Isomerization during hydrogenation of soap: II. Potassium elaidate and potassium linoleate

Potassium elaidate in slightly alkaline solution was hydrogenated for up to 7 hr with 1.5% of Rufert nickel catalyst at 150 C and 20 kg/sq cm pressure. Potassium linoleate was similarly hydrogenated with 1.0% catalyst for 7 hr, and the hydrogenation continued for another 7 hr after addition of 0.5% fresh catalyst. Periodic samples from each were analyzed for component acids. The positional isomers in thecis andtrans monoenes, isolated by preparative argentation thin layer (TLC) or column chromatography, were estimated after oxidation to dicarboxylic acids. Some diene fractions were isolated for further examination. In potassium elaidate hydrogenation,cis monoenes were initially produced in considerable amounts, but to a lesser extent thereafter. Positional isomers were similarly distributed in bothcis andtrans monoenes after prolonged hydrogenation. In the hydrogenation of potassium linoleate, a drop in iodine value (IV) of 60 units occurred in the first hour, and 38% oftrans monoenes (in which the 10- and 11-monoenes constitute 32% each) were formed. The IV then fell only slowly, and up to 38% ofcis monoene (mostly 9- and 12-isomers) was formed. Addition of fresh catalyst caused a major shift ofcis monoenes totrans forms. The diene fraction was mostly nonconjugated material with the first double bond at the 9, 8 and 10-positions. Minor amounts of conjugated dienes were present as well as a dimeric product.     

Isomerization during hydrogenation. I. Oleic acid

Summary It was found that during the hydrogenation of octadecenoic acids, migration of the double bonds takes place equally in each direction. The positional isomers that are formed are composed of the 1∶2 equilibrium mixture ofcis andtrans. A partial hydrogenation-dehydrogenation theory may be applied to explain the simultaneous formation of both positional and geometrical isomers. Presented at the annual spring meeting of the American Oil Chemists' Society, San Antonio, Tex., Apr. 12–14, 1954.     

Isomerization phenomena during hydrogenation of methyl oleate and methyl elaidate over nickel-silica catalysts

Methyl oleate was hydrogenated at temperatures varying from 50–175 C over three nickel-silica catalysts of different pore-size distribution. Methyl elaidate was reduced over one of these catalysts at temperatures between 75–150 C. From the detailed double bond distributions information was obtained on transport phenomena in the pores of the catalyst. It was established that the migration of the double bond in methyl oleate proceeds with a stepwise mechanism, and evidence was obtained that the double bond in methyl elaidate migrates significantly faster than that in methyl oleate, while the rate of hydrogenation of these esters was equal. Thetrans-cis ratio of the geometrical isomers which are formed by double bond migration varies strongly during hydrogenation.     

Isomerization during hydrogenation. III. Linoleic acid

Summary The isomerization that takes place during the catalytic hydrogenation of linoleic acid and methyl linoleate producescis andtrans 9, 10, 11, and 12 monoenes. The double bond at the 12 position appears to hydrogenate slightly faster than that in the 9 position. More octadecenoic acids with double bonds at the 10 or 11 positions are produced during a selective (high temperature, low pressure) hydrogenation than during a non-selective process. Although the degree of selectivity of the hydrogenation is determined by the amount of isomerization of the original pentadiene system to a conjugated diene, only part of the methylene-interrupted diene goes through this type of isomerization even during a highly selective hydrogenation. The half hydrogenation-dehydrogenation reaction mechanism is applied to explain the simultaneous positional and geometrical isomerizations.     

Isomerization during hydrogenation. IV. Methyl eleostearate

Summary The hydrogenation of methyl eleostearate with and without solvent has been studied. The data indicate the stepwise addition of two moles of hydrogen to the conjugated triene to produce equimolar amounts of 9-, 10-, 11-, 12-, and 13-octadecenoates. Additional evidence for thecis-9,trans-11,trans-13 structure of α-eleostearic acid was obtained. Presented at annual meeting, American Oil Chemists’ Society, Apr. 23–25, 1956, Houston, Tex.     

