Patent GB-882987-A (GB)
Title: Iron-complex salts, their manufacture and preparations containing them
IPC: C05D9/02
Filed: 1959-08-10
Abstract: The invention comprises iron complexes of imino-dicarboxylic acids of the general formula <FORM:0882987/IV (b)/1> in which R represents an aryl residue (which may be substituted), x is either 1 or 2, y is an integer not exceeding 4, and z is an integer not exceeding 3, and also the alkali and alkaline-earth metal salts of the complexes. These iron compounds assist the healthy growth of plants.  The salts are obtained by reacting, in aqueous solution, the appropriate imino-dicarboxylic acid, an iron salt, and a compound that provides the necessary salt-forming cations.  By lowering the pH value of the solution of the iron-complex salt, the free iron-complex acid can be precipitated. The required imino-dicarboxylic acids are obtained by the methods described in Specification 718,509.  In addition to the phenols specified in the earlier Specification, the following may be used as starting-materials: b -naphthol, 2- and 4-hydroxydiphenyl, 4-hydroxydiphenyl ether, 2-cyclohexylphenol, and 4-benzylphenol.  In Example 1, the compound having the structure <FORM:0882987/IV (b)/2> is obtained by mixing p-chlorophenol, formaldehyde and the sodium salt of iminodiacetic acid in alkaline solution, and acidifying the mixture with mineral acid.  The compound is stirred with water; and ferric sulphate followed by sodium carbonate are added, and the temperature is raised to 80 DEG C.  The solution is evaporated in vacuo, and the sodium salt of the iron-complex is obtained as a dark-brown powder.  Example 4 describes the preparation of the free ironcomplex compound by digesting the aboveformulated 1 - hydroxy - 2,6 - di - [(N,N1 - bis - carboxymethyl)-aminomethyl]-4-chlorobenzene with freshly-precipitated ferric hydroxide.  Example 5 describes the preparation of the magnesium salt of the same complex.  Example 3 relates, inter alia, to the sodium salts of ferricomplexes of 1-hydroxy-2,6-di-[(N,N1-bis-carboxyethyl) - aminomethyl] - 4 - phenylbenzene and 1 - hydroxy - 2,6 - di - [(N,N1 - bis - carboxymethyl) - aminomethyl] - 4 - methoxy - benzene.ALSO:Iron deficiency diseases in plants are treated by applying an iron complex of an iminodicarboxylic acid of the general formula in <FORM:0882987/I/1> which R represents an aryl residue (which may be substituted), x is either 1 or 2, y is an integer not exceeding 4, and z is an integer not exceeding 3, or an alkali or alkaline-earth metal metal salt of such a complex.  The iron compound may be mixed with an inert solid carrier, such as kaolin or talcum and dusted over the plant-to-be -treated; but preferably an aqueous solution of the compound is sprinkled over the plant.  Example 6 describes the treatment of citrus trees, growing on sandy-clay soil and suffering from iron chlorosis, with a mixture of equal parts of sand and of the sodium salt of the ferri-complex of 1-hydroxy-2,6-di-[(N,N1-biscarboxymethyl) - aminomethyl] - 4 - chlorobenzene; the mixture is washed into the soil with water. Example 7 describes the treatment of chlorotic vines with a dilute aqueous solution of the magnesium salt of the same complex, the solution also containing magnesium sulphate heptahydrate.  For the preparation of the iron compounds (see Group IV(b)).  Specification 718,509 is referred to.