Solvent hexane-benzene

Solvents Hexane Benzene CH2CL2 CHCL3 THF AN MeOH H20... 

The dipole moments of a large number of alkylmercuric halides in various organic solvents (hexane, benzene, dioxan, pyridine, ethylacetate) have been reported.158... 

Diastereoselective addition in Et20/HMPT (1 1) leads to the (5)-aldehyde with an enantiomeric excess of 40%, whereas in -hexane the (2 )-aldehyde is formed with 80% ( ) enantiomeric excess. The (2 )-configured aldehyde is also obtained in benzene and in dichloromethane, but with lower ee values of 50% and 25%, respectively. Inverse results were obtained with a chiral oxazolidine prepared from ( )-cinnamaldehyde and (+)-ephedrine. Here, the (5)-aldehyde with ee = 79% is formed in -hexane, and the (7 )-aldehyde in Et20/HMPT (1 1) with ee = 50% [703], This result may be due to different structures of the organocopper reagent, and hence of the diastereomorphic activated complexes, in nonpolar solvents ( -hexane, benzene, dichloromethane) and in EPD solvents (Et20/HMPT) [703]. 

As most hydrosilanes are oils, hydrosilylation is usually carried out without solvent using an equimolar amount or an excess of the hydrosilane. In cases where a substrate is solid or extremely volatile, solvents are employed. Both nonpolar solvents (hexane, benzene, toluene, xylene) and polar solvents (THE, dig-lyme, nitrobenzene, acetone) are applicable, although some polar solvents may affect the yield and selectivity of hydrosilylation, as in equation (3). 

MacGee, in 1947, published a comprehensive review of the early days of solvent extraction (143, 144). Many solvents, such as benzene, aviation gasoline, methanol, ethanol, isopropanol, carbon disulfide, diethyl ether, ethylenedichloride, carbonte-trachloride, trichlorethylene, and the various petroleum naphthas were evaluated. However, by 1947, the most common solvents used in the United States were the light paraffinic petroleum fractions, such as the hexanes, heptanes, and pentanes. Hexane, because it was easily evaporated and left no residual obnoxious odors or tastes, was finally chosen. Later, this decision was further supported by Eaves et al. (145), who investigated the extraction of cottonseed by five commercial solvents (hexane, benzene, ethyl, ether, acetone, and butanone) and concluded that none compared favorably with hexane as an extractant for cottonseed. 

Polymer 2 is insoluble in nonpolar solvents (hexane, benzene, toluene). Like 1, it is rapidly hydrolyzed in moist air. The polymer has Lewis acid properties, for example, it catalyzes the ring-opening polymerization of THF, and the aldol condensation-polymerization of acetone. The molecular weight of 2 cannot be determined directly, but was instead estimated from the molecular weights of polymers made from it, as described below. 

The base, or amino acid mixtures or their hydrochlorides (ca. 1 mg), is dissolved in a small amount of methanol or THF (10-20/il) and is heated with pivalic anhydride (200/il) and triethylamine (10-15) at 70-110 °C for 30 minutes. Alternatively, a mixture of pivalic anhydride, triethylamine and methanol (20 1 1, 250/d) is used. The reaction mixture, if cloudy, is centrifuged and the supernatant is evaporated to dryness in a stream of nitrogen or in vacuo. The product may be taken up in a suitable solvent (hexane, benzene, chloroform etc.) for analysis [135-137]. 

Layer Silica gel G (standard method) solvent hexane-benzene-pyridine (66 4-20-1- 15), 6- cm run of duration 30 min. 

Coupling agents are used at a rate of 0.3-3% by weight of filler. They are applied in a solution in water or in nonpolar solvents (hexane, benzene). In practice the solution concentration varies between 0.1 and 0.3 g Hydrolysis of coupling agents is done at pH between 3.5 and 5 [69,78]. It is also necessary to clean fibers from impurities and lubricants by washing with solvents or by firing at 250-600°C [81]. 

The Matlin group has shown that irradiation of cyclooctadienone 36 in the presence of vinyl ethers produces 7-norbornanones 41 and oxa-triquinanes 42 (Table 81.5). The reaction is envisioned as proceeding via the step-wise cycloaddition to oxyaUyl 37. The electron-rich vinyl ether stabilizes the incipient cationic center in 43, which then undergoes internal O- and C-alkylation of the enolate moiety to give 41 and 42. The product distribution and yields did not show any significant variation with the polarity of the solvent (hexanes, benzene, CHjClj or neat vinyl ether). It is interesting to note that no enone-alkene [2-1-2]-adduct was observed, even when ethyl vinyl ether was used as solvent. This is in contrast to the behavior of pyran-4-one, where irradiation in neat furan produced [2-1-2]-adducts. The photo-excited state lifetime of 36 is limited by rapid cis,trans-isomerization to 40, which does not permit intermolecular capture to be competitive. 

Nitrobenzyl bromide [100-11-8] M 216.0, m 98.5-99.0 . Recrystd four times from abs EtOH, then twice from cyclohexane/hexane/ benzene (1 1 1), followed by vac sublimation at 0.1mm and a final recrystn from the same solvent mixture. [Lichtin and Rao J Am Chem Soc 83 2417 1961.] Has also been crystd from pet ether (b 80-100°, lOmL/g, charcoal). It slowly decomposes even when stored in a desiccator in the dark. IRRITANT. 

Solvents mentioned include hexane, benzene, liquid sulphur dioxide, chloroform, methylene dichloride and ethyl bromide. Where chlorinated solvents are employed the polymer is separated by addition of methanol, filtered, washed with methanol and the product dried in vacuo at 60°C. 

