Nonconjugated Dienes Research Articles

Photochemical reactions with non-conjugated dienes

Abstract

Determination of Double Bonds in Ethylene Propylene Terpolymer Rubbers

Abstract Developments in the field of sulfur vulcanized unsaturated ethylene propylene terpolymer rubbers, also known as EPT rubbers, have progressed rapidly in recent years. Considerable success has been achieved in producing EPT rubbers from ethylene, propylene, and various dienes. Initial difficulties, involving introduction of double bonds into already known ethylene propylene copolymers, were soon overcome when it became clear that it was not the then commonly conjugated dienes such as butadiene and isoprene, but rather nonconjugated dienes, which were required for successful terpolymerization with ethylene and propylene, according to the Ziegler process. As with butyl rubber, it is sufficient, for vulcanization purposes, to incorporate one or two mole per cent of such dienes into the terpolymer. It is especially important, not only for polymerization, but also for rubber processing, to know the type and amount of unsaturation. In this article we wish first of all to report on double bond determinations in general and then, in particular, on qualitative and quantitative dicyclopentadiene determinations in ethylene propylene terpolymers. It is especially important, not only for polymerization, but also for rubber processing, to know the type and amount of unsaturation. In this article we wish first of all to report on double bond determinations in general and then, in particular, on qualitative and quantitative dicyclopentadiene determinations in ethylene propylene terpolymers.

Addition of diboron tetrachloride to some cyclic olefins and dienes

The study of the reaction of diboron tetrachloride with unsaturated hydrocarbons has been extended to include some cyclic olefins and dienes. Addition of diboron tetrachloride to cyclopentene yields the expected product, 1,2-bis(dichloroboryl)cyclopentane. Hydrolysis of this yields the 1,2-diboronic acid of cyclopentane, which upon oxidation by alkaline hydrogen peroxide apparently yields only the trans-1,2-cyclopentanediol. Diboration of non-conjugated cyclic dienes can be effected in a stepwise fashion. Thus, the addition of diboron tetrachloride to 1,4-cyclohexadiene results in either 4,5-bis(dichloroboryl)cyclohexene or 1,2,4,5-tetrakis(dichloroboryl)cyclohexane. When conjugated cyclic dienes are treated with diboron tetrachloride polymerization of the diene is the principal result. Similarly, 2-butyne is trimerized to form hexamethylbenzene upon treatment with diboron tetrachloride.

Triterpene compounds—IX : Mercuric acetate oxidation of a melaleucic acid derivative

Methyl acetylmelaleucate (VIII) is shown to react with mercuric acetate to give the non-conjugated diene (IX).

Polyisocyanates as Curing Adjuvants for Ethylene—Propylene Terpolymers

Abstract Ethylene—propylene—nonconjugated diene terpolymers yield vulcanizates of high modulus and tensile strength in the presence of strongly reinforcing fillers. In many applications where low cost, light color, or nonconductivity are required, it is necessary to use poorly reinforcing mineral fillers. The combination of poorly reinforcing mineral filler and amorphous EP terpolymer yields vulcanizates which do not have the excellent stress-strain properties characteristic of many black loaded stocks. The purpose of this paper is to present a new method of obtaining superior properties in mineral filled EP terpolymer vulcanizates.

Homogeneous catalytic hydrogenation of unsaturated fats: Iron Pentacarbonyl

AbstractIron 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舑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.

Physico-Chemical Characteristics of Canadian Milk Fat. Unsaturated Fatty Acids

Summary Seasonal and regional variations in ethenoid acids of Canadian milk fat have been established from 327 authentic samples, representative of every month of the year and of 29 creameries across Canada. About 30% of the fatty acids in milk fat were unsaturated; 12% of these were polyunsaturated acids, with one-third being of the conjugated type. The average values and the 95% fiducial limits, in brackets, were as follows: conjugated dienes 1.13% (0.24–2.01), conjugated trienes 0.021% (0.001–0.033), conjugated tetraenes 0.002% (0.000–0.005), nonconjugated dienes 1.31% (0.78–1.84), nonconjugated trienes 0.89% (0.32–1.46), nonconjugated tetraenes 0.19% (0.07–0.31), nonconjugated pentaenes 0.12% (0.02–0.22), nonconjugated hexaenes 0.042% (0.001–0.083), total polyethenoid acids 3.71% (2.82–4.60), monoethenoid acids 26.1% (21.8–30.4), ethanoid acids 65.8% (60.5–71.1). The ethanoid acids which varied with the season were the conjugated dienes and trienes, the nonconjugated trienes and pentaenes, and the monoethenoid acids. They were all higher in summer than in winter milk fat. Triene values were higher in Ontario, and monoethenoid acids were higher in the coastal than in the other provinces. The most significant feature of the seasonal variations was the close relationship between iodine value, monoethenoid acids, conjugated dienes, and non-conjugated trienes. Of the total iodine value, 74% was contributed by monoethenoid acids, 14% by dienes, 8% by trienes, and 4% by tetraenes, pentaenes, and hexaenes. The occurrence of conjugated dienes in relatively large amounts and of hexaenes in all samples is of special interest as characteristics of milk fat.

