Normal hexane

Carbon dioxide (C02) Carbon monoxide (CO) Ethylene (C2H4) Hexane-normal (C6H14) Hydrogen (H2) Methane (CH4)... 

Hydrocarbon Solvents. There are two types of hexane normal, or n-hexane, and commercial, extraction-grade hexane, n-Hexane is pure and boils at 69°C (156°F). Extraction-grade hexane is not pure. The -hexane content typically varies from approximately 48% to 98%, as shown in Table 6 (146). 

Nonylphenoxy)-3,6,9,12,15-pentaoxaheptadecan-1-ol, dihydrogen phosphate. See Nonoxynol-6 phosphate 14-(Nonylphenoxy)-3,6,9,12-tetraoxatetradecan-1-ol. See Nonoxynol-5 Nonylphenyl phosphite (3 1). SeeTris (nonylphenyl) phosphite Nonyl phenyl polyethylene glycol Nonyl phenyl polyethylene glycol ether. SeeNonoxynol Nordhausen acid. See Sulfuric acid Normal hexane. See Hexane Normal lead acetate. See Lead acetate Normal propyl alcohol. See Propyl alcohol... 

At low temperatures, using the original function/(T ) could lead to greater error. In Tables 4.11 and 4.12, the results obtained by the Soave method are compared with fitted curves published by the DIPPR for hexane and hexadecane. Note that the differences are less than 5% between the normal boiling point and the critical point but that they are greater at low temperature. The original form of the Soave equation should be used with caution when the vapor pressure of the components is less than 0.1 bar. In these conditions, it leads to underestimating the values for equilibrium coefficients for these components. 

Nonpolar organic mobile phases, such as hexane with ethanol or 2-propanol as typical polar modifiers, are most commonly used with these types of phases. Under these conditions, retention seems to foUow normal phase-type behavior (eg, increased mobile phase polarity produces decreased retention). The normal mobile-phase components only weakly interact with the stationary phase and are easily displaced by the chiral analytes thereby promoting enantiospecific interactions. Some of the Pirkle-types of phases have also been used, to a lesser extent, in the reversed phase mode. 

Solvent Resistance. Elastomeric fibers tend to swell in certain organic solvents mbber fibers swell in hydrocarbon solvents such as hexane. Spandex fibers become highly swollen in chlorinated solvents such as tetrachloroethylene [127-18-4] (Perclene). Although the physical properties of spandex fibers return to normal after the solvent evaporates, considerable amounts of its stabilizers may have been extracted. Therefore, the development of stabilizers that are more resistant to solvent extraction has become important as solvent scouring during mill processing replaces aqueous scouring at many mills, especially in Europe (26). 

Fig. 3. (a) Flame ionization detector (fid) response to an extract of commercially processed Valencia orange juice, (b) Gas chromatography—olfactometry (geo) chromatogram of the same extract. The abscissa in both chromatograms is a normal paraffin retention index scale ranging between hexane and octadecane (Kovats index). Dilution value in the geo is the -fold that the extract had to be diluted until odor was no longer detectable at each index. 

Isomerization. Isomerization is a catalytic process which converts normal paraffins to isoparaffins. The feed is usually light virgin naphtha and the catalyst platinum on an alumina or zeoflte base. Octanes may be increased by over 30 numbers when normal pentane and normal hexane are isomerized. Another beneficial reaction that occurs is that any benzene in the feed is converted to cyclohexane. Although isomerization produces high quahty blendstocks, it is also used to produce feeds for alkylation and etherification processes. Normal butane, which is generally in excess in the refinery slate because of RVP concerns, can be isomerized and then converted to alkylate or to methyl tert-huty ether (MTBE) with a small increase in octane and a large decrease in RVP. 

Highly pure / -hexane can be produced by adsorption on molecular sieves (qv) (see Adsorption, liquid separation) (43). The pores admit normal paraffins but exclude isoparaffins, cycloparaffins, and aromatics. The normal paraffins are recovered by changing the temperature and/or pressure of the system or by elution with a Hquid that can be easily separated from / -hexane by distillation. Other than ben2ene, commercial hexanes also may contain small concentrations of olefins (qv) and compounds of sulfur, oxygen, and chlorine. These compounds caimot be tolerated in some chemical and solvent appHcations. In such cases, the commercial hexanes must be purified by hydrogenation. 

Hexane is classified as a flammable liquid by the ICC, and normal handling precautions for this type of material should be observed. According to the ACGIH, the maximum concentration of hexane vapor in air to which a worker may be exposed without danger of adverse health effects is 125 ppm benzene is rated at 10 ppm. 

