Trans Isomer Content Research Articles

A Rapid Method for the Determination of Isolated Trans Isomers in Fats and Oils by IR Spectrophotometric Method

The trans isomers present in fats and oils can be determined by the rapid liquid-film method from measurements of the infrared absorption at two wavelengths, one due to trans conformation of the double bond and the other due to ester group. The ratio of the two absorbances has a linear relationship with the trans isomer content. This method thus provides a simple determination of trans isomer without weighing in accuracy or messing up an exact volume.

Analysis of Hexalure as Related to Its Attractancy to Pink Bollworm Moths12

Attractancy of alkenol acetate insect attractants in the field can be correlated with their content of cis and trans isomers as determined by capillary gas chromatography. An estimate of the percentage trans isomer also can be obtained from the height of the 10.3-μ peak in the infrared spectrum. The trans isomer of hexalure is virtually unattractive to pink boll worm moths, as is a mixture comprising 54% of the trans isomer and 46% of the cis isomer.

Hydrogenation of Triolein with Various Catalysts

Triolein was hydrogenated under various operating conditions. Five types of catalysts were employed. Platinum and palladium catalysts were used at 50°C and each of three types of nickel catalyst was used at 160°, 180°, 200° and 220°C. The hydrogenated products were subjected to lipase hydrolysis (lipolysis) to remove a portion of the acyl groups on the α, α'-positions. The hydrogenated products and fatty acids liberated by lipolysis were analyzed for fatty acid compositions and for content of the trans isomers. In case of nickel boride catalyst, the results showed that the oleoyl groups on α, α'-positions of triolein molecule are hydrogenated slightly faster than that on β-position. The other catalysts have not shown the selectivity of hydrogenation toward the position of acyl groups. There was no relation to be discussed between the position of acyl groups and the formation of trans isomers during hydrogenation with each nickel catalyst. Upon comparison at the same iodine value, trans isomer content in hydrogenated products was the most in case of nickel boride catalyst.

Diethylstilbestrol cis- trans isomerization and estrogen activity of diethylstilbestrol isomers

Facile isomerization of molecular diethylstilbestrol (DES) occurs by a second order reaction on solution in organic solvents. The isomerization of the disodium salt of DES which occurs in basic methanolic solutions is a reversible first order reaction. Mechanisms of the isomerization processes of molecular and anionic DES are proposed. The estrogenic response of isolated disodium salt of cis-DES was determined to be approximately 45% of the activity observed for trans-DES using a mouse uterine weight assay. Since the trans isomer is believed to be considerably more active biologically because of its structural similarity with estradiol, it appears that the observed appreciable activity of the cis-DES test solution is a consequence of the isomerization in vivo to the trans isomer. These results may have significance in the use of DES as a ruminant growth promoter since estrogenic response appears not to be restricted solely to the amount of trans isomer content.

Synthesis of Polyprenyl Alcohols

PURPOSE:Reaction of a prenyl halide with a novel %-allyl complex gives a hydroxylprotected prenyl alcohol, from which free prenyl alcohol of high trans-isomer content is obtained by removal of the protecting group.

Trans Isomers in thermally Oxidized Lipids

Oxidation patterns of cottonseed oil, methyl oleate and methyl linoleate with aeration at a rate of 300ml/min/100g of lipid at various temperatures ranging from 0 to 180°C for 24hr were investigated by measuring refractive index, viscosity, loss in weight, iodine value, and the content of total trans isomers (not only trans oleate, but cis-trans conjugated, trans-trans conjugated, and trans-trans nonconjugated linoleates).Cis-trans conjugated linoleate was not found in any oxidized lipids. Total trans isomers content in the oxidized cotton seed oil, methyl oleate and methyl linoleate has appreciably increased for the lipid oxidized at or above 90, 120 and 60°C respectively, compared with those treated below the critical temperatures. Besides these contents were approximately constant in the lipids oxidized above their critical oxidation temperatures of 90, 120, 60°C, respectively. As an exception, total trans isomers content of methyl linoleate oxidized at 180°C becomes appreciably small.

Positional isomers formed during the hydrogenation of cottonseed oil

SummaryA commercial cottonseed oil was hydrogenated under nonselective, normal, and selective conditions. The operating variables used were within the ranges of those ordinarily found in large‐scale operations. For each run samples were withdrawn at iodine values of approximately 75, 62, and 48; and these samples were analyzed for the position of the donble bonds, content oftrans isomers, and content of linoleins.Double bonds were found in the 6 through 14 positions of the monounsaturated fatty acid groups resulting from the hydrogenations. On the basis of the percentage distribution of the double bonds, there appeared to be no marked tendency for the linoleoyl group to form 9‐ or 12‐isomers of the oleoyl group. In the early stages of the selective hydrogenation the rate at which double bonds shifted from the 9‐position was greater than the rate at which double bonds were hydrogenated.The conditions of hydrogenation did not have a marked effect on the distribution of the double bonds at iodine values of about 62 and 48.The conditions of hydrogenation did have a marked effect on the percentage oftrans bonds. At an iodine value of approximately 75 the content oftrans bonds, expressed as weight percentage of trielaidin, was 9.4 for the nonselective hydrogenation and 27.3 for the selective hydrogenation while at an iodine value of approximately 48 these values increased to 21.6 and 37.7, respectively.