Succinic acid derivative degradable chelants, uses and compositions thererof

DETAILED DESCRIPTION OF THE INVENTION The present invention is to the use of a mixture of at least one polyamino disuccinic acid and one or more polyamino monosuccinic acids, also referred to herein as succinic acid mixtures.
As used herein the term succinic acid includes salts thereof.
It has been unexpectedly found that when a mixture of such compounds is used to chelate a metal ion, such as iron, said mixtures show a greater ability to chelate the metal ion and such complexes have a greater stability than what would be expected from the sum of the individual compounds.
Such mixtures also show an unexpected increase in biodegradability as measured by the OECD 301B Modified Sturm Test.
Polyamino disuccinic acids are compounds having two or more nitrogen atoms wherein 2 of the nitrogens are bonded to a succinic acid (or salt) group, preferably only two nitrogen atoms each have one succinic acid (or salt) group attached thereto.
The compound has at least 2 nitrogen atoms, and due to the commercial availability of the amine, preferably has no more than about 10 nitrogen atoms, more preferably no more than about 6, most preferably 2 nitrogen atoms.
Remaining nitrogen atoms most preferably are substituted with hydrogen atoms.
More preferably, the succinic acid groups are on terminal nitrogen atoms, most preferably each of which nitrogens also has a hydrogen substituent.
Because of steric hindrance of two succinic groups on one nitrogen, it is preferred that each nitrogen having a succinic group has only one such group.
Remaining bonds on nitrogens having a succinic acid group are preferably filled by hydrogens or alkyl or alkylene groups (linear, branched or cyclic including cyclic structures joining more than one nitrogen atom or more than one bond of a single nitrogen atom, preferably linear) or such groups having ether or thioether linkages, all of preferably from I to about 10 carbon atoms, more preferably from 1 to about 6, most preferably from 1 to about 3 carbon atoms, but most preferably hydrogen