Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
1999-10-29
2001-03-06
Lee, Howard C. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S055200, C536S055300, C514S055000
Reexamination Certificate
active
06197942
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
FIELD OF THE INVENTION
This invention relates to a chitooligosaccharide derivative.
2. Prior Art Statement
The chitooligosaccharide, i.e. an oligomer of the N-acetyl glucosamine derived from chitin, has been attracting attention for its biodegradability and excellence in bioadaptability.
The chitooligosaccharide has, however, been finding utility only in a limited range of applications on account of its high solubility in water.
SUMMARY OF THE INVENTION
This invention is aimed at providing a novel derivative of the chitooligosaccharide which possesses adapt ability to living organisms, raises absolutely no environmental problems and is suitable for new applications.
Specifically, this invention concerns a derivative of the chitooligosaccharide, i.e. a novel substance which consists essentially of “m” number of:
and “n” number of
and possessing an OH group at the 4 position or 1 position of the terminal constituent unit, wherein m=1-20, n =1-20, m+n=2-21, and m
=5-0.05, and R represents a saturated or unsaturated aliphatic acyl group of 3-24 carbon atoms.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Specific examples of the saturated or unsaturated fatty acid represented by R include linear or branched saturated or unsaturated aliphatic acyl groups of 3-24, preferably 6-18, carbon atoms such as acryloyl, propionyl, butylyl, isobutylyl, valeryl, isovaleryl, pivaloyl, hexanoyl, octanoyl, decanoyl, lauroyl, myristoyl, palmitoyl, stearoyl, oleoyl, eicosanoyl, docosanoyl, and tetracosanoyl. Preferred examples of the acyl group include octanoyl, decanoyl, lauroyl, myristoyl, palmitoyl, stearoyl, and oleoyl.
The reason for limiting the number of carbon atoms of the acyl group to the range of 3-24 is that the number of carbon atoms of the fatty acid contained in oil, fat or wax as the raw material for the fatty acid falls in this range.
The reason for limiting the number of carbon atoms of the acyl group to the preferred range of 6-18 is that the chitooligosaccharide derivative, when used as a surfactant, acquires excellent properties as manifested in emulsifying power, permeability, and solubility.
The reason for the particular preferability of octanoyl, decanoyl, lauroyl, myristoyl, palmitoyl, stearoyl, and oleoyl groups is that the emulsion prepared by using the chitooligosaccharide derivative as a surfactant exhibits excellent stability (ability to retain the state of emulsification for a long time) and manifests high compatibility with the fatty acid forming oil, fat, and wax on account of having the same component as the fatty acid.
The reason for limiting the integers, m and n, used in the formula representing the derivative of the chitooligosaccharide of this invention both to the range of 1-20, preferably to the range of 1-9, is that the size of the sugar chain moiety of the derivative must be limited to a proper range in consideration of the solubility in the solvent (for the solubility is degraded by an unduly large sugar chain).
The reason for limiting the sum, m+n, to the range of 2-21, preferably the range of 2-10, is that the size of the sugar chain moiety of the derivative must be limited, as mentioned in the preceding paragraph, to a proper range in consideration of the solubility in the solvent.
The reason for limiting the ratio, m
, to the range of 5-0.05, preferably to the range of 1-0.2, is that an unduly large ratio of introduction deviating from this range barely allows the derivative to manifest the effect of a surfactant and makes control of the ratio of introduction difficult.
The chitooligosaccharide derivative of this invention can be obtained by deacetylating chitin into chitosan, hydrolyzing the chitosan to obtain a chitooligosaccharide, and causing this chitooligosaccharide to react with an acetylating agent and an acylating agent represented by R—O—R or R—Cl in the presence or absence of a solvent. Where R happens to represent the acyl group of a higher fatty acid, the acid chloride of R—Cl proves preferable in terms of reactivity.
The solvent is preferred to be a polar solvent capable of dissolving and dispersing an oligosaccharide. Specific polar solvents answering this description include dimethyl formamide, dimethyl acetamide, dimethyl sulfoxide, acetic acid, pyridine, acetonitrile, dioxane, and morpholine. The acylating agent may be added dropwise to such a solvent in the presence of a base such as pyridine or triethyl amine. The acylating agent is used in an amount in the approximate range of 0.1-1 mol, per mol of the glucosamine residue. The base is used in an amount in the approximate range of 1 mol to an excess amount based on one mol of the acylating agent. Where the acid chloride is used, it is preferred to be diluted with a chlorine type solvent. The reaction is carried out at a temperature in the range of 0-40° C. for a period in the range of 1-3 hours.
The reaction of acylation prefers the introduction of the R group of inferior reactivity to precede the acetylation. This reaction has only to be effected by sequentially adding the acetylating agent such as, for example, acetyl chloride or acetic anhydride after the addition of the acylating agent such as R—Cl or R—O—R.
When the reaction of acetylation is effected on acetic anhydride in the presence of sodium acetate by using a hydrated alcohol such as an aqueous 50% methanol solution as a solvent, the remaining amino group can be perfectly acetylated because the solvent has high solubility in an oligosaccharide.
The chitooligosaccharide derivative of this invention, depending on the purpose of use, does not need to be used as an isolated refined simple compound. As a surfactant, it is practical to use it in the form of various mixtures of compounds represented by the formulas mentioned above.
The chitooligosaccharide derivative of this invention can be used as a nonionic surfactant. It promises utility in a wide range of applications particularly because it is low in toxicity and is little affected by coexisting ions or pH value. Specifically, it can be expected to be used as bubble stabilizer, emulsifier, dispersant, and detergent in foodstuffs, pharmaceutical preparations, toiletry articles, cosmetic articles, and agricultural pesticides. Specific examples of cosmetic articles include various oil-in-water type and water-in-oil type creams such as vanishing cream, cold cream, emollient cream, cleansing cream, massage cream, moisture cream, and hand cream.
For example, the chitooligosaccharide derivative of this invention is useful as a surfactant because it possesses a long-chain hydrophobic group in combination with a hydrophilic group originating in saccharide.
The chitooligosaccharide derivative of this invention is biodegradable and safe from causing environmental problems because it is composed of a saturated or unsaturated fatty acid, glucosamine, and acetic acid.
Since the surfactant which is formed of the chitooligosaccharide derivative of this invention is a nonionic type surfactant, the properties thereof are not affected by such factors as pH, ionic strength, and coexisting ions.
When the number of carbon atoms of the fatty acid to be introduced is increased, the tendency to form a micelle increases and the ability to form emulsion is heightened. When the number of carbon atoms is decreased, the permselectivity is improved and diffusion into fine tissue is facilitated. It therefore suffices to select the fatty acid to be introduced to suit the intended use. It is also permissible to have different species of fatty acid mixed in one and the same molecule or to use different oligosaccharides of the introduced fatty acid in a mixed state.
REFERENCES:
patent: 5175149 (1992-12-01), Stacey et al.
patent: 5549718 (1996-08-01), Lerouge et al.
patent: 5696098 (1997-12-01), Muraki
Agency of Industrial Science and Technology Ministry of Internat
Lee Howard C.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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