How is Ethanedioic acid ammoniate (1:1) (CAS: 5972-72-5) typically synthesized?

Ethanedioic acid ammoniate (1:1) (CAS: 5972-72-5) is synthesized by the direct reaction of oxalic acid with ammonium hydroxide in a 1:1 molar ratio. The reaction is typically carried out in water at room temperature with continuous stirring. Commonly, the mixture is heated to ensure complete reaction and then filtered to obtain the desired salt. The product is usually washed with water and dried under reduced pressure.