Method of forming a chelating composition
A method includes combining monosodium glutamate and/or glutamic acid with formaldehyde to form a first combination; adding hydrogen cyanide to form a second combination comprising a monosodium salt of glutamic acid diacetonitrile, a cyclic GLMN, and a sodium salt of glutamic acid N-monoacetonitrile, maintaining a temperature of the second combination at less than about 16° C. and a pH of less than about 7; converting nitrile groups to carboxylate groups thereby forming a third combination comprising water and at least about 47 weight percent of the tetrasodium salt of GLDA, wherein a reaction yield is at least about 91%; providing a fourth combination comprising water and the tetrasodium salt of GLDA and having a pH of less than about 7; and combining the third and fourth combinations to form the chelating composition.
1 . A method of forming a chelating composition, said method comprising the steps of:
combining monosodium glutamate and/or glutamic acid with formaldehyde to form a first combination;
adding hydrogen cyanide to the first combination to form a second combination comprising a monosodium salt of glutamic acid diacetonitrile, a cyclic GLMN, and a sodium salt of glutamic acid N,N′-monoacetonitrile,
maintaining a temperature of the second combination at less than about 16° C. and a pH of less than about 7; and
converting nitrile groups of the monosodium salt of glutamic acid diacetonitrile to carboxylate groups thereby forming the chelating composition comprising water and at least about 47 weight percent of the tetrasodium salt of glutamic acid N,N-diacetic acid based on a total weight of the chelating composition as determined using an Fe-Total Sequestering Value, wherein the chelating composition has a pH of greater than about 9 and a viscosity of less than about 1350 mPa·s measured at about 5° C. or less than 350 mPa·s measured at about 20° C. using a Brookfield DV II plus viscometer with spindle S18 and a temperature controlled bath, and wherein a reaction yield of MSG after conversion into the nitrile groups of the monosodium salt of GLDN followed by saponification to form the tetrasodium salt of glutamic N,N-diacetic acid is at least about 91%.
2 . The method of claim 1 further comprising the step of evaporating water from the chelating composition such that the weight percent of the tetrasodium salt of glutamic acid N,N-diacetic acid in the chelating composition is at least about 47 weight percent based on a total weight of the chelating composition as determined using an Fe-Total Sequestering Value.
3 . The method of claim 1 wherein the tetrasodium salt of glutamic acid N,N-diacetic acid present in the chelating composition in an amount of from about 47 to about 60 weight percent based on a total weight of the chelating composition as determined using an Fe-Total Sequestering Value.
4 . The method of claim 1 further comprising the step of maintaining the temperature of the first combination at less than about 11° C.
5 . The method of claim 1 wherein a temperature of the second combination is maintained at less than about 10° C. and wherein the hydrogen cyanide is added to the first combination for a total time of about 15 to about 120 minutes.
6 . The method of claim 1 wherein the step of combining monosodium glutamate and/or glutamic acid with formaldehyde is further defined as:
combining monosodium glutamate and/or glutamic acid with formaldehyde; and/or
combining glutamic acid and caustic to form monosodium glutamate in situ and then combining the monosodium glutamate with formaldehyde; and/or
combining glutamic acid and a disodium salt of glutamic acid to form monosodium glutamate in situ and then combining the monosodium glutamate with formaldehyde.