Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1994-03-28
2001-07-17
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S329500, C525S380000
Reexamination Certificate
active
06262183
ABSTRACT:
Hydroxamic acids are known for their special ability to form complexes with heavy metals, particularly iron(III). The intense colors and the high stabilities of many of these complexes have led to the development of various analytical procedures based upon these reactions. A number of hydroxamic acids also show biological activity, such as urease inhibition and anticoagulant activity.
Although the literature on hydroxamic acids is extensive and the chemistry well defined, there is little concerning polymers bearing hydroxamic acid groups.
In one case, vinyl monomers bearing hydroxamic acid groups were reported to polymerize under a variety of conditions. The monomers acrylo-, methacrylo-, crotono-, and cinnamohydroxamic acids were prepared by reaction of the corresponding ester with hydroxylamine. In a second case, however, Becke and Mutz,
Chem. Rev
., 98,1322 (1965), reported an unsuccessful attempt to prepare acrylohydroxamic acid from ethyl acrylate due to competing Michael addition. Use of the acid chloride was successful, but with only an 8% yield of pure monomer. M. Narita et al.in
Bull. Chem. Soc.Japan
, 45,3149 (1972) reported the preparation of methacrylohydroxamic acid from the ester, but found that the monomer resisted attempts at copolymerization with styrene-divinylbenzene.
In other reports, the hydroxamic acid group is generated on or added to preformed polymers of various kinds. U.S. Pat. No. 2,402,604 discloses treatment of maleic anhydride copolymers with hydroxylamine, as does Cocea et al. in
Bul.Inst.Politeh.Iasi
11,159 (1965)
Chem.Abst
. 64 19800a (1966). Various groups have also used the treatment of polyacrylonitrile with hydroxylamine followed by hydrolysis of the intermediate amidoxime, yielding, in part, pendant hydroxamic acid groups, for the metallation of acrylic fabrics.
Ion exchange resins based upon the hydroxamic acid groups have been prepared from Amberlite XRC-50 by conversion of the carboxyl groups to the acid chloride or to the ester, followed by treatment with hydroxylamine. Used in a column, the modified resin shows a significant increase in the retardation of various metal ions. The acid chloride method has also used by M. Vrancken and G. Smets in
J.Polym.Sci
., 14,521 (1954) by treating poly (acryloyl chloride) with hydroxylamine in dimethylformamide. The copolymerization of various hydroxamic acid-substituted phenols and catechols into phenolic resins has been reported to give a fairly selective ion exchange resin for heavy metals.
The reaction of esters with hydroxylamine, normally a standard procedure for preparing hydroxamic acids, has been used by M. Narita et al,
Bull.Chem.Soc. Japan
45,3149 (1972); by W. Kern and R. C. Schultz,
Agnew Chem
. 69, 153, (157); and by M. Hatano et al in
Koyo Kagakev Zasshi
69, 571 (1966) and
Chem Abstr
. 65, 15532g (1966), in a number of instances, with mixed results, for preparing polymers. Of particular note is the work of Kern and Schultz, who, through reaction of poly(zethylacrylate) with hydroxylamine, reported a polymer containing to 80% acrylohydroxamic acid, 14% acrylic acid, and 6% methyl acrylate, and which formed the characteristic red-brown iron(III) complex. The ratio of hydroxamic acid to iron in the complex was found to be 3:1.
In other reports, styrene-divinylbenzene copolymers containing ethyl acrylate or the active esters p-nitrophenyl acrylate or p-nitrophenyl methacrylate either failed to react with hydroxylamine or resulted in polymers containing a considerable fraction of carboxyl groups. However, hydroxamic acid polymers could be prepared through reaction of the active ester substituted polymer with O-benzylhydroxylamine followed by treatment with hydrogen bromide.
In searching for polymeric chelating agents for treating cases of extreme iron poisoning, the trihydroxamic acid, deferoxamine-B, has been grafted to several polymers through reaction at the free amine group.
