Total Unsaturation

The methods described in this section cover only the determination of total unsaturation in polymers. 

A wide range of physical and chemical techniques have been employed in such analyses. The application of these techniques to the determination of particular functional groups is discussed under two main headings. 

The methods described in this section cover only the determination of total unsaturation. Distinction between different types of unsaturation, (e.g., cis, trans 1,2, trans 1,4) will be discussed in a subsequent volume. 

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Matrix Components The term matrix component refers to the constituents in the material aside from those being determined, which are denoted as analyte. Clearly, what is a matrix component to one analyst may be an analyte to another. Thus, in one hand for the case of analyses for elemental content, components such as dietary fibre, ash, protein, fat, and carbohydrate are classified as matrix components and are used to define the nature of the material. On the other hand, reference values are required to monitor the quality of determinations of these nutritionally significant matrix components. Hence, there is a challenging immediate need for certified values for dietary fibre, ash, protein, fat, and carbohydrate. Concomitantly, these values must be accompanied by scientifically sound definitions (e.g. total soluble dietary fibre, total sulpha-ted ash, total unsaturated fat, polyunsaturated fat, individual lipids, simple sugars, and complex carbohydrates). 

In the present case, the proportion of A2-isomer in the original dehydration mixture may be estimated to be 42% of the total unsaturated esters, while an equilibrium mixture contains about 67% of the conjugated compound.3 Thus, the amount of conjugated isomer in the mixture may be considerably increased by base-catalyzed isomerization of the unsaturated esters. For other unsaturated esters, both the composition of the dehydration mixture3 7 and the equilibrium ratio of tile two isomers 3 x vary, depending on the position and... 

Average rate of consumption of total unsaturated group of consumption 0-50%... 

Pyridine and its partially or totally unsaturated derivatives such as tetrahydropy-ridines, DHPs, and piperidines are ubiquitous cores found in numerous natural product skeletons and in synthetic compounds of primary interest for synthetic chemistry, agrochemistry, or pharmacology. Among the various methodologies available for the synthesis of these compounds, multicomponent approaches have attracted much attention in the last few years. Most of these sequences are initiated by a Michael addition. 

To determine the concentration of cis-vinylene groups in irradiated specimens, the original cw-polybutadiene itself was used as a standard, and a value for A (assumed independent of concentration) was determined from Av and logr (I0/I)vo of unirradiated specimens. The total concentration of unsaturation was accepted (15) as 100% of theoretical and the density as 0.90 gram per cc. The cis concentration was obtained by subtracting from the total unsaturation the trans-vinylene and vinyl contents determined from the calibration curves developed as described below. The value of A so determined was 2.67 X 103 liters/mole-sq. cm. 

In all spectra, there was a decrease in intensity in the side vinyl band at 910 cm."1. This decrease was most rapid in the mixed polymers which contained an appreciable fraction of the olefin groups in this form. In polymers with low concentrations of vinyl groups (high cis and high trails polymers) the rate of disappearance of vinyl isomers appeared to be low until the total unsaturation had been reduced to about half its initial value. This behavior is depicted in Figure 3, which shows the... 

The irreversible chemisorption of Garner is thus shown to be, in fact, reversible at higher pressures w ithout appreciable reduction of the surface. Nevertheless, on pumping out at say 250° after an exchange reaction some CO was held tenanciously by the surface and could be removed rapidly at this temperature only by the addition of 02 the total unsaturation towards 02 amounted to <5% of the surface. During the exchange reactions of CO on ZnO at 2-cm. pressure, a small amount of C02 was... 

Polyenoic fatty acids (acids with more than one double bond in the chain) play a leading role where total unsaturation is observed to change. According to current concepts, the structure and functioning of cell membranes are maintained through the agency of a binary film composed of phospholipids and cholesterol. The phospholipids consist of polar, outwardly directed heads and fatty acid tails immersed in the membrane (Fox, 1972 Singer and Nicholson, 1972 Chapman, 1973). In this binary film, there are inclusions of protein molecules. 

Total Unsaturation Not more than 3.0 molar percent, as... 

Total Unsaturation Determine as directed under Total Unsaturation, Appendix IV. 

This method measures total unsaturation in a sample by the multivariate analysis of Fourier transform infrared spectra. It correlates the absorbance in the spectral regions corresponding to two major types of unsaturation with their concentrations. This is an extension of univariate least squares analysis that correlates a single band absorbance height or area with concentration. 

Chemical Tests and Determinations, 753 Chewing Gum Base, 782 Bound Styrene, 782 Molecular Weight, 783 Quinones, 784 Residual Styrene, 784 Total Unsaturation, 785 Chicle, 249... 

The nature of the Lewis acid and the residence time in the reactor drastically affect the ratio exo/endo of these terminal unsaturations. AICI3-based initiation leads to about 10% of vinylidenes with respect to total unsaturations, whereas the use of BF3-based catalysts, allowing a shorter contact time between the acid and the polymer and thus limiting isomerization, increases this exo structure to 70% or more [25,29]. The vinylidene double bond is much more reactive than the endo one, and favors considerably the furt her terminal functionalization of the oligomers for example, maleination, epoxidation, ozonolysis, reaction with phosphorus pentasul-fide, etc. (Fig. 2). 

