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New Synthesis of Ferrocene Monocarboxylic Acid and Systematic Studies on the Preparation of Related Key-Intermediates

“…The spectra obtained ( 1 H-NMR in CDCl 3 and IR in KBr disk or liquid film of the crude chloride) were in agreement with those expected for the structure of monosubstituted ferrocenes [53,62,63], and also in agreement with the literature [46,65].…”

“…It is known that silver(I) ion oxidizes ferrocenes [27], but it has also been reported [37] (and verified by us) that ferricenium salts (oxidized ferrocenes) revert to ferrocene in the presence of sodium hydroxide. b) Another new method we used is a modified oxidative cleavage (haloform reaction) of the easily prepared [53] acetyl ferrocene using sodium metaperiodate in neutral aqueous medium. When we carried out the reaction between ferrocenecarboxaldehyde, silver nitrate and sodium hydroxide in aqueous ethanol, we obtained ferrocenemonocarboxylic acid in high yields (91±98%, several runs).…”

“…Elemental Analysis (%) for C 26 IR ( KBr disk, cm ±1 ) 3100 (C±H stretching, Cp ring); 2950 (C±H stretching, piperazine ring); 2500±2000 (N±H stretching, ammonium salt); 1700 (carboxylate stretching); 1640 (C±C stretching, Cp ring); 1380 (C±N stretching); 1100 and 1000 (ªferrocene bandsº characteristic of monosubstituted ferrocenes [53,62] Elemental Analysis (%) for C 26 IR ( KBr disk, cm ±1 ) 3100 (C±H stretching, Cp ring); 2950 (C±H stretching, piperazine ring); 2500±2000 (N±H stretching, ammonium salt); 1700 (carboxylate stretching); 1640 (C±C stretching, Cp ring); 1380 (C±N stretching); 1100 and 1000 (ªferrocene bandsº characteristic of monosubstituted ferrocenes [53,62] …”

“…The mixture was stirred for 4±8 hours, added to water, neutralized with HCl 1 : 1 until pH: 6.5±7.0. We made tentative assignments, based on the general structure of monosubstituted ferrocenes [53,62,63] and on general rules for the interpretation of the IR spectra of organic compounds [66]. The product was obtained in the form of orange brown crystals, mp 163, 164±165, 169°C (lit.…”

Synthesis and Characterization of New Ferrocene‐Containing Ionic Liquids

“…The synthetic route for these compounds started with monoacylation of ferrocene with ω‐bromoacid chlorides (Scheme ). Although AlCl 3 is the most commonly used Lewis acid for this reaction, we chose to use BF 3 · OEt 2 23b because, whereas AlCl 3 often gives a mixture of the mono‐ and diacylated product, it is known that only monoacylation occurs with this Lewis acid 23b. It must be mentioned that irrespective of the Lewis acid used, Zn‐powder was required for the acylation process with ω‐bromoacid chlorides, because, as Bhatt et al23a reported in 1992, either decomposition (black‐coloring of solution) or oxidation of the ferrocene unit was observed in the absence of elemental Zn.…”