The cooled contents of the 2S0-ml. flask containing ferrous chloride (Note 6) are added to the cold sodium cyclopentadienide solution while passing a stream of nitrogen through both flasks. The combined mixture is stirred for 1.25 hours at a temperature just below reflux. Solvent is removed by distillation, and the ferrocene is extracted from the residue with several portions of refluxing petroleum ether (b.p. 40-60°). The product is obtained by evaporation of the petroleum ether solution. Ferrocene may be purified by recrystallization from pentane or cyclohexane (hexane, benzene, and methanol have also been used) or by sublimation. The 3ueld is 31-34 g. (67-73%) (Note 7), m.p. 173-174°. 

The mixture is cooled to room temperature, then filtered. The solvent is removed under reduced pressure, leaving the tribromide (47) as a foam. The foam is mixed with sodium iodide (9.55 g, 0.064 mole) and acetone (74 ml) and heated under reflux in a nitrogen atmosphere for 3.5 hr. The acetone is removed under reduced pressure and the residue is treated with chloroform and aqueous sodium thiosulfate solution. The chloroform layer is separated and washed with sodium thiosulfate solution until it is free from iodine, then dried over magnesium sulfate, filtered and evaporated to dryness under reduced pressure. The crude product (48) is obtained as a brown sohd (4.85 g) which is chromatographed over alumina (122 g, Merck acid-washed). The column is developed with hexane, benzene and ethyl acetate mixtures. The product (3.43 g) is eluted by benzene and benzene-ethyl acetate (10 1). Recrystallization from acetone yields purified 3jS-acetoxy-pregna-5,14,16-trien-20-one (48), 3.25 g, mp 158-159° 309 m/ (e 10,700). 

Additional product is isolated from the mother liquors which are combined, concentrated in vacuo and the resulting oily residue column chromatographed on neutral alumina using hexane, benzene and ether as successive solvents. The product is isolated by concentrating in vacuo the first few major compound-bearing fractions (10% ether in benzene). The solids are combined and recrystallized from methanol and then from benzene-hexane, melting point 102°C to 105°C. 

Reversed-phase silica gel column Place a cotton wool plug at the bottom of a glass chromatography column. Pack 5 g of reversed-phase silica gel slurried with a solvent mixture of n-hexane-benzene-methanol (80 20 0.4, v/v/v) into the glass column. Place an anhydrous sodium sulfate layer about 1 -cm thick above and below the silica gel bed Bell jar-type filtering apparatus Buchner funnel, 11-cm i.d. 

Glass chromatography column, 15-mm i.d. x 400 mm with a stopcock Silica gel column Place a cotton wool plug at the bottom of glass chromatography column and then add anhydrous sodium sulfate in a layer 1-cm thick. Weigh 10 g of silica gel and pour it into the tube with n-hexane-benzene (1 3, v/v). Rinse the silica gel column with the same solvent system and place an anhydrous sodium sulfate in a layer 1-cm thick on the top the column. 

Prepare a silica gel column as described in Section 3. Dissolve the residue prepared in Section 6.2.2 in 3mL of n-hexane-benzene (1 3, v/v) and transfer the solution to the column. Rinse the flask twice with 5 mL of the same solvent system and also transfer these solutions to the column. Allow the solution to percolate through the column and discard the eluate. Add 190 mL of n-hexane-benzene (1 3, v/v) to the column. Discard the first 60 mL of eluate and collect the second 130 mL of eluate in a 300-mL round-bottom flask. Evaporate the eluate to dryness under reduced pressure. 

Principles and Characteristics Pare et al. [475] have patented another approach to extraction, the Microwave-Assisted Process (MAP ). In MAP the microwaves (2.45 GHz, 500 W) directly heat the material to be extracted, which is immersed in a microwave transparent solvent (such as hexane, benzene or iso-octane). MAP offers a radical change from conventional sample preparation work in the analytical laboratory. The technology was first introduced for liquid-phase extraction but has been extended to gas-phase extraction (headspace analysis). MAP constitutes a relatively new series of technologies that relate to novel methods of enhancing chemistry using microwave energy [476]. 

Results showing the effectiveness of the A1- and A2-dialins in coal liquefaction relative to control solvents, naphthalene, Decalin, and fetralin, are presented in Tables 3.1 and 3.2. In both these tables, each row provides the conversion of the coal sample to each of hexane-, benzene-, and pyridine-solubles (plus gases) by the indicated solvent. Table 3.1 contains data derived at a temperature of 400 C and a reaction time of 0.5 hr. Among the control solvents, it can be seen that the naphthalene... 

These studies have been recently extended to the reaction of n-butylamine (di-BA) and piperidine (PIP) with other aromatic substrates, such as l-chloro-2,4-dinitrobenzene (CDNB) and 4-chloro-3-nitrotrifluoromethylbenzene (CNTFB) in hexane, benzene, mesitylene and binary mixtures of hexane with the aromatic solvents, and the results are consistent with Scheme 4 which includes the proposal of a preferential solvation with the donor solvent, D115. As expected, a decrease in rate was observed in the reactions with butylamine with increasing amounts of the donor solvent, which was attributed to the formation of the EDA complex with the solvent. The result is expressed by equation 18 which, in the limiting case where Ks [Pg.1247]

Non-polar solvent Hexane Heptane Isooctane Cyclohexane Cyclopentane Carbon disulfide Carbon tetrachloride Benzene... 

The aerial parts were leached by soaking 100 g of fresh plants in 100 mL of distilled water. Soil extracts were prepared in a 2 1 proportion. The organic extracts of leaves were obtained with the following solvents hexane, ethyl acetate, chloroform, benzene, acetone, and methanol. The essential oils were obtained by steam distillation and the pure substances with several extraction techniques (11, 12, 13, 14). 

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