Process for making an alkyl polyglycoside

Abstract

Process for making C6-C14-alkyl polyglycoside, said process comprising the following steps: (a) Converting a mono-, di- or polysaccharide with aliphatic C6-C14-alcohol in the presence of an acidic catalyst at a temperature in the range from 103 to 107°C, and removing water formed by distillation, (b) Increasing the temperature by 2 to 12°C, (c) Continuing the conversion at the temperature as increased in step (b), and removing water formed by distillation, (d) Optionally, removing nonreacted aliphatic C6-C14-alcohol at a pressure in the range from 1 to 20 mbar at a temperature from 140 to 200 °C.

Description

[0001] 240452

[0002] Process for making an alkyl polyglycoside

[0003] The present invention is directed towards a process for making Ce-Ci4-alkyl polyglycoside, said process comprising the following steps:

[0004] (a) Converting a mono-, di- or polysaccharide with aliphatic Ce-Ci4-alcohol in the presence of an acidic catalyst at a temperature in the range from 103 to 107°C, and removing water formed by distillation,

[0005] (b) Increasing the temperature by 2 to 12°C,

[0006] (c) Continuing the conversion at the temperature as increased in step (b), and removing water formed by distillation,

[0007] (d) Optionally, removing nonreacted aliphatic Ce-Ci4-alcohol at a pressure in the range from 1 to 20 mbar at a temperature from 140 to 200 °C.

[0008] Alkyl polyglycosides are versatile surfactants, for example for laundry detergents and automatic dishwashing detergents as well as hand dishwash detergents and personal care applications such as, but not limited to soaps, lotions and shampoos. They offer numerous technical advantages such as good foaming in hand dishwash applications and in shampoos, and they are biodegradable. Usually, they are manufactured by converting a saccharide with a fatty alcohol in the presence of an acid.

[0009] However, the current processes are time consuming and create by-products such as polydextrose and an olefin - the latter as dehydration product of fatty alcohol.

[0010] It was an objective of the present invention to provide a process that is suitable for providing polyglycosides with less by-products.

[0011] Accordingly, the process defined at the outset has been found, hereinafter also referred to as “inventive process” or “process according to the (present) invention”. The inventive process comprises three steps, step (a), step (b), step (c), and preferably a step (d), hereinafter in short also referred to as (a), (b), (c), and (d), respectively. Steps (a) to (d) are described in more detail below. Step (d) is an optional step.

[0012] The inventive process is preferably performed batch-wise, and steps (a) to (c) or (d), respectively, are performed subsequently.

[0013] Step (a) includes converting a mono-, di- or polysaccharide with aliphatic C6-Ci4-alcohol in the presence of an acidic catalyst at a temperature in the range from 103 to 107°C, and removing water formed by distillation. 240452

[0014] 2

[0015] In one embodiment of the present invention, the alkyl-polyglycoside to be synthesized has the general formula (I)

[0016] (G)u-OR1(I)

[0017] The variable u is the degree of polymerization and is in the range from 1.1 to 4, preferred are 1.1 to 2 and in particularly preferred are 1.2 to 1.8. In the context of the present invention, the variable u refers to average values, and u is not necessarily a whole number. In a specific molecule only whole groups of G can occur. It is preferred to determine the value of u by High Temperature Gas Chromatography (HTGC).

[0018] R1is selected from C4-Ci8-alkyl, straight chain or branched, linear being preferred.

[0019] G is selected from monosaccharides with 4 to 6 carbon atoms, preferably from glucose and xylose and even more preferably, G is glucose or a combination of glucose and up to 20 mol-% xylose.

[0020] In one embodiment of the present invention, R1is selected from linear C4-Ci6-alkyl, for example n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, myristyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, and n-octadecyl. Preferred are n-butyl, n- hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-tridecyl, myristyl, n-hexadecyl, and n-octadecyl. In embodiments wherein the respective alkyl polyglycoside is made from a sugar and a bio-based alcohol such as alcohols derived from palm kernel oil, R1is selected from a combination of linear C4-Ci8-alkyls.

[0021] In one embodiment of the present invention, R1is selected from branched Ce-Cis-alkyl, with one or more branchings, for example one or two or three. Preferably, a branching is in the 2- position, thus derived from a Guerbet alcohol, or the branched Ce-Cis-alkyl is iso-alkyl. Examples are iso-hexyl, 2-methylpentyl, iso-heptyl, 2-ethylhexyl, iso-heptyl, iso-octyl, isononyl, isodecyl, 2-(n-propyl)heptyl (“2-propylheptyl”), 2-isopropyl-heptyl, 2-isopropyl-5-methylhexyl, 2-n- propyl-6-methylhexyl, combinations of at least two of 2-propylheptyl, 2-isopropyl-heptyl, 2- isopropyl-5-methylhexyl, and 2-n-propyl-6-methylhexyl, 2-n-butyloctyl, iso-dodecyl, iso-tridecyl, iso-myristyl, iso-pentadecyl, iso-hexadecyl, iso-octadecyl.

