Process for the preparation of polyaminocarboxylic acids and chelate compounds thereof
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 formula (I). The invention also relates to a process for the preparation of a chelate compound, which is a complex of the compound of formula (I) with iron.
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 − Y + , wherein
Y is independently selected from the group consisting of Li + , Na + , K + , and NH + ; and; wherein
A is selected from:
(CH 2 ) n linear aliphatic system, wherein n=2, 3 or 4; and
an aromatic system of formula:
wherein R 1 , R 2 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 a phenolic precursor with glyoxylic acid and an aryl- or alkyldiamine;
(b) adding an iron source in a molar ratio with respect to the aryl- or alkyldiamine of step (a) between 0.1:1 and 0.5:1, wherein the iron source is metallic iron Fe 0 ;
(c) mixing for a duration between 1 and 4 hours and at a temperature between 50° C. and 90° C. to obtain a reaction mixture comprising the compound of general formula (I).
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.
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, and benzene-1,2-diamine.
4 . The process according to claim 1 , wherein said phenolic precursor, glyoxylic acid and aryl- or alkyldiamine are employed in a molar ratio between 2.2:2.2:1 and 1.8:1.8:1.
5 . The process according to claim 1 , wherein step (a) is carried out in an aqueous basic environment obtained by adding a base.
6 . The process according to claim 5 , wherein the molar ratio of said base to aryl- or alkyldiamine of step (a) is between 2:1 and 7:1.
7 . 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) between 0.15:1 and 0.4:1.
8 . The process according to claim 1 , wherein the mixing of step (c) is performed for a duration between 2 and 3 hours and at a temperature between 55° C. and 85° C.
9 . A process for the preparation of a chelate compound of the compound of general formula (I) of claim 1 with Fe, said process comprising the steps of (a) to (c) according to claim 1 and further comprising:
(d) adding the iron source to the reaction mixture obtained after step (c) of the process according to claim 1 ;
(e) mixing to complete the chelation reaction and obtain a second reaction mixture comprising the chelate compound;
(f) optionally drying the second reaction mixture of step (e) to obtain the chelate compound in form of powder.
10 . The process according to claim 9 , wherein total amount of the iron source added in steps (b) and (d) is in a molar ratio with respect to the aryl- or alkyldiamine of step (a) between 0.7:1 and 1:1.
11 . The process according to claim 1 , wherein step (a) is performed in an aqueous basic environment.
12 . The process according to claim 1 , wherein the phenolic precursor is a salt of p-hydroxybenzoic acid or a salt of p-phenolsulfonic acid.
13 . The process according to claim 12 , wherein the salt of p-hydroxybenzoic or the salt of p-phenolsulfonic acid is each independently an alkali salt.
14 . The process according to claim 1 , wherein the phenolic precursor is selected from sodium p-hydroxybenzoate, potassium p-hydroxybenzoate, sodium p-phenolsulfonate, and potassium p-phenolsulfonate.
15 . The process according to claim 5 , wherein the base is selected from the group consisting of NaOH, KOH, LiOH, NH4OH, and a combination thereof.
16 . 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) between 0.2:1 and 0.35:1.
17 . The process according to claim 9 , wherein the total amount of the iron source added in steps (b) and (d) is in a molar ratio with respect to the aryl- or alkyldiamine of step (a) between 0.8:1 and 1:1.
18 . The process according to claim 9 , wherein the total amount of the iron source added in steps (b) and (d) is in a molar ratio with respect to the aryl- or alkyldiamine of step (a) between 0.9:1 and 1:1.
19 . The process according to claim 9 , wherein the total amount of the iron source added in steps (b) and (d) is in a molar ratio with respect to the aryl- or alkyldiamine of step (a) equal to the stochiometric molar ratio 1:1.