METHOD FOR PRODUCTION OF COMPLEX-FORMING AGENT Russian patent published in 2022 - IPC C07C227/26 C07C229/16 C11D3/33 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for the production of a complex-forming agent, which is methylglycinediacetic acid (MGDA) and its salts with alkaline metals. The specified method includes stages (a)-(d). At the stage (a), nitrile is provided, corresponding to the general formula (Ia) or (Ib), wherein M is selected from alkaline metal and hydrogen, and combinations thereof. At the stage (b), saponification is carried out with total amount of alkali from 2.5 to 2.9 mol of alkaline metal hydroxide per mol of nitrile corresponding to the general formula (Ia) or (Ib) respectively, and with pH value in the range from 9.5 to 11.5 in the end of the stage (b). At the stage (c), such amount of alkaline metal hydroxide is added so that the total content of alkali is from 2.9 to 3.15 mol per mol of nitrile corresponding to the general formula (Ia) or (Ib) respectively, wherein, if 2.9 mol of alkaline metal hydroxide per mol of nitrile is used in total, then amount of alkali at the corresponding stage (b) is in the range from 2.5 to less than 2.9 mol. At the stage (d), additional saponification or neutralization is carried out.

EFFECT: proposed method allows for obtaining a complex-forming agent with long-term coloring resistance, which is easily transformed into solid substance.

9 cl, 4 tbl, 9 ex