Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus esters
Patent
1992-05-22
1993-05-11
Cintins, Marianne M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus esters
558 87, 558129, 558130, 558 85, C07F 940, C07F 96571
Patent
active
052102599
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of dialkyl esters of carboxymethylphosphonic acid by oxidation of the corresponding dialkyl esters of 2-hydroxyethylphosphonic acid with oxygen in the presence of a catalyst.
Dialkyl esters of carboxymethylphosphonic acid can be used as complexing agents or as intermediates in the preparation of organophosphorus products.
It is known to prepare diethyl esters of carboxymethylphosphonic acid by heating benzyl chloroacetate with triethylphosphite and subsequent hydrogenolysis of the benzyl ester of the diethyl esters of carboxymethylphosphonic acid obtained as an intermediate. Di-n-butyl carboxymethylphosphonate had been prepared in an analogous fashion. (D. J. Martin, C. E. Griffin, J. Org. Chem. 30 [1965] 4034). Diethyl ester of carboxymethylphosphonic acid has also been prepared from the corresponding ethyl ester by partial hydrolysis with an equimolar amount of KOH in aqueous ethanol. The corresponding dimethyl ester was prepared from the methyl ester of dimethyl carboxymethylphosphonates by partial hydrolysis with KOH in methanol, and the corresponding di-n-butyl ester from the tributyl ester by partial hydrolysis with aqueous KOH (R. A. Malevannaya et al., Zh. Obshch. Khim. 41 [1971] 1426-1434).
However, in the hydrolysis of triesters of carboxymethylphosphonic acid in alkaline medium, by-products are frequently produced, since, apart from the ester group, the P-alkoxy group can also be hydrolytically cleaved. With the use of KOH, the subsequent work-up leads, moreover, to the formation of a stoichiometric amount of salt, the removal of which poses problems.
The aim was therefore to develop a process which delivers dialkyl esters of carboxymethylphosphonic acid in high yield and purity, without producing large amounts of unwanted salt at the same time. The present invention now makes such a process available.
The object of the present invention is a process for the preparation of dialkyl esters of carboxymethylphosphonic acid of the formula (RO).sub.2 P(O)CH.sub.2 CO.sub.2 H, in which R is a straight-chain or branched alkyl radical having 1 to 20 carbon atoms, preferably having 1 to 8 carbon atoms, a cycloaliphatic radical having 5 to 8 carbon atoms, a phenyl or naphthyl radical which can be substituted, an aralkyl radical having 7 to 10 carbon atoms, or in which the (RO).sub.2 P group forms a ring which contains 2 to 5 carbon atoms which can be substituted, characterized in that dialkyl ester of 2-hydroxyethylphosphonic acid of the formula (RO).sub.2 P(O)CH.sub.2 CH.sub.2 OH, in which R has the above-mentioned meaning, is reacted with oxygen in the presence of water and a catalyst which contains at least one metal selected from the platinum metals group.
The substituents on the phenyl or naphthyl radical are preferably one or more alkyl radicals having 1 to 6 carbon atoms, alkoxy having 1 to 6 carbon atoms or halogen, preferably chlorine or bromine. As an alkyl radical or cycloaliphatic radical, R can also contain heteroatoms, preferably oxygen or nitrogen.
Metals selected from the platinum metals group which may be mentioned are for example platinum, palladium, iridium, rhodium and ruthenium, palladium and/or platinum being preferred. Particular preference is given to catalysts which exclusively contain platinum as the metal of the platinum group.
The metals mentioned are preferably applied to a support, in particular activated charcoal. The weight fraction of the metals in this case is expediently 1 to 10% of the total weight of the catalyst. Suitable catalysts are for example commercial catalysts having 5 to 10% by weight of platinum on activated charcoal.
In the process according to the invention, it is expedient to add to the starting material a quantity of water such that the content of dialkyl ester of hydroxyethylphosphonic acid in the resulting solution is 5 to 30% by weight, preferably 10 to 20% by weight.
The preferred oxidant is pure oxygen. However, mixtures of oxygen with gases inert to the reactants under the reaction condit
REFERENCES:
patent: 4151172 (1979-04-01), Ondetti et al.
Leupold Ernst I.
Roscher Gunter
Cintins Marianne M.
Hoechst Aktiengesellschaft
Page Margaret J.
LandOfFree
Process for the oxidation of dialkyl esters of 2-hydroxy-ethylph 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 oxidation of dialkyl esters of 2-hydroxy-ethylph, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the oxidation of dialkyl esters of 2-hydroxy-ethylph will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1351595