How is Ammonium 2,2'-({2-[bis(carboxymethyl)amino]ethyl}imino)diacetate hydrate (CAS: 304675-80-7) typically synthesized?

Ammonium 2,2'-({2-[bis(carboxymethyl)amino]ethyl}imino)diacetate hydrate (CAS: 304675-80-7) is synthesized through a multi-step process involving the reaction of 2,2'-iminodiacetic acid with bis(carboxymethyl)amine. The synthesis typically requires the use of acetic anhydride, and the process is completed under mild conditions. The yield is around 90%, and the product is isolated by filtration and washing, followed by drying.