Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus acids or salts thereof
Patent
1998-01-08
1999-04-27
Burn, Brian M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus acids or salts thereof
C07F 922
Patent
active
058980822
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to processes for the preparation of N-phosphonomethylglycine (glyphosate), a broad spectrum herbicide which is widely used throughout the world. In particular, the invention relates to a means of reducing the amount of glyphosate which is expelled with the effluent from the manufacturing processes.
There are several well known manufacturing routes by which glyphosate can be prepared, for example the routes set out in U.S. Pat. No. 3,969,398, U.S. Pat. No. 3,799,758, U.S. Pat. No. 3,927,080, U.S. Pat. No. 4,237,065 and U.S. Pat. No. 4,065,491, but all of these routes have a common problem. This is that, however efficient the process, there will usually be some wastage of product. Potentially, the presence of glyphosate in effluent can present environmental problems because of its herbicidal properties.
Wastage of product is, of course, also undesirable from the point of view of the manufacturer who wishes to produce glyphosate as economically as possible and so, for all of these reasons, it is essential that as little of the product as possible is expelled with effluent from the plant.
EP-A-0323821 addresses the problem of treating the waste stream from a glyphosate plant and suggests the solution of contacting the waste stream with a transition metal catalyst in a mixture or solution. The mixture or solution must be contacted with a molecular oxygen-containing gas and the reaction mass heated to a sufficient temperature to initiate and sustain the oxidation reactions of phosphonomethylglycine derivatives. This process has the disadvantage, however, that it is expensive since the catalyst, the contacting with the molecular oxygen containing gas and the heating all add to the cost. In addition, the reaction must often be conducted at elevated pressure which, again, increases the costs of the treatment process.
The present invention relates to an efficient and cost effective process for removing glyphosate or a salt or derivative thereof from a mixture in which it is present wherein the mixture is the effluent from a glyphosate manufacturing process.
In a first aspect of the present invention there is provided a process for removing N-(phosphonomethylglycine) (glyphosate) or a salt or ionic form thereof from an aqueous mixture in which it is present, wherein the aqueous mixture is an effluent from a glyphosate manufacturing process, the process comprising adding to the mixture ions capable of forming an insoluble or partially soluble complex glyphosate salt, and removing the complex salt from the mixture.
Examples of water soluble salts of glyphosate include the sodium (for example monosodium and disodium salts), potassium, ammonium, trimethylsulfonium and isopropylammonium salts. Ionic forms of glyphosate include the protonated form or the zwitterion.
When the ions are added to an aqueous mixture containing glyphosate, the present inventors have discovered that a complex salt appears to form. The complex salt is insoluble in water and precipitates out of solution. The ions added to the mixture may be iron (III), calcium, magnesium or aluminium ions. However, iron (III) ions are preferred since they form the least soluble complex salts which are, therefore, most easily removed.
The formation and/or the solubility of the complex salt may be pH dependent and, usually, acid or neutral conditions may be required. In the case of iron (III) the pH of the glyphosate-containing mixture may be adjusted to pH 6 or less before the addition of the iron (III) salt. It is preferred that the pH is from 1 to 4, for example about pH 3.
The ions which are added to the glyphosate-containing mixture will preferably be added in the form of a water soluble salt. Since, as mentioned above, the formation of the complex salt appears to be pH dependent, the salt should be one which is soluble in acidic solutions, for example of pH 5 or less. In the case of iron (III) the soluble salt may be, for example, the sulphate, chloride or hydroxide.
The formation of complex salts of glyphosate with metal ions has
REFERENCES:
patent: 4033896 (1977-07-01), Mitchell et al.
patent: 4079006 (1978-03-01), Mitchell
patent: 5087740 (1992-02-01), Smith
Subramaniam et al., `Metal Complexes of Glyphosate`, J. Agric. Food Chem., vol. 36, No. 6, 1988, pp. 1326-1329.
McBride, M. et al.: Soil Sci. Soc. Am. J. 53:1668-1673 (1989).
Piccolo, A. et al, CA 117:228347 (1992).
Zykova, G.V. et al., CA 112:11673 (1989).
Nilsson, G., CA 91:51017 (1979).
Hensley, D.L. et al., CA 90:49511 (1978).
Dhansay, M.A. et al., CA 120:16661 (1993).
Subramaniam, V. et al., CA 109:196680 (1988).
Motekaitis, R. et al., CA 104:25036 (1985).
Glass, R.L., CA 101:205947 (1984).
Madsen, H.E.L. et al., CA 88:142427 (1978).
Burn Brian M.
Davis Brian J.
LeCroy David P.
Zeneca Limited
LandOfFree
Process for the preparation of N-phosphonomethylglycine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the preparation of N-phosphonomethylglycine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of N-phosphonomethylglycine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-686084