Pentane physical properties

Physical Properties. Benzene, C H, toluene, C Hj-CH, and petrol (a mixture of aliphatic hydrocarbons, e.g., pentane, hexane, etc.) are colourless liquids, insoluble in and lighter than water. Benzene and toluene, which have similar odours, are not readily distinguishable chemically, and their physical constants should therefore be carefully noted benzene, m.p. 5 (solidifies when a few ml. in a dry test-tube are chilled in ice-water), b.p. 8i toluene, m.p. —93°, b.p. 110°. Petroleum has a characteristic odour. 

PS Foams. The eady history of foamed PS is available (244), as are discussions of the theory of plastic foams (245). Foamable PS beads were developed in the 1950s by BASF under the trademark of STYROPOR (246—248). These beads, made by suspension polymerization in the presence of blowing agents such as pentane or hexane, or by post-pressurization with the same blowing agents, have had an almost explosive growth, with 200,000 metric tons used in 1980. Some typical physical properties of PS foams are Hsted in Table 10 (see Foamed plastics). 

Methane is the main constituent, with a boiling point of 119 K (—245°F). Ethane, with a boiling point of 184 K (—128°F) may be present in amounts up to 10 percent propane, with a boiling point of 231 K (—44°F), up to 3 percent. Butane, pentane, hexane, heptane, and octane may also be present. Physical properties of these hydrocarbons are given in Sec. 2. 

Di-p-chloro-bis(i74-l,5-cyclooctadiene)dirhodium(I) is a yellow-orange, air-stable solid. It can be used directly as obtained for preparative purposes5 or as a precursor for homogeneous catalysts.3,4 It can be recrystallized from dichloro-methane-diethyl ether to give orange prisms. The compound is soluble in dichloro-methane somewhat less soluble in acetone and insoluble in pentane and diethyl ether. Characteristic strong bands occur in the infrared spectrum at 819, 964, and 998 cm 1 (Nujol mull). The cyclooctadiene vinylic protons resonate in the 1H NMR spectrum at t 5.7 and the allylic protons at t 7.4-8.3 (deuteriochloroform solution). Other physical properties are given by Chatt.1... 

The most common method for the separation and concentration of flavor chemicals before chromatography is solvent extraction. If the aroma active components in a sample are less than a microgram/liter then solvent extraction followed by fractional distillation can be used to concentrate the analytes above 1 4g/liter. This is done for two reasons (1) to remove the odorants from some of the interfering substances and nonvolatiles, and (2) to concentrate the sample for greater sensitivity. The choice of solvent(s) depends on a number of issues, but similar results can be obtained with many solvents. Table Gl.1.2 lists a number of solvents, their polarity, and physical properties. Pentane is the least polar and ethyl acetate the most. The sample must be an aqueous or dilute sample, dissolved or slurried into water to a final concentration of 80% to 90% water. Dilute aqueous samples will present the greatest polarity difference between the solvent and the sample, driving more volatiles into the extracting solvent. 

The polarity of an alkene is not much different from the polarity of an alkane. Therefore, the physical properties of an alkene are similar to those of the corresponding alkane. For example, 1-pentene melts at — 138°C and boils at 30°C, values that are comparable to those of pentane, which melts at — 130°C and boils at 36°C. 

Abstract. Tungstated zirconia catalysts are stable and highly selective catalytic materials for the isomerization of alkanes when promoted by platinum and a transition metal oxide and when dihydrogen is present in the feed. Physical properties and the catalytic performance of these solids for the isomerization of n-pentane are discussed. 

The names methane, ethane, propane, and butane have historical roots. From pentane on, alkanes are named using the Greek word for the number of carbon atoms, plus the suffix -ane to identify the molecule as an alkane. Table 3-2 gives the names and physical properties of the n-alkanes up to 20 carbon atoms. 

For example, the solubility of pentane in water is only 5.0 x 10"3 mol/L at 25°C. Hydrocarbon compounds, such as those found in crude oil, do not dissolve in water. Instead they float on the surface. This physical property helps clean-up crews minimize the devastating effects of an oil spill. 

