Solvent carbon number

The amount of asphaltene precipitate from one crude oil is dependent on the carbon number of the alkane solvent. A decrease in the solvent carbon number results in an increase in the asphaltene precipitate. This observation would suggest that asphaltenes and resins are not greatly different materials. Rather, a continuum exists in the solubility behavior. An increase in boiling point in heavy oil is generally accompanied by an increase in both aromaticity and in the concentration of heteroelements or polar aromatic molecules (Corbett, 1969). Similarly, there is a gradual... 

Figure 2. Effect of solvent carbon number on insolubles (Arabian Light atmospheric...

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

Thermolysis-mass spectrometry is ideal for examining the amount of residual monomer and processing solvents present in polymers. In thermolysis, the polymer is heated from room temperature to 200-300 °C, and is then often held isothermally in order to drive off volatile components. Low-temperature pyrolysis (350-400 °C) of PP compounds in direct mass-spectral analysis has shown volatiles from PP at every carbon number to masses well above 1000 Da [37]. 

However, the elution behaviour of aromatic and aliphatic compounds is often different (even though their carbon numbers and van der Waals volumes are very similar) in eluents containing different organic modifiers. These variations are due to differences in the solubility of analytes in the organic solvent. 

The mineral-based oils are produced from heavy-end crude oil distillates. Distillate sneams may be treated in several ways, such as vacuum-, solvent-, acid-, or hydrotreated, to produce oils with commercial properties. Hydrocarbon types ranging from C15 to C50 are found in the various types of oils, with the heavier distillates having higher percentages of the higher-carbon-number compounds. 

The approach to calculate the van der Waals and cavity terms from the molecular surface areas can be used for the calculation of partition coefficients. The results show that for the distribution of hydrocarbons between water and n-octanol the calculated partition coefficient is linear in carbon number. Qualitatively similar data are obtained for the distribution between other solvents and water and the results can be used to predict the retention in liquid>liquid chromatography. On the other hand, if retention in RPC occurs due to reversible binding at the surface of the stationary phase, the significant parameter is not the total surface area of the eiuite but rather the net decrease in the molecular surface area of the stationary phase ligates and that of the eiuite upon binding, i.e., the contact area in the complex. 

RP-HPLC with nonaqueous solvents and UVD at 246 nm was developed for the determination of low level POVs of vegetable oils. These measurements are specific for conjugated diene peroxides derived from vegetable oils with relatively high linoleic acid content. These measurements may be supplemented by nonspecific UVD at 210 nm and ELSD for detection of all eluted species. The elution sequence of the triglycerides in a nonaqueous RP-HPLC is linearly dependent on the partition number of each species, Vp, which is defined as = Nq — 2Ni, where Nq is the carbon number and is the double bond number. In the case of hydroperoxides = Nq — 2Nd — Vhpo, where Vhpo is the number of hydroperoxyl groups in the molecule (usually 1 for incipient POV). For... 

As a solvent, carbon dioxide does have a number of advantages over more conventional techniques. Because the critical point is only at 304 K (i.e., 31°C), temperature sensitive substances can be extracted without any degradation. This is particularly... 

Figure 8.1. Relation of solubility parameters (solpars or Hildebrand 8 values) and carbon numbers in various homologous series of solvents. (4) Normal alkanes, (B) normal chloroalkanes, (C) methyl esters, (D) alkyl formates and acetates, (E) methyl ketones, (F) alkyl nitriles, ) normal alkanols, (H) alkyl benzenes, and (I) dialkyl phthalates.

Naphtha Various volatile and often flammable liquid hydrocarbon mixtures used as solvents and diluents consists mainly of hydrocarbons with higher boiling point than gasolines and lower boiling point than kerosene principal component of chemical dispersants used prior to 1970. Naphthenes Class of hydrocarbons with similar physical and chemical properties to alkanes insoluble in water, generally boil at 10-20°C higher than corresponding carbon number alkanes. Narcosis Stupor or unconsciousness produced by chemical substances. 

The autoxidation of hydrocarbons catalyzed by cobalt salts of carboxylic acid and bromide ions was kinetically studied. The rate of hydrocarbon oxidation with secondary hydrogen is exactly first order with respect to both hydrocarbon and cobalt concentration. For toluene the rate is second order with respect to cobalt and first order with respect to hydrocarbon concentration, but it is independent of hydrocarbon concentration for a long time during the oxidation. The oxidation rate increases as the carbon number of fatty acid solvent as well as of cobalt anion salt are decreased. It was suggested that the cobalt salt not only initiates the oxidation by decomposing hydroperoxide but also is responsible for the propagation step in the presence of bromide ion. 

Such solvent systems continued to be used even though the lack of solubility of triacyl-glycerols with carbon numbers greater than 46 in this mobile phase has been noted. The solvent gradients that would be required for optimum separations of complex triacylglycerol mixtures are not compatible with RI detection. Therefore, ultraviolet detectors have also been used, but the range of mobile phases is limited, since TGs absorb only in the far-UV range. 

Acetal (4) undergoes 5 N 1 hydrolysis in aqueous solution at high pH, it is easily monitored via the /7-nitrophcnoxidc chromophore produced.3 The reaction has been used to probe hydration effects in co-solvents alcohols, ammo acids, and peptides— the last two as models for such effects in enzymes. Primary alcohols retard the reaction in proportion to their carbon number, but the ammo acids and peptides show more complex effects, which are interpreted in tenns of interactions between the overlapping hydration shells of the amino and carboxylate groups. 

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