Hydrogenation of fats and oils. Isomerization during hydrogenation

This presentation includes a survey of the development of the presently accepted theory for the formation of isomers based on a half hydrogenation-dehydrogenation mechanism with atomic hydrogen, an appraisal of the relevant work of recent years for its significance when applied to the problem of isomerization, and certain experimental evidence from other fields of heterogeneous catalysis of interest in the hydrogenation of fats and oils. Effects of temperature, pressure, catalyst concentration, and degree of agitation used in commercial plants on the degree of isomerization are discussed. In addition the conditions necessary for the proper application of the term “selective” to a hydrogenation are examined. An interpretation of recent work to reduce isomerization while retaining selectivity by extending the normal range of the variables and by the use of solvents is covered. Selected works on catalysis from related fields are used to indicate possible modifications of the isomerization mechanism and, perhaps, to reveal fruitful avenues of research. Presented at the AOCS meeting in New Orleans, 1962.     

Shifting of the double bond in methyl oleate during hydrogenation

Summary The displacement of the double bond of methyl oleate during hydrogenation with a nickel-kieselguhr catalyst at 180°C. was investigated, particularly with respect to the analysis of dicarboxylic acids, obtained either by oxidation of the reaction products with KMnO₄ in acetic acid or by means of ozone. In the oxidation experiments with KMnO₄ a considerable degradation of lower molecular dicarboxylic acids occurs that makes a quantitative analysis of the isomerization phenomena uncertain. According to the ozonization experiments an equal migration of the double bond in both directions, toward and opposite the ester group, takes place.     

Isomerization during hydrogenation. II. Methyl cis-10, cis-12-octadecadienoate

Summary Methylcis-10,cis-12-octadecadienoate was prepared and found to have an ultraviolet absorption peak at 235 mμ, α=95. The infrared spectrum revealed no diagnostic peaks for thecis,cis conjugated system. The hydrogenation of the ester showed that when one mole of hydrogen was added, 1–2, 1–4, and 3–4 addition took place with equal ease to produce an equimolar mixture ofcis-10-,trans-11-, andcis-12-octadecenoates. An explanation of the reaction is offered on the basis of the structure of the diene system.     

Reactions of methoxy hydroperoxides derived from methyl oleate. Catalytic hydrogenation

Yield improvements in carbonyl compounds obtained by catalytic hydrogenation of methyl oleate ozonolysis products have been achieved by use of catalyst poisons and by the proper choice of catalyst support. Byproduct dimethyl azelate formation with palladium on charcoal was about 20% in the absence of a poison; 10%, with sodium acetate present in the support; 8%, with triethyl amine in solution. Palladium on calcium carbonate-lead acetate gave about 7%, palladium on zine oxide with pyridine or lead acetate present gave 9%. The literature is reviewed on the catalytic hydrogenation of methoxy hydroperoxides derived from ozonolyses in methanol. Presented in part at the Ozone Symposium, Southwest Regional Meeting of the American Chemical Society, Houston, Texas, December, 1963. A laboratory of the No. Utiliz. Res. and Dev. Div. ARS. USDA.     

Isomerization during hydrogenation. V. Methylcis 6-,cis 9-,cis 12-octadecenoates

The partial hydrogenation of mixtures of methylcis 6-,cis 9- andcis 12-octadecenoates followed by the determination of the unreacted monoenes indicated the double bonds in these positions are hydrogenated at the same rates. However, study of a hydrogenation under high isomerization conditions indicated the double bonds very near the carboxyl hydrogenate faster than those near the terminal methyl. Presented at the AOCS Meeting in Atlanta, 1963.     

Modification of vegetable oils. XI. The formation of trans isomers during the hydrogenation of methyl oleate and triolein

Summary 1. During the hydrogenation of methyl oleate, trans isomers are formed at a very rapid rate. As much as 38% of trans isomers formed while the first 10% of methyl stearte was formed. 2. The rate of formation of trans isomers in methyl oleate undergoing hydrogenation is increased by increasing the temperature, increasing the catalyst concentration, and decreasing the degree of dispersion of the hydrogen. 3. The hydrogenation of methyl oleate always resulted in the establishment of an equilibrium between cis and trans isomers, and irrespective of the conditions employed the concentration of trans isomers was always 67%, calculated on the basis of total unsaturated constituents. 4. It is concluded that all of the iso-oleic acids formed during the hydrogenation of methyl oleate adsorb hydrogen at the same rate as oleic acid and are adsorbed and desorbed from the nickel catalyst with equal ease. 5. Trans isomers are formed at a slightly lower rate during the hydrogenation of triolein than in the case of methyl oleate. 6. Partial hydrogenation of triolein also results in the establishment of an equilibrium between cis and trans isomers of oleic acid but at values of less than 67% of trans constituents (based on the total unsaturated constituents) observed with methyl oleate. The equilibrium concentration was found to vary with the conditions of hydrogenation and was found to be 62% at 200°C. and 57% at 175°C. Report of study made under the Research and Marketing Act of 1946. Presented at the 24th Fall Meeting of the American Oil Chemists’ Society, San Francisco, Calif., Sept. 26–28, 1950. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Selective hydrogenation with copper catalysts: I. Isolation and identification of isomers formed during hydrogenation of linolenate

