PROCESS FOR THE PREPARATION OF ALKYL GLYCOSIDES

Abstract: The present invention relates to a process for the preparation of alkyl glycosides by reacting an alcohol with a saccharide or a lower-alkyl glycoside in the presence of a catalyst, wherein the catalyst is a mesoporous silica-based molecular sieve material. This process allows to produce alkylated mono- and disaccharides. Preferably, an MCM-41 type material is used as the catalyst.

Description: Title: Process for the preparation of alkyl glycosides The present invention relates to a process for the preparation of alkyl glycosides. More in particular, the invention relates to a process wherein an alcohol is reacted with a saccharide, preferably a mono- or disaccharide, or a short chain alkyl glycoside in the presence of a catalyst. Alkyl glycosides, specifically those having at least 8 carbon atoms in the alkyl chain, are well-known mild nonionic surfactants. In detergent formulations, alkyl glycosides act as surfactants and foam builders. In addition, alkyl glycosides are known which exhibit liquid crystalline properties. Further, these glycosides are applied as wetting agents and emulsifiers, both in food and non-food uses. In these applications, alkyl glycosides are desirable components, because they are readily biodegradable. In the prior art, the preparation of alkyl glycosides in good yield is essentially restricted to the preparation of alkyl glucosides and related aldoses . Often some oligomerization of glucose takes place so that a mixture of alkyl glucoside, alkyl diglucoside and alkyl triglucoside is formed. Such mixtures are commercially available under the name alkyl polyglucoside (APG) . The average degree of oligomerization is, e.g., 1.5. Although it is often stated in the prior art that many of the known preparation methods are effective with any type of reducing sugar, the actual examples are restricted to alkylation reactions performed on sugars of the aldose type, such as glucose, galactose and mannose. From experiments, it appears that when these processes are applied for the preparation of alkylated ketoses, e.g. sorbose or fructose, or fructose-containing disaccharides such as lactulose or leucrose, the alkyl glycoside desired is only obtained in relatively low yields, especially because these ketoses tend to degrade quickly to, for instance, dehydrated products. In WO 94/09019, a process is described for the preparation of alkyl glycosides wherein an alcohol is reacted with a saccharide or an alkyl glycoside having a short alkyl chain. This reaction is effected in the presence of an acid catalyst selected from the group consisting of acid clays, activated silica-alumina-based cracking catalysts, and mixtures thereof. In the description of said international patent application it is indicated that the process may be used for the alkylation of hexoses, pentoses and alkyl glycosides of these saccharides having up to 6 carbon atoms i the alkyl chain. However, in fact, the process is only illustrated for the preparation of alkyl fructosides starting from fructose or an alkyl fructoside. The catalyst used in this known process preferably is an amorphous silica-alumina. Before use, the catalyst must be activated or reactivated by a heat treatment to a temperature of between 300 and 800°C. The amount of catalyst used may be from 10 to 300% based upon the weight of the (alkyl)saccharid used as a starting product. In the examples of WO- 4/09019 an amount of approximately 100 wt.% of catalyst is used. Johnson et al. describe the reaction of fructose and methanol using a silica-alumina cracking catalyst (Ketjencat) in an article in Tetrahedron: Asymmetry 5. (1994), 2475-2484. The present invention aims to provide an improved proces for preparing alkyl glycosides which process is more generall applicable. In fact, the object of the invention is to provid a process which is applicable to the preparation of a large number of alkyl glycosides, including di- and oligosaccharides. This particularly applies to ketoses, e.g. 2-ketosugars, which are prone to dehydration, and other degradation reactions, when treated with conventional strong acid catalysts such as sulfuric acid and organic sulfonic acids . This aim is reached by using another type of catalyst in the preparation process. More in particular, if an ultra-larg pore molecular sieve material is