Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-09-08
2003-07-08
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C562S568000
Reexamination Certificate
active
06590120
ABSTRACT:
This application is a 371 of PCT/FI99/00180 filed Mar. 8, 1999.
FIELD OF THE INVENTION
The invention relates to methods for the preparation of N-bis-[2-(1,2-dicarboxy-ethoxy)-ethyl]-amine derivative, and to the products of the method, and to the uses of those products.
The general formula I of the compounds that can be prepared according to the invention is
where R
1
is:
an alkyl hydrocarbon chain containing 1-30-carbon atoms,
an alkyl hydrocarbon chain containing 1-30 carbon atoms as well as 1-10 carboxylic acid groups attached to said chain, or alkali or earth alkali metal salt thereof,
an alkyl hydrocarbon chain containing 1-30 carbon atoms and 1-10 carboxylic acid esters attached to said chain,
a polyethoxylated hydrocarbon chain containing 1-20 ethoxyl groups,
a carboxylic acid amide containing 1-30 carbon atoms, where N—R
1
bond is an amide bond, or
an N-alkyl-N-bis-[2-(1,2-dicarboxy-ethoxy-(ethyl]-amine containing 1-20 carbon atoms in the alkyl chain, or an alkali or earth alkali metal salt thereof,
and R
2
and R
3
are: hydrogen, an alkali metal ion or an earth alkali metal ion or an alkyl group containing 1-30 carbon atoms.
The compounds to be prepared find use especially as chelating agents.
BACKGROUND OF THE INVENTION
Transition metal ions and earth-alkali metal ions are bound as water-soluble chelates, for example, in various washing processes. Chelates of metal ions are used in photography chemicals in the developing processes.
When oxygen or peroxide compounds are used in the total chlorine free (TCF) bleaching of pulp it is important to remove the transition metals from the fiber before bleaching, since transition metal ions catalyze the decomposition of peroxy compounds, thus forming radical compounds. In consequence of these reactions the strength properties of the fiber are deteriorated.
Peroxy compounds such as hydrogen peroxide and peroxy acids can also be used in the so-called ECF-bleaching (elemental-chlorine-free-bleaching). Also in sequences which use chlorine dioxide or a combination of chlorine dioxide and peroxy acids, as described in the application FI-974221, a chelating agent can advantageously be used. Traditionally chelating agents are used in the alkaline peroxide bleaching of mechanical pulps such as SGW (stone groundwood), TMP (thermomechanical pulp), PGW (pressure groundwood), CTMP (chemi-theromechanical pulp), etc. A chelating agent can be used directly in the bleaching or as a pretreatment before the bleaching proper. This is especially the case when a multistage peroxide bleaching is employed.
At present, the complexing agents most commonly used in the applications mentioned above are ethylenediaminetetraacetic acid (EDTA) and its salts and di-ethylenetriaminepentaacetic acid (DTPA) and its salts. These are excellent complexing agents, but their biodegradability is poor.
Patent applications FI-960758, FI-960757, FI-960756 and FI-960755 disclose the use of aspartic acid derivatives as chelators in the bleaching of pulp. Such chelators include ethylenediaminedisuccinic acid (EDDS) and its alkali and earth-alkali metal salts, as well as iminodisuccinic acid (ISA) and its alkali and earth-alkali metal salts. EDDS and ISA are effective chelators of transition metals. In addition, they are biodegradable.
EDDS-type aspartic acid derivatives with longer hydrocarbon chain than in EDDS, are known from JP patent applications 7 261 355 and 6 282 044. One such substance is N,N′-(oxide-2,1-ethanediyl)-bis-L-aspartic acid.
