KR20120118010A - Method of chlorinating polysaccharides or oligosaccharides - Google Patents

Abstract

The present invention relates to a process for chlorination of polysaccharides or oligosaccharides comprising the following steps:
A) dissolving the polysaccharide or oligosaccharide in a solvent system comprising at least one ionic liquid, and
B) reacting the polysaccharide or oligosaccharide with a chlorinating agent.

Description

Chlorination of polysaccharides or oligosaccharides {METHOD OF CHLORINATING POLYSACCHARIDES OR OLIGOSACCHARIDES}

The present invention describes a method for chlorination of polysaccharides or oligosaccharides comprising the following steps:

A) dissolving the polysaccharide or oligosaccharide in a solvent system comprising at least one ionic liquid, and

B) reacting the polysaccharide or oligosaccharide with a chlorinating agent.

Cellulose is the most important renewable raw material and represents an important starting material for the textile and paper and nonwovens industries, for example. It also serves as a raw material for cellulose derivatives and modification methods and processes, including cellulose ethers and cellulose esters. Such derivatives and modifications have many uses, for example in the textile, food, building and surface coating industries. There is therefore particular interest in how cellulose can be modified and also for modified cellulose for various technical applications.

In addition, low molecular weight cellulose or modified cellulose corresponding to low degree of polymerization (DP) is required in many technical applications.

Decomposition methods of cellulose yielding cellulose with low DP are described in WO 2007/101811 (decomposition by use of acid), WO 2007/101812 (decomposition at elevated temperature) and WO 2007/101813 (decomposition by nucleophile). Known.

WO 2008/000666 describes acylation and degradation of cellulose in ionic liquids. However, the process is a two step process. The DP of cellulose in the first stage is lowered according to the technique of WO 2007/101811 or WO 2007/101812, and the low molecular weight cellulose obtained in the second stage is acylated.

Accordingly, there is a need to provide a simple method for the modification and degradation of polysaccharides or oligosaccharides, in particular cellulose.

Applicants have now found an easy way to prepare chlorinated polysaccharides or oligosaccharides; Applicants have also found a method for chlorination and degradation of polysaccharides or oligosaccharides.

Step A)

In step A) of the process, the polysaccharide or oligosaccharide is dissolved in a solvent system comprising at least one ionic liquid.

Polysaccharide

Examples of polysaccharides or oligosaccharides include cellulose, and hemicellulose and also starch, glycogen, dextran, and tunisin. Further examples are polycondensates of D-fructose, for example inulin, and also especially chitin and alginic acid. Polysaccharides or oligosaccharides, in particular cellulose, can be chemically modified to some extent, for example by etherification or esterification of hydroxyl groups.

Preferably the polysaccharide or oligosaccharide is cellulose, hemicellulose or chemically modified cellulose.

In a more preferred embodiment of the invention, cellulose is used as the polysaccharide. Most preferably the cellulose used is not modified.

Preferred polysaccharides or oligosaccharides, in particular cellulose, used in the process have a degree of polymerization (DP) of at least 50, more preferably at least 150 or most preferably at least 300. The maximum value of DP may for example be 1000, more preferably 800 or at most 600.

Degree of polymerization (DP) is the number of repeat units in the average polymer chain. DP can be calculated as follows: DP = total Mw of polymer / Mw of repeat units. Molecular weight is a weight average molecular weight. DP can be measured by gel permeation chromatography (GPC) or size exclusion chromatography (SEC).

Solvent Based and Ionic Liquids

The solvent system may be one solvent or solvent mixture. The solvent system may be an ionic liquid alone or a mixture of different ionic liquids or a mixture of ionic liquids and other organic, nonionic solvents.

As a nonionic solvent, polar solvents that can be mixed homogeneously with the ionic liquid and do not cause precipitation of polysaccharides, for example ethers or ketones, for example dioxane, dimethyl sulfoxide, dimethylformamide, dimethylacetamide or sulphate Polan can be used. Preferred is dioxane.

The content of the ionic liquid in the solvent system is preferably at least 20% by weight, more preferably at least 50% by weight, most preferably at least 80% or 90% by weight.