used as a catalyst, a large number of saccharides or alkyl saccharides can be alkylated with high selectivity. Further, it is sufficient to use a relatively low amount of catalyst. As a matter of fact, it is possible to obtain a good yield and selectivity in the proces of the invention while using only one-tenth of the amount of catalyst necessary in the process of WO-94/09019. According to the invention, the process for the preparation of alkyl glycosides is characterized by reacting an alcohol with a saccharide or a lower-alkyl glycoside in th presence of a catalyst, wherein the catalyst is a mesoporous silica-based molecular sieve material. This process can be operated in a continuous way, as will be shown in example 22. Mesoporous silica-based molecular sieve materials of the type to be used in the process of the invention are generally described in U.S. patents nos . 5,098,684 and 5,102,643. These patents also describe processes for the preparation of the mesoporous silica-based molecular sieves which are used as a catalyst in the process of the invention. As regards suitable molecular sieves and their preparation', explicit reference is made to these general descriptions. Molecular sieve materials which can suitably be used in the process of the present invention are described in detail in the review article of J.L. Casci in Studies in Surface Science and Catalysis, Vol. 85 (1994) Eds. J.C. Jansen, M. Stδcker, H.G. Karge and J. Weitkamp, Elsevier Science B.V., which document is incorporated herein by reference. These materials include MCM-41 and M41S-type materials and the Kanemite based materials. The mesoporous material used as a catalyst in the proces of the present invention possesses pores within the range of 20-80 A. The material can be distinguished from other porous inorganic solids by the regularity of the large open pores . As a matter of fact, the suitable catalytic material has an appearance showing characteristics of both amorphous or paracrystalline materials and crystalline framework materials such as zeolites . In accordance with the present invention it has been found that the esoporosity of the material gives access to especially the mono- and disaccharides to be alkylated. In the pores, the mono- and/or disaccharide moieties react with the alcohol and, subsequently, the alkylated sugar leaves the pores, easily. This process cannot occur in common microporous zeolites. Silica-based mesoporous molecular sieve molecules which are useful in the process of the present invention can be prepared according to a liquid templating mechanism involving cationic associated surfactants. Thereto, inorganic oxides which will form the molecular sieve crystal structure are mixed and crystallized in manners which are known per se in the presence of associates of an organic directing agent. Suc a directing agent is an ammonium or phosphonium ion of the formula RιR 2 R 3 R 4 Q + , wherein Q represents N or P, and wherein is a linear aliphatic chain having at least 12 carbon atoms, and R 2 "R 4 are short chains and generally methyl. Sometimes al an (R) 4 N + -salt is added, wherein R represents a methyl or eth group. Preferably, the mesoporous silica-based molecular sieve material is MCM-41. MCM-41 is described by Beck et al . in the Journal of the American Chemical Society 114 (1992) 10834- 10843. MCM-41 possesses a more or less hexagonal arrangement of more or less parallel channels uniformly sized mesopores o about 20-80 A. In a preferred embodiment, MCM-41 is used in its acid form (H-MCM-41) . The silicon/aluminum ratio in MCM-41 may be varied from about 10 to infinite. Dependent on the glycoside to be alkylated, the Si/Al ratio of the best suited catalyst varies The preparation of silica-based molecular sieve compound used in the process of the invention can further be illustrated by Schmidt et al . in the Journal of the Chemical Society Chemical Communications (1994) 1493-1494; and by Janicke et al . in Studies in Surface Science and Catalysis (1984) 243-250. It is within the scope of the person skilled in the art to determine which silicon/aluminum ratio of MCM-41 is the most suitable to obtain a catalyst for a certain glycoside alkylation reaction. It is an important advantage that in the process of the invention a large number of saccharides may be converted to alkyl glycosides. The present process makes