WO1996011936A1

WO1996011936A1 - Process for preparing light-coloured alkyl and/or alkenyl oligoglycosides

Info

Publication number: WO1996011936A1
Application number: PCT/EP1995/003929
Authority: WO
Inventors: Karl Schmid; Michael Neuss; Manfred Weuthen; Michael Langen
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1994-10-14
Filing date: 1995-10-05
Publication date: 1996-04-25
Also published as: DE4436761A1; AU3745595A

Abstract

In an improved process for preparing light-coloured alkyl and/or alkenyl oligoglycosides, (a) a bleaching solution containing active oxygen compounds and alkaline earth salts is prepared and (b) the bleaching solution is added to an aqueous alkyl and/or alkenyl oligoglycoside paste with 40 to 70 % by weight solid content and a Höppler viscosity in a range from 100 to 2,000 mPas at 20 to 80 °C, provided that during bleaching the pH value be set from 9 to 11 by admixture of alkali and after bleaching at maximum 11.5.

Description

Process for the preparation of light colored alkyl and / or alkenyl oligoglycosides

Field of the Invention

The invention relates to a process for the preparation of light-colored alkyl and / or alkenyl oligoglycosides, in which aqueous pastes of the nonionic surfactants are added to bleach solutions which contain alkaline earth metal salts in addition to active oxygen compounds, and to certain pH conditions during and after the bleaching complies with.

State of the art

Alkyl oligoglycosides, in particular alkyl oligoglucosides, are nonionic surfactants which, due to their excellent detergent properties and high ecotoxicological compatibility, are becoming increasingly important. The manufacture and use of these substances have recently been described in a number of review articles, of which the publications by H.Hensen in Skin Care Forum, 1, (Oct. 1992), D.Balzer and N.Ripke in Seifen¬ are representative oils-fat-waxes 118, 894 (1992) and B.Brancg in Soap-oils-fat-waxes 118, 905 (1992) should be mentioned. They are usually prepared from glucose and fatty alcohols, which are acetalized in the presence of acidic catalysts. The catalyst is then neutralized with sodium hydroxide solution and magnesium oxide. In order to shift the reaction equilibrium to the side of the products, the fatty alcohol is used in a large excess. The acetalization is therefore generally followed by a step in which the unreacted alcohol is separated off by distillation. Even with gentle distillation from the thin layer, however, the product becomes discolored, which makes bleaching necessary. In addition to the formation of dark colored decomposition products, colored bodies can also be formed by oxidation of the pastes in the presence of atmospheric oxygen [cf. P. Heyns et al. in Appl. Chem. j> 9, 600 (1957), VJ Traynelis et al. in J.-A. Chem. Soc. f___, 298 (1964) and C.Agami in Bull. Soc.Chim.France 1022 (1965)] or dehydration in the sense of a Dumas-Stass reaction [cf. G.Lock in Chem. Ber. 3, 551, 855 (1930) and H. Reid et al. in J.Am.Chem.Soc. .61, 99 (1939)].

In this connection, a number of processes are known from the prior art which can be used to lighten the color of darkly colored alkyl polyglucosides. The patent US 3565885 (CPC Int.) Describes, for example, the bleaching of alkyl glucosides in the presence of basic ion exchangers.

In the documents EP-A 0165721 and EP-A 0338151 from AEStaley Manufacturing Co. the bleaching of glucosides with peroxides and sulfur dioxide as well as the use of reducing agents mittein such as Raney nickel proposed under hydrogenating conditions.

Hüls AG has also applied for a patent for various processes for bleaching alkyl glucosides: For example, EP-A 0306650, EP-A 0306651 and EP-A 0306652 propose treating the crude glucosides in the solvent with active carbon, which Separate solvent and bleach the distillation residue with hydrogen peroxide. The documents EP-A 0389753 and EP-A 0526710 disclose processes in which the bleaching takes place using an ozone-containing gas mixture at a pH of 3 to 11 or by irradiation with a 100-1000 watt lamp.

In the two patent applications EP-A 0387913 and EP-A 0388857 by Kao Corp. It is proposed to destroy unreacted hydrogen peroxide to stabilize the alkyl glucosides by adding boranates.

Finally, Henkel KGaA applied for a patent for the bleaching of alkyl glucosides, in which the bleaching is carried out with hydrogen peroxide under alkaline conditions [WO 90/03977] or in the melt [WO 90/03216]. The use of magnesium ions, alkali silicates, sugar acids, aluminum compounds, hydrotalcites or triacetin as bleach boosters is known from the documents WO 93/13112, WO 93/13113 and DE 4225223.

