Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus acids or salts thereof
Patent
1991-12-18
1993-01-12
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus acids or salts thereof
C07F 938
Patent
active
051792281
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to improvements introduced into a method of obtaining N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid with oxygen or a gas containing oxygen, utilising as catalyst a noble metal supported on activated carbon. Specifically, the improvements of the invention relate to a treatment directed towards minimising the loss of the noble metal catalyst which occurs in this type of reaction.
ANTECEDENTS OF THE INVENTION
N-phosphonomethylglycine, described in the U.S. Pat. No. 3,799,758, is a known herbicide and its use is very widespread. Since its appearance on the market, various methods for obtaining it have been described and patented. One of these methods, specifically, the one claimed in the Spanish Patent No. 415.335 in the name of the Monsanto Company (equivalent to the U.S. Pat. No. 258,281, on May 5, 1972) provides a method of obtaining N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid with oxygen or a gas containing oxygen, utilising a noble metal (Pd, Pt, Rh) supported on activated carbon as catalyst for the reaction. Although this method allows for obtaining N-phosphonomethylglycine in acceptable yield and state of purity, it has the disadvantage that the losses of the noble metal used as catalyst are so great (may be as much as 30%) that said method is not economically profitable and that the losses of the noble metal increase the price of the finished product to such an extent that the method is not viable on an industrial scale.
On the other hand, it is a fact known by the technical experts in catalysis that the losses of the noble metal which occur in the both acidic and basic catalytic methods, is by dissolution of said metal in the reaction water, thus requiring a complex and costly treatment to recover said metal. Consequently, this type of method is not viable in practice for obtaining finished products with slightly increased value.
Therefore it would be advantageous to have available a method which allows for obtaining N-phosphonomethylglycine of sufficient purity in good yield by oxidation of N-phosphonomethyliminodiacetic in the presence of a noble metal catalyst which overcomes the disadvantages referred to previously. In particular, it would be advantageous for this method to minimise the losses of noble metal used as catalyst in such a way that they do not substantially increase the cost of the finished product, with the object of rendering this method industrially viable.
Consequently, an object of the invention is the introduction of improvements over the known methods of obtaining N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid with oxygen, in the presence of a noble metal supported on activated carbon as catalyst, providing that said improvements minimise the losses of noble metal, by means of implementation of a treatment intended to recover practically the total amount of the catalyst utilised, without loss of its catalytic activity.
BRIEF DESCRIPTION OF THE INVENTION
The improvements of the invention may be stated as specifically to minimise the losses of the noble metal catalyst used for obtaining N-phosphonomethylglycine by oxidation of N-phosphonomethyliminodiacetic acid. For minimising these losses, the invention proposes effecting a flushing-out with nitrogen once the oxidation reaction is completed.
Due to this, it follows that the content of noble metal in the reaction solution is less than 1 ppm, compared with a content of said metal greater than 70 ppm which is present in said solution if the flushing-out with nitrogen is not effected. Therefore, this flushing-out with nitrogen minimises the losses, lowering the percentage loss from 30% to less than 1%, in this way making this type of method economically viable. The obtaining of these improvements will be referred to in detail in the following description.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a series of betterments or improvements directed towards minimising the
REFERENCES:
patent: 4147719 (1979-04-01), Franz
patent: 4579689 (1986-04-01), Hershman et al.
patent: 4582650 (1986-04-01), Felthouse
patent: 4952723 (1990-08-01), Fields, Jr. et al.
patent: 4965402 (1990-10-01), Riley et al.
Martin Ramon Juan L.
Munoz Madronero Julio
Bissell Henry M.
Dees Jos,e G.
Ercros S.A.
Nazario Porfirlo
LandOfFree
Preparation of N-phosphonomethylglycine by oxidation of N-phosph does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of N-phosphonomethylglycine by oxidation of N-phosph, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of N-phosphonomethylglycine by oxidation of N-phosph will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1221397