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# United States Patent [19J 

# Smith 

# [54] PROCESS FOR PURIFYING N-PHOSPHONOMETHYLGLYCINE 

[75] Inventor: Lowell R. Smith, Kirkwood, Mo. 

[73] Assignee: Monsanto Company, St. Louis, Mo. 

[21] Appl. No.: 561,483 

[22] Filed: Jul. 30, 1990 

[63] Continuation of Ser. No. 394,998, Aug. 17, 1989, aban- doned. 

[51] Int. Cl.5 ................................................ C07F 9/38 

[52] U.S. Cl ....................................................... 562/17 

[58] Field of Search .......................................... 562/17 

## [56] References Cited 

4,197,254 4/1980 Gaertner ............................... 562/17 

## Related U.S. Application Data 

## U.S. PATENT DOCUMENTS 

# [11] Patent Number: 5,087,740 

# [45] Date of Patent: Feb. 11, 1992 

<img src='content_image/936224.jpg'>

## FOREIGN PATENT DOCUMENTS 

127415 11/1978 Japan . 

Primary Examiner-]. E. Evans 

Attorney, Agent, or Firm-Frank D. Shearin 

## [57] ABSTRACT 

N-Phosphonomethylglycine can be purified and con› centrated from aqueous solutions containing N-phos› phonomethylglycine and impurities, such as N-formyl› N-phosplionomethylglycine, phosphorous acid, and the like, by passing the aqueous solution through an ion exchange column containing a weakly basic ion ex› change resin to remove such impurities. 

## 8 Claims, No Drawings 

<img src='content_image/936210.jpg'>

US005087740A 