[0022] Another preferred example is 3-ethyl 8-methyl decyl. 240452

[0023] 3

[0024] In a more preferred embodiment, alkyl polyglycoside is selected from branched Cs-Cis-alkyl polyglycosides such as compounds of general average formula (1.1).

[0025] R2R3-CHCH2-O-GU-H (1.1) wherein:

[0026] R2is hydrogen or Ci-Ce-alkyl, straight-chain or branched, in particular ethyl, n-propyl, isopropyl, n-butyl and iso-butyl,

[0027] R3is -(CH2)2-R2, straight-chain or branched, wherein R2is defined as above.

[0028] G is defined as above, more preferably glucose, or glucose with up to 20 mole-% of xylose. u is in the range from 1.1 to 4, preferred are 1.1 to 2 and in particularly preferred are 1.2 to

[0029] 1.8, u being an average number, vide supra.

[0030] In one embodiment of the present invention, step (a) is performed at a pressure in the range from 5 to 100 mbar absolute. It is possible to perform step (a) at a constant pressure. It is preferred to lower the pressure during conducting step (a), for example by starting at a pressure in the range from 50 to 100 mbar and then lowering it to 5 to 40 mbar.

[0031] In one embodiment of the present invention, the molar ratio of saccharide units to R1-OH at the beginning of step (a) is in the range from 1.3 to 1.7, preferably from 1.4 to 1.5.

[0032] Examples of acidic catalysts are sulfuric acid, phosphoric acid and organic acids such as sulfonic acids. Preferred are sulfonic acids such as para-toluene sulfonic acid, linear C10-C12- alkylbenzenesulfonate, sulfosuccininc acid and a-sulfo fatty acids.

[0033] In one embodiment of the present invention, step (a) has a duration in the range from 60 to 3600 minutes, preferably 90 to 180 minutes.

[0034] In one embodiment of the present invention, step (a) is performed in a stirred tank reactor. On laboratory scale, step (a) may be performed in a round bottom flask with distillation bridge.

[0035] During step (a), water formed in the course of the reaction is removed by distillation.

[0036] Step (a) may be supported by mixing operations, for example by stirring. 240452

[0037] 4

[0038] A solution of alkyl polyglycoside in excess R1-OH is formed.

[0039] As soon as no water removal may be detected, step (b) may be commenced.

[0040] In step (b), the reaction temperature is increased by 2 to 12°C. Such increase is preferably performed within a time of 1 to 150 minutes, more preferably from 20 to 100 minutes. A preferred increase in accordance with step (b) is in the range of from 4 to 10°C. On laboratory scale, for example when making 500 g or less alkyl polyglycoside, an increase in temperature in the range of from 5 to 12 °C is preferred, and such increase can be performed within 5 to 15 minutes.

[0041] Preferably, during step (b) the pressure is left unchanged in comparison to step (a).

[0042] Any water formed during step (b) is preferably removed by distillation as well.

[0043] Step (c) includes continuing the conversion at the temperature as increased in step (b), and thus continuing to remove water formed in the course of the reaction by distillation.

[0044] Preferably, the pressure is the same as ion step (a).

[0045] In one embodiment of the present invention, step (c) has a duration in the range of from of from 10 to 180 minutes, preferably (15 to 45 minutes). It is preferred to detect the end of step (c) by the ceasing of water formation or the consumption of the mono-, di- or polysaccharide.

[0046] The optional step (d) includes removing nonreacted aliphatic C6-Ci4-alcohol at a pressure in the range from 1 to 60 mbar at a temperature from 140 to 200 °C. While for the use of alkyl polyglycoside in personal care applications, performing a step (d) is preferred, step (d) is not required if only analytical purposes are intended.

[0047] In one embodiment of the present invention, step (d) may be performed in continuously operated distilling apparatuses like a thin-film evaporator, a wiped-film evaporator, a falling-film evaporator or a similar device.

[0048] Step (d) may be conducted in one stage or in multiple stages at different pressures and temperature within the range indicated above. A multiple stage distillation may use several devices of the same kind or a combination of different kinds of distillation apparatuses. 240452

[0049] 5

[0050] In an alternative embodiment of step (d), to distill batchwise by gradually increasing the temperature and lowering the pressure within the ranges indicated above by, for example reducing the pressure in a still to 30 mbar to 50 mbar and heating to 140°C to 160°C for several hours or to ensure a continuous flow of distilled R1-OH. The distillation is completed by lowering the pressure to < 10 mbar and increasing the temperature to 180°C to 200°C for 15 minutes to 60 minutes.