it possible to convert monosaccharides or lower alkyl monosaccharides to higher alky monosaccharides by reacting the starting compound with a higher alcohol, e.g., an alcohol having at least 8 carbon atoms in the alkyl chain. Further, it has surprisingly been found that in accordance with the present invention, disaccharides can be alkylated by contacting disaccharides with an alcohol in the present of a mesoporous silica-based molecular sieve material. In this process, it is possible to use any kind of alcohol, both short chain alcohols such as methanol and higher alcohol especially C 4 -alcohols and higher. Especially, alkylated disaccharides having 1-5 carbon atoms in the alkyl chain are obtained in higher yields. For instance, allyl or butyl fructoside and butyl leucroside can be prepared in quantitative yields. Short chain alkylated mono- and disaccharides can be use as starting compounds for long chain (lipase catalysed) surfactants and emulsifiers. The process of the present invention is applicable to ketoses such as fructose and sorbose. As said herein above, fructose and sorbose are sugars which normally degrade quickl in the alkylation processes of the prior art. Further, aldose such as ribose are alkylated, as well. Especially, ribose is alkylated in a very selective way. Mono- and disaccharides as well as their corresponding lower alkyl derivatives are alkylated in good yield and selectivity. Especially the fact that in the process of the invention disaccharides are alkylated in a selective way and in good yield is entirely unexpected and surprising. Disaccharides are generally subject to alcoholysis under (strong) acid catalysis, and as a result alkylated monosaccharides are formed. In the present description and the claims, the term "lower alkyl" refers to alkyl moieties having 1-5 carbon atoms. The alcohol which is one of the starting materials in the process of the invention may be selected from a very large number of alcohols. Any primary or secondary alcohol may suitably be used in the alkylation process. Preferably a linear primary alcohol is applied. This guarantees excellent biodegradability of the alkylated sugar. Further, the starting alcohol may be mono- or polyhydric. It may possess unsaturated carbon-carbon bonds. Moreover, the alcohol may be an aralkyl alcohol, or an alcohol comprising ether groups, while cyclic and heterocyclic alcohols may be used, as well. Preferably, the alcohol is a monohydric alcohol having 10-24 carbon atoms. The reaction is preferably conducted in a medium consisting essentially of the alcohol which is used in the alkylation reaction. The excess of alcohol can be recycled. The reaction temperature is not critical as long as the temperature is not higher than the melting point of the starting sugar in the reaction medium. If the temperature exceeds the melting point of the sugar, undesirable side reactions may occur which detract from the selectivity and/or yield of desired reaction. The efficiency of the conversion decreases considerably when the temperature exceeds the melting point of the sugar. Depending on the structure of the saccharide, mixtures of alkyl saccharides are formed in which the saccharide part adopts a five-ring structure (furanose form) or a six-ring structure (pyranose form) . By varying the Si/Al ratio in the catalyst used, the furanose/pyranose ratio can be modified. Thus fructose yields a mixture of 1 pyranose and 2 furanose forms upon alkylation as depicted below Moreover - on the analogy of the alkyl glucosides -, some oligomerisation may take place. The mixture of alkylated fructoses can be applied as it is. It is possible to crystallise the pyranose form from the mixture and obtain this compound in a pure form. Thus, after completion of the reaction, it is possible to separate the reaction mixture in the respective components using well known techniques. However, for many applications, e.g. as a component in detergent compositions, the crude reaction mixture may be used per se, after removal of the excess of alcohol e.g. by vacuum distillation, by short-way distillation (also known as molecular distillation) or extraction. The present invention also relates to a silica-based molecular sieve compound for use in the process of the invention, which compound is obtainable by stirring a long chain (C 10 -C 36 ) alkyltrimethylammonium chloride, bromide