Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-02-23
2002-10-15
Geist, Gary (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
Reexamination Certificate
active
06465690
ABSTRACT:
This invention relates to a process for the preparation of polyamino succinic acids and derivatives thereof in which process a primary alcohol is used as a solvent. In particular, this invention relates to a process for the preparation of ethylenediamine monosuccinic acid, its salts or chelates, its esters, and its lactams.
BACKGROUND OF THE INVENTION
Chelants or chelating agents are compounds which form coordinate covalent bonds with a metal ion to form chelates. Chelates are coordination compounds in which a central metal atom is bonded to two or more other atoms in at least one other molecule (called ligand) such that at least one heterocyclic ring is formed with the metal atom as part of each ring.
Chelants are used in a variety of applications including food processing, soaps, detergents, cleaning products, personal care products, pharmaceuticals, pulp and paper processing, gas conditioning, water treatment, metalworking and metal plating solutions, textile processing solutions, fertilizers, animal feeds, herbicides, rubber and polymer chemistry, photofinishing, and oil field chemistry. Some of these activities result in chelants entering the environment. For instance, agricultural uses or detergent uses may result in measurable quantities of the chelants being present in water. It is, therefore, desirable that chelants degrade after use.
Biodegradability, that is susceptibility to degradation by microbes, is particularly useful because the microbes are generally naturally present in environments into which the chelants may be introduced. Commonly used chelants like ethylenediamine tetraacetic acid (EDTA) are biodegradable, but at rates somewhat slower and under conditions considered by some to be less than optimum. (See, for example, Tiedje, “Microbial Degradation of Ethylenediaminetetraacetate in Soils and Sediments,” Applied Microbiology, August 1975, pp. 327-329.)
It would be desirable to have a chelant useful in areas such as those mentioned above wherein such chelant is greater than about 60 percent biodegradable within less than 28 days according to the OECD 301B Modified Sturm Test or greater than about 80 percent biodegradable within less than 28 days according to the Semicontinuous Activated Sludge Test (ASTM D 2667 89).
It has been found that racemic ethylenediamine monosuccinic acid (EDMS); also named N-(2-aminoethyl) aspartic acid (AEA), and its salts are excellent chelants and are readily biodegradable. Several chelates of EDMS are also readily biodegradable and in some cases may readily exchange their metals for other metals. These chelates have the advantage of forming non-hygroscopic solids. Since EDMS and its salts and chelates are quite useful in the applications mentioned above, it would be advantageous to have a simple and economical process for producing these compounds.
British Patent No. 757,704 and U.S. Pat. No. 2,761,874, both by Bersworth, teach the preparation of EDMS by dissolving ethylenediamine in tetiary butanol and slowly adding diethyl maleate while keeping the temperature below 50° C., preferably below 35° C. The lower temperature was necessary to reduce the production of undesired byproducts. The resulting diethyl ester of EDMS is then hydrolyzed with sodium hydroxide to give disodium EDMS. This method of production is cumbersome and expensive.
Japanese Patent Application Kokai No. 57116031 A2 (Tokyo Organic Chemical Industries, Ltd.), Chemical Abstracts Number 98:54482, teaches that disodium EDMS can be prepared by refluxing sodium maleate hydrate (89 g, 0.50 mole if monohydrate, 0.45 mole if dihydrate) in water with 250 ml (224.9 g, 3.74 mole) ethylenediamine for 8.5 hours to produce 125 g (0.57 mole) disodium EDMS. Attempts to reproduce this preparation have failed to produce pure EDMS. Significant contamination with tetrasodium ethylenediamine disuccinate (EDDS) is present.
J. Am. Chem. Soc. 1984, 106, 2819-2837 reports the preparation of (R)-N-(2-aminoethyl) aspartic acid and (S)-N-(2-aminoethyl) aspartic acid in small quantities. These compounds are prepared by reacting maleic acid (18 g) with [Co(en)
2
CO
3
]Br (50 g) in one liter of boiling water, concentrating this to 100 ml, crystallizing overnight, washing the resulting crystals first with methanol/water and then with methanol. The crystals (9.9 g) are then dissolved in 50 ml boiling water and reacted with 17 g NaClO
4
H
2
O, and the product crystallized by cooling to 0° C. The crystallization procedure was repeated, and the crystals (7.7 g) washed with methanol. The washed crystals (3.9 g) were placed in 100 ml liquid ammonia and swirled with 0.2 g NaNH
2
for two minutes followed by quenching with 2 g ammonium bromide and suspension in 15 ml of 1 M perchloric acid, filtration, recrystallization from 25 ml boiling water with addition of 1 g sodium perchlorate and 5 ml ethanol to produce 1.9 g solid. This solid is then dissolved in 41 ml of water and treated with H
2
S, sorbed onto an acid loaded AG 50W-X2 resin column (4.5×10 cm), rinsed with 14 ml water, and eluted with aqueous ammonium hydroxide, concentrated, and crystallized with addition of methanol. After redissolution in water, recrystallization with ethanol, and drying over P
4
O
10
in vacuo, 0.62 g of N-(2-aminoethyl) aspartic acid was isolated for an overall yield of 4.4 percent. This poor yield would make the preparation too expensive as an industrial process.
Since polyamino monosuccinic acids such as EDMS and derivatives thereof are desirable products, there is a great need and interest in the industry for a simple process for the manufacture thereof which process is more economical than known processes.
It has been surprisingly discovered that reacting a maleate or fumarate dialkyl ester, such as, for example, dimethyl maleate, with a polyamino compound, such as ethylenediamine, results in markedly purer polyamino monosuccinic acid product and simpler reaction conditions when the solvent for the reaction is a primary alcohol rather than the solvents currently used or described in the literature.
SUMMARY OF THE INVENTION
The present invention concerns a process for preparing a polyamino monosuccinic acid, a salt or chelate thereof comprising
(a) reacting a diester of maleic or fumaric acid or a mixture thereof with a polyamino compound in a primary alcohol as a solvent;
(b) hydrolyzing the product obtained in step (a); and
(c) separating the primary alcohol.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a simple, convenient and more economical way to prepare a polyamino monosuccinic acid, a salt or chelate thereof. It has been surprisingly discovered that reacting an ester of maleic or fumaric acid with a polyamino compound in a primary alcohol solvent to produce the monoalkyl ester of polyamino monosuccinic lactam followed by hydrolysis with a hydroxide or oxide of an alkali metal or an alkaline earth metal results in a product with fewer side products than when secondary or tertiary alcohols are used as the solvent and does not require cooling of the reaction vessel.
The use of the primary alcohols, rather than the tertiary butanol described in the literature, allows the reaction of alkylenediamine and dialkyl maleate or dialkyl fumarate to be run at ambient temperature and produces purer product (less EDDS, maleate, and fumarate contamination).
The hydrolysis in step (b) of the present process is a well known process and it can be performed under either alkaline or acidic conditions. when the hydrolysis is performed under alkaline conditions, it is usually performed under aqueous conditions with a metal oxide or metal hydroxide. The preferred metal oxides and metal hydroxides are oxides and hydroxides of alkali metals and alkaline earth metals. Sodium hydroxide and potassium hydroxide are particularly preferred metal hydroxides.
When the hydrolysis is performed under acidic conditions, it is usually performed under aqueous conditions. Sulfuric and hydrochloric acids are particularly preferred acids.
The separation of the primary alcohol solvent from the polyamino monos
Burkholder Brian D.
Crump Druce K.
Strickland Alan D.
Wilson David A.
Geist Gary
The Dow Chemical Company
Tucker Zachary C.
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