In one preferred embodiment of the invention, the solvent system is a mixture comprising at least one ionic liquid and at least one nonionic solvent, in particular dioxane. In the mixture, the content of the ionic liquid is preferably 20 to 90% by weight, with the remainder being nonionic solvent (s).

The solvent system preferably contains no water or has only a low content of water of less than 5% by weight. In particular, the content of water is less than 2% by weight.

The term ionic liquids are salts (compounds composed of cations and anions) having a melting point below 200 ° C., preferably below 150 ° C., particularly preferably below 100 ° C. and very particularly preferably below 80 ° C. at atmospheric pressure (1 bar). ).

In a particularly preferred embodiment, the ionic liquid is a liquid under normal conditions (1 bar, 21 ° C.), ie at room temperature.

Preferred ionic liquids include organic compounds as cations (organic cations). Depending on the valence of the anion, the ionic liquid may include additional cations, including metal cations, in addition to organic cations.

Particularly preferred cations of ionic liquids are exclusively organic cations or mixtures of different organic cations in the case of polyvalent anions.

Suitable organic cations are especially organic compounds having heteroatoms such as nitrogen, sulfur, oxygen or phosphorus; In particular, the organic cation is a compound having an ammonium group (ammonium cation), oxonium group (oxonium cation), sulfonium group (sulfonium cation) or phosphonium group (phosphonium cation).

In certain embodiments, the organic cation of the ionic liquid is an ammonium cation, which for the purposes of the present invention is a nonaromatic compound having a localized positive charge on a nitrogen atom, for example a compound comprising tetravalent nitrogen (quaternary ammonium Compound) or a compound comprising trivalent nitrogen (one bond is a double bond), or an aromatic compound having an unlocalized positive charge and at least one nitrogen atom, preferably one or two nitrogen atoms in the aromatic ring system.

Preferred organic cations are quaternary ammonium cations, preferably having three or four aliphatic substituents, particularly preferably C1-C12-alkyl groups, which may be optionally substituted on the nitrogen atom with hydroxyl groups.

Particular preference is given to organic cations comprising heterocyclic ring systems having one or two nitrogen atoms as constituents of the ring system.

Monocyclic, bicyclic, aromatic or nonaromatic ring systems are possible. Mention may be made, for example, of bicyclic systems as described in WO 2008/043837. The bicyclic system of WO 2008/043837 is a diazabicyclo derivative, preferably made of a 7-membered ring and a 6-membered ring, containing an amidinium group; Particular mention may be made of 1,8-diazabicyclo [5.4.0] unde-7-cenium cations.

Very particularly preferred organic cations include 5- or 6-membered heterocyclic ring systems having one or two nitrogen atoms as constituents of the ring system.

Possible organic cations of this type are, for example, pyridinium cations, pyridazinium cations, pyrimidinium cations, pyrazinium cations, imidazolium cations, pyrazollium cations, pyrazolium cations, imidazolinium cations, Thiazolium cation, triazolium cation, pyrrolidinium cation and imidazolidinium cation. Such cations are for example mentioned in WO 2005/113702. The nitrogen atoms of the cations are hydrogen or organic groups, usually hydrocarbon groups, in particular C 1 -C 16 -alkyl groups, in particular C 1 -C 10 -alkyl groups, in particular when substitution is necessary to have a positive charge Preferably substituted with a C1-C4-alkyl group.

The carbon atoms of the ring system may also be substituted with organic groups, preferably hydrocarbon groups, in particular C1-C16-alkyl groups, in particular C1-C10-alkyl groups, particularly preferably C1-C4-alkyl groups, which do not exceed 20 carbon atoms. Can be.

Particularly preferred ammonium cations are quaternary ammonium cations, imidazolium cations, pyrimidinium cations and pyrazollium cations.

Imidazolium cation of formula (I)

Pyridinium cation of formula II

And pyrazolium cations of formula III

[Wherein the radical has the following meaning:

R is an organic group having 1 to 20 carbon atoms,

R1 to R5 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms, and in the case of imidazolium (Formula I) and a pyrazolium cation (Formula III), R1 is preferably an organic group having 1 to 20 carbon atoms ]

This is especially mentioned.

Most preferred are imidazolium cations of formula I; In particular, R and R1 are imidazolium cations wherein each is an organic radical having 1 to 20 carbon atoms and R2, R3 and R4 are each an H atom or an organic radical having 1 to 20 carbon atoms.

