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US-20260125407-A1 - PROCESS FOR THE PREPARATION OF POLYAMINOCARBOXYLIC ACIDS AND CHELATE COMPOUNDS THEREOF

US20260125407A1US 20260125407 A1US20260125407 A1US 20260125407A1US-20260125407-A1

Abstract

The present invention relates to a process for the preparation of polyaminocarboxylic acids, in particular phenolic aryl- or alkyldiaminepolycarboxylic acids, preferably a compound of formula (I): wherein X is selected from the group consisting of: H, COOH, COO − Y + , OH, linear or branched C 1 -C 5 alkyl, CH 2 OH, SO 3 H, SO 3 − Y + , wherein: —Y + is independently selected from the group consisting of: Li + , Na + , K + , and NH 4 + ; and wherein A is selected from: −A (CH 2 )n linear aliphatic system, wherein n=2, 3 or 4, preferably 2 or 3; and—an aromatic system of formula (II): wherein R1, R2 are independently selected from the group consisting of H, OH, and linear or branched C 1 -C 5 alkyl; said process comprising the step of reacting, a phenol compound, glyoxylic acid and an aryl- or alkyldiamine in the presence of an iron source to obtain a reaction mixture comprising the compound of

Inventors

  • ALESSANDRO BIASONE

Assignees

  • VALAGRO S.P.A.

Dates

Publication Date
20260507
Application Date
20251231
Priority Date
20191203

Claims (13)

  1. 1 . A process for the preparation of a compound of general formula (I): wherein X is selected from the group consisting of: H, COOH, COO − Y + , OH, linear or branched C 1 -C 5 alkyl, CH 2 OH, SO 3 H and SO 3 − Y + , wherein Y is independently selected from the group consisting of Li + , Na + , K + , and NH 4 + ; and wherein A is selected from: (CH 2 ) n linear aliphatic system, wherein n=2, 3 or 4, preferably 2 or 3; and an aromatic system of formula: wherein R1, R2 are independently selected from the group consisting of H, OH, and linear or branched C 1 -C 5 alkyl; said process comprising the steps of: (a) reacting, preferably in an aqueous basic environment, a phenolic precursor, glyoxylic acid and an aryl- or alkyldiamine; (b) adding an iron source, preferably said iron source being selected among metallic iron Fe 0 and an iron salt; (c) mixing to obtain a reaction mixture comprising the compound of general formula (I).
  2. 2 . The process according to claim 1 , wherein the phenolic precursor of step (a) is selected from the group consisting of phenol, hydroquinone, p-cresol, p-hydroxybenzoic acid, p-phenolsulfonic acid and salts thereof, preferably is selected from a salt of p-hydroxybenzoic acid and a salt of p-phenolsulfonic acid, wherein the salt of p-hydroxybenzoic or p-phenolsulfonic acid is an alkali salt, even more preferably the salt being selected from the group consisting of sodium p-hydroxybenzoate, potassium p-hydroxybenzoate, sodium p-phenolsulfonate and potassium p-phenolsulfonate.
  3. 3 . The process according to claim 1 , wherein the aryl- or alkyldiamine of step (a) is selected from the group consisting of: ethylenediamine, propane-1,3-diamine, butane-1,4-diamine, benzene-1,2-diamine.
  4. 4 . The process according to claim 1 , wherein said phenolic precursor, glyoxylic acid and aryl- or alkyldiamine are employed in a molar ratio comprised between 2.2:2.2:1 and 1.8:1.8:1.
  5. 5 . The process according to claim 1 , wherein the reaction of step (a) is carried out in an aqueous basic environment obtained by adding a base, preferably selected from the group consisting of NaOH, KOH, LiOH, NH 4 OH and combinations thereof, to the aqueous environment of the reaction.
  6. 6 . The process according to claim 5 , wherein the molar ratio of said base to aryl- or alkyldiamine of step (a) is comprised between 2:1 and 7:1, even more preferably between 3:1 and 7:1.
  7. 7 . The process according to claim 1 , wherein the iron source employed in step (b) is an iron salt, preferably selected from a Fe(II) and/or Fe(III) salt, more preferably a Fe(III) salt.
  8. 8 . The process according to claim 1 , wherein the iron source added in step (b) is employed in a molar ratio with respect to the aryl- or alkyldiamine of step (a) comprised between 0.1:1 and 0.5:1, preferably comprised between 0.15:1 and 0.4:1, even more preferably between 0.2:1 and 0.35:1.
  9. 9 . The process according to claim 1 , wherein the mixing of step (c) is performed for a time comprised between 1 and 4 hours, preferably between 2 and 3 hours and is preferably performed at a temperature comprised between 5° and 90° C., preferably between 55 and 85° C.
  10. 10 . A process for the preparation of a chelate compound, which is the complex of the compound of general formula (I) with Fe, said process comprising the steps of: (d) adding an iron source to the reaction mixture obtained after step (c) of the process according to claim 1 , preferably said iron source being selected among metallic iron Fe 0 ; (e) mixing to complete the chelation reaction and obtain a reaction mixture comprising the chelate compound; (f) optionally drying the reaction mixture of step (e) to obtain the chelate compound in form of powder.
  11. 11 . The process according to claim 10 , wherein the total amount of iron source added in steps (b) and (d) is in a molar ratio with respect to the aryl- or alkyldiamine of step (a) comprised between 0.7:1 and 1:1, preferably between 0.8:1 and 1:1, more preferably 0.9:1 and 1:1, even more preferably equal to the stochiometric molar ratio 1:1.
  12. 12 . The process according to claim 11 , wherein the iron source employed in step (d) is an iron salt, preferably selected from a Fe(II) and/or Fe(III) salt, more preferably a Fe(II) salt.
  13. 13 . A process for the preparation of a chelate compound, which is the complex of the compound of general formula (I) with Fe, said process comprising the steps of: (d) adding an iron source to the reaction mixture obtained after step (c) (e) of the process according to an iron salt, preferably said iron source being employed in an amount depending from the quantity of the iron source added in step (b) according to claim 8 ; (f) mixing to complete the chelation reaction and obtain a reaction mixture comprising the chelate compound; (g) optionally drying the reaction mixture of step (e) to obtain the chelate compound in form of powder.

