Toluene tetrahydrofuran

Corrective Action Application Case 1 - Groundwater at the MEMOREX Computer Tape Plant (Santa Clara, California) was contaminated by a leaking underground solvent storage tank (Skladany et al., 1987). Chemical analysis of the groundwater identified the presence of methyl ethyl ketone (MEK) up to 500 ppm xylenes together with ethyl benzene up to 40 ppm cyclohexanone up to 30 ppm cyclohexanol up to 10 ppm acetone up to 10 ppm and toluene, tetrahydrofuran, 2-butanol, and methyl propyl ketone each less than 1 ppm. A biological... 

Toluene is a useful co-solvent in metal-ammonia reductions as first reported by Chapman and his colleagues. The author has found that a toluene-tetrahydrofuran-ammonia mixture (1 1 2) is a particularly useful medium for various metal-ammonia reductions. Procedure 8a (section V) describes the reduction of 17-ethyl-19-nortestosterone in such a system. Ethylene dibromide is used to quench excess lithium. Trituration of the total crude reduction product with methanol affords an 85% yield of 4,5a-dihydro-17-ethyl-19-nortestosterone, mp 207-213° (after sintering at 198°), reported mp 212-213°. For the same reduction using Procedure 5 (section V), Bowers et al obtained a 60% yield of crude product, mp, 196-199°, after column chromatography of the total reduction product. A similar reduction of 17-ethynyl-19-nortestosterone is described in Procedure 8b (section V). The steroid concentration in the toluene-tetrahydrofuran-ammonia system is 0.05 M whereas in the ether-dioxane-ammonia system it is 0.029 M. 

The single most important consideration in nonaqueous GPC is sample solubility. Although adsorption is not an infrequent problem, finding a solvent for a polymer is usually the hard step in analysis. The most common solvents for nonaqueous GPC are toluene, tetrahydrofuran, chloroform, and DMF. A number of potentially useful solvents are toxic, corrosive, or expensive,... 

Technically, two matched thermistors are placed within a thermally insulated compartment with a saturated solvent atmosphere. A droplet of solvent is placed onto one, a droplet of solute onto the other thermistor (Figure 4). Solvent will condense into the solution droplet and raise its temperature until the solution has the same vapour pressure as the solvent. At this point, the temperature difference between the two droplets is read. Solvents with sufficient vapour pressure, such as toluene, tetrahydrofuran, or chloroform, are best suited for strong signals, but water has also been used successfully. 

Thus, an opposite sense of asymmetric induction was found in the solvent system toluene/HM-PA compared to toluene/ tetrahydrofuran, dioxolane or trimethylamine. Optimized conditions for each electrophile are tetrahydrofuran for iodomethane, dioxolane for allyl and benzyl bromide, and trimethylamine for methyl bromoacetatel8. Starting from a-substituted fl-oxo esters, quaternary asymmetric centers arc generated (see Table 6). 

Place p-bromotoluene (1.71 g, 10 mmol) and zinc bromide (1.13 g, 5 mmol) in 5 1 toluene tetrahydrofuran (24 mL) in a flask with an ultrasonic probe,3 a magnetic stirrer, a side-arm, and a tubing adapter connected to a mercury bubbler. 

Prepare a solution of 3-methyl-2-cyclopenten-1-one (0.384 g, 4 mmol) and Ni(acac)2 (21 mg, 0.08 mmol) in 5 1, toluene tetrahydrofuran (2 mL), and slowly add this solution to the organozinc reagent prepared above at 0°C. 

However, to test polymer heterogeneity, which we believe must exist, light scattering data were obtained on this polymer in three different solvents toluene, tetrahydrofuran, and methyl isobutyl ketone. 

It should be noted that the metal-poly-yne polymers except Pt-D -D1 are soluble in a variety of organic solvents such as benzene, toluene, tetrahydrofuran, and methylene chloride in spite of the fact that they contain a heavy metal in the backbone, whereas polymers containing conjugated unsaturation such as polyacetylene and poly(p-dieth-ynylbenzene) are practically insoluble in orgnaic solvents. Even a high molecular weight sample (Mw = 105) of Pt-D1 polymer dissolves in trichloroethylene at least up to a concentration of 50wt-%. 

