Conjugation of polyunsaturated fats with dimsylsodium

The conjugation of polyunsaturated fatty esters, including soybean oil, trilinolein, soybean methyl esters, and methyl linolenate and linoleate, with the sodium salt of dimethyl sulfoxide (dimsylsodium) as catalyst has been investigated. Methyl esters are ca. 95% conjugated within 2 hr. Glycerides react more slowly but are similarly conjugated within 24 hr. The glyceride linkages are not destroyed as they would be with aqueous or alcoholic alkali. Highly conjugated oils can thus be prepared. ARS, USDA.     

Oleyl alcohol from animal fats by catalytic reduction

Catalysts effective in the selective reduction of methyl oleate or oleic acid to oleyl alcohol at 350 C and 3000 psi were Cr−Zn, Zn−Cd−Cu, Cr−Zn−Cd, Cr−Zn−Cd−Al and Zn−Cd−Al combinations. By-products were hydrocarbons, ethers and an unchromatographable still residue. Presented in part at the AOCS Meeting, San Francisco, April 1969. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Efficiency of transfer of polyunsaturated fats into milk

Polyunsaturated milk has been produced by feeding cows safflower oil enclosed in a casein coat protected with formaldehyde (SOC-F) or formaldehyde-treated soybean (SB) preparations. The efficiency of transfer of dietary 18∶2 ranged from 17 to 42% for various lots of SOC-F and was only 2–8% for SB (per cent transfer=18.2 in milk fat per dietary 18∶2×100). The 18∶2 content of the milk fat increased from basal levels of 2–3% of total fatty acids to 35% with certain SOC-F levels and 7% with SB. Major compensatory changes were noted in 14∶0 and 16∶0 fatty acids. Blood cholesterol, triglycerides and nonesterified fatty acids all increased markedly as cows were fed increasing amounts of SOC-F. There was no increase in cholesterol in the milk. Presented at the AOCS Meeting, Los Angeles, April 1972.     

Selective homogeneous hydrogenation of triunsaturated fats catalyzed by tricarbonyl chromium complexes

The need for a selective catalyst to hydrogenate linolenate in soybean oil has prompted our continuing study of various model triunsaturated fats. Hydrogenation of methylβ-eleostearate (methyltrans,trans,trans-9,11,13-octadecatrienoate) with Cr(CO)₃ complexes yielded diene products expected from 1,4-addition (trans-9,cis-12- andcis-10,trans-13-octadecadienoates). Withα-eleostearate (cis,trans,trans-9,11,13-octadecatrienoate), stereoselective 1,4-reduction of thetrans,trans-diene portion yielded linoleate (cis,cis-9,12-octadecadienoate). However,cis,trans-1,4-dienes were also formed from the apparent isomerization ofα- toβ-eleostearate. Hydrogenation of methyl linolenate (methylcis,cis,cis-9,12,15-octadecatrienoate) produced a mixture of isomeric dienes and monoenes attributed to conjugation occurring as an intermediate step. The hydrogenation ofα-eleostearin in tung oil was more stereoselective in forming thecis,cis-diene than the corresponding methyl ester. Hydrogenation of linseed oil yielded a mixture of dienes and monoenes containing 7%trans unsaturation. We have suggested how the mechanism of stereoselective hydrogenation with Cr(CO)₃ catalysts can be applied to the problem of selective hydrogenation of linolenate in soybean oil. No. Market. Nutr. Res. Div., ARS, USDA.     

Selective hydroformylation of polyunsaturated fats with a rhodium-triphenylphosphine catalyst

Soybean, safflower and linseed oils and their methyl esters were effectively hydroformylated with a rhodium and triphenylphosphine catalyst system. The product from safflower methyl esters, hydroformylated at 100 C and 1000 psi synthesis gas (H₂ + CO), proved to be a mixture of formylstearate, formyloleate and diformylstearate. At 150 C and 15 00 psi synthesis gas the formyloleate was hydrogenated and the product formed was a mixture of mono- and diformylstearates. The unsaturated monoformyl fraction (100 C) was tentatively identified as a mixture consisting mainly of methyl 9(10)-formyl-cis-12-and methyl 12(13)-formyl-cis-9-octadecenoates. The saturated monoformyl fraction (150 C) was a more complex isomeric mixture of methyl formylstearate. The diformyl fractions from hydroformylated safflower and linseed esters were identified as mixtures consisting mainly of 9,12-(10,13)- and 10,12-(11,13)-diformyloctadecanoates. When hydroformlyation of polyunsaturated fats was interrupted,cis-unsaturated formyl oils resulted. Presented at AOCS Meeting, Houston, May 1971. Northern Marketing and Nutrition Research Division, ARS, USDA.     

