US 12,234,201 B2
Making ethylenediaminetetraacetic acid
Deboleena Chakraborty, Midland, MI (US); Edward D. Daugs, Midland, MI (US); Kenneth E. Stockman, Midland, MI (US); and Ronald Peterson, Midland, MI (US)
Assigned to Dow Global Technologies LLC, Midland, MI (US); and Dow Silicones Corporation, Midland, MI (US)
Appl. No. 17/603,846
Filed by Dow Global Technologies LLC, Midland, MI (US); and Dow Silicones Corporation, Midland, MI (US)
PCT Filed Jun. 3, 2020, PCT No. PCT/US2020/035805
§ 371(c)(1), (2) Date Oct. 14, 2021,
PCT Pub. No. WO2020/251812, PCT Pub. Date Dec. 17, 2020.
Claims priority of provisional application 62/861,147, filed on Jun. 13, 2019.
Prior Publication US 2022/0234993 A1, Jul. 28, 2022
Int. Cl. C07C 227/02 (2006.01); C07C 255/25 (2006.01)
CPC C07C 227/02 (2013.01) [C07C 255/25 (2013.01)] 6 Claims
 
1. A method of making ethylenediaminetetraacetic acid (EDTA) comprising the steps:
(a) providing a reaction mixture (a) comprising ethylenediamine (EDA) and glycolonitrile (GN), wherein reaction mixture (a) comprises 0% to 0.1% by weight, based on the weight of reaction mixture (a), of any base having pKa of the conjugate acid (PKaH) of 13 or higher;
(b) causing or allowing reaction mixture (a) to react to form a dinitrile compound having structure DN:

OG Complex Work Unit Chemistry
(c) bringing the DN into contact with aqueous solution of a base having pKaH of 11 or higher, and causing or allowing the resulting mixture to react to form a diacid compound having structure DA:

OG Complex Work Unit Chemistry
wherein each —R has the following structure:

OG Complex Work Unit Chemistry
wherein each M is independently hydrogen or an alkali metal;
(d) causing or allowing the DA to react, either sequentially or simultaneously, with additional GN to form products (Pd);
(e) causing or allowing products (Pd) to react with a base having pKaH of 11 or higher to form EDTA.