In most cases the chelators are disposed to waste waters after their use. In order to minimize the nitrogen load in waste waters the nitrogen contents of the chelator should be as low as possible. Biodegradable chelators of the type EDDS, wherein some of the nitrogen atoms have been replaced with oxygen atoms, are disclosed in JP patent applications 7 120899 and 7 120894. The applications disclose the use of various isomers of N-[2-(1,2-dicarboxyethoxy)-ethyl]-aspartic acid (EDODS) in photographic chemicals. A method to prepare EDODS by La
3+
-catalyzed O-alkylation of maleic acid salts has been described in the literature (J. van Vestrenen et al., Recd. Trav. Chem. Pays. Bas., vol. 109, 1990, p. 474-478).
However, in working tests performed by the applicants, EDODS did not prove to be a sufficiently effective chelator in pulp and paper applications. One possible explanation for the poor chelation result is the length of the carbon chain between the dicarboxyl ethoxy ethyl groups. If the carbon chain is not sufficiently long, strains are produced in the molecule during complexing and the metal complex will not be sufficiently stable.
SUMMARY OF THE INVENTION
In a previous application WO97/45396 by the present applicant there were disclosed compounds according to the formula II.
These compounds include N-bis-[2-(1,2-dicarboxy-ethoxy)-ethyl]-amine (BCEEA), N-tris-[2-(1,2-dicarboxy-ethoxy)-ethyl]-amine (TCEEA) and N-bis-[2-(1,2-di-carboxy-ethoxy)-ethyl]-aspartic acid (BCEEAA), as well as the alkali metal and earth alkali metal salts of the said compounds, preferably Na
+
, K
+
, Ca
2+
and Mg
2+
salts.
In the molecular structure of said compounds, the central atom is a secondary or tertiary nitrogen atom and additionally, the molecule contains four or six carboxylic acid groups, which coordinate effectively with transition metal ions. The carbon chains are sufficiently long in terms of the formation of advantageous bond angles.
The object of the present invention is to provide methods for the preparation of effective chelating agents which would be biodegradable and contain a minimum amount of nitrogen.
According to the invention compounds of the formula (I) can be prepared according to the method where an alkali or earth alkali metal salt of maleic acid is brought to a reaction with an N-substituted diethanolamine with a substituent group R
1
, to react with the two ethanol groups of said diethanolamine while the substituent group R
1
bound to the N atom is essentially unreactive with said maleic acid salt and thus preserved in the derivative obtained as a product, and optionally further reacting the product with a substitution agent, for example 2-bromoacetic acid or 2-chloroacetic acid to obtain a second product. With the exception of the compound referred to as BCEEAA in the above the compounds of the formula (1) are new compounds.
The invention thus comprises preparation of amine compounds according to the formula (I) by using alkali metal or earth-alkali metal salts of maleic acid and N-substituted diethanolamines as starting material in the presence of a lanthanide or earth alkali metal catalyst, in accordance with the following reaction.
where R
1
has a meaning as defined above in connection with the formula (I)
and R
2
and R
3
alkyl, alkali or earth alkali metal ions.
The preferred meanings of R
1
are alkyl and (CH
2
)
n
COOR, where n=1-20 and R=alkyl, alkali or earth alkali metal.
The maleic acid salt which is the intermediate stage in the synthesis can be prepared in an aqueous solution by preferably using, available initial substances such as maleic anhydride and alkali metal or earth alkali metal compounds. Alkali metal compounds suitable for the reaction include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and lithium carbonate. Earth alkali metal compounds suitable for the reaction include magnesium hydroxide, magnesium oxide, magnesium carbonate, calcium oxide, calcium hydroxide, and calcium carbonate.
The formation of maleate is an exothermal reaction. When maleic anhydride is added to water, maleic acid is formed. When an alkali is added to this solution at a suitable rate, the temperature of the reaction mixture will increase to 80-90° C., which is a temperature preferable for the performing of the alkylation reaction.
The amino alcohol, which is a diethanol amine derivative, and the lanthanum compound used as the catalyst can thereafter be added rapi
Aksela Reijo
Paren Aarto
Renvall Ilkka
Barts Samuel
Kemira Chemicals Oy
Pennie & Edmonds LLP
Zucker Paul A.
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