Polymerization of hepta-1,5-diene on complex catalysts

THE difficulty of obtaining vulcanizable rubbers by the copolymerization of a-olefins consists mainly in the method of introducing double bonds into the copolymer. Attempts to synthesize a polymer of this type from ethylene or propylene with the addition of acetylene or diene hydrocarbons have been unsuccessful [1-3]. I t seemed to ~s to be possible to obtain the desired polymer by the copolymerization of ~-olefins with non-conjugated dienes containing both internal and external double bonds. I t was assumed that the external double bonds would take part in the polymerization and the unreactive internal double bonds would remain unaffected. As the subject of investigation, we selected hepta-l,5-diene. The first stage of the work consisted in a s tudy of the homopolymerization of hepta-l,5-diene in solution under the influence of catalysts of the Ziegler-Natta type. At the present time, it is known that in the presence of Ziegler-Natta catalysts, compounds containing two non-conjugated vinyl groups give polymers consisting of cyclic units [5. 6].

Intramolecular‐intermolecular polymerization of nonconjugated diolefins

AbstractThe literature dealing with the formation of cyclic recurring units in the polymerization of nonconjugated dienes by an intramolecular‐intermolecular polymerization mechanism is reviewed. Carbocyclic rings and heterocyclic rings containing oxygen, nitrogen, phosphorus, silicon, and tin are considered.

Isolation of Milk Phospholipids and Determination of Their Polyunsaturated Fatty Acids

Summary Several methods were compared for recovery and purification of mixtures of phospholipids from dried buttermilk. Samples were analyzed for phosphorus, nitrogen, and unsaturated fatty acids. Evidence was obtained that phospholipids purified by repeated acetone precipitation are not representative of the original milk phospholipids. An improved procedure was developed to extract the lipids from buttermilk with ethanol, ether, and chloroform. Most of the phospholipids were separated from the other lipids by precipitation with acetone. Acetone-soluble phospholipids were recovered by chromatography with silicic acid columns. The two fractions were combined and nonlipid contaminants were removed by washing. In an alternative procedure, the lipids were extracted from buttermilk with methanol and chloroform before the foregoing method was used to isolate the phospholipids. The amounts of unsaturated fatty acids were estimated from spectrophotometric data and iodine values. A representative sample of milk phospholipids (3.72% phosphorus, 2.23% nitrogen, iodine value 53.8) contained 26.3% monocne, 1.5% conjugated diene, and 5.8, 2.4, 1.3, and 1.5% nonconjugated diene, triene, tetraene, and pentaene acids, respectively. Percentages of each of these acids in the total fatty acids (with corresponding percentages for milk fat from the same source given in parentheses) were: 39.8 (32.1), 2.3 (1.4), 8.8 (1.6), 3.6 (0.9), 2.0 (0.3), and 2.2 (0.2), respectively. The phospholipids contained 41.3% saturated fatty acids and the milk fat 63.5%. These data show that there was a selective concentration of nonconjugated polyunsaturated acids in milk phospholipids.

Structure of hydroperoxides obtained from autoxidized methyl linoleate

SummaryA sample of debromination methyl linoleate has been autoxidized to a peroxide value of 671 m.e./kg. at approximately 0°C. in the dark. An essentially pure concentrate of methyl octadecadienoate monohy‐droperoxide was quantitatively separated; infrared and ultraviolet spectral studies were made on the peroxide concentrate and on the corresponding hydroxyl derivative obtained by reducing the peroxides with stannous chloride.The infrared data showed no conjugated peroxides having geometric configurations other than cis, trans; the same data also showed that the peroxide concentrate contained at least 90% conjugated cis,trans forms. Calculations based on ultraviolet spectrophotometric methods also indicated that the peroxides were at least 90% conjugated. The remaining 10% of the sample is most likely nonconjugated diene hydroperoxide. Since analogous cis, cis conjugated dienes have not been isolated and their infrared and ultraviolet properties are unknown, their presence here in small amounts is possible. Ultraviolet and infrared spectra of the reduced compounds conform closely to those of the peroxides except for reduction in the intensity of the OH bond at 2.88 μ.The infrared absorption spectra of the C−H structure and carbonyl groups of an essentially pure conjugated cis, trans methyl octadecadienoate monohydroperoxide were recorded, using a LiF prism.The infrared absorption spectra of the C−H strucfraction isolated from methyl linoleate autoxidized in the dark at 24°C. indicated that appreciable amounts of conjugated trans, trans hydroperoxides were present, in addition to those of the cis, trans type. It is possible that the conjugated cis, trans isomers were formed originally but were labile at the higher temperature and in the presence of catalysts (e.g., peroxides) were transformed to the thermodynamically more stable conjugated trans, trans isomer.