Until now, all commercially available ionic liquids suitable for use as electrolytes in electrodeposition have been relatively high-priced, i.e.
in the order of about 50 Euros up to about 1,000 Euros per kilogram.
Ionic liquids are non-volatile salts with a melting point below 100°C.
Many are liquid even at room temperature and they represent a relatively new class of solvents.
Moreover, there is a need for a method to deposit metals on a substrate that requires only a low metal concentration in the solvent, as this gives an improvement from an economic point of view and makes the process more controllable.
A number of examples of the use of ionic liquids are disclosed for example on Merck's and lolitec's web pages: February 3, 2006).It is known that, in general, ionic liquids may be used in many applications, e.g.as reaction solvents, extraction solvents, electrolytes in batteries and electrodeposition, catalysts, heat exchange fluids, as additives in coatings.The choline saccharinate reaction product of Preparation Example 1 first is an oily substance and later is in the crystal form because of the presence of 0.3 mol H2O per mol of choline saccharinate. in Chemical Communications 2004, (6), 630-631 disclose ionic liquids of saccharinate and acesulphamate anions and a quaternary ammonium cation such as a triethylmethyl ammonium or an imidazolium cation. However, none of the above documents discloses or suggests the suitability of N-acyl sulphonyl imide based or fatty alkyl based ionic liquids for use in a method to electrodeposit metals on a substrate.In Preparation Example 3 choline saccharinate is prepared by reacting choline chloride and sodium saccharinate. The above-indicated ionic liquids formed are safe - potentially food grade - and can be applied as a solvent in an electrodeposition or electropolishing method, since they contain a relatively low concentration of metal salt.