Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2001-01-30
2003-01-28
O'Sullivan, Peter (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S018700, C536S055100, C536S055300, C536S120000, C536S123000, C536S123130, C536S124000, C536S126000
Reexamination Certificate
active
06512109
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for producing glycoside polymers or glycosides which are useful as materials for functional foods, biodegradable fibers, medicaments, and the like. More particularly, it relates to a method for producing glycoside polymers such as high molecular weight polysaccharides, polysaccharide-like polyesters or glycosides from natural resources such as glucose by using a solid superacid catalyst.
BACKGROUND ART
Synthetic fibers originated from petroleum such as polyamides (e.g. nylon) or polyesters are produced from petroleum originated in fossil, but such materials are limited resources and hence will be exhausted in future. By the way, some glycosides have an amino group (an alkaline functional group) and/or a carboxyl group (an acidic functional group) which are a functional group characteristic in such petroleum materials and hence may be useful as a material for producing fibers. However, it has never been succeeded to derive these glycosides into commercially usable fibers, except cellulose which is a polyacetal.
On the other hand, glycosides are extracted from sugarcare, coconut palm, prawn, crabs, sea tangle, woods, and the like, and hence those are unlimited resources and will be not exhausted forever. Besides, enzyme being capable decomposing glycosides are distributed widely in various organisms such as microorganisms, mammalia, etc., and hence, synthetic fibers produced by using these glycosides will probably be biodegradable. Accordingly, it will be much required to develop a method for producing synthetic fibers by using glycosides as the starting material.
The known methods for producing these synthetic fibers and starting materials therefor such as glycoside polymers or glycosides will roughly be classified into three methods, that is, a stepwise glycosylation method, a liquid polymerization method, and a bulk polymerization method.
As the stepwise glycosylation method, there has been used various Keonigs-Knorr's glycosylation reactions for a long time (Chem.Rev.,93,1503(1993)) The stepwise glycosylation method comprises extending the chain of the glycoside molecules one-by-one. In this method, since glycosides are a polyfunctional molecule and have many hydroxy groups in the molecule, it is necessary to protect the most hydroxy groups other than the hydroxy group to be formed into glycoside bond, and only said hydroxy group to be reacted shall be remained without being protected in the reaction.
As the solution polymerization method, various methods are know, for example, a ring opening polymerization of anhydrous saccharides by Schuerch et al. (Adv. Carbohydr. Chem. Biochem., 39, 157 (1981)), a cyanoethylidene method by Kochetkov et al. (Tetrahedron, 43, 2389 (1987)), a method utilizing a reverse glycohydrolase by Kobayashi et al. (Adv. Polym. Sci., 121, 1 (1995)).
The ring opening polymerization can give high molecular weight stereoregular polysaccharides. However, since this method is an ion polymerization, the reaction shall be carried out under high vacuum condition. Besides, this method has to use a solvent such as dichloromethane which is harmful in view of environmental disruption.
The cyanoethylidene method can produce stereoregular polysaccharides having complicated structure, but it is problem in side-production of cyanides during the polymerization reaction, which are extremely toxic cyanic acid derivatives, such as potassium cyanide. Accordingly, this method is very dangerous.
Next, the method using an enzyme has been succeeded for production of cellulose, but it is difficult to obtain a high molecular weight product in high yield. Moreover, the enzyme to be used has a substrate specificity and hence, usable glycosides are very limited. So, this method is not generally available.
The final method, bulk polymerization method can form a glycoside bond by carrying the reaction without using solvent, wherein the glycosides are molten with heating and an acetal exchange reaction proceeds to form the glycoside bond. The bulk polymerization method of glucose, etc. by Richards et al. comprises melting a glycoside having unprotected hydroxy groups by heating at a high temperature and then subjecting to the polymerization in the presence of dichloroacetic acid catalyst (Carbohydr. Res., 208, 93 (1990)). However, this method still has a defect such as coloring of the product, and due to the side reaction, the product has less purity. Moreover, the catalyst used therein dissolves in the reaction system or in various solvents, and hence, it is difficult to remove the catalyst from the reaction mixture.
DISCLOSURE OF INVENTION
An object of the present invention is to prove an improved method for producing materials advantageous in view of keeping environment in good conditions, for example, materials useful for producing functional foods, biodegradable fibers, etc. by using glycosides which are unlimited resources in simple procedure and safety. Another object of the invention is to provide a method for producing polymers or glycosides by using glycosides having unprotected saccharide chains without a solvent or in an aqueous solvent in a simple step contrary to the conventional methods which require very complicated steps, and further, the catalyst used in the method is recycled.
The present inventors have found that when a glycoside is subjected to a melt polymerization or solution polymerization by using as a catalyst a specific solid superacid, the desired glycoside polymers can be produced in an extremely high yield, and further that when a glycoside is reacted with an alcohol in the presence of the solid superacid, the desired glycosides can easily be produced, and then the present invention has been accomplished.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to a method for producing glycoside polymers by subjecting a compound of the formula (1):
wherein R
1
is —OH, R
2
is —OH or —NHCOCH
3
, R
3
is —CH
2
OH, —COOH or —CH
3
, to a melt polymerization or solution polymerization in the presence of a solid superacid.
The starting compound of the formula (1) includes, for example, monosaccharides such as D-glucose, D-galactose, D-mannose (in the above formula (1), R
1
: —OH, R
2
: —OH, R
3
: —CH
2
OH), L-fucose (in the above formula (1), R
1
: —OH, R
2
: —OH, R
3
: —CH
3
), and the like, aldonic acids such as D-glucuronic acid, D-galacturonic acid (in the above formula (1), R
1
: —OH, R
2
: —OH, R
3
: —COOH), aminosugars such as N-acetyl-D-glucosamine, N-acetyl-D-galactosamine (in the above formula (1), R
1
: —OH, R
2
: NHCOCH
3
, R
3
: —CH
2
OH).
The solid superacids to be used as a catalyst include any conventional compounds which have hitherto been used as a catalyst in isomerization of alkyl group, or introduction of a keto group into aromatic hydrocarbons, for example, the following compounds:
SO
44
/ZrO
2
, SO
4
/SnO
2
, SO
4
/HfO
2
, SO
4
/TiO
2
, SO
4
/Al
2
O
3
, SO
4
/Fe
2
O
3
, SO
4
/SiO
2
, WO
3
/ZrO
2
, MoO
3
/ZrO
2
, WO
3
/SnO
2
, WO
3
/TiO
2
, WO
3
/Fe
2
O
3
, and B
2
O
3
/ZrO
2
(cf K. Arata et al. J. Am. Chem. Soc., 101, 6439 (1979)) One or more of the above compounds are used. The amount thereof is not specified and is an amount effective for catalyzing the polymerization reaction, but it is usually in the range of 0.1 to 10 equivalent, preferably 1.0 equivalent to the starting compound (1).
Any commercially available solid superacids may be used as they stand, but those commercial products are sometimes wetted with atmospheric moisture, and hence, it is preferable to calcine the material by super-heating. For instance, the commercially available zirconia sulfate (SO
4
/ZrO
2
) is usually calcined at about 650° C. for about 2 hours.
The melt polymerization and the solution polymerization can be carried out by conventional methods.
More particularly, it is carried out as follows.
When the compounds of the formula (1) have a melting point, for example, in case of D-glucose or D-glucuronic acid, they are subjected to a melt polymerization in the following manner to give
Hokkaido Electric Power Company, Incorporated
O'Sullivan Peter
Wenderoth , Lind & Ponack, L.L.P.
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