Endres-quality

A further error in IL synthesis can originate from purification processes. In order to remove the often yellowish color of ionic liquids after synthesis they are commonly purified over silica or alumina powder (see above). Once we obtained a liquid where the supplier invested a lot of effort to deliver Endres-quality . [EMIMJTFSA was made with the best available educts in the add-base routine from diluted aqueous [EMIMJOH and H-TFSA. This approach exdudes metal and halide impurities. The supplier removed the slight yellowish color by purification over silica. For this purpose the supplier used quite a fresh silica, which had not been used in any purification process before. One has to bear in mind that the dominant impurities, even in hiqh quality silica, are aluminum species. Figure 11.26 shows the 1st, the 7th and the 15th cydes of this liquid on Au(l 11). Apparently... 

Endres, H.E. Air Quality Measurement and Management. In Sensors in Intelligent Buildings, Sensors Applications Volume 2, edited by O. Gassmann, H. Meix-ner, Wiley-VCH Weinheim (2000), p. 85-103. 

Juran JM, Endres A. Quality improvement for services. Wilton, CT Juran Institute Inc, 1986. 

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