A particular problem in the production of alkyl and / or alkenyl oligoglycosides, however, is that pastes bleached by conventional processes do indeed immediately have a satisfactory color quality after treatment with the active oxygen compound, but darken quickly after storage, in particular at elevated temperatures, color numbers then being achieved which at best correspond to those before bleaching. This effect is observed in particular in products which are adjusted to a pH above 11.5 to protect them from microbial attack in accordance with the teaching of WO 92/08781 (Henkel).

Finally, there is no process by means of which aqueous pastes, if appropriate after bleaching, can also be appropriately brightened and stabilized.

The object of the invention was therefore to provide an improved process for the preparation of light-colored alkyl and / or alkenyl oligoglycoside pastes which are stabilized against microbial attack, according to which not only very light-colored but also temperature and la¬ stable products can be obtained.

Description of the invention

The invention relates to a process for the preparation of light-colored alkyl and / or alkenyl oligoglycosides of the formula

(I)

^ O-CGJp (I)

in the R * for an alkyl and / or alkenyl radical with 4 to 22 carbon atoms, G for a sugar radical with 5 or 6 carbon atoms lenstoffatomen and p stands for numbers from 1 to 10, which is characterized in that one

(a) produces a bleaching solution containing active oxygen compounds and alkaline earth metal salts and

(b) adding the bleaching agent solution to an aqueous alkyl and / or alkenyl oligoglycoside paste which has a solids content of 40 to 70% by weight and at 20 to 80 ° C. a Höppler viscosity in the range from 100 to 2,000 mPas,

with the proviso that the pH during the bleaching is adjusted to 9 to 11 by adding alkali and after the bleaching to a maximum of 11.5, preferably 10.5 to 11.2.

Although the products obtainable by the process according to the invention are just as light in color immediately after bleaching as products obtained by conventional bleaching, it has surprisingly been found that the products treated in accordance with the invention practically do not darken even after prolonged storage at elevated temperatures. The invention includes the knowledge that the subsequent formation of color bodies can be reliably prevented if a pH value of 11.5 is not exceeded after bleaching. Alkyl and / or alkenyl oligoglycosides

Alkyl and alkenyl oligoglycosides are known substances which can be obtained by the relevant processes in preparative organic chemistry. As a representative of the extensive literature, reference is made here to the documents EP-AI 0301298 and WO 90/03977.

The alkyl and / or alkenyl oligoglycosides can be derived from aldoses or ketoses with 5 or 6 carbon atoms, preferably glucose. The preferred alkyl and / or alkenyl oligoglycosides are thus alkyl and / or alkenyl oligoglucosides.

The index number p in the general formula (I) gives the degree of oligomerization (DP degree), ie. H. the distribution of mono- and oligoglycosides is present and stands for a number between 1 and 10. While p must always be an integer in a given compound and can in particular assume the values p = 1 to 6, the value p is for a specific alkyl oligoglycoside an analytically calculated quantity, which usually represents a fractional number. Alkyl and / or alkenyl oligoglycosides with an average degree of oligomerization p of 1.1 to 3.0 are preferably used. From an application point of view, preference is given to alkyl and / or alkenyl oligoglycosides whose degree of oligomerization is less than 1.7 and in particular between 1.2 and 1.4.

The alkyl or alkenyl radical R ¹ can be derived from primary alcohols having 4 to 11, preferably 8 to 10, carbon atoms. Typical examples are butanol, capro alcohol, Caprylic alcohol, capric alcohol and undecyl alcohol and their technical mixtures, such as are obtained, for example, in the hydrogenation of technical fatty acid methyl esters or in the course of the hydrogenation of aldehydes from Roelen's oxo-synthesis. Alkyl oligoglucosides of chain length are preferred

1 ^DLS 3), which are obtained as a preliminary step in the separation by distillation of technical Cg-Cig coconut oil alcohol and which may be contaminated with a proportion of less than 6% by weight of Ci2 alcohol, and also alkyl oligoglucosides based on technical Cg / n -Oxo alcohols (DP = 1 to 3).

The alkyl or alkenyl radical R ¹ can also be derived from primary alcohols having 12 to 22, preferably 12 to 14, carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and their technical mixtures, which can be obtained as described above. Al¬ kyloligoglucoside are preferably based on hydrogenated Ci2 / 14- ^"κ ° kosal- alcohol with a DP of 1 to 3

In a particularly advantageous embodiment of the invention, alkyl oligoglucoside pastes of the formula (I) are bleached, in which R ^{1 represents} an alkyl radical having 8 to 18 carbon atoms.

