Tetrahydrofuran drying

The minimum amount of catalyst needed to obtain maximum selectivity was determined to be 5 mol%. Larger quantities had no effect. Consistent with other literature reports[17], very small quantities of water (5 mol% = 2.5 mg E O/g 3) lowered the selectivities (Table 11.6, entry 4). Water sensitivity required thorough drying of the equipment, the starting materials and the solvents. In the case of tetrahydrofuran, drying was achieved by using activated 5 A molecular sieves (KF titration >0.005%). On the other hand, solvents used for crystallization of the starting material (3), such as 2-propanol and acetonitrile showed little effect on the enantioselectivities of the reaction (entries 6 and 7). 

B (Alternative) 0.05 M (II), 0.76 ml glacial acetic acid in 75 ml tetrahydrofuran (dry) are added slowly with stirring and cooling over one-half hour to a solution of 25.2 ml dimethylsulfate and 0.76 ml glacial acetic acid in 30 ml dry tetrahydrofuran. After two hours, filter and wash the precipitate with ether. Dissolve precipitate in 10% aqueous solution of KCN and heat one hour at 70°. Filter, wash precipitate with water and dry to get (III). 

Tetrahydrofuran dried over 4 A molecular sieves was purchased from Fluka Chemical AG and purged with dry argon. 

The same yield of 4,4 -dichlorodibutyl ether was obtained from redistilled tetrahydrofuran dried over sodium or a good-quality commercial grade obtained from the Electrochemicals Department of the E. I. du Pont de Nemours and Company and dried over Drierite. 

HSiCls, EtsN, 2-chloro-l,3-dimethylimidazolinium chloride, dry tetrahydrofuran, dry methyl terf-butyl ether, dry diethyl ether. 

A mixture of 10 g of finely powdered anhydrous LiCl, 20 g of powdered anhydrous CuCl (note 1) and 40 g of dry tetrahydrofuran was heated under reflux for 15 min. 

This complex should be used when the organolithium is in solution in a hydrocarbon solvent. For organolithium reagents prepared in ether (see Note 4), the same complex may be used or, more conveniently, copper iodide (Cull can be used. The Cul purchased from Prolabo or Merck 4 Company, Inc. may be used directly. Other commercial sources of Cul (Fluka, Aldrich Chemical Company, Inc., Alfa Products, Morton/Thiokol, Inc.) furnish a salt which affords better results when purified. 1 mol of Cul is stirred for 12 hr with 500 ml of anhydrous tetrahydrofuran, then filtered on a sintered glass funnel ( 3), washed twice with 50 ml of anhydrous tetrahydrofuran, once with 50 ml of anhydrous ether and finally dried under reduced pressure (0.1 imO for 4 hr. 

Dimethyl carbonate is available from Aldrich Chemical Company, Inc. The checkers dried the tetrahydrofuran Immediately before use by distillation from the sodium ketyl of benzophenone under a nitrogen atmosphere. The submitters purchased sodium hydride (50% oil dispersion) from Alfa Products, Morton/Thiokol, Inc. The checkers used 12.24 g of a 50% dispersion of sodium hydride in mineral oil obtained from the same supplier. The dispersion was washed with three portions of pentane to remove the mineral oil and the remaining sodium hydride was allowed to dry under nitrogen. 

Alternatively, if free from the 2-isomer, dissolve in tetrahydrofuran, dilute with H2O to ppte the alcohol. Collect, dry and sublime in a vacuum at 130°. [Chem Ber 92 1629 1959.]... 

Poly(A7-vinylcarbazole) [25067-59-8], Ppted seven times from tetrahydrofuran with MeOH, with a final freeze-drying from benzene. Dried under vacuum. 

Carbonate ionophore I [ETH 6010] (heptyl 4-trifluoroacetylbenzoate) [129476-47-7] M 316.3, b 170°/0.02 Torr, d 0.909. Purified by flash chromatography (2g of reagent with 30g of Silica Gel 60) and eluted with EtOAc/hexane (1 19). The fractions that absorbed at 260nm were pooled, evapd and dried at room temp (10.3 Torr). The oily residue was distd in a bubbled-tube apparatus (170°/0.02 Torr). Its IR (CHCI3) had peaks at 1720, 1280, 940cm and its sol in tetrahydrofuran is 50mg/0.5mL. It is a lipophilic neutral ionophore selective for carbonate as well as being an optical humidity sensor. [Anal Chim Acta 233 41 1990.]... 

Dilongifolyl borane [77882-24-7] M 422.6, m 169-172 . Wash with dry Et20 and dry in a vacuum under N2. It has m 160-161 in a sealed evacuated capillary. It is sparingly soluble in pentane, tetrahydrofuran, carbon tetrachloride, dichloromethane, and chloroform but the suspended material is capable of causing asymmetric hydroboration. Disappearance of solid indicates that the reaction has proceeded. [J Org Chem 46 2988 1981.]... 

Titanium trichloride [7705-07-9] M 154.3, m >500 , pKj 2.55 (for hydrolysis of Ti to TiOH ). Brown purple powder that is very reactive with H2O and pyrophoric when dry. It should be manipulated in a dry box. It is soluble in CH2CI2 and tetrahydrofuran and is used as a M solution in these solvents in the ratio of 2 1, and stored under N2. It is a powerful reducing agent. [Inorg Synth 6 52 I960, Synthesis 833 7989.]... 

The tetrahydrofuran may be used directly without drying or purification. 

Note 9) in 500 ml. of dry tetrahydrofuran i.q added to the gtirred basic mixture heated to 65° over a period of approximately 8 hours a light nitrogen stream is used to carry the methylenecyclopropane into the cold trap. After the addition is complete, the reaction mixture is stirred and heated to 65° for 3 more hours (Note 10). The trap flask contains 58 g. (43%) of methylenecyclopropane (Note 11). 

---