Normal Fluids. Asymmetrical compounds having Httle molecular interaction, eg, carbon monoxide, / -butane, and / -hexane, deviate slightly from the theory of corresponding states and are considered to be normal fluids. 

The simplest form of ternary RCM, as exemplified for the ideal normal-paraffin system of pentane-hexane-heptane, is illustrated in Fig. 13-58 7, using a right-triangle diagram. Maps for all other non-azeotropic ternary mixtures are qiiahtatively similar. Each of the infinite number of possible residue curves originates at the pentane vertex, travels toward and then away from the hexane vertex, and terminates at the heptane vertex. 

As an example of the use of the nomograph, the line is shown which would be drawn to determine the solubility of n-hexane in water at 25°C. The coordinates given in Table 1 for normal paraffins have been used X = 15.0, Y = 20.0. The predicted solubility is 2 x 10 mole fraction The experimental value is 1.98 x 10as given by McAuliffe and Price. ... 

The column was operated in the normal phase mode using mixtures of n-hexane and ethanol as the mobile phase. Equation (13) is validated by the curves relating the corrected retention volume to the reciprocal of the volume fraction of ethanol in Figure 19. It is seen that an excellent linear relationship is obtained between the corrected retention volume and the reciprocal of the volume fraction of ethanol. 

The only known reaction of a furan with a dihalocarbene is that recently reported between benzofuran and dichlorocarbene in hexane at 0°. The initial adduct (7) could not be isolated but on hydrolysis gave the ring-expanded product 8, possibly via 9, in 15% yield. Benzothiophene was recovered in 92% yield under the same conditions. 2,5-Dihydrofuran reacted with dichloro- and dibromo-carbene to give the products of allylic insertion, 2-dihalogenomethyl-2,5-dihydrofuran, as well as the normal addition products. ... 

Gel permeation ehromatography (GPC)/normal-phase HPLC was used by Brown-Thomas et al. (35) to determine fat-soluble vitamins in standard referenee material (SRM) samples of a fortified eoeonut oil (SRM 1563) and a eod liver oil (SRM 1588). The on-line GPC/normal-phase proeedure eliminated the long and laborious extraetion proeedure of isolating vitamins from the oil matrix. In faet, the GPC step permits the elimination of the lipid materials prior to the HPLC analysis. The HPLC eolumns used for the vitamin determinations were a 10 p.m polystyrene/divinylbenzene gel eolumn and a semipreparative aminoeyano eolumn, with hexane, methylene ehloride and methyl tert-butyl ether being employed as solvent. 

Figure 12.18 LC-SFC analysis of mono- and di-laurates of poly (ethylene glycol) ( = 10) in a surfactant sample (a) normal phase HPLC trace (b) chromatogram obtained without prior fractionation (c) chromatogram of fraction 1 (FI) (d) chromatogram of fraction 2 (F2). LC conditions column (20 cm X 0.25 cm i.d.) packed with Shimpak diol mobile phase, w-hexane/methylene chloride/ethanol (75/25/1) flow rate, 4 p.L/min UV detection at 220 nm. SFC conditions fused-silica capillary column (15 m X 0.1 mm i.d.) with OV-17 (0.25 p.m film thickness) Pressure-programmed at a rate of 10 atm/min from 80 atm to 150 atm, and then at arate of 5 atm/min FID detection. Reprinted with permission from Ref. (23).

One example of normal-phase liquid chromatography coupled to gas chromatography is the determination of alkylated, oxygenated and nitrated polycyclic aromatic compounds (PACs) in urban air particulate extracts (97). Since such extracts are very complex, LC-GC is the best possible separation technique. A quartz microfibre filter retains the particulate material and supercritical fluid extraction (SPE) with CO2 and a toluene modifier extracts the organic components from the dust particles. The final extract is then dissolved in -hexane and analysed by NPLC. The transfer at 100 p.1 min of different fractions to the GC system by an on-column interface enabled many PACs to be detected by an ion-trap detector. A flame ionization detector (PID) and a 350 p.1 loop interface was used to quantify the identified compounds. The experimental conditions employed are shown in Table 13.2. 

When analytes lack the selectivity in the new polar organic mode or reversed-phase mode, typical normal phase (hexane with ethanol or isopropanol) can also be tested. Normally, 20 % ethanol will give a reasonable retention time for most analytes on vancomycin and teicoplanin, while 40 % ethanol is more appropriate for ristocetin A CSP. The hexane/alcohol composition is favored on many occasions (preparative scale, for example) and offers better selectivity for some less polar compounds. Those compounds with a carbonyl group in the a or (3 position to the chiral center have an excellent chance to be resolved in this mode. The simplified method development protocols are illustrated in Fig. 2-6. The optimization will be discussed in detail later in this chapter. 

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