Three symmetric substances originating from triethyl phosphate were specifically synthesized with varying degree of fluorination at the side chain. Different concentrations of each phosphate were evaluated as co-solvent with regard to their flammability and the electrochemical cycling performance. With higher degree of fluorination and a higher amount of the phosphate in the electrolyte, the self-extinguishing time (SET), a value to determine and compare the flammability of electrolytes, could be significantly lowered to yield a non-flammable electrolyte mixture. A specifically designed SET device is introduced, which offers more accurate results due to lowered standard deviations by minimizing random and systematic errors. As the application of phosphates as co-solvents results in a trade-off in cycling performance, a thorough determination in regard to the ionic conductivity, the anodic oxidation stability and the compatibility with anode and cathode material was carried out in half- and full-cells. The manuscript strives to establish a deeper understanding of the influence that the utilization of phosphates as co-solvents entail with special focus on the fluorination degree. It could be shown that the partially fluorinated phosphate offers the best cycling results and therefore the lowest trade-off in performance, while a severe improvement in SET could be achieved compared to the reference electrolyte.

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The behavior of linear and cyclic fluorinated 1,3,5-triketones and their metal derivatives towards common halogenating agents was examined, and optimal reaction conditions for the straightforward synthesis of mono-, di-, and tetrahalogenated products were found (Schemes 1 -3). An aromatization through a double HBr elimination from an a,a'-dibrominated cyclohexanone was shown to be a promising synthetic route to 1,1'-(2-hydroxy-1,3-phenylene)bis[2,2,2-trifluoroethanones] (= 2,6-bis(trifluoro-A C H T U N G T R E N N U N G acetyl)phenols; Scheme 4). Additionally, the 1,3,5-triketones prepared add readily H 2 O or alcohols to produce novel bridged 2,6-dihydroxypyran-4-ones (Scheme 2). The structure of the obtained compounds 6a and 7a was confirmed by X-ray structure analysis.

An efficient and reliable method to synthesize 2,6-bis(trifluoroacetyl)phenols bearing various substituents in the 4-position was developed. These valuable fluorinated building blocks were obtained from the corresponding cyclohexanones in a facile and convenient procedure, demonstrated to be superior to the traditional approaches. The application of this methodology to cyclohexane-1,4-dione opened access to 2,5-bis(polyfluoroacyl)-1,4-hydroquinones. Structural peculiarities of the obtained phenols as well as their 1,3-dicarbonyl or 1,3,5-tricarbonyl precursors are discussed on the basis of multinuclear NMR spectroscopy.