or trimethylalkylammonium hydroxide, a silica source, an alumina source, e.g., sodium aluminate, and tetraalkylammonium hydroxide in water, heating the mixture to the reaction temperature until a finely divided solid product is formed, washing the solid product with water until a neutral pH is reached, drying the solid product and calcining it at a temperature of between 450°C and 550°C, preferably at about 540°C. A long chain alkyl group preferably comprises at least 12 carbons in the chain, and is, e.g. a cetyl (hexadecyl) group. In a preferred embodiment, the solid product is additionally brought in its acid form. This can be effected by refluxing the product in an aqueous ammonium nitrate solution, followed by washing with water until a neutral pH is obtained; drying and calcining at a temperature of between 350-500°C, preferably about 450°C, preferably by raising the temperature by l°C/min and maintaining the temperature at about 450°C for 16-24 hours. A product which is entirely in the H + -form can be treated with a solution comprising alkali metal ions, normally sodium ions. By this treatment a controlled amount of alkali metal ions can be introduced, or by other words: a controlled alkali metal to hydrogen ratio can be obtained in the catalyst. Before the catalyst is used, it is not necessary, and in fact disadvantageous, to activate the catalyst contrary to the catalyst used in the process of WO 94/09019. Any real deactivation does not seem to take place. However, in use the catalyst of the present invention may become somewhat less active, because organic deposits will be formed at its surface. The organic deposits can be removed by calcination. The catalyst used in the present invention is at least about 10 times as effective as the catalyst used in the process of WO 94/09019. Without being too active or agressive, it can be used at a higher reaction temperature than the prior art catalyst. The present invention will be described in more detail while referring to the following examples. The examples are meant to illustrate the invention, not to restrict the invention. Example 1: Preparation of MCM-41. 200 g of the ion exchanging resin DOWEX ® 1X8-200 (Janssen Chimica) in its Cl ' -form were rinsed with 1 1 of an aqueous 1 M NaOH solution. A cetyltrimethylammonium hydroxide solution was prepared by ion exchanging 70 g cetyltrimethylammoniuin chloride (Ci δ TMACl; 25 wt.% in water; Aldrich) and 12.5 g of the exchanged DOWEX resin. The ion exchange resin was filtered off over a folded filter. The filtrate was collected in a polypropylene flask of 500 ml to be used as a template in the crystallization reaction. To the filtrate 48 g of silica (Ludox ® HS-40; 40 wt.% Siθ 2 ; 0.32 mole Siθ 2 ; DuPont de Nemours), 23.68 g tetraethyl ammonium hydroxide (TEAOH; 40 wt.% in water; Aldrich), 2.00 g sodium aluminate (NaAlθ 2 ; 54% AI 2 O 3 ; 41% a 2 θ; Riedel de Haen) and 12.8 g water was added, bringing the total water amount on 6.0 mole. This mixture was intensively stirred in the closed polypropylene flask for 2 hours at ambient temperature. Subsequently, the stirring was continued for 2 weeks at 100°C using an oil bath. After this period, examination of the mixture under a polarisation microscope revealed that the gel material had disappeared, and a finely divided material was forme . The resulting solid was recovered by centrifugation and washed with demineralized water until neutrality. The solid product obtained was dried in air at room temperature and calcined in an oven having a temperature of 540°C (temperature gradient: l°C/min; 16 hours at 540°C) . Example 2: Preparation of H-MCM-41. The calcined product of Example 1 was refluxed in 250 ml 1 M NH 4 NO 3 (p.a.; Merck) for 3 hours. The solid product obtained was filtered off, washed with water until a neutral pH, followed by drying. The obtained H-MCM-41 was calcined at a temperature of 450°C (l°C/min; 16 hours at 450°C) . The product obtained was characterized by X-ray Powder Diffraction (Diffractometer Philips PW 1840; X-ray tube Cu LFF 40kV 50 mA) . The samples were scanned in the 2θ-range of 0.980-45.000 in steps of 0.020 with a count time of 2.00 seconds at each point. ICP-analysis was performed using a Perkin-Elmer 1100 Flame-AAS (Si) and a Perkin-Elmer Plasma-40 ICP-OES (Al) . N 2 -adsorption porosimetry was carried out using a Micrometrics