Patent GB-827521-A (GB)
Title: New organic copper compounds and solutions and mixtures containing the same, and processes for the preparation of such compounds
Inventor: PEROLD IZAK STEPHANUS
IPC: C05D9/02
Filed: 1957-03-27
Abstract: A water-soluble alkali metal (or ammonium) copper citrate complex compound is obtained by the de-ionising or de-activating of copper (Cu) from copper sulphate or other known copper salt or compound by causing the said salt or compound to react with citric acid in the presence of water and of sodium hydroxide or other alkali metal hydroxide or ammonium hydroxide so as to form in solution an alkali metal (or ammonium) copper citrate complex compound.  The complex is of greenish-blue crystalline form and has the probable formula <FORM:0827521/IV (b)/1> wherein R is the cation of the alkali employed, and may be recovered by crystallizing out from the solution or by evaporating the solution to dryness.  When copper sulphate is used in the preparation 6 gram-molecules of alkali and 2 gram molecules of citric acid are required per gram atom of copper and in this case a gram molecule of alkali sulphate is also formed but this need not be removed from the complex.  Other copper compounds which may be used are the chloride, nitrate, carbonate, hydroxide, oxide and (to a lesser extent) phosphate of copper.  In an example finely divided solid sodium hydroxide (6 mols.) is added to a stirred aqueous solution of citric acid (2 mols.) (or the citric acid is added to a stirred aqueous solution of the sodium hydroxide) and 1 mol. of powdered cupric sulphate is added to the hot stirred solution, the complex (together with some sodium sulphate) being recovered by evaporating the solution to dryness at 100 DEG  C. to 120 DEG  C.  The complex may be added to a suitable preselected medium or solvent to provide a composition which will enable copper to be readily assimilated by plants or animals (see Groups I and VI).ALSO:A composition suitable for application to the soil comprises a mixture of a water-soluble alkali metal (or ammonium) copper citrate complex with a suitable solvent or medium, e.g. irrigation water, soil, or a fertilizer, e.g. superphosphate, the said complex being obtained by reacting copper sulphate or other known copper salt or compound with citric acid in the presence of water and of an alkali metal hydroxide for ammonium hydroxide (see Group IV(b)).  The composition may additionally contain either or both of the alkali metal (or ammonium) cobalt citrate complexes disclosed in Specification 827,522 and/or the alkali metal (or ammonium) copper tartrate complex disclosed in Specification 827,523.ALSO:A composition serving as a source of copper for the purpose of combating copper deficiency diseases in animals (including humans) or other living organisms comprises a solution or mixture of a water-soluble alkali metal (or ammonium) copper citrate complex compound, the solution or mixture being obtained by adding a predetermined quantity of the complex compound to a medium or solvent which will serve as a vehicle for the complex, without interfering with the assimilation of the copper by the said organism, the said complex compound being obtained by reacting copper sulphate or other known copper salt or compound with citric acid in the presence of water and of sodium hydroxide or other alkali metal hydroxide or ammonium hydroxide (see Group IV (b)). The medium used for the composition may be one from which the living organism draws or is intended to draw sustenance or nutrition, e.g. drinking water in the case of animals.  The drinking water for animals may suitably contain from 9 to 30 grams of the complex to each 1000 litres of water.  The composition may additionally contain either or both of the alkali metal (or ammonium) cobalt citrate complexes disclosed in Specification 827,522 and/or the alkali metal (or ammonium) copper tartrate complex disclosed in Specification 827,523.