Dipl.-Chem. Pengcheng Zhang

Ionic liquids with fluorine-containing cations offer a wide range of interesting properties, including viscosity, melting point, density, conductivity, solubility, liquid range, thermal and hydrolytic stability.^[1] Hirschberg et. al. investigated the stabilities of the ionic liquids [EMIM][(C₂F₅)₃PF₃], [BMPL][(C₂F₅)₃PF₃], [BMPL][OTf] and [BMPL][B(CN)₄] against diluted fluorine (5 vol% in nitrogen). Their research showed that the cations of the ionic liquids were difficult to fluorinate.^[2] My work focuses on the direct fluorinations of the cations of ionic liquids in a segmented-flow mini reactor and the subsequent characterization of the fluorinated products. The synthesis is supported by quantum chemical calculations.

In cooperation with the group of Prof. Woias (IMTEK, Freiburg i. Br.), new types of mini and micro reactors will be developed. The direct fluorination of organic substrates represents a class of very rapid and exothermic reactions, resulting in challenges for process control during batch syntheses. The segmented-flow reactor is advantageous over traditional methods in terms of heat and mass transfer control, leading to a product synthesis with a high degree of chemical selectivity.^[3] The main advantages of such reactors are a result of the very high surface-to-volume ratios in small channels. A silicon based micro reactor with 300 µm channels will be designed. Micro-nozzles of a variety of dimensions and shapes will allow the study of fluorine microbubble generation and the effects of the resulting increased mass/heat transport. A variety of different fluorine-resistant passivation layers will be tested.

 

[1] H. Xue, J. n. M. Shreeve, Eur. J. Inorg. Chem. 2005, 2573.    

[2] M. Hirschberg, N. Ignat'ev, A. Wenda, H. Willner, J. Fluorine Chem. 2012, 137, 50.

[3] P. Lang, M. Hill, I. Krossing, P. Woias, Chemical Engineering Journal, 2012, 179, 330-337.