ASAP-2400 and a Gemini-2360. These analytical methods led to the conclusion that a H-MCM-41 was formed, wherein the Si/Al ratio was 15. Hereinbelow, this product will be referred to as H-MCM-41/15. In table 1, analytical data of the catalyst prepared are shown. Example 3 : Preparation of MCM-41 type catalysts having other Si/Al ratios. Using the methods described in Examples 1 and 2, H-MCM-41 catalysts having other Si/Al ratios were prepared. In table 1, analytical data of the catalysts prepared are shown. Table1 Porosimetry Surface area Synthesis Si/Al Si/Al NaAIO2 AI2O3 (BEET method) MPD 1 Vads 2 Time Yield (ICP) (g) (mol) (m 2 /g) (nm) (ml/g) (days) (g) 15 14 2.00 0.01 940 3.05 0.709 7 12 30 42 0.94 0.005 13 13.9 60 68 0.50 0.003 1222 2.85 0.775 14 13.2 60 * 1 18 0.50 0.003 20 19 100 107 0.31 0.002 1131 2.85 0.714 14 15.5 oo >200 0 0 20 19 * In a modification of the above procedure a cetyltrimethyl ammonium chloride solution was used without ion exchange to the hydroxide form. This also yielded a MCM-41 type material. 1 MPD = mean pore diameter 2 Vads = adsorption volume Before use as a catalyst, the MCM-41 type materials were subjected to another calcination at 400°C (l°C/min; 16 hours at 400°C) to assure equal activities. Samples of these calcined products were stored in a desiccator and aged for at least four days before use. Example 4 : Alkylation reactions. 3.0 g of a mono- or disaccharide in 100 ml 1-butanol were brought into a roundbottomed flask which was connected to a Soxhlet apparatus in such a way that the reaction could be carried out under vacuum. The mixture was heated to the desired reaction temperature depending on the saccharide used (see Table 2 below) . Subsequently, 0.3 g of H-MCM-41 and 250 μl tetradecane (internal standard for GC) were introduced. If necessary the pressure was reduced in such a way that a constant reflux of 1-butanol was achieved. The water formed during the reaction was absorbed by zeolite KA (3A pellets; Aldrich) which was contained in the Soxhlet apparatus. Periodically, samples were taken which were analysed by GC. GC-analysis was performed on a Hewlett-Packard 5890 Series II gas chromatograph equipped with a 7673 auto injector and a Chrompack 50 x 0.32 mm CP-Sil 5 CB, 0.12 mm column. Peaks were detected using FID and were integrated on an HP 3396A integrator. Samples were derivatised by reaction with a stock solution consisting of pyridine (104 ml), N,N-bis(tri- methylsilyl)trifluoroacetamide (26 ml), and trimethylsilyl chloride (13 ml) . Typically, after four hours all saccharide was dissolved. Reaction was continued overnight to assure total conversion of the saccharide. After 24 hours the reflux condenser was replaced with a distillation head. 49.6 g 1-dodecanol (Merck) was added to the reaction mixture and the temperature was reduced to 80°C. From the resulting mixture 1-butanol was distilled off under reduced pressure. Subsequently, the temperature was increased to 120°C. Periodically, samples were taken which were analysed by HPLC and GC. After 24 hours the reaction was stopped and the reaction mixture was filtered over a glass filter and the residue washed with diethyl ether. HPLC analysis was carried out on a system equipped with a Waters M45 pump, a Millipore-Waters 8x100 mm 4μm Nova-Pak C18 cartridge contained in a Millipore Waters 8x10 Radial Compression unit, a Shodex RI SE-61 refractive index detector and Shimadzu SPD-6A UV-detector (220 nM) ; methanol/water (80:20 and 90:10 v/v) at 1.0 ml/min were used as eluent. Peaks were integrated using a Spectra-Physics SP 4270 integrator. Iab_e_2 Reaction temperatures for the reaction with 1-butanol Saccharide Melting point °C Reaction temperature °C D-fructose 1 10 85 L-sorbose 158 reflux isomaltulose 125 95 lactulose 173 reflux leucrose 156 reflux D-ribose 90 80 D-Fructose was obtained from Merck; L-sorbose was obtained from Janssen Chimica; isomaltulose was obtained from Sudzucker A.G.; lactulose was obtained from Solvay-Duphar; leucrose was obtained from Pfeifer & Langen. The six different H-MCM-41 catalysts prepared in Examples 2 and 3 were tested in the subsequent alkylation of D-fructose via the butyl derivative thereof to dodecyl fructosides. The results are given in Table 3. Table 3 H-MCM-41 Yield to alkyl Furanoside/pyr- Si/Al ratio monosaccharide anoside ratio (%) after 4 hrs 15 57 n.d. 30 53 2.8 60 57 3.2 1 18 55 n.d. 100 57 3.9 0 (n.d. = not determined) The 15 and the 30 H-MCM-41 showed some colour formation which means that some degradation occurred. Alkylations of other saccharides were performed using 60 and 100 H-MCM-41. These processes yielded essentially colourless product mixtures. As can be seen from table 3, the furanoside to pyranoside ratio can be varied and controlled by using different silicon to aluminum ratios. It is within the scope of the person skilled in the art to adapt the process circumstances and starting compounds dependent on the desired products. Example 5: Reaction of D-fructose with 1-butanol. 