Interference of peroxides with the determination of total carbonyls in autoxidized fats

The contribution of hydroperoxides to the carbonyl content of autoxidized fats measured by a colorimetric 2,4-dinitrophenylhydrazone procedure has been studied. Carbonyls were determined in radiation oxidized methyl myristate, in autoxidized methyl esters of oleie, linoleic and linolenic acids and in autoxidized oils, before and after reduction of hydroperoxides to hydroxyl groups. The results indicate that hydroperoxides decompose to carbonyl compounds during the carbonyl determination and give carbonyl contents that are too high. The extent of the interference depends on the nature of the peroxides and, therefore, on the fatty acid composition of the material and on other factors probably associated with the conditions during autoxidation and subsequent storage. For these reasons it is not possible to apply a correction for peroxide interference based on the determined peroxide value. Carbonyl determinations on autoxidized lipids should be preceded by reduction of the peroxides to non-carbonyl compounds, and care should be taken to prevent losses of low molecular weight carbonyls during this procedure. Presented at the AOCS meeting, Houston, 1965.     

CO气氛中液相催化COS水解活性的研究

在鼓泡反应器中，采用液相催化剂，对高浓度CO气氛中高浓度COS的水解反应进行考察，研究催化剂浓度、气液体积比、温度的变化对COS水解转化率及催化体系稳定性的影响，得出最佳工艺条件，并对反应机理进行初步探讨。结果表明,COS水解转化率随气液体积比增大而降低，随催化剂浓度增大而升高；在常温、常压和气液体积比为150 h^－1的条件下，质量分数为10%的催化剂水溶液中COS的水解转化率可达100%，连续使用20 h转化率不变。     

Conversion of polyunsaturates in vegetable oils tocis-monounsaturates by homogeneous hydrogenation catalyzed with chromium carbonyls

Chromium carbonyl complex catalysts were used to selectively hydrogenate polyunsaturates in vegetable oils into products retaining 90% to 95%cis configuration and their liquid properties. The product from soybean oil contained 42–69% monoene, 10–40% diene and 0–4% triene. The product from safflower oil contained 73–82% monoene and 8–17% diene. About 45–55% of the double bonds in monoenes from hydrogenated soybean oil remained in the C₉ position, and the rest was distributed between C₁₀, C₁₁, and C₁₂. Preliminary oxidative and flavor stability evaluations showed that these hydrogenated soybean oils compared favorably with a commercial sample of hydrogenated-winterized soybean oil. Liquid fatty acids prepared by saponification of hydrogenated soybean and safflower oils (IV 90–100) had analyses about the same as those of commercial oleic acid. Presented before the Division of Agricultural and Food Chemistry, 156th American Chemical Society National Meeting, Atlantic City, N.J., September 1968.     

Trans and polyunsaturated fatty acid content of some bakery fats

Twenty-seven commercial bakery products marketed in Belgium were analyzed by gas-liquid chromatography for their trans (TFA) and polyunsaturated fatty acid (PUFA) content. The mean PUFA level for the bakery fats in our study was 8.85% (S.D. = 9.90%) and the TFA content ranged from 0.0–18.81% (mean = 5.99%; S.D. = 5.02%). The unfavourable fatty acid profile of most of the analyzed bakery fats can be explained by the frequent use of animal fat and partially hydrogenated oils. The average daily intake of TFA from bakery products by the Belgian population was calculated at 0.43g/person/day. As it is expected that their consumption will increase in the future, lower TFA levels in bakery fats are necessary to avoid that these products become a more important dietary source of TFA.     

Conjugation of polyunsaturated fats: Activity of some group VIII metal compounds

Conjugation of methyl linoleate was studied by treatment with RHC₃ orcisCl₂[(C₆H₅)₃]P₂PtSnCl₂. PdCl₂ appeared as effective as RhCl₃ in hot alcohols in conjugating linolenate but PdCl₂ decomposed to metal. Both RhCl₃ and the Pt-eomplex catalyzed transesterification in alcohols, especially the latter. When the conjugation is carried out in methanol at 180 C, the Pt-complex yielded as much as 64% conjugated dienes from linoleate in 24 hr. However, typical results inn-butyl carbitol at 150 and 180 C were only 25–35% conjugated dienes as methyl esters with either RhCl₃ or the Pt-complex. No. Utiliz. Res. Dev. Div., ARS, USDA.     

