Purification of n-(phosphonomethyl)glycine

1. A process for the purification of glyphosate (PMG), having glycine, N-methyl-N-(phosphonomethyl)glycine or glyphosine impurities, comprising:

1) dissolving or suspending a material comprising PMG, having glycine, N-methyl-N-(phosphonomethyl)glycine or glyphosine impurities, in water, in the presence of a base, to produce a composition comprising a PMG salt in an aqueous base,

2) contacting the composition with an acid, such that the PMG salt is neutralized, forming a precipitate of PMG, and

3) isolating the precipitate of PMG,

with the proviso that the composition of step 1) is not concentrated or filtered using a nanofiltration membrane.

2. The process of claim 1 wherein the amount of base is from 0.5 to 1.2 molar equivalents, based on the moles of PMG material.

3. The process of claim 1 wherein amount of acid utilized for neutralization is from 0.5 to 1.3 molar equivalents, based on the moles of PMG material.

4. The process of claim 1 wherein the base is sodium hydroxide.

5. The process of claim 1 wherein the acid is hydrochloric acid.

6. The process of claim 1 wherein the purified PMG product contains less than 0.1 wt. percent glycine, based on the total weight of the purified PMG product.

7. The process of claim 1 wherein the purified PMG product contains less than 0.1 wt. percent N-methyl-N-(phosphonomethyl)glycine, based on the total weight of the purified PMG product.

8. The process of claim 1 wherein the purified PMG product contains less than 0.2 wt. percent glyphosine, based on the total weight of the purified PMG product.

9. The process of claim 1 wherein the product of step 2) has a pH of from 0.9 to 2.9.

10. The process of claim 1 wherein the product of step 2) has a pH of from 0.9 to 1.25.