CER Labs 2-3 Figure 1. Friedel-Crafts Acylation.
Claim: An acetyl group was efficiently introduced to ferrocene by Friedel-Crafts Acylation (Figure 1). We isolated our crude yield while comparing 2 purification techniques: column chromatography and recrystallization. TLC, NMR, and IR spectroscopy were used throughout the process to identify ferrocene and acetylferrocene in addition to evaluating the levels of purity.
Evidence: The objective of our experiments was to prepare acetylferrocene from ferrocene. The overall reaction was carried out using 6.1 equivalents of liquid acetic anhydride to 1.8 equivalents of phosphoric acid and concluded with an aqueous workup with NaOH. The initial reaction mixture containing ferrocene, acetic anhydride, and phosphate acid was mixed on a hot stir plate. During this period, reflux was observed, and the mixture appeared dark brown in color. To quench the reaction, the reaction mixture was transferred onto ice. NaOH was slowly added into the mixture, which resulted in acetic acid byproduct from the acetic anhydride reactant/solvent. This resulted in a clumpy and dark mixture. During
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The 1:1 hexane to ethyl acetate solvent resulted in the best separation because it not only showed extra spots that the other solvent mixtures did not have, but also the 4 spots were relatively dispersed with Rf values at 0.77, 0.56, 0.27, and 0.10 (Figure 2). Missing spots were also noted on the hexane only TLC plate. The orange eluent was ultimately chosen as our major product because it had significantly different TLC results than the 3 yellow eluents with the same Rf of 0.23 (Figure 3). The percent yield for this purification method was 248% and the extrapolated percent purified yield was around 135 %, which are both erroneously high. These high percent yield may be due to extra water weight or not fully evaporated