催化动力学分光光度法测定钛白粉中微量铬

研究催化动力学分光光度法测定钛白粉中的微量铬。结果表明，催化体系溶液中Cr（Ⅵ）质量浓度在0～0．2mg·L^-1范围内时催化体系溶液与空白试验溶液的吸光度差（△A）与Cr（Ⅵ）质量浓度线性关系良好；测定适宜条件为：硫酸溶液（浓度为0．2mol·L^-1）用量2．5ml，溴酸钾溶液（浓度为0．03mol·L^-1）用量1mL，加热时间4min，加热方式100℃水浴；其它离子对测定的干扰小，方法的准确性和回收率高。     

催化动力学光度法测定废水中痕量铬(VI)

在pH值为4.0的缓冲溶液中,磷酸和棉红在100℃下反应生成天蓝色物质(λmax=675nm),该物质在微量铬(VI)的催化下被溴酸钾氧化褪色,建立了测定痕量铬(VI)的催化动力学新方法,方法的检出限是0.76ng·mL-1,线性范围0～0.06μg·mL-1,用于测定电镀废水中铬(VI),结果令人满意。     

催化动力学光度法测定废水中痕量铬(Ⅵ)

在pH值为4.0的缓冲溶液中,磷酸和棉红在100℃下反应生成天蓝色物质(λmax=675nm),该物质在微量铬(Ⅵ)的催化下被溴酸钾氧化褪色,建立了测定痕量铬(Ⅵ)的催化动力学新方法,方法的检出限是0.76ng·mL-1,线性范围0～0.06μg·mL-1,用于测定电镀废水中铬(Ⅵ),结果令人满意.     

Homogeneous catalytic hydrogenation of unsaturated fats: Iron Pentacarbonyl

Iron pentacarbonyl is an effective homogeneous catalyst for the reduction of polyunsaturated fats. Hydrogenation of soybean oil and its methyl esters has been achieved at 180C, hydrogen pressures of 100-1,000 psi, and 0.05–0.5 molar concentrations of catalyst. Analyses of partially reduced products show considerable isomerization of double bonds, reduction of linolenate and linoleate with little or no increase in stearate, and accumulation ofcis,trans- andtrans, trans-conjugated dienes, and isolatedtrans monoenes. The unreduced trienes include diene conjugated fatty esters. The nonconjugated dienes contain large amounts oftrans and nonalkali conjugatable unsaturation. Considerable scattering of double bonds is evident in different fractions between the C₄ and C₁₆ positions. Complex formation between iron carbonyl and unsaturated fats is also indicated. The course of the homogeneous hydrogenation catalyzed by iron pentacarbonyl appears similar to the heterogeneous catalytic reaction. Metal carbonyls are well known for their isomerizing effects and their ability to form stable complexes with olefins. These homogeneous complexes provide suitable model systems to study the mechanism of catalytic hydrogenation of fats.     

Homogeneous catalytic hydrogenation of unsaturated fats: Metal acetylacetonates

Hydrogenation of linseed and soybean methyl esters was achieved at 100–180C, 100–1000 psi H₂ and 0.05–0.25 moles catalyst per mole of ester. The relative activity of metal acetylacetonates in decreasing order was: nickel (III), cobalt (III), copper (II) and iron (III). Reduction occurred readily in methanol solution but only slowly in dimethylformamide and acetic acid. No reduction occurred in the absence of solvents. Soybean oil was also hydrogenated rapidly with nickel (III) acetylacetonate in methanol, but in this system the triglycerides were converted to methyl esters. Nickel (III) acetylacetonate was the most selective catalyst toward linolenate hydrogenation. Methyl linoleate and linolenate hydrogenated with nickel(III) acetylacetonate were fractionated into monoenes, dienes and trienes. Thecis monoenes separated in 62 to 68% yield had double bonds in the original position. The remainingtrans monoenes had extensively scattered unsaturation. The dienes and trienes showed no conjugation, but some of the double bonds in the dienes were not conjugatable with alkali. Little stearate was formed. Presented at AOCS meeting in Chicago, 1964 No. Util. Res. and Dev. Div. ARS, USDA     

Isomerization of unsaturated fatty esters by iron pentacarbonyl. Preparation of iron tricarbonyl complexes of polyunsaturated fats

Iron pentacarbonyl is a powerful isomerization agent of unsaturated fatty esters. Highly conjugated fats are obtained when polyunsaturated fatty esters are treated with an excess Fe(CO)₅ to form complexes followed by decomposition of the complexes with FeCl₃. Iron tricarbonyl complexes were prepared in 80 to 95% yields from methyl linoleate, linolenate and polyunsaturated fatty esters of soybean, linseed and safflower oils by heating at 180–185C with 2 moles Fe(CO)₅ per mole ester under nitrogen pressure. Decomposition of these complexes with FeCl₃ resulted in 90 to 97% conjugation of the polyunsaturated fatty esters mainly in the alltrans configuration. Isolatedtrans unsaturation reached levels of 18 to 30%. Methyl oleate yielded 74%trans unsaturation but no complex of iron carbonyl was obtained. Presented in part at AOCS meeting in Houston, 1965. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Homogeneous catalytic hydrogenation of unsaturated fats: Cobalt carbonyl