3.0 g of fructose (16.7 mmol) and 100 ml of 1-butanol were reacted following the procedure of Example 4 using 0.3 g of H-MCM-41 (Si/Al 60) as the catalyst. After 24 hours the reaction was stopped and the reaction mixture was filtered over a glass filter and the residue was washed with diethyl ether. The filtrate was subjected to film evaporation and was dried at 50°C under vacuum. Butyl fructoside was obtained in yield of 3.8 g. Example 6 : Reaction of D-fructose with allyl alcohol. 3.0 g of fructose and 100 ml allyl alcohol were reacted following the procedure of Example 4 using 0.3 g of H-MCM-41 (Si/Al 100) as the catalyst. After 24 hours, a complete conversion to allyl fructosides had been achieved according to GC. The reaction was stopped. The reaction mixture was filtered over a glass filter and subsequently the residue was washed with diethyl ether. The filtrate was subjected to film evaporation. The remaining syrup was dissolved in 20 ml ethanol and 10 ml diethyl ether were added. Crystallisation at -8°C during 24 hours afforded 0.56 g of allyl β-D-fructopyranoside. Example 7 : Reaction of D-fructose with allyl alcohol. 3.0 g of fructose, 100 ml allyl alcohol, 0.3 g H-MCM-41 (Si/Al 60) and 250 μl tetradecane (internal standard for GC) were refluxed. Water was extracted using zeolite 3A in a soxhlet apparatus . The reaction was monitored by GC and after 8 h. all fructose was converted to allyl fructosides. The catalyst was filtered off using a glass filter and was washed with diethyl ether. The filtrate was subjected to film evaporation to remove the solvents. The resulting syrup was dissolved in 20 ml ethanol and 10 ml diethyl ether was added. Subsequently, the mixture was maintained at -8°C. Afte 24 hours 0.66 g allyl-β-D-fructopyranoside was precipitated. Example 8 : Reaction of leucrose with 1-butanol. 3.0 g of leucrose 100 ml of 1-butanol were reacted following the procedure of Example 4 using 0.3 g H-MCM-41 (Si/Al 30) as the catalyst. After 24 hours the reaction was stopped. The reaction mixture was filtered over a glass filte 16 and the residue washed with diethyl ether. The filtrate was subjected to film evaporation and was dried at 50°C under vacuum. Butyl leucroside was obtained in a yield of 3.5 g. Example 9 : Reaction of leucrose with 1-butanol 3.0 g of leucrose, 150 ml 1-butanol, 0.3 g H-MCM-41 (Si/Al 30) and 500 μl tetradecane were refluxed. Water was extracted using zeolite A in a Soxhlet apparatus . The reaction was stopped after 24 hours, and the catalyst was removed by filtration. Unreacted butanol was removed from the filtrate by film evaporation. The yield of butyl leucroside was 3.2 g (92%) . Example 10 : Octyl leucroside 3.5 g butyl leucroside as prepared in example 9, 65 ml octanol and 0.3 g H-MCM-41 (Si/Al 30) were heated to 80°C under vacuum. The butanol released during reaction was distilled off. After 24 hours, the reaction was stopped. It occurred that a 60% conversion to octyl leucrosides was obtained (GC) . The catalyst was removed by filtration. The filtrate was added in 200 ml diethyl ether. This mixture was maintained at 0°C. A precipitate was formed after 24 hours. The precipitate consisted of butyl leucrosides, octyl leucroside and 1-octanol. It was brought in 50 ml water and 50 ml dichloromethane was added. The resulting milky emulsion was separated in two clear layers by centrifugation. The same procedure was repeated until all 1-octanol was removed. Example 11: Butyl isomaltuloside 3.0 g isomaltulose, 150 ml 1-butanol, 0.3 g H-MCM-41 (Si/Al 100) and 500 μl tetradecane were refluxed. Water was extracted using zeolite 3A in a soxhlet apparatus. The reaction was monitored using GC and after 2 h. all isomaltulose was reacted. The catalyst was removed by filtration and 1-butanol was removed by evaporation. The yiel of butyl isomaltulosides was 3.4 g (97%). Example 12 : Ethyl isomaltuloside 3.0 g isomaltuloside, 150 ml absolute etanol and 0.3 g H-MCM-41 (Si/Al 100) were refluxed. Water was extracted using zeolite 3A. After 6 hours the reaction was stopped. The reaction mixture was filtered and ethanol was evaporated. 