azelaaldehydate and a fraction which appears to consist mainly of hydroperoxy-ozonides) were isolated from ozonizations of methyl oleate in pentane and methylene chloride at −65C. The relative amounts of these compounds were determined in ozonizations of methyl oleate in pentane, methylene chloride and ethyl acetate. Present concepts of the mechanism of the reaction are elaborated on the light of new information on the products of the ozonization of methyl oleate and related compounds under various conditions. Supported in part by Grant no. AM-05018, U. S. Public Health Service, National Institutes of Health. Presented at the AOCS meeting in Atlanta, 1963.     

Lipase-catalyzed synthesis of oleyl oleate in pressurized and supercritical solvents

Supercritical and pressurized solvents were used as a biochemical reaction media. As a model system esterification of oleic acid with oleyl alcohol, catalyzed by lipase from Rhizomucor miehei (Lipozyme ^IM) was used. Due to the limitation of the process that may arise from the non-polarity of carbon dioxide, which preferentially dissolves hydrophobic compounds, studies were performed also with other gases (n-butane, n-propane, n-propane:n-butane mixture). The initial reaction rates at 20°C are in n-butane around 5 mmol/(g∗︁h) and in the mixture n-propane:n-butane around 6 mmol/(g∗︁h). They are approximately 2–3 times higher than in CO₂. At 50°C the reaction rates in n-butane and in n-propane:n-butane mixture are higher in comparison with CO₂ only at the pressure, which is subcritical for CO₂. The maximal initial reaction rate of 13 mmol/(g∗︁h) was observed in SC-CO₂ at 250 bar and 50°C. The maximal conversion of 87.1% was observed in n-butane at 20°C and 20 bar but the reaction time was 5 h. 86% conversion was reached in only one hour at 50°C and 100 bar in SC-CO₂.     

Conjugated dienes and trienes from methyl oleate and methyl linoleate

Methyl oleate and methyl linoleate were converted to conjugated dienes and trienes, respectively, by selecting and modifying the conventional procedures usually applied to the generation and characterization of fatty hydroperoxides. Conditions have been studied in the laboratory for: (a) the optimum production of hydroperoxides with a minimum of by-products, (b) the effective separation and concentration of the resulting hydroperoxide, (c) the economic reduction of the hydroperoxide mixture, (d) simple dehydration of the reduced product, and, (e) recovery of the resulting polyene-rich material. If the processing sequence is halted after the reduction step, the resulting product,is a mixture of allylic hydroxy monoene or diene methyl esters. Our investigations have been extended to include studies on the methyl esters of commercial oleic acid and the mixture of methyl esters resulting from alcoholysis of lard oil. Products containing 20–25% conjugated diene and lesser proportions of conjugated triene were obtained. Presented at the AOCS Meeting, Houston, April 1965. E. Utiliz, Res. Dev. Div., ARS, USDA.     

Volatile compounds from thermally oxidized methyl oleate

Thermal oxidation of methyl oleate was studied over a range of temperatures from 50 C to 150 C for periods of time up to 30 min. Degradation was quantitatively followed by gas liquid chromatography (GLC) and liquid scintillation counting of the products of methyl oleate-U-¹⁴C heated under a stream of compressed air. Heptane, octane, 2-decanone, benzene,o-xylene, methyl hexanoate, methyl heptanoate and methyl octanoate were identified by GLC and mass spectrometry. Mass spectral evidence also was obtained for methyl pimelaldehydate, methyl suberaldehydate and methyl azelaaldehydate. Organic synthesis confirmed the identity of methyl azelaaldehydate. Most of the products formed suggested that autoxidation was responsible for the degradation occurring at the temperatures employed in this study. Paper No. 2628 from the Oregon Agricultural Experiment Station.     

Hydrogen sulfide adducts of methyl oleate and linoleate

Sulfur compounds derived from photochemical addition of hydrogen sulfide to methyl oleate and linoleate were separated by preparative gas chromatography. The major compounds were investigated by NMR, mass and IR spectroscopy and by elemental analysis. The primary product of the methyl oleate reaction was methyl 9(10)-mercaptostearate. Gas chromatograms of the product from methyl linoleate showed four principal peaks. From mass spectra and NMR data, we identified methyl 9-(2-pentyl-1-thiolan-5-yl)nonanoate, methyl 8-(2-hexyl-1-thiolan-5-yl)octanoate and methyl 9-(3-hexyl-1,2-dithiolan-5-yl)nonanoate. Evidence for the formation of methyl mercapto-octadecenoates and methyl dimercaptostearates was also obtained. ARS, USDA.     

Acetoxylation of methyl oleate with a resin catalyst

The reaction of methyl oleate with acetic acid in the presence of a reticulated cation exchange resin produces methyl acetoxystearate. Saponification of this compound and subsequent acidification yields hydroxystearic acid. Time, temperature, acetic acid:ester ratio, and resin:ester ratio were examined for their effect on yield of methyl acetoxystearate. A yield of approximately 45% of theory was reached under the best conditions. The cation exchange resin promoted ester inter-change with the formation of oleic acid, acetoxy-stearic acid, and methyl acetate. An estolide polymer was formed, probably by ester inter-change between acetoxylated methyl oleate and oleic acid. Acetoxy esters were separated from unreacted methyl oleate and ester polymers by fractional distillation. Molecular weight and GLC data substantiate the product structure. Several other short-chain carboxylic acids were reacted with methyl oleate but gave lower yields of acyloxylated product than acetic acid. Presented at the AOCS Meeting in Cincinnati, October 1965. No. Utiliz. Res. Der. Div., ARS, USDA.     

油酸甲酯连续合成工艺及其动力学研究

在固定床反应器中,以阳离子交换树脂为催化剂,油酸与甲醇液液并流反应制备油酸甲酯。考察了反应各影响因素,获得较适工艺条件为:催化剂装载量20 g,醇酸摩尔比2∶1,反应温度60℃,停留时间40 min。在此条件下,油酸转化率可达99.43%。对油酸与甲醇的反应动力学进行了研究,以拟均相模型对实验数据进行拟合,得出30℃、40℃、50℃、60℃下的正、逆反应速率常数。反应速率随温度的升高而加快,二者关系符合Arrhenius方程,该反应的活化能为60.687 kJ/mol。