Lithium ethyl carbonate

In an effort to gain fundamental understanding on those key ingredients in the SEI, Xu et al. from the US Army Research Laboratory (ARL) synthesized a series of model lithium alkyl carbonate compounds to simulate the proposed chemical species on the anode surface, including lithium methyl carbonate (LMC), lithium ethyl carbonate (LEC), LEDC, and LPDC, as summarized in Scheme 5.6 [38]. 

Composite electrodes made of two carbon components were evaluated experimentally as anodes for Li-ion batteries. The electrochemical activity of these electrodes in the reaction of reversible lithium intercalation ffom/to a solution of LiPF6 in ethyl carbonate and diethyl carbonate was studied. Compositions of the electrode material promising for the usage in Li-ion batteries were found. 

The electrolyte used in the lithium cell studies was typically 1,2M LiPF6 in ethylene carbonate (EC) propylene carbonate (PC) methyl ethyl carbonate (MEC) in a 3 3 4 mixture. The cells were cycled at room temperature using Maccor Series 4000 control unit in a galvanostatic mode under a constant current density of 0.1 to 1 mA/cm2. 

Cinnamyl ethyl carbonate did not react with the lithium salt of benzyl carbamate. 

Transesterification was not found with ethyl carbonates or lithium phenolates. 

Butyl lithium Ethyl 4-bromobutyrate Potassium carbonate Hydrochloric acid... 

In case of the direct reaction of the natural oil or lower alkyl ester of natural fatty acid and the amine the reaction method for producing the amide derivatives is as follows That is, about 1 mol of the said oils and 1 to 100 equivalent mols of the said amines are mixed in the absence or presence of solvents such alcohols as methanol, ethanol or the like, such aromatic hydrocarbons as benzene, toluene, xylene or the like, such halogenoalkanes as methylene chloride, chloroform, carbon tetrachloride or the like, and such alkenes or alkanes as petroleum ether, benzene, gasoline, ligroin or cyclohexane, such ethers as tetrahyrofuran, dioxane and the like, or a mixture thereof, and the mixture is subjected to the reaction in the absence or presence of catalyst amount or equimolar amount to the amine of an auxiliary agent of condensation, such as alkoholate of alkali metal, i.e. lithium, methylate, lithium ethylate, sodium methylate, sodium ethylate, potassium-t-butylate and the like, or acidic auxiliary agents, i.e. p-toluenesulfonic acid and the like, thereby to yield the amide derivatives. In this reaction, a formal alcohol may be removed from the reaction system. 

The electrolyte solution consists of a lithium salt in an organic solvent. Commonly used salts include lithium hexafluorophosphate, lithium perchlorate, lithium tetra-fluoroborate, lithium hexafluoroarsenate, lithium hexafluorosilicate, and lithium tetraphen)dborate. Organic solvents used in the electrolyte solution are ethylene carbonate, dieth)d carbonate, dimethyl carbonate, methyl ethyl carbonate, and propylene carbonate, to name the most important ones. When a lithium ion battery is charged, the positive lithium ions move from the positive electrode to the negative one. The process to insert the lithium ions into the graphite electrode is called intercalation. When the cell is discharging, the reverse occurs. 

Water decomposes lithium alkyl carbonates, which are used as solvents in the non-aqueous electrolytes in lithium-ion cells. Among the commonly used alkyl carbonates, such as ethyl carbonate, diethyl carbonate, propylene carbonate, dimethyl carbonate, and others, all have shown to be negatively affected by the presence of water. Based on the direct detrimental effects of water on LiPFs salts and on electrolyte carbonate-based solvents as well as the damage inflicted by the indirectly produced trace HF (Eq. (17.4)) on electrode materials, the importance of water removal from the prospective lithium-ion materials is clear. 

An inspection of Tables 17.1 and 17.2 shows that appropriate solvents for lithium batteries mainly belong to classes 6 and 7 and include cyclic (EC, PC) and open-chain (DMC, methyl ethyl carbonate (MEC), diethyl carbonate (DEC), methyl propyl carbonate (MPC) esters and several ethers (dioxolane (DIOX), dimethoxy ethane (DM E), tetrahydrofuran (THE)), as well as inorganic sulfur compounds (SO2, SO2CI2, SOCI2). Sulfur compounds are mainly used as liquid cathode materials. 

HF calculations of the structures and vibrational frequencies of monomers and dimers of lithium alkyl carbonates (methyl, ethyl, and propyl carbonate lithium) and lithium alkoxides (lithium methoxide, lithium ethoxide, lithium propoxide, and lithium butoxide) indicate that they adopt dimeric structures. Dimerisation energies of 214 kJ mol for lithium alkyl carbonates and 266 kJ mol for lithium alkoxides are calculated and are found to be approximately independent of the chain length. 

Lee JT, Lin YW, Jan YS (2004) Allyl ethyl carbonate as an additive for lithium-ion battery electrolytes. J Power Sourc 132 244—248... 

To absolution of 1.00 mol of ethyl lithium in 800-900 ml of diethyl ether (see Chapter II, Exp. 1) was added, with cooling between -20 and -10°C, 0.50 nol of dry propargyl alcohol, dissolved in 100 ml of diethyl ether. Subsequently 1.1 mol of trimethylchlorosilane was introduced over a period of 25 min with cooling between -15 and +5°C. After stirring for an additional 2 h at about 30°C the suspension was poured into a solution of 30 g of acetic acid in 150 ml of water. After stirring for 1 h at room temperature the layers were separated and the aqueous layer v/as extracted four times with diethyl ether. The combined ethereal solutions were washed with sodium hydrogen carbonate solution in order to neutralize acetic acid, and were then dried over magnesium sulfate. The diethyl ether was removed by evaporation in a water-pump vacuum and the residue distilled... 

The vinyl ether may be further purified by dissolving it in 15 ml of dry ether and adding a solution of 0.25 g of lithium aluminum hydride in 10 ml of dry ether. The mixture is refluxed for 30 minutes, and excess hydride is destroyed by addition of ethyl acetate (1 ml). Ice-cold dilute (0.5 N) sulfuric acid (25 ml) is gradually added to the cooled mixture, the ethereal layer is rapidly separated, the aqueous layer is extracted once with 10 ml of ether, and the combined ethereal solution is washed once with water and dried over potassium carbonate. Removal of the solvent, followed by distillation of the residue affords about 85% recovery of the pure vinyl ether, bp 102-10376 mm, 1.5045. 

In ( )-[2-(l-propenyl)-l, 3-dithian-2-yl]lithium, no problem of EjZ selectivity arises. It is easily prepared by deprotonation of the allylic dithiane87,88 with butyllithium in THF, whereas deprotonation of the 2-propylidene-l, 3-dithiane requires the assistance of HMPA. The addition to saturated aldehydes proceeds with excellent y-regioseleetivity and anti selectivity88,89. As often observed in similar cases, aldehydes which bear an, p2-carbon atom adjacent to the carbonyl group give lower selectivities. The stereoselectivity decreases with ketones (2-bu-tanone y/a 84 16, antiisyn 77 23)88. The reaction with ethyl 2-oxopropanoate is merely nonstereoselective90, but addition of zinc chloride improved the syn/anti ratio to 96 4, leading to an efficient synthesis of ( )-crobarbatic acid. 

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