The total unsaturation from Equation (7) can be apportioned into contributions from alicyclic structural moieties such as furanose and pyra-nose rings, aromatic structural moieties such as benzene rings, and carbonyl-containing moieties such as carboxylic acids, esters, amides, aldehydes, and ketones. Olefinic moieties such as the unsaturated alkyl chains of some lipids are thought to be of only minor importance. Equation (7) can thus be rewritten as... 

A summary of the median values of selected chemical properties of FAs, HAs, and NOM is given in Table 6, which includes both the properties for which complete statistical summaries were presented in Figures 3-10 and other derived or modeled properties that provide additional insight into the similarities and differences among these materials. The derived parameters include the average oxidation state of carbon (Zc), which is calculated from Equation (6), and total unsaturation (Utotai)> which is calculated from Equation (7). 

The median elemental compositions of FAs, HAs, and NOM are rather similar, and so consequently are properties such as the average oxidation state of organic carbon and the total unsaturation of these materials. Most of the elemental compositions that were included in this review lie outside the biomass triangle on a van Krevelen plot, indicating that DOM is not simply a residue of biomass. It has clearly gained oxygen and lost hydrogen, as would be expected for partial oxidation of biomass to CO2 and H2O. 

Hexane-extracted wheat germ consisted of about 56% linoleic acid (18 2 n6), which is an essential fatty acid (Table 4) (27). Total unsaturated and polyunsatu-... 

The fatty acid composition of the extracts was not affected by temperature, pressure, and the extraction method (Table 4). Supercritical carbon-dioxide-extracted oil samples had similar fatty acid composition to that of the Soxhlet-extracted oil (Table 4). All of the wheat germ extracts consisted of about 56% linoleic acid (18 2 n-6), which is an essential fatty acid (Table 4). The total unsaturated and polyunsaturated fatty acid (PUFA) content of the wheat germ oil was about 81 % and 64%, respectively. The SC-CO2 extraction of wheat germ resulted in extracts with similar tocopherol and tocotrienol compositions to those of the Soxhlet extracts (Table 8) (50). These results indicate that SC-CO2 technology can be used for extraction and fractionation of WGO components to obtain products with high quality. 

The fatty acid profile of two cold-pressed black raspberry seed oils demonstrated high concentrations of both n-3 and total unsaturated fatty acids. The concentration of ot-linolenic acid (18 3n-3) was 35% of total fats, and unsaturated fatty acids comprised 98-99% (Table 1). Linoleic acid was the predominant fatty acid (Table 1) however, the ratios of n-6 to n-3 fatty acids were very low at 1.6 1. The other measurable fatty acids included oleic (18 ln-9) and palmitic (16 0) acids (Table 1). The overall fatty acid composition of black raspberry seed oil was very similar to red raspberry seed oil (1) (Table 1). 

Watermelon seed oil was prepared and evaluated for its physicochemical properties (22, 23). The seed oil consisted of 59.6% linoleic acid (18 2n-6) and 78.4% total unsaturated fatty acids (Table 4). The predominant fatty acid in the oil was linoleic acid, which was followed by oleic, palmitic, and stearic acids. Linolenic, palmitoleic, and myristic acids were minor constituents. The refractive index, acid value, peroxide value, and free fatty acids of watermelon seed oil were determined to be 1.4696 (25°C), 2.82 (mg KOH/g oil), 3.40 (mequiv oxygen/kg oil), and 1.41 (% as oleic acid), respectively. The saponification value of watermelon seed oil was 201 (mg KOH/g oil), and its iodine value was 115 (g iodine/100-g oil), which was significantly higher than pumpkin at 109 (g iodine/lOO-g oil) (22, 23). 

Rose, Rosa canina L., also known as dogberry or hop fruit, is in the Rosaceae family. The fruit of this particular species of rose is generally used to prepare a stew. The seeds from Rosa canina L. were investigated for their chemical composition and nutritional values for medicinal purposes. Seed oils were prepared from fruits grown at three locations in Turkey and evaluated for their fatty acid composition (31). Linoleic acid was the primary fatty acid detected, which ranged from 48.6-54.4% of total fatty acids, followed by a-linolenic acid (16.4-18.4%) and oleic acid (14.7-18.4%) (Table 4). The seed oil contained approximately 85% total unsaturated fatty acids, indicating that Rosa canina L. seed oil may be an excellent source for unsaturated and essential fatty acids. 

Paprika Capsicum annuum) is a commonly used flavor enhancer, and following production, the seeds are treated as waste. Paprika seed oils have been evaluated for their physicochemical properties (22, 23, 32). Paprika seed oil contained more than 82% of total unsaturated fatty acids, with polyunsaturated fatty acids comprising 67.8% of total fatty acids (Table 4) (22, 23). Oleic acid was the second major fatty acid at approximately 15% of the total. This fatty acid profile was consistent with a previous observation by Domokos et al. (32) on the fatty acid profile of Hungarian paprika seed oils. Linoleic acid comprised 74.4% of the total fat, whereas oleic and palmitic acid made up 9.8% and 11.2% of total fat, respectively (32). The paprika seed oil was determined to contain 870 mg/kg oil total tocopherols, 380 mg/kg oil carotenoids, and 0.92% phytosterols (32). 

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