In the case of the imidazolium cation of formula (I), it is preferred that R and R1 are each independently an organic radical having 1 to 10 carbon atoms. In particular, R and R1 are each aliphatic radicals, in particular aliphatic radicals without further heteroatoms, for example alkyl groups. It is particularly preferred that R and R1 are each, independently of one another, a C1-C10- or C1-C4-alkyl group.

In the case of the imidazolium cation of formula (I), R 2, R 3 and R 4 are each independently of each other an H atom or an organic radical having 1 to 10 carbon atoms; In particular R 2, R 3 and R 4 are each an H atom or an aliphatic radical. It is particularly preferable that R 2, R 3 and R 4 are each independently of one another an H atom or an alkyl group; In particular R2, R3 and R4 are each, independently of one another, an H atom or a C1-C4-alkyl group. Very particular preference is given to each of R2, R3 and R4 being H atoms.

Ionic liquids may include inorganic or organic anions. Such anions are mentioned, for example, in the above-mentioned WO 03/029329, WO 2007/076979, WO # 2006/000197 and WO 2007/128268.

Possible anions are in particular anions from the following group:

The group of halides and halogen-comprising compounds of the formula:

^{F -, Cl -, Br -} , I -, BF 4 -, PF 6 -, AlCl 4 -, Al 2 Cl 7 -, Al 3 Cl 10 -, AlBr 4 -, FeCl 4 -, BCl 4 -, SbF 6 _{^{-, AsF 6 -, ZnCl 3}} -, SnCl 3 -, CuCl 2 -, CF 3 SO 3 -, (CF 3 SO 3) 2 N -, CF 3 CO 2 -, CCl 3 CO 2 -, CN -, SCN ^{-, OCN -, NO 2 -} , NO 3 -, N (CN) -;

Groups of sulfates, sulfites and sulfonates of the formula:

_{^{SO 4 2 -, HSO 4 -}} , SO 3 2 -, HSO 3 -, R a OSO 3 -, R a SO 3 -;

A group of phosphates of the formula:

_{^{PO 4 3 -, HPO 4 2}} -, H 2 PO 4 -, R a PO 4 2 -, HR a PO 4 -, R a R b PO 4 -;

A group of phosphonates and phosphinates of the formula

_{^{R a HPO 3 -, R a}} R b PO 2 -, R a R b PO 3 -;

A group of phosphites of the formula

_{^{PO 3 3 -, HPO 3 2}} -, H 2 PO 3 -, R a PO 3 2 -, R a HPO 3 -, R a R b PO 3 -;

A group of phosphonites and phosphinites of the formula

_{^{R a R b PO 2 -,}} R a HPO 2 -, R a R b PO -, R a HPO -;

Group of carboxylates of formula

R ^a COO ^-;

Group of borate of formula:

_{^{BO 3 3 -, HBO 3 2}} -, H 2 BO 3 -, R a R b BO 3 -, R a HBO 3 -, R a BO 3 2 -, B (OR a) (OR b) (OR c) (OR ^d ) ^- , B (HSO ₄ ) ^- , B (R ^a SO ₄ ) ^- ;

The group of boronates of the formula:

_{^{R a BO 2 2 -, R}} a R b BO -;

Groups of carbonates and carbonate esters of the formula:

_{^{HCO 3 -, CO 3 2 -}} , R a CO 3 -;

Groups of silicates and silicate esters of the formula:

_{^{SiO 4 4 -, HSiO 4 3}} -, H 2 SiO 4 2 -, H 3 SiO 4 -, R a SiO 4 3 -, R a R b SiO 4 2 -, R a R b R c SiO 4 -, HR _{^{a SiO 4 2 -, H 2}} R a SiO 4 -, HR a R b SiO 4 -;

A group of alkylsilane and arylsilane salts of the formula:

_{^{R a SiO 3 3 -, R}} a R b SiO 2 2 -, R a R b R c SiO -, R a R b R c SiO 3 -, R a R b R c SiO 2 -, R a R b SiO _^32;

Carboximides, bis (sulfonyl) imides and sulfonylimides of the formula:

;

;

The group of methides of the formula:

