Heptane solvent

Fig. 1. Examples of the kinetic curves during ethylene polymerization by chromium oxide catalysts. Support—SiOs temperature—80°C polymerization at constant ethylene pressure in perfect mixing reactor. Curve 1—catalyst reduced by CO at 300°C. Curve 2— catalyst activated in vacuum (400°C) polymerization in the case of (1) and (2) in solvent (heptane) ethylene pressure 10 kg/cm2 02 content in ethylene 1 ppm, HsO 3 ppm. Curves 3, 4, 5, 6—catalyst activated in vacuum (400°C) polymerization without solvent ethylene pressure 19 (curve 3), 13 (curve 4), 4 (curve 5), and 2 (curve 6) kg/cm2 02 content in ethylene 1 ppm, HsO = 12 ppm.

Solvent Heptane Pyridine DMF Acetic acid Methanol Water... 

Fig. 5. Formation of butane as a function of time, during the dissociative chemisorption of different sulfur compounds on Pd/ALOj (T = 20°C, P = I bar, solvent = heptane).

The best results have been obtained in the non-polar solvents heptane or 0-xylene. Polar aprotic solvents such as Me2CO, MeCN, DMSO or dioxane gave poor yields and byproduct formations. Water-free conditions to avoid hydrolysis of BC14- have been necessary. The best fluorination yields have been achieved in the 373-393 K temperature interval (in 0-xylene with TBAF, tetrabutylammonium fluoride). An increase in the yield was observed if an excess of the diazonium salt was used. The total labelling procedure took 50 min. The tetrachloroborate incorporates fluoride by a halide exchange reaction (equation 3)9 10. 

Figure 8. Comparison of elemental analyses of SRC from liquefaction of Wyodak coal in —019 (-----------) and —035 (-------) solvents (heptane precipitation data)...

The PET was commercial (0.18 mm) Kodak ESTAR film base. The PE was commercial (0.10 mm) high density (HD) PE. To eliminate surface contamination, the polymer samples were ultrasonically cleaned in a series of solvents (heptane, dichloromethane, ethanol and ethyl acetate) and dried in a dry nitrogen atmosphere in a glove bag attached directly around the insertion probe of the spectrometer. Immediately after drying, the polymer samples were inserted into the preparation chamber of the spectrometer where they were evacuated to 5 x 10 9 Torr. The polymer samples were than annealed (PET 90° C, PE 60° C) for several hours to drive off any residual solvent, water, or adsorbed gases. 

Fractionation of an asphaltene by stepwise precipitation with hydrocarbon solvents (heptane to decane) allows separation of the asphaltene by molecular weight. The structural parameters determined using the x-ray method (Table II) show a relationship to the molecular weight (16). For the particular asphaltene in question (Athabasca), the layer diameters (La) increase with molecular weight to a limiting value similar relationships also appear to exist for the interlamellar distance (c/2), micelle height (Lc), and even the number of lamellae (Nc) in the micelle. 

Tryptophan at Wq was relatively easy to identify with 64 positive correct assignments, whereas W93 was much more difficult (35 positive correct). The number of tentative correct calls for W23, eleven, was the hipest for any residue in the sequence. Several facilities (62/78) indicated the use of modified solvents (heptane sulfonic acid or premix buffers) known to improve the yield of arginine. Of the 31 facilities positively identifying R25,24 used these modified solvents (Hewlett-Packard 6/24, Applied Biosystems 18/24), and 7 did not (Applied Biosystems 4/7, Beckman-Porton 3/7). 

Alternatively, unroasted sesame seeds are pressed once followed by solvent extraction to recover the oil from residue. The oxidative stability of sesame oil was found to be dependent on the extraction method and seed pretreatment (64). Extraction of the sesame seeds after effective seed crushing with polar solvent, heptane-isopropanol (3 1, v/v), would yield a more stable oil from whole sesame seeds because more antioxidative substances and phospholipids could be extracted. Phospholipids may act as synergists to antioxidants (81). 

Normal phase Methanol or other polar solvent Heptane + 10% polar compound (isopropanol, ethyl acetate)... 

Solvent Heptane best, toluene all right, polar solvents no good. 

The effect of lean solvent (heptane) solubility of EHEC as well as the cosolvent efficiency of small additions of isopropyl alcohol is illustrated in Table VIII. About 4% isopropyl alcohol is sufficient to make heptane dissolve EHEC, yielding uniform clear solutions at a nonvolatile concentration as high as 20%. 

Materials. All organic solvents were manufactured by Fisher Scientific Company. The extraction solvent heptane, and the trace contaminant toluene, were of reagent and purified grades respectively. The Internal standard for the gas chromatograph, methanol, was certified ACS. 

Fig. 11 Kinetic curves of the TEA-modified Phillips catalyst (PC600/TEA) at Al/Cr molar ratios of 2.08 white symbols), 3.12 (grey symbols), and 4.16 (black symbols), before ethylene slurry polymerization. Polymerization conditions catalyst amount, 100 mg polymerizatitui temperature, 60°C ethylene pressure, 0.15 MPa solvent heptane, 20 niL...

Fig. 27 Ethylene polymerization kinetic curves of catalysts activated by TEA cocatalyst during slurry polymerizatimi (a) Phillips catalyst al) and Cat-A/1.5 catalyst a2) (Al/Cr molar ratio = 20.0) (b) Cat-A/1.5 catalyst (W) and S-2 catalyst b2) (Al/Cr molar ratio = 15.0). Polymerization conditions catalyst amount, 160 mg polymerization temperature, 90°C ethylene pressure, 0.15 MPa solvent, heptane, 70 mL...

Polymerization ctmditions catalyst amount, 100 mg polymerization temperature, 90°C ethylene pressure, 0.3 MPa solvent, heptane, 200 mL cocatalyst TEA in heptane, Al/Cr molar ratio = 15 nd not detected... 

---