Pentacarbonyl(methoxymethylcarbene)chroniiuin(0) is a dull-yellow, crystalline solid mp 34°. It slowly decomposes in the solid state at room temperature in air, but may be stored at 5° for a few days before appreciable decomposition is observed. It is soluble in aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and other common laboratory solvents such as benzene, 1,4-dioxane, tetrahydrofuran, chloroform, dichloromethane, and methanol, and is slightly soluble in ethanol. The infrared spectrum (cyclohexane solution) has v(CO) bands at 2065, 1985, 1965, and 1950 cm-1. The H nmr spectrum in chloroform-d shows the methoxy proton resonance at t6.15 and the methyl proton resonance at t7.70. Other physical properties are reported in the literature.6,7... 

Asphaltene content bears directly on the physical properties of the liquid product. Viscosity is of particular interest because of the importance of this parameter to operation of liquefaction plants and as a measure of the extent of liquefaction. The correlation between asphaltene content and the viscosity of the liquid has been a subject of a number of investigations (23-27). The logarithm of the viscosity ratio, In 7j/rj0 (where i and y0 are the viscosities of the solution and solvent, respectively) was found to be a linear function of concentration when asphaltene was redissolved in the pentane-soluble oil isolated from a coal-derived liquid (24). The slopes of these lines, termed the logarithmic viscosity numbers, are a measure of the contribution to the viscosity of a solution attributable to asphaltene. By comparison of logarithmic viscosity numbers of asphaltenes and their acidic and basic subfractions, it was determined that intermolecular association, which is especially strong between the acid and base subfractions, is responsible for a significant portion of the viscosity of these solutions. 

Z(Oz) series. It is not obvious how this result, which is opposite to that observed for the aromatic neutral fractions, is reconciled with a separation of acids based upon their physical properties, such as solubilities, in pentane and benzene. Similar to the result attained for the aromatic hydrocarbons, the carbon-number distributions for the acid fractions are characterized by the occurrence of maxima early in the distributions of weight percents in the various specific-Z series. However, for corresponding compound types (i.e., the same basic ring structure) the range in carbon number is significantly shorter for the acids than for the aromatic hydrocarbons. 

To test these hypotheses, a tar sand bitumen containing 20 wt % pentane asphaltenes was characterized and processed by hydropyrolysis before and after removal of asphaltenes. Product yields and structure were determined and the influence of asphaltenes on results was determined by inferrence. Feedstocks and products were characterized according to elemental analysis, physical properties, simulated distillation, and carbon-type analysis. Inferences made in this study are discussed in the context of the reported literature. 

The question now arises, how may we determine which one of the various formulas, in the case of the five hexanes for instance, is to be assigned to each individual compound of definite physical properties To which one of the butanes, pentanes and hexanes do we assign the straight chain formula or the name normal In the case of the butanes the answer and the reason for it are found in a new synthesis of one of the butanes. We have given one synthesis of the two butanes, viz., from propyl iodide and methyl iodide. As one propyl iodide yields one butane and the other yields the isomeric butane, we know that one of the two isomeric butanes must have the straight chain or normal formula. But we do not know whether the propyl iodide from which the butane boiling at + i is prepared, is really the one possessing the normal or the iso formula. Therefore, it will be seen that the relationship between the isomeric propyl iodides and the isomeric bu-... 

These are two distinctly different compounds, with different chemical and physical properties for example, they have different boiling points. Similarly, three isomers of pentane, C5HJ2 exist, and so on. 

Because alkanes are nearly nonpolar, their physical properties are determined by dispersion forces. The four-C alkanes boil lower than the five-C compounds (Table 15.3). Moreover, within each group of isomers, the more spherical member (isobutane or neopentane) boils lower than the more elongated one ( -butane or ii-pentane). As you saw in Chapter 12, this trend occurs because a spherical shape leads to less intermolecular contact, and thus lower total dispersion forces, than does an elongated shape. 

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