Ethers and nitrogen

Dimethyl ether and nitrogen were dried by passage through columns of Drierite. Boron trifluoride etherate (Eastman Practical Grade) was redistilled. Epichlorohydrin (Eastman Organic Chemicals) and methylene chloride (Fisher Scientific Company) were used as received. 

A solution of diazomethane in diethyl ether is required to prepare the Me HODEs in Basic Protocol 2. To prepare this reagent, a nitrogen stream is saturated with diethyl ether, and this is bubbled into a mixture of Diazald, potassium hydroxide, methanol, and diethyl ether. The reaction produces a gaseous mixture of diazomethane, diethyl ether, and nitrogen. The gaseous mixture can be used immediately or trapped and stored in cold diethyl ether. This method is from Gardner (1997) and Schlenk and Gellerman (1960). For another description of the required apparatus, refer to the latter reference. 

Gaseous diazomethane, diethyl ether, and nitrogen collect in the head space of the second vessel. This gaseous solution can be trapped in dry ice-cooled diethyl ether for storage and later use (steps 5 to 7) or can be used immediately by bubbling directly into a methanolic sample. 

Indirect evidence for this proposal is found in correlations between heats of mixing and frequency shifts. Systematic relationships have been noted between Ava of methanol-rf in a variety of bases and AH of solution of chloroform in these same bases, first by Gordy and Stanford (812) and later by Tamres and co-workers (1823, 1995, 1824, and 1996). Most of the data of Tamres et aL are shown in Fig. 3-7 together with their straight line correlations. These three distinct base types (aromatics, ethers, and nitrogen bases) display different intercepts, but the slopes are surprisingly similar. 

Anionic polymerizations are initiated in polar systems by bases and Lewis bases. For example, alkali metals, alcoholates, metal ketyls, metal alkyls, amines, phosphines, and Grignard compounds act as initiators. However, the polymerization mechanism does not depend on the nature of the initiator alone. For example, tertiary amines and phosphines do not only initiate anionic polymerizations under certain conditions, they can also initiate zwitterion polymerizations. In addition, polyinsertions can proceed in less polar systems. Thus, anionic polymerizations are often carried out in polar solvents. Ethers and nitrogen compounds, such as tetrahydrofuran, ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), pyridine, and ammonia are most commonly used. 

Anionic polymerizations require polar systems, since polyinsertions and not anionic polymerizations occur in strongly apolar systems. Consequently in many cases the polymerizations are carried out in polar solvents. Ethers and nitrogen bases are especially suitable for such solvents. Tetrahydrofuran, ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), pyridine, and ammonia are often used. 

TLC has been carried out on silica gel G layers, using the solvents I benzene II benzene-ethanol (90 + 3) III benzene-ethanol (90 + 6) IV propane-1,2-diol-methanol (50 + 50) and V chlorobenzene-propane-1,2-diol-methanol (33 + 33 + 33). In this way, ferrocenyl-methanol, ferrocene ketones, esters, ethers and nitrogen-containing derivatives can be separated, whereas ferrocene and ferrocenyl-hydro-carbons migrate with the front n-hexane is suitable for separating these last named. 

The key initiation step in cationic polymerization of alkenes is the formation of a carbocationic intermediate, which can then interact with excess monomer to start propagation. We studied in some detail the initiation of cationic polymerization under superacidic, stable ion conditions. Carbocations also play a key role, as I found not only in the acid-catalyzed polymerization of alkenes but also in the polycondensation of arenes as well as in the ring opening polymerization of cyclic ethers, sulfides, and nitrogen compounds. Superacidic oxidative condensation of alkanes can even be achieved, including that of methane, as can the co-condensation of alkanes and alkenes. 

Passing a stream of nitrogen at 95—100°C through a reaction mixture of ethyl ether and 30 wt % oleum prepared at 15°C results in the entrainment of diethyl sulfate. Continuous operation provides a >50% yield (96). The most economical process for the manufacture of diethyl sulfate starts with ethylene and 96 wt % sulfuric acid heated at 60°C. The resulting mixture of 43 wt % diethyl sulfate, 45 wt % ethyl hydrogen sulfate, and 12 wt % sulfuric acid is heated with anhydrous sodium sulfate under vacuum, and diethyl sulfate is obtained in 86% yield the commercial product is >99% pure (97). 

It melts at 39°C and may be purified by vacuum sublimation. The Hquid boils at 233°C to give a monomeric vapor in which the Ti—Br distance is 231 pm. Titanium tetrabromide is soluble in dry chloroform, carbon tetrachloride, ether, and alcohol. Like titanium tetrachloride, TiBr forms a range of adducts with molecules such as ammonia, amines, nitrogen heterocycles, esters, and ethers. 

Bismuth tribromide may be prepared by dissolving Bi O in excess concentrated hydrobromic acid. The slurry formed is allowed to dry in air, then gendy heated in a stream of nitrogen to remove water, and finally distilled in a stream of dry nitrogen. Bismuth tribromide is soluble in aqueous solutions of KCl, HCl, KBr, and KI but is decomposed by water to form bismuth oxybromide [7787-57-7] BiOBr. It is soluble in acetone and ether, and practically insoluble in alcohol. It forms complexes with NH and dissolves in hydrobromic acid from which dihydrogen bismuth pentabromide tetrahydrate [66214-38-8] H2BiBr 4H2O, maybe crystallized at —lO C. 

Xmax) 850 (287nm) in hexane, X ax 275, 287 and 297nm nm. Purified by chromatography on columns of magnesium oxide-Supercel (a diatomaceous filter aid) or alumina [Rabourn et al. Arch Biochem Biophys 48 267 1954]. Stored as a solution in pet ether under nitrogen at -20°. 

Thiothienoyltrifluoroacetone [4552-64-1] M 228.2, m 61-62". Easily oxidised and has to be purified before use. This may be by recrystd from benzene or by dissolution in pet ether, extraction into IM NaOH soln, acidification of the aqueous phase with 1-6M HCl soln, back extraction into pet ether and final evapn of the solvent. The purity can be checked by TLC. It was stored in ampoules under nitrogen at 0" in the dark. [Muller and Rother Anal Chim Acta 66 49 1973.]... 

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