;

;

A group of alkoxides and aryloxides of the formula:

R ^a O ^-;

A group of halometalates of the formula

[M _r Hal _t ] ^s-

[Wherein M is a metal, Hal is fluorine, chlorine, bromine or iodine, r and t are positive integers and represent the stoichiometry of the complex, and s is a positive integer and represents the charge of the complex];

Groups of sulfides, hydrogensulfides, polysulfides, hydrogenpolysulfides and thiolates of the formula:

^{S 2 -, HS -, [} S v] 2-, [HS v] -, [R a S] -,

In which v is a positive integer from 2 to 10; And

Complex metal ions such as Fe (CN) ₆ ^3- , Fe (CN) ₆ ^4- , MnO ₄ ^-, Fe (CO) ₄ ^- group.

In the anion, R ^a , R ^b , R ^c and R ^d are each independently of one another,

Hydrogen;

C ₁ -C ₃₀ -alkyl and aryl-, heteroaryl-, cycloalkyl-, halogen-, hydroxy-, amino-, carboxy-, formyl-, -O-, -CO-, -CO-O- or -CO-N <substituted derivatives thereof, for example methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl (isobutyl), 2-methyl-2 -Propyl (tert-butyl), 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-2-butyl, 3-methyl-2- Butyl, 2,2-dimethyl-1-propyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2- Methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2-methyl-3-pentyl, 3-methyl-3-pentyl, 2,2-dimethyl-1-butyl, 2, 3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, heptyl, octyl, Nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, ecosil, hendecyl, docosyl, tricosyl, Tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacyl, phenylmethyl (benzyl), diphenylmethyl, triphenylmethyl, 2-phenylethyl, 3-phenylpropyl, cyclopentyl Methyl, 2-cyclopentylethyl, 3-cyclopentylpropyl, cyclohexylmethyl, 2-cyclohexylethyl, 3-cyclohexylpropyl, methoxy, ethoxy, formyl, acetyl or C _q F _{2 (qa) + ( 1-b)} H _{2a + b} (wherein q ≦ 30, 0 ≦ a ≦ q and b = 0 or 1) (e.g. CF ₃ , C ₂ F ₅ , CH ₂ CH ₂ -C _{(q- 2)} F _{2 (q-2) +1} , C ₆ F ₁₃ , C ₈ F ₁₇ , C ₁₀ F ₂₁ , C ₁₂ F ₂₅ );

C ₃ -C ₁₂ -cycloalkyl and aryl-, heteroaryl-, cycloalkyl-, halogen-, hydroxy-, amino-, carboxy-, formyl-, -O-, -CO- or -CO-O- Substituted derivatives thereof such as cyclopentyl, 2-methyl-1-cyclopentyl, 3-methyl-1-cyclopentyl, cyclohexyl, 2-methyl-1-cyclohexyl, 3-methyl-1-cyclohexyl, 4-methyl-1-cyclohexyl or C _q F _{2 (qa)-(1-b)} H _{2a -b wherein} q ≦ 30, 0 ≦ a ≦ q and b = 0 or 1;

C ₂ -C ₃₀ -alkenyl and aryl-, heteroaryl-, cycloalkyl-, halogen-, hydroxy-, amino-, carboxy-, formyl-, -O-, -CO- or -CO-O- Substituted derivatives thereof, such as 2-propenyl, 3-butenyl, cis-2-butenyl, trans-2-butenyl or C _q F _{2 (qa)-(1-b)} H _{2a -b} ( Wherein q ≦ 30, 0 ≦ a ≦ q and b = 0 or 1);

C ₃ -C ₁₂ -cycloalkenyl and aryl-, heteroaryl-, cycloalkyl-, halogen-, hydroxy-, amino-, carboxy-, formyl-, -O-, -CO- or -CO-O Substituted derivatives thereof, for example 3-cyclopentenyl, 2-cyclohexenyl, 3-cyclohexenyl, 2,5-cyclohexadienyl or C _q F _{2 (qa) -3 (1-b)} H _2a-3b (wherein q ≦ 30, 0 ≦ a ≦ q and b = 0 or 1);