2.9 g ethyl isomaltuloside remained. Example 13 : (2-hydroxyethyl) isomaltuloside 3.0 g isomaltulose, 150 ml ethylene glycol and 0.3 g H-MCM-41 (Si/Al 100) were heated to 80°C under vacuum. The conversion (measured by GC) was 60%. Example 14 : Reaction kinetics for the formation of octyl fructoside 3.0 g fructose, 42 ml 1-octanol and 0.3 g catalyst were heated to 80°C under vacuum. Water was extracted using zeolite 3A in a soxhlet apparatus . The reaction was monitored using HPLC. It appears from figure 1 that the Si/Al ratio of the catalyst does not have a pronounced influence on the octyl fructoside yield. It does have a clear influence on the furanoside/pyranoside ratio. (fig- l and lb) Example 15: Isomerisation of octyl fructosides After 24 hours the reactions described in example 14 were stopped and the catalyst was removed. To the filtrate of one of these reactions 200 ml diethyl ether was added. The mixture was maintained 24 hours at 0°C providing a precipitate of 0.5 g octyl-β-D-fructopyranoside (85% over the formed pyranoside) . The furanosides remained in solution. The filtrate of one of the other reaction mixtures was dried over MgS0 4 . MgSθ 4 was removed and 200 ml diethyl ether and 0.5 ml distilled acetyl chloride was added. The mixture was maintained at 0°C overnight and subsequently filtered off. 3.3 g solids precipitated. GC analysis showed a mixture of 80% octyl β-D-fructopyranoside and 20% fructose; 85% of the octyl fructosides formed were precipitated as pyranoside. A third filtrate was also dried over MgS0 4 . After removal of MgSθ 4 , 0.5 ml distilled acetyl chloride was added, the mixture was stirred during 24 hours yielding a white suspension. The isomerisation was monitored using HPLC, (see figure 2) . Example 16 : (2-hydroxyethy1) fructosides 3.0 g fructose, 15 ml ethylene glycol, 0.3 g H-MCM-41 (Si/Al 60) and 250 μl tetradecane were heated to 80°C under vacuum. The reaction was followed with GC. After 24 hours 65% of the fructose was converted to (2-hydroxyethyl) fructosides. Example 17 : (2, 3-dihydroxypropyl) fructosides 3.0 g fructose, 20 ml glycerol, 0.3 g H-MCM-41 (Si/Al 60) and 250 μl tetradecane were heated to 80°C under vacuum. The reaction was followed with GC. After 24 hours 60% of the fructose was converted to the six different (2,3-dihydroxypropy1) fructosides . Example 18 : decyl fructosides 3.0 g fructose, 42.1 g 1-decanol and 0.3 g H-MCM-41 (Si/Al 60) were heated to 80°C under vacuum. After 24 hours 50% of the fructose was converted to decyl fructosides (HPLC) Example 19 : dodecyl fructosides 3.0 g fructose, 48.6 1-dodecanol and 0.3 g H-MCM-41 (Si/Al 60) were heated to 80°C under vacuum. After 24 hours 40% of the fructose was converted to dodecyl fructosides (HPLC) . A substantive part of the 1-dodecanol was removed using short-way destination (80°C, 0.55 mbar). Subsequently, the different isomers were separated using preperative HPLC. Example 20: dodecyl ribosides 2.5 g ribose, 48.6 1-dodecanol, 250 μl tetradecane and 0.3 g H-MCM-41 (Si/Al 60) were heated to 80°C under vacuum. After 24 hours 40% of the ribose were converted to dodecyl ribosides (HPLC) . Example 21: Use of tert-butyl alcohol as solvent 3.0 g fructose, 42 ml 1-octanol, 150 ml tert-butyl alcohol and 0.3 g H-MCM-41 (Si/Al 60) were refluxed (T=92°C, Pt-100 transducer) . Water was extracted using zeolite 3A in a modified Dean-Stark apparatus. The reaction was monitored using HPLC. After 24 hours the conversion was 60%, however, the equilibrium was not yet established, as can be seen from Figure 3. Example 22: Continuous synthesis of dodecyl fructosides 10.0 g fructose was brought in a modified Dean-Stark apparatus. A second one was loaded with zeolite 3A. 1.0 g H-MCM-41 (Si/Al 60), 150 g 1-dodecanol and 200 ml tert-buyl alcohol were refluxed in a flask. The fructose was slowly soluted in the tert-butyl alcohol and subsequently dropwise added to the 1-dodecanol and catalyst. After 24 hours all fructose was solved and 70% was converted to dodecyl fructosides.