Description

TECHNICAL FIELD The present invention relates to a process for the preparation of polyaminocarboxylic acids, in particular phenolic aryl- or alkyldiaminepolycarboxylic acids, which comprises using a Fe source during the synthesis step. The present invention also relates to a process for the preparation of chelate compounds which are the corresponding complexes of said polyaminocarboxylic acids with Fe. BACKGROUND ART In agriculture iron chelate compounds are widely used to treat iron chlorosis affecting plants growing in calcareous and/or alkaline soils. Aromatic polyaminocarboxylates such as ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (EDDHA) and its derivates: ethylenediamine-N,N′-bis[(2-hydroxy 5-sulfo) phenylacetic acid](EDDHSA), ethylenediamine-N,N′-bis(2-hydroxy-4-methylphenylacetic acid) (EDDHMA), ethylenediamine-N,N′-bis[(2-hydroxy-5-chlorophenyl)acetic acid](EDDHCA), are chelating compounds able to chelate iron and largely used in agriculture for the prevention and/or treatment of chlorosis disease in plants. They are normally synthesized from their respective phenolic precursors, ethylenediamine and glyoxylic acid through a Mannich-like one-pot reaction. The known synthesis processes to produce EDDHA, EDDHSA, EDDHMA, EDDDHA EDDHCA yield their respective racemic (RR, SS) and meso (RS, SR) isomers. One of the side effects of the known processes is the further reaction of the desired products with the starting reagents to generate oligomeric products (OP). Despite their stability in aqueous solution, such oligomeric products are less stable in soils and soil material, in particular in calcareous soils; therefore, they are less effective as fertilizer than the non-oligomeric compounds. Although for EDDHA the formation of ortho-para and para-para regioisomers is a relevant issue, for EDDHSA, EDDHCA or EDDDHA, this problem is hampered by the presence of the sulfonic, carboxylic and hydroxyl groups respectively, which are in para position of the phenolic ring. As described, for example, by Petree et al. in U.S. Pat. No. 4,130,582, for the synthesis of EDDHA, the formation of ortho-para and para-para isomers and oligomeric products is prevented by using a large excess of phenol. The phenol excess is then removed with extraction in organic solvent. This approach has the great disadvantage that a large excess of phenol is required to limit the formation of the unwanted o,p-EDDHA and p,p-EDDHA isomers, thus leading to a reaction mixture unsuitable for the final chelation step with a Fe(II/III) salt without prior removal of the phenol excess. In case of EDDHSA and EDDHCA synthesis, the removal of unreacted phenol with an organic solvent is not feasible; hence the syntheses are carried out in nearly stoichiometric conditions using 2 mol of the phenolic reactant, 2 mol of glyoxylic acid and 1 mol of alkyldiamine in aqueous solution. The formation of significant amount of oligomeric product (EDDHSA-OP, EDDCA-OP) is unavoidable and, in some cases, their concentration in the finished products exceeds that of the desired chelating compound. In agriculture there is still a strong need for alternative processes for the preparation of polyaminocarboxylic acids, in particular phenolic aryl- or alkyldiaminepolycarboxylic acids and the corresponding Fe chelate compounds which can limit the formation of undesired by-products such as condensation by-products and unwanted isomers. An object of the present invention is to provide a process for the preparation of polyaminocarboxylic acids, in particular a phenolic aryl- or alkyldiaminepolycarboxylic acid and a corresponding Fe chelate compound which overcomes the disadvantages of the processes known in the art and leads to an increase of the yield of the chelating agent, especially of the racemic stereoisomers that show a higher stability constant with Fe with respect to the meso isomers, and to a reduction of the condensation by-products. SUMMARY OF THE INVENTION The present invention relates to a process for the preparation of polyaminocarboxylic acids, preferably phenolic aryl- or alkyldiaminepolycarboxylic acids, more preferably for the preparation of a compound of general formula (I): wherein X is selected from the group consisting of: H, COOH, COO−Y+, OH, linear or branched C1-C5 alkyl, CH2OH, SO3H, SO3−Y+, wherein: Y+ is independently selected from the group consisting of: Li+, Na+, K+, and NH4+; and wherein A is selected from: a (CH2)n linear aliphatic system, wherein n=2, 3 or 4, preferably 2 or 3; andan aromatic system of formula: wherein R1, R2 are independently selected from the group consisting of H, OH, and linear or branched C1-C5 alkyl; said process comprising the step of reacting, a phenol compound, glyoxylic acid and an aryl- or alkyldiamine in the presence of an iron source, preferably selected among metallic iron and an iron salt, to obtain a reaction mixture comprising the compound of general formula (I). The present inve