Esters glymes

Much analytical study has been required to estabHsh the materials for use as solvents and solutes in lithium batteries. References 26 and 27 may be consulted for discussions of electrolytes. Among the best organic solvents are cycHc esters, such as propylene carbonate [108-32-7] (PC), C H O, ethylene carbonate [96-49-1] (EC), C H O, and butyrolactone [96-48-0] and ethers, such as dimethoxyethane [110-71-4] (DME), C H q02, the glymes,... 

To an ice-cold mixture of iPr2NH (31 mL, 0.22 mol) and THF (3mL) was added 1.6 M BuLi in hexane (140 mL, 0.22 mol). A thick liquid resulted and this was added to a soln of 2-methylpropylboronic acid pinacol ester (2 34 g, 0.19 mol) and CH2C12 (18 mL, 24 g, 0.27 mol) dissolved in glyme (165 mL) and cooled to — 78 °C. The mixture was allowed to warm to rt and stirred for 2h. It was diluted with CH2C12 (165 mL), to yield a white precipitate, which was removed by filtration and washed with CH2C12 (2 x 25 mL). The filtrates were combined, concentrated under reduced pressure, and then distilled using a 12-inch spinning-band column. Product was obtained as an oil yield 16.9 g (39%) bp 90-93 °C/ 2.0 Torr. 

The esters, 7-ethoxycyclopropyl acetate (7 a) and benzoate (7b) have been synthesized by the addition of the Simmons-Smith reagent 22> to 1-ethoxy vinyl acetate and benzoate, respectively.4) A potential difficulty in this reaction lies in the fact that zinc iodide, a Lewis acid, is generated in the process and may induce cyclopropane ring opening (Section 4.3.3). However, when glyme is used as a solvent, the acid-labile bonds remain intact since the zinc salt is insoluble in this medium.23)... 

This section deals only with solvents whose reduction products are insoluble in the presence of lithium ions. The list includes open chain ethers such as diethyl ether, dimethoxy ethane, and other polyethers of the glyme family cyclic ethers such as THF, 2Me-THF, and 1,4-dioxane cyclic ketals such as 1,3-dioxolane and 1,3-dioxane, esters such as y-butyrolactone and methyl formate and alkyl carbonates such as PC, EC, DMC, and ethylmethyl carbonate. This list excludes the esters, ethyl and methyl acetates, and diethyl carbonate, whose reduction products are soluble in them (in spite of the presence of Li ions). Solutions of solvents such as acetonitrile and dimethyl formamide are also not included in this section for the same reasons. Figure 6 presents typical steady state voltammo-grams obtained with gold, platinum, and silver electrodes in Li salt solutions in which solvent reduction products are formed and precipitate at potentials above that of lithium metal deposition. These voltammograms are typical of the above-mentioned solvent groups and are characterized by the following features ... 

Single-stage procedures are most commonly used for the Reformatsky reaction with aldehydes and ketones. A mixture of a-halo ester and carbonyl substrate is added to a suspension of zinc at a rate sufficient to maintain the reaction. In the original procedure of Reformatsky, no solvent was used but modem practice is to use benzene or an ether solvent such as diethyl ether, THF, glyme or dimethoxymethane. The reaction is often conducted at reflux temperature, probably to avoid surges from the highly exothermic nature of the reaction. However, in a comparison with a number of aldehydes and ketones, much higher yields were obtained at room temperature than at reflux in benzene (equation 11). ... 

The adjective "open" is a commonly used misnomer. Only if the solvent has a highly elevated boiling point, so that emission of VOCs is within acceptable limits, are these tanks truly open to the ambient atmosphere. VOC solvents (in the US) such as glymes, some other glycol ethers (Ref. 3, Chapter 14), or methyl esters of dibasic (Ref. 3, Chapter 19) or soy-derived acids (Ref. 3, Chapter 6) might be used in this manner. Otherwise, the "open" tank might well be an OTVD in which no heat is applied. 

The dimethyl ethers of oligoethylene glycols (glymes) have long been known to enhance the reactivities of soluble metal salts. For example, in 1960 Zaugg and coworkers described the rate enhancement of sodiomalonate ester alkylation in benzene solution by glymes and a large number of other aprotic, polar additives. 

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