A method for the manufacture of a metal salt of a hydroxy-substituted aromatic compound comprises reacting a hydroxy-substituted aromatic compound with a base comprising a metal cation in an aqueous medium to provide a mixture comprising water and a metal salt of the hydroxy-substituted aromatic compound; contacting the mixture with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at a prevailing pressure; introducing an optionally substituted C1-6 aliphatic alcohol; and removing water and the alcohol to provide a slurry comprising the metal salt of the hydroxy-substituted aromatic compound and the water-immiscible solvent.

A method for the manufacture of a metal salt of a hydroxy-substituted aromatic compound comprises reacting a hydroxy-substituted aromatic compound with a base comprising a metal cation in an aqueous medium to provide a mixture comprising water and a metal salt of the hydroxy-substituted aromatic compound; contacting the mixture with a substantially water-immiscible solvent at a temperature greater than the boiling point of water at a prevailing pressure; introducing an optionally substituted C1-6 aliphatic alcohol; and removing water and the alcohol to provide a slurry comprising the metal salt of the hydroxy-substituted aromatic compound and the water-immiscible solvent.

A method for producing an aqueous electrolyte comprising a redox-active coordination compound of a transition metal which comprises reacting an oxide of the corresponding transition metal in an aqueous reaction medium with a chelating agent in a hydrothermal reaction zone at a temperature in the range of from 100 C. to 160 C. for a period of from 4 hours to 48 hours.