Homogeneous hydrogenation of unsaturated fats by cobalt carbonyl has been compared with the previously reported catalysis by iron carbonyl. Soybean methyl esters, methyl linoleate and linolenate have been hydrogenated at 75–180C, 250–3,000 psi H₂ and 0.02 molar concn of catalyst. The cobalt carbonyl catalyst is more active at lower temp than iron carbonyl. The partially reduced products are similar to those observed with iron carbonyl, but the reaction differs in showing much less accumulation of conjugated dienes, no selectivity toward linolenate, almost complete absence of monoene hydrogenation to saturates, less double bond migration and moretrans isomerization. No evidence was found for a stable complex between cobalt carbonyl and unsaturated fats as previously observed with iron carbonyl. The rates of hydrogenation/double bond were the same for linoleate and linolenate on one hand, and for alkali-conjugated linoleate and nonconjugated linoleate on the other. Presented at AOCS Meeting in Minneapolis, 1963. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, USDA.     

The detection and estimation of small amounts of chromium in fats

Summary Fats which have been treated with chromic acid usually contain traces of chromium. Small amounts of chromium may be detected and estimated by means of diphenylcarbazide. Small amounts of other metals, especially iron, aluminium, copper and silica which are apt to be found in the ash of fats, do not interfere in this reaction.     

Dietary fat composition and tocopherol requirement: IV. Safety of polyunsaturated fats

In a long-term multigeneration study, conducted in our laboratories for 32-years, with occasional longevity and histopathological evaluations included, rats of our own inbred strain (originally of Wistar derivation) were fed semisynthetic diets comprising whole wheat, skim milk powder, and fat in the form of margarine products. The total source of tocopherols was the dietary fat itself. Saturated fatty acid content (S) remained relatively constant at about 20% of the fat and total tocopherol level also remained constant at about 0.12% of the fat. Polyunsaturated fatty acid (P) content, however, progressively increased almost fourfold, from 7.5% to 28.5% and alphatocopherol levels decreased to one-half level, from 0.033% to 0.016% of the fat. Hence, the ratio of polyunsaturated fatty acids to alpha-tocopherol content changed markedly from 227∶1 to 1780∶1, with other factors (relative to fat composition) held constant during the 32-year period of feedings and observations. Fat level in the diet increased over the years from 9.2% to 16.0% or from about 21% to about 33% of the caloric intake. Thus, quality and quantity of the fat in the diet progressively changed, and the impact of these changes was evaluated by comparing biological performances of the successive generations. Growth and reproduction and lactation performances were noted to be regularly satisfactory and comparable from generation to generation throughout the experimental period. Longevity studies conducted on arbitrarily selected generations also provided data showing no deleterious effects associated with a dietary change. Histopathological examinations of tissue revealed minimal myocarditis and no malignant tumors which could be attributed to a dietary factor. No vitamin E deficiencies were observed. Even the in vitro peroxide hemolysis values for the red blood cells of the animals, fed the diets containing the higher levels of polyunsaturated fatty acids, were low, indicating that the dietary fats provided sufficient absorbable tocopherol to protect the potentially oxidizable unsaturated fatty acids in the erythrocyte membrane. Biochemical data reflected responses to aging and not to any specific diet fed. It is concluded that a diet providing as much as 33% of the calories as a fat, the latter containing up to 28.5% polyunsaturated fatty acids, substantially of the essential fatty acid type, with a P/S ratio of up to 1.6∶1 and a polyunsaturated fatty acid to alphatocopherol ratio as high as 1780∶1] produces no undesirable effects in the rat. Presented in part at a symposium entitled “Long Term Nutritional Effects of Dietary Fats” at the International Society for Fat Research World Congress, September 30, 1970, Chicago, Illinois.     

Conjugation of polyunsaturated fats: Methyl linoleate with tris(triphenylphosphine) chlororhodium

Tris(triphenylphosphine) chlororhodium in methanol produces nearly 95% conjugated dienes from methyl linoleate. The dienes are principally cis,trans- and cis,cis-conjugated. Since deuterium is introduced into the products when deuterated methanol is the solvent, a dihydride complex is the probable intermediate. The reaction is sluggish in chloroform, possible because the dihydride cannot easily form. The catalyst is activated in chloroform with hydrogen. Since no reduction occurs in the absence of hydrogen, hydrogenation likely occurs by hydrogenolysis of the alkyl complex of the dihydride olefin rather than a transfer of both hydrogens from the hydride complex. Presented at the AOCS Meeting, New Orleans, April 1970. No. Utiliz. Res. Dev. Div., ARS, USDA.