Solvent purification tetrahydrofuran

General Considerations. The following chemicals were commercially available and used as received 3,3,3-Triphenylpropionic acid (Acros), 1.0 M LiAlH4 in tetrahydrofuran (THF) (Aldrich), pyridinium dichromate (Acros), 2,6 di-tert-butylpyridine (Acros), dichlorodimethylsilane (Acros), tetraethyl orthosilicate (Aldrich), 3-aminopropyltrimethoxy silane (Aldrich), hexamethyldisilazane (Aldrich), tetrakis (diethylamino) titanium (Aldrich), trimethyl silyl chloride (Aldrich), terephthaloyl chloride (Acros), anhydrous toluene (Acros), and n-butyllithium in hexanes (Aldrich). Anhydrous ether, anhydrous THF, anhydrous dichloromethane, and anhydrous hexanes were obtained from a packed bed solvent purification system utilizing columns of copper oxide catalyst and alumina (ether, hexanes) or dual alumina columns (tetrahydrofuran, dichloromethane) (9). Tetramethylcyclopentadiene (Aldrich) was distilled over sodium metal prior to use. p-Aminophenyltrimethoxysilane (Gelest) was purified by recrystallization from methanol. Anhydrous methanol (Acros) was... 

Materials. Styrene (Aldrich) was purified by distillation from CaH2 before use. n-Butyllithium (Aldrich) was used without further purification. Tetrahydrofuran (Fisher Scientific) was purified in a solvent still by distillation from a sodium/benzophenone mixture. Toluene (Fisher Scientific) was used without further purification. Reagent grade methylene chloride (Baker Chemical Co.) was dried on 5A° molecular sieves. Reagent grade triethy-lamine (Baker) was dried over KOH. Methanesulfonyl chloride (Aldrich, 98%) was used without further purification. 

Loutfy et al. (1985a) have shown that the infrared absorption of CllnPc is unchanged upon purification by train sublimation or ball milling in halogenated solvents or tetrahydrofuran. The x-ray powder diffraction spectra likewise indicated that all these materials were the same polymorph. Dispersion generation layers showed both increased 830 nm sensitivity and increased dark... 

A solution of the acylated thiocyanatohydrin in a minimal amount of 5% potassium hydroxide in diglyme (other solvents such as methanol, ethanol or tetrahydrofuran have also been used) is stirred for 2 days at room temperature. Water is added to the reaction mixture to precipitate the product which is filtered or extracted with ether (or chloroform). The ether extract is washed several times with water, dried (Na2S04), and concentrated under vacuum. The thiirane usually can be crystallized from an appropriate solvent pair. Chromatography over alumina has been used for the purification of episulfides. 

Both polymers 10 and 11 are soluble in common organic solvents, melt without decomposition, and can be drawn into the fibers. Molecular weights of the polymers 10 and 11, determined by gel permeation chromatography with tetrahydrofuran as the eluant after purification by reprecipitation from benzene-ethanol, showed a broad monomodal molecular weight distribution. The degree of polymerization depends on particle size of sodium metal. Polymers with molecular weights of 23,000-34,000 are always obtained, if fine sodium particles are used. 

All the procedures described were performed using dry solvents which were freshly distilled under nitrogen. Tetrahydrofuran and ether were distilled from sodium benzophenone ketal under nitrogen, and dichloromethane from calcium hydride under nitrogen. Petroleum ether (b.p. 40-60 °C) was distilled. Starting materials and solvents were used as obtained from commercial suppliers without further purification unless specified otherwise. 

Tetrahydrofuran (THE) and oxepane (OXP) were distilled from CaH2 prior to use. All other reagents and solvents are commercially available in reagent grade purity and were used without further purification. 

Carotenoids A large number of solvents have been used for extraction of carotenoids from vegetables matrices, such as acetone, tetrahydrofuran, n-hexane, pentane, ethanol, methanol, chloroform [427-431], or solvent mixtures such as dichloromethane/methanol, tetrahydrofuran/methanol, -hexane/acetone, or toluene or ethyl acetate [424,432-435], SPE has been used as an additional purification step by some authors [422,426], Supercritical fluid extraction (SEE) has been widely used, as an alternative method, also adding CO2 modifiers (such as methanol, ethanol, -hexane, water, methylene chloride) to increase extraction efficiency [436-438], In addition, saponification can be carried out, but a loss of the total carotenoid content has been observed and, furthermore, direct solvent extraction has been proved to be a valid alternative [439],... 

The following chemicals were obtained from Aldrich Chemical Company, Inc. and used without further purification 1,3-dimethoxybenzene (99%) butyl lithium (1.6 M in hexanes) 1-formylpiperdine (99%) boron trifiuoride-diethyl ether (purified, redistilled) 2,3-dichloro-5,6-dicyano-l,4-benzo-quinone (98%), and pyridine hydrochloride (98%). All solvents were reagent grade and were obtained from Fisher Scientific and used without further purification except where noted. Silica gel (230-400 mesh) was obtained from EM Scientific. Chloroform was stored over activated, 4-A molecular sieves for at least 24 h prior to use. Tetrahydrofuran (optima grade) was distilled from sodium benzophenone. Pyrrole (99%) was obtained from Aldrich Chemical Company, Inc. and distilled from calcium hydride. 

The submitters used reagent grade tetrahydrofuran (available from Fisher Scientific Company) from a freshly opened bottle. The checkers used tetrahydrofuran purified by distillation from lithium aluminum hydride. See Org. Syn., 46, 105 (1966), for warning regarding purification of this solvent. 

Materials. Spectroscopic-grade solvents were used where fluorescence or contact angle measurements were to be made, appropriate purification steps were taken. The tetrahydrofuran was distilled from lithium aluminum hydride. For contact angle measurements, the following liquids and their surface tensions (dynes/cm.) at 20° were used water, 72.6 formamide, 58.2 ethylene glycol, 47.7 methylene iodide, 50.8 1-bromonaphthalene, 44.6 and n-hexadecane, 27.6. 

Equimolar amounts of pyrryl fulgide (62e) and malonitrile were dissolved in dry tetrahydrofuran (THF) 2 equivalent molars of diisopropylamine dissolved in dry THF were added dropwise to this solution. After addition, the mixture was maintained at ambient temperature for 2.5 h and the white precipitate appeared (disalt 30%). The disalt was filtered off and thoroughly dried under vacuum pressure, then dissolved in 1,2-dichloroethane and treated with acetyl chloride for 2 h without exposure to UV light. Removal of the solvent and purification by silica-gel column... 

---