Elaidinization

In general, the presence of fatty acid groups in the phosphoHpid molecule permits reactions such as saponification, hydrolysis, hydrogenation, halogenation, sulfonation, phosphorylation, elaidinization, and ozonization (6). 

Hay and Morrison (1970) identified the monoenoic positional and geometric isomers in milk fat and determined the amounts of each total acid class and percentage of trans isomers. The geometric and positional isomers of the monoenes are primarily the result of biohydrogenation of polyunsaturated fatty acids in the rumen. Stearate is also produced, and cis-9-18 l accounts for most of the monoenes. The several positional isomers in trans 16 1 and 18 1 are due to the positional isomerization of double bonds which accompanies elaidinization. 

Several active elaidinization catalysts are known76 of which selenium and sulphur dioxide certainly are the most attractive ones. With liquid sulphur dioxide optimum results are obtained under relatively mild conditions (iio-ii5°C, 35 atm., 3 h) the low reaction temperature is favourable for the application of the hardened oils in the margarine industry. 

The course of the elaidinization reaction can be followed graphically by means of the critical demixing temperature of the oil, using, for example, aniline as a solvent. According to Dahmen the rise in the critical demixing temperature is approximately proportional to the degree of elaidinization (cf. Fig. 85). 

In Fig. 85 the critical demixing temperature of isomerized olive is plotted against the percentage of elaidinized oil (calculated on the amount of elaidinic acid that can... 

Fig. 85. Elaidinization of olive oil. Critical demixing temperatures /od p cl ted against...

In 1989, a different approach was published by Orito [60], in which elaidinization ((Z) —> ( ) double bond isomerization) is used to obtain ( )-MNA from a (Z, )-mixture ofdiastereomers (Scheme 4.6). Gannet had observed that the iodine-induced photoisomerization of the methyl ester of MNA (48) gave only a 7 3 ( /Z) mixture [59], but Orito obtained a better diastereomeric ratio (8 1) using nitrous acid. Remarkably, no double-bond migration to form the more stable trisubstituted olefin was observed. This discovery paved the way to a very simple and general synthesis of the acidic component of capsaicinoids. Thus, a Wittig reaction of the phosphonium salt of a 6-bromohexanoic acid (49) with isobutyraldehyde (SO) afforded a 1 11... 

As shown in Table I, a concentration of 20% or more crude trans--gyplure in formulations of cis-gyplurt is sufficient to cause inactivation the mechanism of this inactivation is not known. The trans- form was prepared by elaidinization of the cis isomer with nitrous acid. The propyl and butyl analogs of w-gyplure were completely devoid of activity in field tests. These results show that a cis double bond and an acetoxy group are necessary for activity (27). 

Den EinfluB der spezifischen Oberflache zeigen Versudie zur chro-matographischen Trennung des Gemisches der Methylester von Elaidin-und Olsaure (E 7). Zur Trennung warden zwei Kationenaustauscher... 

For nondrying oils only those isomerization processes are of value which bring about an increase of the melting point (hardening) of the oils. This type of reactions includes elaidinization cis-trans conversions) of esters of oleic acid and other mono-unsaturated fatty acids. 

In both these isomerization processes liquid sulfur dioxide has been found to be an active catalyst. The optimum reaction conditions, and particularly the temperature, are sufficiently different to allow a completely selective performance of each type of transformation. This is of special interest in the processing of semidrying oils, such as soybean, cod-liver, and herring oils 1,2). It is possible to harden these oils by heating them in the presence of liquid sulfur dioxide to 110 to 115° at a pressure of 35 atm. for 2 to 3 hrs. Crystallization of the partly solidified reaction products yields a solid fraction, containing the elaidinized mono-unsaturates, and a liquid portion, which is enriched in the poly-unsaturates and shows improved drying properties, A further improvement of this liquid portion can be achieved by... 

The course of the elaidinization reaction can be followed by dilatometric measurements (11), consistency determinations (12), by means of critical demixing temperatures, using aniline or triacetin as a solvent (9), or, more directly, by infrared spectrophotometry (13). 

Olive oily which is obtained from the fruit of the olive tree, contains about 28 per cent of solid fat consisting of palmatin and a little arachidin. The rest is mostly olein. Substances present in smaller quantities are linolein, cholesterol, free fatty acids, and unsaponifiable matter. The oil is used as a salad oil, as a lubricant, in soap stock, and for other purposes. Its iodine value is 77 — 88. The elaidin test produces a solid mass within two hours. On account of its high cost it is frequently adulterated with cottonseed, peanut, lard, and other oils. 

In the hydrogenation of fatty oils such as cottonseed or peanut oil, it is often desirable to saturate only one double bond of the doubly unsaturated esters present. If such hydrogenations are carried out in the presence of a nickel catalyst containing even traces of nickel sulfide, an isomerization takes place so that the product contains isooleates (elaidates). Paterson (14) observed that this so-called elaidinization does not take place in the presence of nickel catalysts free of sulfur. Bailey, Fuege, and Smith (15) found that a nickel catalyst prepared from nickel sulfate catalyzed elaidinization." Ziels and Schmidt (16) recom-... 

The gelation time for A. montana is longer than that of A. fordii. Surprisingly the oil is permanently prevented from elaidinizing by heating to 200-225 C for a short time. No explanation has been offered. 

Boyle (1661) mentions that olive and almond oils become thick when acted upon by red fuming aqua fortis (which dissolves camphor), but the observation was not noticed imtil J. J. E. Poutet, a Marseilles apothecary, found that olive oil solidifies when shaken with a solution of mercury in nitric acid, and he proposed this as a test for olive oil. It was found, however, that other oils behaved similarly. Felix Boudet, a Paris apothecary, found that the mercury solution acts only when it contains free nitrous acid, and showed that a new substance is formed which he called elaidin, and considered to be a compound of glyceryl oxide and a new acid, elaidic acid. Laurent, by the action of nitric acid on oleic acid obtained eladaic acid. He isolated from the product what he called suberic, pimelic, adipic, and azelaic acids, which he formulated adipic pimelic and azelaic His pimelic acid... 

Dehydration of a suitable precursor at high temperature under vacuo initially yielded a polyester (8), upon which pyrolysis afforded the trans-9,trans-11-18 2 isomer. For this procedure ricinoleic acid was first elaidinized, which means a transformation of the ds- double bond into a trans- double bond (9). The so formed ricinelaidic acid was then heated under vacuum at 235°C. Intermolecular esterification (estolide formation) yielded polyesters with a molecular weight of 1500 to 1600. Pyrolysis and simultaneous distillation furnished a crude product, which was recrystallized in 95% ethanol to furnish the desired trans-9,trans-W- % 2 isomer in a 35% yield. 

Figure 15.2 shows typical binary (surfactant + water) phase diagrams of monoglycerides for three molecules with decreasing Krafft temperature (l-monopahnitin, 1-mono-elaidin and 1-mono-olein). With 1-monopalmitin, the dominant meso-phase is the lamellar (neat) phase, which swells to a maximum water layer thickness, dw, of 2.1 nm at 40% water. At higher water content (>60%) a disperse phase is produced in the temperature range 55-68 °C, whereas above 68 °C a cubic phase in equilibrium with water is formed. 

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