Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1991-12-12
1993-10-05
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
5483001, 544399, C07C22900
Patent
active
052507289
ABSTRACT:
Synthesis of ethylenediaminetriacetic acid (ED3A) or its salts is disclosed. A salt of N,N'-ethylenediaminediacetic acid (ED2AH.sub.2) is condensed with formaldehyde to form a stable 5-membered ring intermediate. The addition of cyanide across this cyclic material forms ethylenediamine N,N'-diacetic acid-N'-cyanomethyl or salts thereof (mononitrile-diacid). The nitrile in aqueous solutions may be spontaneously cyclized to form 2-oxo-1,4-piperazinediacetic acid (3KP) or salts thereof, which is the desired cyclic intermediate. In the presence of excess base, salts of ED3A are formed in excellent yield and purity. Alternatively, the starting material is ED2AH.sub.a X.sub.b, where x is a base cation, e.g., an alkali or alkaline earth metal, a is 1 to 2, and b is 0 to 1 in aqueous solutions. The reaction mixture also can be acidified to ensure complete formation of carboxymethyl-2-oxopiperazine (the lactam) prior to the reaction. Formaldehyde is added, essentially resulting in the hydroxymethyl derivative. On the addition of a cyanide source, 1-cyanomethyl-4-carboxymethyl-2-ketopiperazine (mononitrile diacid) or a salt thereof is formed. Upon the addition of any suitable base or acid, this material may be hydrolyzed to 3KP. The addition of a base will open this ring structure to form the salt of ED3A.
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Cullen Barry A.
Gaudette Roger R.
Parker Brian A.
Hampshire Chemical Corp.
Shippen Michael L.
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