ChemInform Abstract: A Simple Conversion of 1‐Chloroethyl Carbonates to Fluoroformates: Value in the Preparation of Tertiary Alkyl Fluoroformates.

Dang, V. A.; Olofson, R. A.; Wolf, P. R.; Piteau, Marc; Senet, J.‐P. G.

doi:10.1002/chin.199034092

Cited by 4 publications

(4 citation statements)

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“…Asymmetric fluorinated linear carbonate.-The asymmetric fluorinated linear carbonates were synthesized from the corresponding fluorinated alcohols with methyl or ethyl chloroformate following a procedure in the literature. 17 In a typical procedure for trifluoroethyl methyl carbonate (F-EMC), 2,2,2-trifluoroethanol (Sigma-Aldrich, 50.02 g, 0.5 mol, 1 equiv), triethylamine (Sigma-Aldrich, 55.65 g, 0.55 mol, 1.1 equiv), and 4-dimethylaminopyridine (Sigma-Aldrich, 0.61 g, 5 mmol, 1% mol) were mixed together in a round-bottom flask and cooled to 0 • C. Methyl chloroformate (Sigma-Aldrich, 47.25 g, 0.5 mol, 1 equiv) was added into the mixture dropwise via a syringe pump over the course of 6 h. The mixture was then allowed to warm up to ambient temperature and stirred for 24 h. The reaction was then quenched with 1N HCl solution, and the product was washed further with HCl and then brine solution. After being dried with 4 Å molecular sieves, the crude product was fractional distilled twice to obtain pure product (99.7% by gas chromatography) with an isolated yield of 50% and 15 ppm water content as measured by Karl-Fischer titration.…”

Section: Methodsmentioning

confidence: 99%

Fluorinated Electrolytes for 5-V Li-Ion Chemistry: Probing Voltage Stability of Electrolytes with Electrochemical Floating Test

Xue

et al. 2015

J. Electrochem. Soc.

122

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A series of electrolyte formulations containing fluorinated cyclic carbonates and fluorinated linear carbonates with LiPF 6 has been evaluated as electrolyte solvents for high-voltage Li-ion batteries. The anodic stability of the new electrolytes on fully charged spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode was examined by electrochemical floating tests. The effects of fluorine substitution on the cyclic and linear carbonate, ratio of cyclic vs. linear carbonate, and LiPF 6 concentration on the electrolyte oxidation stability were investigated. Based on this study, the floating test proved to be an effective tool for identification of stable electrolyte materials. have been proposed. Because of the large number of candidates for high-voltage electrolyte solvents, screening the voltage stability of each solvent would be very labor-intensive. Traditional methods of measuring the oxidation potential of organic solvents usually involves linear/cyclic voltammetry using an inert electrode such as platinum and glassy carbon. However, such measurements are in many cases misleading, because interactions of these organic solvents with actual electrode materials are usually more complicated and may happen at a much lower potential due to the catalytic effect of the cathode material lowering the kinetic barrier of oxidation. Unfortunately, using active cathode material to run voltammetry measurement has a drawback in that the material itself is redox active and can interfere with the observation of electrolyte oxidation. Thus, developing a fast and effective method to screen the voltage stability of electrolyte solvents on actual cathode materials is of vital importance. Herein, we report a method using constant potential electrolysis with a slightly overcharged LNMO cathode as the working electrode, abbreviated as an "electrochemical floating test", where the cell potential is allowed to "float" at different values to evaluate the voltage stability of the electrolyte. For an ideal electrolyte with no impurities and no oxidation at the working electrode, the only current observed when a potential is applied is the capacitance current, which should decline to zero when the equilibrium is reached. However, in reality, the electrolytes are oxidized, and the current intensity measured corresponds to the severity of oxidation. As a result, the leakage currents of each electrolyte at different potentials can be compared to produce a voltage stability profile of a given solvent. The effect of different ratios of mixed solvents and lithium salt concentrations can also be probed. * Electrochemical Society Active Member.z E-mail: zzhang@anl.gov Materials and MethodsTheoretical calculations.-The Gaussian 09 code was used for all calculations.14 Oxidation and reduction potentials were calculated by optimizing the geometries of the neutral and ionic species at the B3LYP/6-31G * level, followed by frequency calculations to determine gas-phase free energies. Solvation effects were taken into account by using a single-point B3LYP/6-31+G * PCM...

