Sulfuric Acid → Glyphosate

Temperature

100 °C

To a suitable reaction vessel was added 150 grams of 5% fuming sulfuric acid and the sulfuric acid heated to 90° C. To the fuming sulfuric acid was added over a one hour period 70 grams of N-(phosphonomethyl) imino-diacetic acid. The reaction mixture was heated at 100° C. for 2 hours at which time a nuclear magnetic resonance spectra indicated that no N-(phosphonomethyl) imino-diacetic acid starting material was present. Water (200 mls.) was added at a temperature of approximately 50° C. and then the reaction mixture vacuum distilled to 100° C. at 17 to 18 inches of mercury. The reaction mixture was then cooled to 30° C. and 375 mls. of 80% isopropanol was added. The isopropanol mixture was then chilled for 2 hours and filtered and the filter cake was washed with 80% isopropanol and 50 mls. of water and dried, yielding 35 grams of N-phosphonomethyl glycine of 93.5% purity. The filtrates and wash were combined and then stripped to 105° C. at 17 to 18 inches of mercury. The stripped material was cooled to 40° C. and 50% sodium hydroxide (235 grams) was added to the mixture to bring the pH to 2.45 at less than 60° C. This mixture was then distilled at atmospheric pressure to 105° C. The residue was cooled to 50° C. and methanol (200 mls.) was added and then the mixture was cooled to 10° C. The cooled mixture was stirred for one hour, filtered and the filter cake was washed with an additional 50 mls. of methanol. The residue was slurried in methanol (200 mls.), cooled to 15° C. and isopropylamine (7.0 grams) was added. This mixture was stirred for 1/2 hour, filtered and the residue was washed with methanol (100 mls.). The methanolic filtrates were combined and methanol was distilled off to a temperature of 70° C. To the residue was added 40 mls. of water and the residual methanol was then removed under vacuum until the pot residue temperature reached 75° C. There was obtained from this residue an additional 38 grams of N-phosphonomethyl glycine as an isopropylamine, salt solution having an assay of 33.8% N-phosphonomethyl glycine.

1. distillationthe reaction mixture vacuum distilled to 100° C. at 17 to 18 inches of mercury
2. temperatureThe reaction mixture was then cooled to 30° C.
3. additionof 80% isopropanol was added
4. temperatureThe isopropanol mixture was then chilled for 2 hours
5. filtrationfiltered
6. washthe filter cake was washed with 80% isopropanol and 50 mls
7. dry with materialof water and dried

ORD record

ord-ac03d38a4f3141229a445667bbdcdc8a

Source dataset

uspto-grants-1977_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04002672