The alkyl and / or alkenyl oligoglycoside pastes preferably have a water content of less than 50% by weight. To a particularly advantageous low viscosity of 100 to To achieve 500 mPas, it has proven to be expedient to use a mixture of Cg-Cio- ^{un (} ** - Ci2-Cιg-alkyl oligoglucoside pastes. If necessary, the pastes can be used to further reduce the viscosity of hydrotropes such as, for example, toluenesulfonate, xylene sulfonate, cumene sulfonate , Butane sulfonate, C4-Cιo * dicarboxylic acids or methyl, ethyl, propyl and / or butyl glucosides contain.

Active oxygen compounds

Active oxygen compounds are to be understood as hypochlorites and substances which have a peroxide group. Typical examples are sodium hypochlorite on the one hand and sodium peroxide, sodium percarbonate, barium peroxide, performic acid, peracetic acid and the like on the other hand. Hydrogen peroxide is preferably used, a technical aqueous solution with an active substance content of 20 to 50 and in particular 25 to 35% by weight usually being used.

Alkaline earth salts

The alkaline earth metal salts in question are preferably selected from the group formed by magnesium oxide, magnesium hydroxide, magnesium methylate, calcium oxide and / or calcium hydroxide.

In addition, alkaline earth metal salts can be used, which are selected from the group consisting of Peroxide-soluble magnesium and / or calcium salts of formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, gluconic acid, citric acid, benzoic acid, dodeylbenzenesulfonic acid, sulfosuccinic acid and / or p-toluenesulfonic acid.

Magnesium oxide and / or magnesium citrate is preferably used.

Bleach solution

The bleaching agent solutions can contain the active oxygen compounds in a concentration of 20 to 50 and preferably 25 to 35% by weight and the alkaline earth metal salts in a concentration of 0.1 to 10, preferably 1 to 7% by weight. It has proven to be advantageous if the bleaching agent solution is freshly prepared, has a pH in the range from 3 to 9, preferably 7 to 8, and the paste is present in an amount of 0.1 to 5% by weight on the paste and the active substance content of the bleach solution.

In addition to the active oxygen compounds and the alkaline earth metal salts, the bleaching agent solutions can contain activators which are capable of forming persistent oxygen compounds. Typical examples are benzoic anhydride, pentaacetyl glucose, ethylenediaminetetraacetate and manganese compounds which are at least finely dispersible in the alkaline pH range. Bleaching process

The bleaching is usually carried out at a temperature in the range from 20 to 80 and preferably 50 to 70 ° C. After bleaching, the alkyl and / or alkenyl oligoglycosides preferably have a solids content above 55, preferably above 60% by weight or a water content of below 45, preferably below 40% by weight. This can include can be achieved by adding anhydrous additives such as, for example, 1 to 10% by weight of fatty alcohol polyglycol ether, 0.1 to 10% by weight of anionic and / or amphoteric surfactants or 0.1 to 5% by weight of inorganic salts to the pastes. An increase in the active substance content is particularly advantageous in order to ensure adequate stabilization against microbial attack even at a pH of maximum 11.5. If necessary, it is also possible to add small amounts of ethanol.

In a preferred embodiment of the invention, the bleaching is carried out under protective gas and the bleached paste is filtered or centrifuged at about 80 ° C. A particular advantage of the process is that it can also be used on aqueous pastes which have already been bleached.

In a further preferred embodiment of the invention, 1 to 10 or 2 to 5% by weight, based on the active substance content, of C1-C4 alkyl oligoglycosides, preferably methyl glucoside, ethyl glucoside and / or butyl glucoside, is added to the bleached pastes. With this measure, the paste viscosity can usually be reduced by a power of ten. which without adversely affecting the thickenability by adding electrolyte salts.

Industrial applicability

The aqueous pastes of the alkyl and / or alkenyl oligoglycosides obtainable by the process according to the invention are practically colorless and have proven to be extraordinarily color-stable even when stored at elevated temperature for a long time. They are suitable for the production of detergents, dishwashing detergents and cleaning products and products for hair and body care, in which they can be present in amounts of 1 to 50, preferably 5 to 25% by weight, based on the composition .

