Patent GB-1479527-A (GB)
Title: Chelation agents and their chelates
IPC: A01N37/44
Filed: 1975-04-07
Abstract: 1479527 Chelation agents and their chelates MANUFACTURE DE PRODUITS CHIMIQUES PROTEX 7 April 1975 [12 April 1974] 14085/75 Heading C2C The invention comprises an aromatic chelation agent comprising a central aliphatic chain formed of one or several groups of three carbon atoms separated by nitrogen atoms and by two external aryl-alkyl groups, the median carbon atom of the central aliphatic chains being hydroxylized. Preferably each of the two external aryl-alkyl groups is constituted by: an aromatic ring separated from the extreme nitrogen atoms of the central group by a group where M is hydrogen, an alkali metal or ammonium with 1 to 4 substitutions; an ortho phenolic carbon hydroxyl carrying the carbonyl function. These chelation agents have as general formula in which R 1  to R 5  are hydrogen, or C 1  to C 3  alkyl groups; S 1  and S 2  are hydrogen, or a CH 2 CH 2 OH group, or a radical having 1 to 12 carbon atoms, N is an integer of 1 to 4, Z 1  to Z 8  are hydrogen or the substituent groups alkyl, alkoxyl, carbonyl, hydroxyl, amino, nitro, halogen or sulpho, which cannot be hydrolysed, M 1  to M 4  are hydrogen, an alkali metal or primary, secondary or tertiary amine salt. The chelating agents may be prepared by (a) reacting two gram-molecules of an alkaline glyoxalate with two gram-molecules of phenol carrying the substituent groups desired with one grammolecule of the amine, in alcohol or in an alcohol-water mixture, such that the reaction takes place in a homogeneous medium, at a temperature of 70‹ to 100‹ C. corresponding to the boiling point of the reaction alkaline mixture of pH usually between 9 and 10, and recovering the chelating product so obtained in an acid form, after acidifying the reaction product to a pH of 4 to 5, distillation, and/or addition of a solvent facilitating precipitation of the chelating agent. The metallic complexes are prepared by adding one gram-molecule of the acid or one of its salts to one gram-molecule of the chosen metal, the reaction generally being carried out in water or in a mixture containing water, (b) firstly reacting one molecule of diamine on two molecules of the selected hydroxyaldehyde with the desired substitutions on the benzene ring, the substituent groups on the nitrogen atoms being replaced by hydrogen in cases where S1 and S 2  are a hydroxyethyl or hydroxy propyl group, secondly adding a molecule of hydrocyanic acid to each CH group of the imine functions present in an anhydrous environment, with hydrocyanic acid about 10% in excess of stoichiometry, in the presence of a second solvent miscible in the solvent used for the reaction, or at least soluble with it in which the nitrile formed is soluble, so that the reaction can be carried out in an homogenous environment, in presence of a mineral or organic acid serving as a catalyst for the reaction and thirdly effecting direct hydrolysis of the product of the preceding reaction, carried out under reflux conditions at the same time as the azeotropic elimination of solvent and the excess of hydrocyanic and hydrochloric acids. The metallic complex is prepared by adding to the above aqueous phase a quantity of metal stoichiometrically calculated; one molecule of amine to one atom of metal.