[0051] It is possible to simultaneously raise the temperature and lower the pressure. It is preferred, though, to first lower the pressure and then raise the temperature.

[0052] In one embodiment of the present invention, step (d) is performed at a constant temperature. In an alternative embodiment, the temperature is raised during step (d) in the above interval.

[0053] In one embodiment of the present invention, step (d) is performed at a constant pressure. In an alternative embodiment, the pressure is lowered during step (d) in the above interval.

[0054] Removal of nonreacted aliphatic C6-Ci4-alcohol during step (d) occurs by distilling it off. It is preferred to collect non-reacted C6-Ci4-alcohol and use it for another batch of Ce-Ci4-alkyl polyglycoside manufacture.

[0055] In one embodiment of the present invention, catalyst is neutralized before the commencement of step (d), for example with NaOH or KOH or MgO.

[0056] By performing the inventive process, Ce-Ci4-alkyl polyglycoside with an excellent purity may be manufactured within a short time. The purity may be characterized by determining the color number and the polydextrose index (in embodiments that are based on glucose) or a related parameter.

[0057] In one embodiment of the present invention, work-up steps like bleaching and neutralization of the catalyst may be performed. As bleaching agent, peroxides may by employed, for example H2O2, especially aqueous solutions of H2O2.

[0058] In one embodiment of the present invention, catalyst is neutralized before or after step (d) with MgO, and carbonate formed during steps (a) to (d) or in a subsequent bleaching step is removed by an intermediary acidification step. 240452

[0059] 6

[0060] Ce-Ci4-alkyl polyglycoside obtained from the inventive process may be used in many applications such as liquid laundry detergents, automatic dishwashing detergents and personal care products like liquid soaps and shampoos.

[0061] The present invention is further illustrated in the following working examples.

[0062] A suspension of 40 g dextrose monohydrate and 121.6 g C12-C14 fatty alcohol was placed in a 500 ml flask with baffles and attached to a rotary evaporator. The flask was evacuated to 30 mbar and the dextrose was dehydrated by means of azeotropic distillation at 45°C to 75°C. A suspension was formed.

[0063] Step (a):

[0064] An amount of 0.65 g Ci2-alkylbenzene sulfonic acid dissolved in 12,2 g fatty alcohol were added as catalyst to the suspension described above. The suspension was then heated to the reaction temperature in accordance with Table 1 . Water formed as a reaction product was distilled off and collected.

[0065] Step (b), inventive examples only: When the water formation ceased, the reaction temperature was increased by 10°C within a period of 2 minutes or 30 minutes, respectively.

[0066] Step (c), inventive examples only: The resultant reaction mixture was kept at the increased reaction temperature until the water formation ceased. The reaction was stopped by addition 80 mg MgO and 4 g NaOH (50%). Step (b) in Experiment # 4 had a duration of 2 minutes, step (b) in Experiment # had a duration of 30 minutes.

[0067] Step (d): no step (d) was performed.

[0068] The crude product was characterized by HPLC and the content of polysugar (polydextrose) and the value of the variable u was determined.

[0069] In the comparison experiments Comp-1 to Comp-3, step (b) was omitted, and the reaction time in Table 1 refers to the complete reaction time. 240452

[0070] 7

[0071] Table 1 : Reaction parameters of comparative and inventive examples

Claims

2404528Patent claims1 . Process for making Ce-Ci4-alkyl polyglycoside, said process comprising the following steps:(a) Converting a mono-, di- or polysaccharide with aliphatic Ce-Ci4-alcohol in the presence of an acidic catalyst at a temperature in the range from 103 to 107°C, and removing water formed by distillation,(b) Increasing the temperature by 2 to 12°C,(c) Continuing the conversion at the temperature as increased in step (b), and removing water formed by distillation,(d) Optionally, removing nonreacted aliphatic Ce-Ci4-alcohol at a pressure in the range from 1 to 20 mbar at a temperature from 140 to 200 °C.

2. Process according to claim 1 wherein the Ce-Ci4-alkyl polyglycoside has the general formula (I)(G)u-OR1(I)G1is selected from monosaccharides with 4 to 6 carbon atoms,R1is Ce-Ci4-alkyl, linear or branched, u is in the range from 1.35 to 1.5, u being an average number.

3. Process according to claim 1 or 2 wherein the polyglycoside is based on glucose.

4. Process according to any of the preceding claims wherein R1is selected from linear Cs- Ci2-alkyl.

5. Process according to any of the preceding claims wherein step (a) has a duration in the range from 90 to 180 minutes.

6. Process according to any of the preceding claims wherein step (c) has a duration in the range from 90 to 180 minutes.

7. Process according to any of the preceding claims wherein steps (a) to (c) are performed at a pressure in the range from 30 to 70 mbar.24045298. Process according to any of the preceding claims containing at least one additional step selected from bleaching steps.

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