Vernon et al in
Anal.Chim.Acta
72,331(1974); 77,145 (1975); 79,229 (1975); 82,369 (1976) and 83,187 (1976) described the preparation and applications of poly(hydroxamic acids)s. The preferred synthesis route was partial hydrolysis of macroporous acrylonitrile divinylbenzene copolymer, followed by hydroxylaminolysis. These resins are used for the separation of metal ions and recovery of uranium from synthetic sea water. A. Winston and E. T. Mazza in
J.Polym.Sci.Polym.Chem.Ed
. 13,2019(1975) and 14,2155(1976) studied the effect of the spacing of hydroxamic acid units in a polymer on its affinity to iron ions. Poly(hydroxamic acid)s were synthesized from acryloyl chloride and B-alanine or from poly(acrylic acid).
R. Phillips and J. S. Fritz in
Anal.Chim.Act
, 121, 225 (1980) synthesized an N-phenylhydroxamic acid resin by attaching N-Phenylhydroxamic acid units to Amberlite XAD-4. The use of poly(acrylonitrile) for the synthesis of poly(hydroxamic acid) was also reported by A. Shah and S. Devi in Analyst 110,1501, (1981). The polymer was used for the separation of lead and copper from aqueous solutions.
U.S. Pat. No. 4,536,296 to Vio discloses using drilling mud with low viscosity and stability at temperatures of up to 200° C. which contains one to ten grams low molecular weight (preferably 10,000) polymer or copolymer having hydroxamic or thiohydroxamic functional groups. The polymers are prepared by polymerization of a vinyl monomer having a hydroxamic or thiohydroxamic functional group alone or in combination with another vinyl monomer at a temperature between about 50° and 110° C. in the absence of oxygen, at a pH of less than 7, for between 0.5 and 20 hours. European Pat No. 0 104,970 to Societe National Elf Aquitaine (Vio and Meunier) discloses a similar method for making drilling mud wherein an aqueous solution of polyacrylamide is reacted at a temperature between 50° C. and 85° C.
Despite the variety of suggested polymers and applications, no one has ever disclosed, nor even suggested, a method using primary amide polymers, such as poly(acrylamide)s, as starting materials for the synthesis of hydroxamic acid polymers where the polymers are reacted with hydroxylamines at low temperature under basic conditions to yield a polymer containing low concentrations of carboxylic acid groups, in addition to the major content of hydroxamic acid groups.
It is therefore an object of the present invention to provide a method to produce polymers having a predominance of hydroxamic acid groups and a very low percentage of caboxylic groups which are relatively inert and biocompatible.
It is a further object of the present invention to provide a method to produce polymers which are biologically active.
It is a still further object of the present invention to provide a method to produce polymers which have high affinity for metal ions and a rapid reaction rate.
SUMMARY OF THE INVENTION
The method of the present invention is to react primary amide polymers, including but not limited to polyacrylamide, derivatives thereof, and other linear, branched and crosslinked primary amide polymers, with hydroxylamine under mild conditions. “Mild conditions” are preferably a temperature in the range of 20° C. to 30° C. and a pH of greater than about 7, preferably at least 10, and more preferably pH 11.5 or greater. The products of this method, produced in high yield, are the corresponding poly(hydroxamic acid)s predominantly containing hydroxamic acid groups as well as unreacted amide groups and low amounts of carboxylic acid groups. The method is as follows:
R═H, Alkyl, aryl
The products of this method are distinguished by the high content of hydroxamic acid groups (70%) and low content of carboxylic acid groups (less than about 15%, usually less than about 3%). Selection of the starting materials and crosslinking with a divinyl compound can be used to determine the water retention capacity. The polymer shows high affinity for iron(III) and copper(II) in the pH range of 0 to 7 and has a high binding rate. This metal affinity is higher than the poly(hydroxamic acid)s previously described. The products are especially u
Cravalho Ernest G.
Domb Abraham J.
Golomb Gershon
Langer Robert S.
Laurencin Cato T.
Cheung William
Cytec Technology Corp.
Schultz Claire M.
Van Riet Frank M.
Wu David W.
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