Examples

Comparative Example VI

1000 g of an aqueous Ci2 / l6 ~ * ^^ l ° * '* ^{: 0} 9l ^ucos: ' - ^ci P ^as ' ^te (Glucopon ( ^R ) 650 EC, Henkel KGaA, Düsseldorf / FRG) with a Gardner Color number 3, 10 g of a 35% strength by weight hydrogen peroxide solution were added at 60 ° C. and the pH of the paste was added dropwise by adding 50% strength by weight sodium hydroxide solution in the range from 10.7 to 11. 1 held. After a bleaching time of 3 h, the paste had a Gardner color number of 0.5. The pH of the paste - measured as a 20% by weight solution of nonionic surfactant in 15% by weight aqueous isopropyl alcohol - was adjusted to 11.5 by adding sodium hydroxide solution. The paste was then stored for 5 days in a closed glass vessel at 90 ° C. The Gardner color number after completion of the heat storage was 3.

Comparative example V2

Comparative example VI was repeated, but the paste was finally adjusted to a pH of 12. During the course of storage, the Gardner color number deteriorated from 0.5 to 5. example 1

Comparative example VI was repeated, but using a bleaching agent solution which additionally contained 0.8 g of magnesium oxide in dispersed solution. After bleaching for 3 hours, the Gardner color number was also 0.5. The paste was adjusted to pH 11.2 as described above. The paste was then stored in a sealed glass vessel at 90 ° C. for 5 days. The Gardner color number after completion of the heat storage was 1.

Example 2

Comparative Examples VI were repeated, but using a bleach solution which had been prepared in the following manner: 0.8 g of magnesium oxide was dissolved in 5.6 g of a 50% by weight citric acid and then 10 g of a 35% by weight Hydrogen peroxide solution added. The bleaching agent solution was added to the paste in portions, the pH being kept in the range from 10.7 to 11.1. The Gardner number was also 0.5. Finally, the paste was again adjusted to a pH of 11.5 with sodium hydroxide solution and 2% by weight, based on the active substance content, of ethyl glucoside was added. The paste was then stored in a sealed glass vessel at 90 ° C. for 5 days. The Gardner color number after completion of the heat storage was 1.

Claims

claims

1. Process for the preparation of light-colored alkyl and / or alkenyl oligoglycosides of the formula (I)

I ^ O-CGJp (I)

in which R ^{1 is} an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G is a sugar radical having 5 or 6 carbon atoms and p is a number from 1 to 10, characterized in that

(b) the bleach solution is added to an aqueous alkyl and / or alkenyl oligoglycoside paste which has a solids content of 40 to 70% by weight and at 20 to 80 ° C. a Höppler viscosity in the range from 100 to 2,000 mPas,

with the proviso that the pH during the bleaching is adjusted to 9 to 11 by adding alkali and to a maximum of 11.5 after the bleaching.

2. The method according to claim 1, characterized in that bleaching alkyl oligoglucoside pastes of the formula (I) in which R ^{1 is} an alkyl radical having 8 to 18 carbon atoms.

3. The method according to claims 1 and 2, characterized gekenn¬ characterized in that hydrogen peroxide is used as the active oxygen compound.

4. The method according to claims 1 to 3, characterized gekenn¬ characterized in that alkaline earth metal salts are used, which are selected from the group formed by magnesium oxide, magnesium hydroxide, magnesium methylate, calcium oxide and / or calcium hydroxide.

5. The method according to claims 1 to 3, characterized gekenn¬ characterized in that alkaline earth metal salts are used, which are selected from the group of magnesium and / or calcium salts of formic acid, acetic acid, propionic acid, glycolic acid, soluble in aqueous hydrogen peroxide. Lactic acid, gluconic acid, citric acid, benzoic acid, dodeylbenzenesulfonic acid, sulfosuccinic acid and / or p-toluenesulfonic acid.

6. The method according to claims 1 to 5, characterized gekenn¬ characterized in that the bleach solution contains the Aktivsauer¬ oxygen compound in a concentration of 20 to 50 wt .-%.

7. The method according to claims 1 to 6, characterized gekenn¬ characterized in that the bleaching solution contains the alkaline earth metal salts in a concentration of 0.1 to 10 wt .-%.

8. The method according to claims 1 to 5, characterized gekenn¬ characterized in that the bleaching is carried out at a temperature in the range from 20 to 80 ° C.

9. Procedure according to claims 1 to 6, characterized gekenn¬ characterized in that the bleached pastes C1-C4 alkyl oligoglycosides are added as a plasticizing agent.