Aryl or heteroaryl having 2 to 30 carbon atoms and alkyl-, aryl-, heteroaryl-, cycloalkyl-, halogen-, hydroxy-, amino-, carboxy-, formyl-, -O-, -CO- or- CO-O- substituted derivatives thereof, for example phenyl, 2-methylphenyl (2-tolyl), 3-methylphenyl (3-tolyl), 4-methylphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl , 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 4-phenylphenyl, 1- Naphthyl, 2-naphthyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 2-pyridinyl, 3-pyridinyl, 4-pyridinyl or C ₆ F _(5-a) H _a (formula In which 0 ≦ a ≦ 5);

Two radicals form an unsaturated, saturated or aromatic ring, which is optionally substituted with a functional group, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatom and / or heterocycle and at least one oxygen and / or sulfur atom and / or Optionally blocked with one or more substituted or unsubstituted imino groups.

In the case of the anions, R ^a , R ^b , R ^c and R ^d Are independently from each other a hydrogen atom or a C1-C12-alkyl group.

Anions that may be mentioned are for example chlorine; bromine; iodine; Thiocyanate; Hexafluorophosphate; Trifluoromethanesulfonate; Methanesulfonate; Carboxylates, especially formate; acetate; Mandelate; Nitrates; Nitrite; Trifluoroacetate; Sulfate; Hydrogensulfate; Methylsulfate; Ethyl sulfate; 1-propylsulfate; 1-butylsulfate; 1-hexylsulfate; 1-octyl sulfate; Phosphate; Dihydrogenphosphate; Hydrogenphosphate; C1-C4-dialkylphosphates; Propionate; Tetrachloroaluminate; Al ₂ Cl ₇ ^-; Chlorozincate; Chloroperate; Bis (trifluoromethylsulfonyl) imide; Bis (pentafluoroethylsulfonyl) imide; Bis (methylsulfonyl) imide; Bis (p-toluenesulfonyl) imide; Tris (trifluoromethylsulfonyl) methide; Bis (pentafluoroethylsulfonyl) methide; p-toluenesulfonate; Tetracarbonyl cobaltate; Dimethylene glycol monomethyl ether sulfate; Oleate; Stearate; Acrylates; Methacrylate; Maleate; Hydrogen citrate; Vinyl phosphonates; Bis (pentafluoroethyl) phosphinate; Borate such as bis [salicylate (2-)] borate, bis [oxalato (2-)] borate, bis [1,2-benzenediolato (2-)-O, O '] borate, tetracyanoborate , Tetrafluoroborate; Dicyanamide; Tris (pentafluoroethyl) trifluorophosphate; Tris (heptafluoropropyl) trifluorophosphate, cyclic arylphosphates such as catecholphosphate (C ₆ H ₄ O ₂ ) P (O) O ⁻ and chlorocobaltate.

Particularly preferred anions are anions from the group consisting of:

Alkyl sulfate

R ^a OSO ₃ ^-,

[Wherein, R ^a Is a C1-C12-alkyl group, preferably a C1-C6-alkyl group;

Alkylsulfonates

R ^a SO ₃ ⁻ ;

[Wherein, R ^a Is a C1-C12 alkyl group, preferably a C1-C6-alkyl group;

Halides, in particular chlorine and bromine, and

Pseudohalides such as thiocyanate, dicyanamide,

Carboxylate R ^a COO ^-;

[Wherein, R ^a Is a C1-C20-alkyl group, preferably a C1-C8-alkyl group], in particular acetate,

Phosphate,

In particular the dialkylphosphates of the formula R ^a R ^b PO ₄ ⁻ , wherein R ^a And R ^b are each independently of the other a C 1 -C 6 -alkyl group; Especially R ^a And R ^b Is the same alkyl group), for example dimethyl phosphate and diethyl phosphate,

And phosphonates, especially the formula R ^a R ^b PO ₃ ^- in the monoalkyl phosphonic acid ester (wherein, R ^a And R ^b Are each independently a C1-C6-alkyl group).

Very particularly preferred anions are as follows:

Chlorine, bromine, hydrogensulfate, tetrachloroaluminate, thiocyanate, dicyanamide, methylsulfate, ethylsulfate, methanesulfonate, formate, acetate, dimethylphosphate, diethylphosphate, p-toluenesulfonate , Tetrafluoroborate and hexafluorophosphate, methylmethylphosphonate (methyl ester of methylphosphonate).