In a procedure similar to the one just described, an attempt was made to fractionate preasphaltenes. Because of the low solubility of preasphaltenes in toluene, tetrahydrofuran was chosen as the solvent for this ion exchange chromatography. The results where the bases were removed first show 40.2% of the material to be basic and 89.7% to be neutral and acidic. The excessive material recovery (129.9%) was determined to be the result of a partial dissolution of the exchange resin in tetrahydrofuran. Similar limitations of the ion exchange method, discussed by others, emphasize the usefulness of the precipitation methods already discussed (8, 9). 

Fig. 15. Absorption spectra of fluorenyllithium in toluene—tetrahydrofuran mixtures. Volume percentages of THF (a) 43% (b) 50% (c) 63% (d) 100%.

The influence of adjacent stereogenic centers on the diastereoselectivity of the cyclization is addressed in entries 4 13. Alkyl or aryl substituents in the homoallylic position lead only to a moderate preference for the 4,6-m-product (Table 14, entries 4 7)9. Surprisingly, the triflu-oromethyl group exerts complete stereocontrol, which is attributed to its steric and additional electronic repulsion of the enolate moiety in the cyclization transition state (for a detailed discussion see the preceding section). The intramolecular reactions of the bissulfone derivatives (Table 14, entries 11 -14)19 feature a contrathermodynamic production of mainly civ-substituted vinylcyclopentanes. Epimerization of the zr-allyl complex is faster than cyclization, so that an equilibrium between the different isomeric zwitterions is established. Due to unfavorable steric interactions with the substituent R, palladium is preferentially located irunx to R in the cyclization transition state favoring the m-product. The use of toluene, tetrahydrofuran, and acetonitrile as solvents results in poorer diastereoselectivities. Some restrictions apply to the kind of nucleophile employed, thus 2-oxo esters may only give the 0-alkylated product (cf. Table 12)2 19-20. 

Polymer materials possess varying physical and structural properties dependent upon the route of synthesis and polymerization, as was discussed in Section 4.1. Properties also depend upon their actual physical form or state. The as prepared samples obtained by chemical polymerization are in the state of powder. Polymer films are prepared by dissolving the powder in an appropriate organic solvent and then letting the solution dry by slow evaporation. Common solvents with poly(alkylthiophene)s are chloroform, tetrachlormethane, toluene, tetrahydrofuran, decaline, anisole, thiophene and some others, whereas acetone. 

Among the many solvents for plastics, the most widely used are toluene, tetrahydrofuran, dimethylformamide, diethyl ether, acetone, and formic acid. In certain cases, chloroethylene, ethyl acetate, ethanol, and water are also useful. It should he noted that the flammability and toxicity of many solvents requires special care In handling. Benzene should be avoided as much as possible. Tables 3.1 and 3.2 show a compilation of the behaviors of the most important plastics in various solvents. For the systematic analysis of plastics, the distinction between soluble and insoluble polymers provides the first separation into two groups. One can then apply chemical methods to investigate these two groups further. 

Solvents Tetrachloromethcine, toluene, tetrahydrofuran, benzene, chloroform, methyl ethyl ketone, and cyclohexanone (2)... 

The complexes [Re(CO)4LI] [L = P(OMe)3, PMe2Ph, PPha] are air-stable, pale-yellow crystalline solids soluble in most common organic solvents (e.g., hexane, benzene, toluene, tetrahydrofuran, and chloroform). They can be identified readily by their IR and NMR spectra (Table I). The IR spectra in polar solvents show the four absorptions characteristic of a cis complex. However, five absorptions are observed for L = P(OMe)3 when the spectrum is recorded in hexane. The IR spectra of some disubstituted complexes, Re(CO)3L2X, are given in Table III. As will be seen, the presence of mono-and disubstituted complexes can be detected readily by IR spectroscopy. The good separation of the methyl resonances [P(OMe)3 and PMezPh ligands] of the mono- and disubstituted - complexes permits ready assessment of product purity. ... 

PMMA, PVAc Chloroform, toluene, tetrahydrofuran FTIR analysis in transmission showed that residual solvent molecules can be trapped in the films and have an effect on transparency, absorption coefficient and refractive index, UV-Vis, reflection, and FTIR (Ahmed 2008)... 

Heating N3P3CU at 250 °C in vacuum and by allowing the conversion to proceed only up to 70%, linear poly(dichloro-phosphazene) could be isolated (see Eq. 3.30). This polymer was soluble in a number of organic solvents such as benzene, toluene, tetrahydrofuran etc., to form clear viscous solutions. 

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