Alternative Methods for Preparation of Gluconate Salts Using Heterogeneous Non-Metal Catalysts

Gluconate salts can be prepared using alternative non-metal catalysts based on methylene blue dye salt derivatives. Novel Methylene blue (MB) salts based on trifluoromethanesulfonate (TfO) and docusate (AOT) anions have been prepared and characterized by spectroscopic techniques, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectra) in order to proof their chemical structure stability as well as final purity. (MB)(TfO) showed a similar behavior of commercial available (MB)Cl as homogenous catalyst for preparation of sodium gluconate. Contrarily, (MB)(AOT) as non-toxic, lower melting point and water-immiscible dye salt has been used as efficient and recycled heterogeneous catalyst for preparation of sodium gluconate in shorter reaction time, higher yields and purity grade. This alternative method can be extended to other relevant gluconate salts such as calcium, barium, magnesium, potassium, lithium and several transition metals.