Particularly preferred ionic liquids consist exclusively of one of the anions mentioned together with organic cations.

Most preferred are imidazolium cations according to formula I and one of the anions, in particular one of the particularly preferred anions, in particular the imidazolium salt with acetate, chlorine, dimethylphosphate or diethylphosphate or methylmethylphosphonate to be. Most preferred is acetate or chloride.

The molecular weight of the ionic liquid is preferably less than 2000 g / mol, particularly preferably less than 1500 g / mol, particularly preferably less than 1000 g / mol, very particularly preferably less than 750 g / mol; For certain embodiments, the molecular weight is in the range of 100 to 750 g / mol or in the range of 100 to 500 g / mol.

Preparation of the solution

In the process of the invention, a solution of polysaccharide or oligosaccharide, preferably cellulose, is prepared in a solvent system. The concentration of polysaccharides or oligosaccharides can vary within wide ranges. It is generally from 0.1 to 50% by weight, preferably from 0.2 to 40% by weight, particularly preferably from 0.3 to 30% by weight and very particularly preferably from 0.5 to 20% by weight, based on the total weight of the solution.

This dissolution process may be carried out at room temperature or with heating, but usually exceeds the melting point or softening temperature of the anionic liquid at temperatures of 0 to 200 ° C., preferably 20 to 180 ° C., particularly preferably 50 to 150 ° C. . However, dissolution can also be accelerated by vigorous stirring or mixing or by the introduction of microwave or ultrasonic energy or by a combination thereof. If a solvent system comprising an ionic liquid and a nonionic solvent is used, the polysaccharide or oligosaccharide can be first dissolved in the ionic liquid and then the nonionic solvent can be added.

Step B)

In step B) the polysaccharides or oligosaccharides, preferably cellulose, are reacted with a chlorinating agent.

The chlorinating agent can be added to the solution obtained after step A), for example as above or in the form of a solution in a suitable solvent.

Common chlorinating agents can be used, for example thionyl chloride, methanesulfonyl chloride, chlorodimethylimium chloride, phosphoryl chloride or para-toluenesulfonic acid chloride.

A preferred chlorinating agent is thionyl chloride.

The chlorinating agent should be added at least in an amount to achieve the desired degree of substitution.

The degree of substitution (DS) of the polysaccharide or oligosaccharide is the average number of hydroxyl groups per 6-ring unit of the polysaccharide or oligosaccharide substituted by chlorine.

The degree of substitution (DS) of a given chlorinated cellulose is defined as the average number of substituted hydroxyl groups per anhydroglucose unit (AGU).

DS is determined from the chlorine content detected in elemental analysis.

The chlorinated polysaccharides or oligosaccharides obtained by the process of the invention preferably have a degree of substitution (DS) of at least 0.5.

Since there are three hydroxyl groups in the AGU of cellulose, the theoretical maximum value of DS in chlorinated cellulose is 3.0. The first hydroxyl group of the cellulose to be substituted by a chlorine atom will generally be the hydroxyl of the hydroxyl-methylene group.

Preferred DS of the chlorinated cellulose obtained by the method of the present invention is 0.5 to 3, more preferably 0.8 to 3 DS. Suitable chlorinated cellulose obtained by the process of the invention may have a DS of, for example, 0.5 to 1.5 or 0.8 to 1.5.

According to the method of the present invention, DS of chlorinated cellulose of 1.0 or more can be easily achieved.

The chlorinating agent can be added in excess, meaning that more chlorinating agent can be added than necessary for the maximum DS. Unreacted chlorinating agent can be removed in a conventional manner and thionyl chloride can be removed, for example, by evaporation.

Chlorinating agents, in particular thionyl chloride, not only affect the substitution of hydroxyl groups by chlorine atoms, but also cause degradation of polysaccharides or oligosaccharides, in particular cellulose. This degradation is caused by the fact that the chlorinating agent hydrolyzes the oxygen bridges (β-1,4-glycosidic acid bonds) between repeating units of the main chain of oligosaccharides or polysaccharides.

Thus, the process of the invention is in fact also a method of chlorination and hydrolysis of polysaccharides or oligosaccharides.

