Mixed hydrocarbons

Sprays. Aerosol spray emulsions are of the water-in-oil type. The preferred propellant is a hydrocarbon or mixed hydrocarbon—hydrofluorocarbon. About 25 to 30% propellent, miscible with the oil, remains in the external phase of the emulsion. When this system is dispensed, the propellant vaporizes, leaving behind droplets of the w/o emulsion (Fig. 2b). A vapor tap valve, which tends to produce finely dispersed particles, is employed. Because the propellant and the product concentrate tend to separate on standing, products formulated using this system, such as pesticides and room deodorants, must be shaken before use. 

Many organic syntheses requHe the use of stericaHy hindered and less nucleophilic bases than //-butyUithium. Lithium diisopropylamide (LDA) and lithium hexamethyldisilazide (LHS) are often used (140—142). Both compounds are soluble in a wide variety of aprotic solvents. Presence of a Lewis base, most commonly tetrahydrofuran, is requHed for LDA solubdity in hydrocarbons. A 30% solution of LHS can be prepared in hexane. Although these compounds may be prepared by reaction of the amine with //-butyUithium in the approprite medium just prior to use, they are also available commercially in hydrocarbon or mixed hydrocarbon—THF solvents as 1.0—2.0 M solutions. 

In a specific application, a large, mixed hydrocarbon gas system may be set up with a turbine-driven compressor as shown in Figure 8-40(a). 

Man-made mineral fibre Mixed hydrocarbons (C3 to CIO) m air Total hexavalent chromium compounds in air Aromatic carboxylic acid anhydndes m air... 

Walker JD, RS Pore (1978) Growth of Prototheca isolates on -hexadecane and mixed-hydrocarbon substrate. Appl Environ Microbiol 35 694-697. 

Toluene in air (charcoal diffusive samplers, solvent desorption and gas chromatography). Mixed hydrocarbons (C5 to CIO) in air. 

The nature of the catalysts, especially those formed in situ from chlo-rorhodium(I) precursors, deserves some comment. The catalysts have been often written as Rh(P )2Cl(solvent), where P and (P )2 represent monodentate and bidentate chiral phosphines, respectively (10), but this almost certainly pertains for nonpolar media only. In polar media, including the mixed hydrocarbon/alcohol solvents usually employed,... 

Superflex A process for converting mixed hydrocarbon streams to olefins. Developed by Arco Chemical. 

Figure 5.33 shows an example dataset of mixed hydrocarbons used as a petrochemical feedstock. These are straight run naphthas, which consist of a wide range of alkane, isoalkane, aromatic and naphthenic... 

Distinctions between water-soluble fractions of mixed hydrocarbons may be made by using solvent extraction of the water-soluble base/neutral and acid fractions with methylene chloride (EPA 1991c Thomas and Delfino 1991a). This separation of base/neutral and acid fractions will permit the GC resolution of the type of water soluble hydrocarbons present in the aqueous phase. Hexane has also been used as a solvent (DellAcqua and Bush 1973), as has pentane (Coleman et al. 1984). 

The basis of the method was stated by Silver (1947). A numerical solution of a condenser for mixed hydrocarbons was carried out by Webb and McNaught (in Chisholm, 1980, p. 98) comparison of the Silver-Bell-Ghaly result with a Colburn-Hougen calculation showed close agreement in this case. Bell and Ghaly (1973) claim only that their method predicts values from 0 to 100% over the correct values, always conservative. A solution with constant heat transfer coefficients is made in Example 8.11 A recent review of the subject has been presented by McNaught (in Taborek et al., 1983, p. 35). 

Solubility. Also involved in concentration of n-alkanes in the C27-C33 range may be the immobility of higher n-alkanes by reason of insolubility in mixed hydrocarbons underground. Immobility may be assisted by adsorptive forces involving minerals or such organic materials as kerogen. 

Some of the advantages of 3S in comparison with conventional technologies for the separation of hydrocarbons from a mixed hydrocarbon gas stream are ... 

Figure 3.8 shows an example dataset of mixed hydrocarbons used as a petrochemical feedstock. These are straight-run naphthas which consist of a wide range of alkane, alkene, aromatic and naphthenic hydrocarbons, mainly in the range of C4-C9. The conventional analytical method for naphtha analysis is temperature-programmed gas chromatography (GC), which can provide a full analysis including C-number breakdown, but which is rather slow for process optimisation purposes. 

Butadiene (> 98%w/w) 20 ooo longtons Catalytic dehydrogenation of n-butenes feedstock of liquid mixed hydrocarbon stream containing 80.5 mol % n-butenes, 11.5 mol % n-butane, and 1 mol % of higher hydrocarbons. 

Using compounds other than those shown in Figure 13.1, give examples of each of the following kinds of hydrocarbons (1) alkanes, (2) unsaturated nonaromatic hydrocarbons, (3) aromatic hydrocarbons, (4) polycyclic aromatic hydrocarbons with multiple rings, and (5) mixed hydrocarbons. 

One toluene production process commences with mixed hydrocarbon stocks and can be used for making both toluene and benzene, separately or simultaneously. The process is a combination of extraction and distillation. An aqueous dimethyl sulfoxide (DMSO) solution is passed countercur-rently against the mixed hydrocarbon feed. A mixture of aromatic and paraffinic hydrocarbons serves as reflux. 

Analytical thin layer chromatography (TLC) was conducted on pre-coated TLC plates, silica gel 60 F254, layer thickness 0.25 mm, manufactured by E. Merck and Co., Darmstadt, Germany. Silica Gel for flash column chromatography was obtained from Silicycle Chemical Division Silica Gel, 60 (particle size 0.040 - 0.063 mm) 230-240 mesh ASTM. All columns were prepared, loaded, and fractions collected according to the specification of Still.37 Ethyl acetate used for chromatography was dried over 4 A molecular sieves for at least 24 hours prior to use. Hexanes are the mixed hydrocarbon fraction (bp 60-70 °C), principally n-hexanes, which was purified as follows the commercial solvent was stirred concentrated sulfuric acid for at least 24 hours, decanted, stirred over anhydrous sodium carbonate for 6 hours, decanted, then distilled. 

Potassium valerate and potassium cenanthylate give the expected mixed hydrocarbon, a decane, as chief product (butyl-caproyl, Wurtz) ... 

Cracking gases. The mixed hydrocarbon gases, many of them unsaturated, which are obtained from the thermal dissociation of larger hydrocarbon molecules during the refining of petroleum. 

Lurgi-Ruhrgas Also known as LR. A process originally intended for pyrolizing fine-grained solids, such as coal, peat, shale, and tar sands, to produce mixed hydrocarbons. The process is based on flash heating in a mixer by means of circulated hot powders, usually obtained from the... 

I n Equal to (0 for pure aromatics. 11 for pure naphthenics or slightly substituted acoinattcs. 12 for mixed hydrocarbons, and 13 for pure paraffinic products. 

---