Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1992-12-07
1994-07-05
Lilling, Herbert J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
25217418, 536 41, 536123, 536124, C08B 3700
Patent
active
053268644
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for the preparation of a calcium-complexing polycarboxy compound based on a polysaccharide.
From a technical standpoint, phosphates are the most suitable calcium-binding agents ("builders") in detergents. However, because the eutrophication of surface waters, the use of phosphates increasingly less desirable and there is therefore a need for to replace phosphates. Such agents must be able to bind calcium, and preferably also magnesium well and, in addition, be biodegradable, non-toxic and readily soluble in water and have no adverse influence on the action of the detergent and must also be inexpensive. agents have already been investigated, but only a few, such nitrilotriacetate, zeolites and polycarboxylates, meet the above-mentioned requirements to an extent which renders them also usable in practice. However, doubts are still being expressed as to the safety of nitrilotriacetate. Zeolites, polycarboxylates and nitrilotriacetate are not degradable, or are degradable to an inadequate extent, and, moreover, zeolites have the disadvantage that, because of the necessary "carrier" effect, they form usable "builders" only in combination with other agents. Polyacrylate is currently commonly used as a "co-builder" of this type.
Oxidised carbohydrates have also been proposed as substitutes phosphates. Polydicarboxysaccharides in particular have suitable characteristics for this purpose. These compounds can be obtained by oxidation of carbohydrates, for example with periodic acid followed by chlorite, or directly with hydrogen peroxide or sodium hypochlorite. During this oxidation, the two vicinal hydroxyl functions in the cyclic hexose unit (for example glucose) of the polysaccharide are converted into two carboxyl functions, with ring opening. Methods of this type have been disclosed, for example, in Netherlands Patent Application 70.12380, and M. Diamantoglou et al., Tenside Detergents 14, 250-256 (1977) and M. S. Nieuwenhuizen et al., Starch/Starke 37, 192-200 (1985).
The known methods for the oxidation of polysaccharides have a number of disadvantages. The use of periodic acid is fairly expensive because of the necessary regeneration of the periodic acid and is laborious because the polysaccharide dialdehyde formed with periodic acid as an intermediate has to be further oxidised to the dicarboxylic acid using other agents, such as chlorite or hypochlorite. Hydrogen peroxide is also a relatively expensive oxidising agent and, moreover, makes the use of a catalyst, such as a tungsten compound, desirable for a sufficiently effective conversion; in addition, the low pH required for this reaction is a drawback because of the depolymerisation which occurs. The reaction with hydrogen peroxide is also not very specific, so that the 6-hydroxymethyl group is also oxidised to some extent and significant depolymerisation (chain shortening) takes place.
Polysaccharides that are oxidised with the known methods are always based on glucose, such as 1,4-.alpha.-glucans or -polyanhydroglucoses (starch, amylose, amylopectin and substances derived therefrom) and 1,4-.beta.-glucans (cellulose and derivatives thereof). Nieuwenhuizen et al. (Starch/Starke 37, 192-200 (1985)) also investigated the oxidation of other polysaccharides, namely inulin (polyanhydrofructose) and alginate (polyanhydromannuronate/guluronate) with periodate/chlorite; the oxidation products thus obtained from these polysaccharides were, however, found to have poorer calcium-complexing properties than the oxidation products of polysaccharides based on glucose, such as starch and starch derivatives.
It has now been found that inulin can be oxidised in such a way that a polycarboxysaccharide is obtained which has a surprisingly high calcium- and magnesium- binding power, combined with a good biodegradability.
The method according to the invention is therefore characterised in that a polycarboxyinulin is prepared by oxidation of inulin in the presence of a low concentration of hypohalite.
Inulin is a polysaccharide which mainly co
REFERENCES:
patent: 4029590 (1977-06-01), Finley
Die Starke vol. 37 No. 6 pp. 192-200 (1985) Nieuwenhuizen et al "Preparation & Calcium Complexation Properties of a Series of Oxidized Polysaccharides".
Chemical Abstracts, vol. 104, No. 20, May, 1986, Abstract No. 170459g for Japanese Patent 60-226502, Nov. 11, 1985.
J. Agn. Chem. for Japan, vol. 28, 1954 for Oxidation of Inulin with Periodate, pp. 357-363-Summary in English.
Die Starke, vol. 15, No. 6, by J. Potze et al. for "Uber den Einfluss der Reaktionsbedingungen auf die Oxydation der kartoffelstarke mit Hypochlorit".
Besemer Arie C.
van Bekkum Herman
Lilling Herbert J.
Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk On
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