Thus, the chlorinated polysaccharides or oligosaccharides obtained, for example chlorinated celluloses, preferably have a lower degree of polymerization (DP) than the DPs of the non-chlorinated polysaccharides or oligosaccharides, in particular the DP of the chlorinated polysaccharides or oligosaccharides obtained from the non-chlorinated starting material. It may be less than 90%, preferably less than 80%, more preferably less than 50%, most preferably less than 20, even less than 10% of DP.

Preferred cellulose, which may have a DP of 50 to 1000, more preferably 100 to 800 (see above), a DP less than 100, for example 5 to 100, or 10 to 100, or 10 to 50 DP Decomposed chlorinated cellulose with can be obtained.

According to the process of the present invention, therefore, chlorinated cellulose is obtained which can have a DS of, for example, 0.5 to 3, specifically 0.5 to 1.5, and a DP of 10 to 100, specifically 10 to 50. Most preferred are chlorinated celluloses with DS of 0.5 to 1.5 and DP of 5 to 100, or chlorinated celluloses of DS of 0.8 to 1.5 and DP of 10 to 50.

During the chlorination reaction, the reaction mixture is preferably maintained at elevated temperature; The temperature may for example be 30 to 150 ° C, more preferably 80 to 130 ° C at ambient pressure (1 bar).

In general, the reaction is carried out in air. However, this can also be carried out under inert gas, ie N ₂ , inert gas or mixtures thereof.

Temperature and reaction time can be selected to achieve the desired degree of DS and DP. For decomposition, no additional additives such as acids or nucleophiles (WO 2007/101811, degradation by use of acids or WO 2007/101813, degradation by nucleophiles) are not required. Also no use of base is required. In a preferred embodiment, chlorination is carried out in the absence of additional base.

As a product of the process, a solution comprising an ionic liquid and a chlorinated polysaccharide or oligosaccharide is obtained.

Chlorinated polysaccharides or oligosaccharides can be isolated from the solution by conventional methods if necessary.

The chlorinated polysaccharides or oligosaccharides are for example added coagulation solvents (nonsolvents for chlorinated polysaccharides or oligosaccharides) or other coagulants, in particular solutions containing base or basic salts such as ammonia or NH ₄ OH and solidifying from the solvent system. Can be obtained from the solution by separating the chlorinated polysaccharides or oligosaccharides. Depending on the manner in which the coagulation solvent and the reaction mixture are mixed, different chlorinated species can be obtained. For example, predominantly monochlorinated species are obtained by pouring a coagulation solvent into the reaction mixture.

On the other hand, predominantly dichlorinated species are obtained by pouring the reaction mixture into a coagulation solvent.

Isolated chlorinated polysaccharides or oligosaccharides, in particular chlorinated cellulose, can be obtained in certain forms. If desired, it may be obtained in the form of fibers, films or pearls, depending on the particular conditions under which chlorinated polysaccharides or oligosaccharides are precipitated.

Isolated or precipitated chlorinated polysaccharides or oligosaccharides can be dried to remove residual solvent.

Solutions of polysaccharides or oligosaccharides or polysaccharides or oligosaccharides isolated from such solutions are useful for a variety of technical applications. Low DP (oligomer) chlorinated cellulose can be used as an intermediate to produce cationic, amphoteric, nonionic, and anionic cellulose oligomers which also have several possible technical uses.

One embodiment of the invention is a method of modifying chlorinated species by at least partial substitution of chlorine with bisphenol A. New substituents are given by the formula:

In the formula, * represents a binding site to cellulose C6 carbon (-CH _2- ).

Example

General process

Heated at 100 ° C. for 2 hours to dissolve cellulose (microcrystalline cellulose (Avicel®, DP = 430)) in ionic liquid, 1-butyl-3-methyl imidazolium chloride (BMIMCl). Dioxane as cosolvent The reaction was cooled to 60 ° C. and thionyl chloride (5 equiv) was added The mixture was stirred for 2 h at 60 ° C. and then excess thionyl chloride was removed in vacuo. Cooled to 5 ° C. and NH ₄ OH was added, the precipitate was filtered off, washed with hot water and dried in a vacuum oven at 65 ° C. DP = 26 DS = 0.8-1.13 Due to the insoluble nature of the dried product, The analysis consisted of CP-MAS NMR (solid state NMR), IR, GPC and elemental analysis.