Methyl linolenate was hydrogenated with 10% copper chromite catalyst at 150 C and atmospheric hydrogen pressure. The product was separated into monoene, diene and triene fractions by countercurrent distribution. These fractions were further separated into various geometrical isomers. The double bond location in the various fractions was determined by reductive ozonolysis. Double bonds in bothcis andtrans monoene fractions, as well as incis,trans andtrans,trans conjugated dienes, were extensively isomerized. A monoene containing vinylic unsaturation was one of the major products. The nonconjugated dienes were mostly dienes whose double bonds were widely separated. Results are explained on the basis of conjugation of the double bonds in linolenate followed by hydrogen addition. Presented in part at the symposium “Hydrogenation Process,” Division of Industrial Engineering Chemistry, 157th American Chemical Society Meeting, Minneapolis, April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Selectivity and isomerization during partial hydrogenation of cottonseed oil and methyl oleate: Effect of operating variables

Results are now available for hydrogenation of cottonseed oil and methyl oleate in which sufficient agitation was provided to eliminate mass transfer resistances from the catalyst surface. The ratio of thetrans-to-cis isomers of oleic acid groups approaches 2.0 even at high pressures and high degrees of agitation. The rates of hydrogenation for bothcis andtrans isomers and for positional isomers are all essentially identical. A reaction scheme has been devised that is consistent with extensive experimental data, and the method of evaluating the relative reaction rate constants for each step is outlined. Using these rates constants, selectivity can be quantitatively evaluated.     

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.     

油酸甲酯催化加氢制备生物烷烃的热力学分析

采用Benson基团贡献法对油酸甲酯加氢脱氧、加氢脱羰和加氢脱羧制备生物烷烃的热力学进行了分析,计算了613~653 K温度区间内油酸甲酯加氢体系的反应热、反应熵变、反应Gibbs自由能变和标准平衡常数,在此基础上采用PRO/Ⅱ软件中的平衡反应器模型分析了温度对油酸甲酯加氢产物分布的影响并和实验数据进行了对比验证。结果表明,油酸甲酯加氢脱氧、加氢脱羧和加氢脱羰制备生物烷烃的反应均为放热反应,放热量依次递减,各反应在613~653 K范围内均能够自发进行且反应完全。升高温度能够提高平衡产物中油酸甲酯加氢脱羰/羧产物的选择性,降低温度则有利于加氢脱氧产物的选择性,加氢脱氧与脱羰/羧产物选择性的比例随温度从613 K升高到653 K相应从1.92降低到0.56,与实验测得的反应数据变化趋势吻合。     

A new broad spectrum antibacterial soap I. General properties

The first soap germicide system to show activity against gram-negative organisms is described. Addition of a new germicidal agent, 2-hydroxy-2′,4,4′-trichlorodiphenyl ether, combination of hexachlorophene and triclocarban which has been used in a soap known to be effective against gram-positive organisms, has broadened its antibacterial spectrum without impairing its mildness, safety and other desirable bar soap characteristics. Properties of the new system, including in vitro and in vivo tests of its antibacterial activity, efficacy and safety, are discussed. Presented at the AOCS Meeting in New Orleans, La. April, 1970.     

粗异戊烯选择加氢过程中2MB1的异构化

在工业试验装置上考察了抽余C5原料中2MB1在加氢除去双烯烃过程中的异构化情况。空速大于3．5h^-1、H2与双烯烃的摩尔比小于2、初期进口温度小于60℃,后期大于75℃对加氢反应和防止2MB1的异构化都有利。这一结果可以用于指导装置的操作。     

Semi-micro analysis of soap. I. Semi-micro determination of the usual constituents

Summary A procedure for the complete semi-micro analysis of soap has been developed. Semi-micro methods are valuable in research work and in legal cases where limited quantities of sample are available. In general, the analytical results obtained on a semi-micro basis and on a macro basis are comparable. Very little special apparatus is required for the semi-micro analysis of a soap, and most of the procedures employed present analogies with the usual methods of soap analysis. By mistake Part II in this series of three articles was published in the September 1948 issue of the Journal, ahead of Part I.