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Section: Methodsmentioning

confidence: 99%

Fluorinated Electrolytes for 5-V Li-Ion Chemistry: Probing Voltage Stability of Electrolytes with Electrochemical Floating Test

Xue

et al. 2015

J. Electrochem. Soc.

122

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“…Benzyl fluoroformate was prepared from the alcohol via the 1-chloroethyl benzyl carbonate, as described earlier [20]. This original report described the benzyl fluoroformate as being isolated in 60% yield after a subsequent distillation.…”

Section: Methodsmentioning

confidence: 99%

Rate and Product Studies of Solvolyses of Benzyl Fluoroformate

Kyong

Ryu

Kevill

2006

IJMS

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Abstract:The specific rates of solvolysis of benzyl fluoroformate have been measured in several hydroxylic solvents at 25.0 °C. For methanolysis, the solvent deuterium isotope effect and activation parameters were determined and activation parameters were also determined for solvolyses in ethanol and 80% ethanol. For several of the binary hydroxylic solvents, measurement of product ratios allowed selectivity values to be determined. An extended Grunwald-Winstein treatment of the data led to sensitivities to changes in solvent nucleophilicity and ionizing power. Comparison with previously determined specific rates for solvolysis of the chloroformate gave fluorine/chlorine rate ratios greater than unity. All of the determinations made were consistent with an addition-elimination (associationdissociation) mechanism, with addition rate-determining.

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“…Trifluoroethyl methyl carbonate (FEMC).-The asymmetric fluorinated linear carbonates were synthesized from the corresponding fluorinated alcohols with methyl chloroformate following a procedure in the literature. 27 2,2,2-trifluoroethanol (Sigma-Aldrich, 50.02 g, 0.5 mol, 1 equiv), triethylamine (Sigma-Aldrich, 55.65 g, 0.55 mol, 1.1 equiv), and 4-dimethylaminopyridine (Sigma-Aldrich, 0.61 g, 5 mmol, 1% mol) were mixed together in a round-bottom flask and cooled to 0 °C. Methyl chloroformate (Sigma-Aldrich, 47.25 g, 0.5 mol, 1 equiv) was added into the mixture dropwise via a syringe pump over the course of 6 h. The mixture was then allowed to warm up to ambient temperature and stirred for 24 h. The reaction was then quenched with 1 M HCl solution, and the product was washed further with HCl and then brine solution.…”

Section: Methodsmentioning

confidence: 99%

The Impact of Different Substituents in Fluorinated Cyclic Carbonates in the Performance of High Voltage Lithium-Ion Battery Electrolyte

Peebles

et al. 2021

J. Electrochem. Soc.

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Ethylene carbonate (EC) has been used as the Solid-Electrolyte Interphase (SEI) former in the conventional electrolyte for decades. However, its low anodic stability leads to severe capacity decay during cycling under high voltage operation. Therefore, finding a viable electrolyte with high anodic stability and the ability to form robust SEI for high voltage lithium-ion batteries is of primary importance. In this study, a series of electrolytes containing various fluorinated cyclic carbonates as the SEI former have been designed, synthesized and evaluated. Linear sweep voltammetry study suggested that fluorinated cyclic carbonates generally possess higher anodic stability than EC. Based on the cycling performance of LiNi0.5Co0.2Mn0.3O2 (NMC532)/ graphite full cells, the electrolyte with DFEC/FEMC (1.0 M LiPF6) inhibited the oxidation side reaction on the cathode and forms a vigorous SEI on the anode. The high voltage NMC532/Graphite cell utilizing the novel electrolyte exhibits excellent cycling durability under both room and elevated temperature. The superior performance of the DFEC based electrolyte was further unveiled by SEM, EDAX and XRD. Both the anode and cathode of the full cell employing DFEC based electrolyte retained their intrinsic structures after cycling while the electrodes cycled in conventional electrolyte showed severe degradation.

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ChemInform Abstract: A Simple Conversion of 1‐Chloroethyl Carbonates to Fluoroformates: Value in the Preparation of Tertiary Alkyl Fluoroformates.

Abstract: 092ChemInform Abstract A series of eleven 1-chloroethyl carbonates such as (III), prepared by reaction of the chloroformate (I) with the alcohols (II), is converted into the corresponding fluoroformates (IV) by treatment with KF in the presence of a crown ether and under reduced pressure.

Cited by 4 publications

References 1 publication

Fluorinated Electrolytes for 5-V Li-Ion Chemistry: Probing Voltage Stability of Electrolytes with Electrochemical Floating Test

Fluorinated Electrolytes for 5-V Li-Ion Chemistry: Probing Voltage Stability of Electrolytes with Electrochemical Floating Test

Rate and Product Studies of Solvolyses of Benzyl Fluoroformate

The Impact of Different Substituents in Fluorinated Cyclic Carbonates in the Performance of High Voltage Lithium-Ion Battery Electrolyte

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