Scheme:

In further experiments (Examples 2 and 3), the amount of cellulose was varied and the temperature (60 ° C.), time (2 hours) and amount of thionyl chloride (5 equivalents) were kept constant. The results of all the examples are shown in the table below:

Analysis of the obtained chlorinated cellulose

Chlorinated cellulose oligomers had poor solubility and therefore could not be analyzed by solution state NMR. IR 1428 cm is typical ^- exhibited a C-Cl band at ^{1 -} CH ₂ -Cl in ¹ oscillation and 751 cm.

CP-MAS NMR Spectroscopy

The structure of the anhydroglucose unit (AGU) of chlorocellulose showing the number of carbon atoms.

C-6 chlorination can be clearly seen in CP-MAS NMR (solid state NMR) as the shift of chemical shift to C-6 carbon. C6-Cl signals are observed at 40 ppm, while unsubstituted C-6 (C6-OH) has a chemical shift near 60 ppm. Dichlorination (C-6 and C-1) can be seen as a shifted chemical signal (C-1 chlorination) of C-1 from 104 ppm to 97 ppm and C-6 chlorination at 40 ppm.

The crystallinity of cellulose can be estimated by blocking the C-4 signal. Two signals for C-4 are observed in the spectrum of the original cellulose. This means that both amorphous and crystalline cellulose are present in the structure. After a uniform chemical modification in which the cellulose is completely dissolved in a given solvent, the crystallinity of the cellulose disappears leading to a less orderly (amorphous) cellulose derivative as a product. In addition, the signal at 81.7 ppm is specified to originate from less ordered carboxylates such as cellulose oligomers. This can be seen in the case of chlorocellulose oligomers where only less ordered (amorphous) C-4 signals are detected.

Claims (14)

A chlorination method of a polysaccharide or oligosaccharide comprising the following steps:
A) dissolving the polysaccharide or oligosaccharide in a solvent system comprising at least one ionic liquid, and
B) reacting the polysaccharide or oligosaccharide with a chlorinating agent. The method of claim 1 wherein the polysaccharide or oligosaccharide is cellulose, hemicellulose or chemically modified cellulose. The method of claim 1 or 2, wherein the ionic liquid
Imidazolium cation of formula (I)

Pyridinium cation of formula II

Or a pyrazollium cation of formula III

[Wherein the radical has the following meaning:
R is an organic group having 1 to 20 carbon atoms,
R1 to R5 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms]
A method having a cation selected from. 4. The process of claim 1 or 3 wherein the ionic liquid is an imidazolium salt. The method of claim 1, wherein the solvent system is a mixture of solvents comprising at least one ionic liquid and at least one nonionic solvent. The method of claim 5 wherein the content of the ionic liquid in the mixture of solvents is at least 20% by weight. The process according to any one of claims 1 to 6, wherein the chlorinating agent is thionyl chloride. The process according to claim 1, wherein the temperature is between 30 and 150 ° C. during chlorination. The chlorinated polysaccharide or oligosaccharide obtained has a degree of substitution (DS) of at least 0.5; Wherein DS is defined as the average number of hydroxyl groups per 6-ring unit of polysaccharide or oligosaccharide substituted with chlorine. The process according to any one of claims 1 to 9, wherein the obtained chlorinated polysaccharide or oligosaccharide has a lower degree of polymerization (DP) than the DP of the non-chlorinated polysaccharide or oligosaccharide. The process according to claim 1, wherein chlorinated cellulose with a DS of 0.5 to 3 and a DP of 10 to 100 is obtained. A solution comprising an ionic liquid and a chlorinated polysaccharide or oligosaccharide. The solution according to any one of claims 1 to 11, wherein the chlorinated polysaccharide or oligosaccharide is added to a solution by adding a coagulation solvent (nonsolvent for chlorinated polysaccharide or oligosaccharide) or other coagulant and separating the coagulated chlorinated polysaccharide or oligosaccharide from the mixture. Obtained from. Chlorinated polysaccharides or oligosaccharides obtained by the process according to any one of claims 1 to 11 or 13.