Claims: Claims 1. A process for the preparation of alkyl glycosides by reacting an alcohol with a saccharide or a lower-alkyl glycoside in the presence of a catalyst, wherein the catalyst is a mesoporous silica-based molecular sieve material. 2. The process of claim 1, wherein the mesoporous silica- based molecular sieve compound is an MCM-41 type material. 3. The process of claim 1 or 2, wherein the mesoporous silica-based molecular sieve compound is an MCM-41 type material which is completely or partly in its acid form. 4. The process of any of the preceding claims, wherein a monosaccharide or lower alkyl monosaccharide is reacted with an alcohol having at least 8 carbon atoms in the chain. 5. The process of any of the claims 1-3, wherein a disaccharide or a lower alkyl disaccharide is reacted. 6. The process of claim 5, wherein a disaccharide is reacted with a Cι- 5 alcohol. 7. The process according to any one of the preceding claims, wherein the saccharide is a Cβ-ketose or a Cs-aldose. 8. The process according to claims 5 or 6, wherein the saccharide is a disaccharide composed of a monosaccharide and a monosaccharide of the fructose type. 9. Silica-based molecular sieve compound for use in the process of any of the preceding claims, which compound is obtainable by stirring a long chain alkyltrimethylammonium chloride or hydroxide, preferably cetyltrimethylammonium chloride or cetyltrimethylammonium hydroxide, silica source, an alumina source, and optionally tetraalkylammonium hydroxide in water, heating the mixture to the refluxing temperature until a finely divided solid product is formed, washing the solid product with water until a neutral pH is reached, drying the solid product and calcining it at a temperature of between 450°C and 550°C. 10. The compound of claim 7, wherein the solid product is additionally brought partially or completely in its acid form. -/EMB

Inventors: DE GOEDE ANTONIUS THEODORUS JO, VAN BEKKUM HERMAN, VAN DER HEIJDEN ANNA MARGARETH, VAN DER LEIJ INGRID GERTRUDE, VAN RANTWIJK FREDERIK, DE GOEDE, ANTONIUS, THEODORUS, JOHANNES, WILHELMUS, VAN BEKKUM, HERMAN, VAN DER HEIJDEN, ANNA, MARGARETHA, VAN DER LEIJ, INGRID, GERTRUDE, VAN RANTWIJK, FREDERIK
Applicants: BEKKUM HERMAN VAN, GOEDE ANTONIUS THEODORUS JOHAN, HEIJDEN ANNA MARGARETHA V D, LEIJ INGRID GERTRUDE V D, RANTWIJK FREDERIK VAN, UNIV DELFT TECH, DE GOEDE, ANTONIUS, THEODORUS, JOHANNES, WILHELMUS, TECHNISCHE UNIVERSITEIT DELFT, VAN BEKKUM, HERMAN, VAN DER HEIJDEN, ANNA, MARGARETHA, VAN DER LEIJ, INGRID, GERTRUDE, VAN RANTWIJK, FREDERIK
Application year: 1996
Main classification: C07H15
IPC codes: C07H15