EP1897931A2 - Method for bleaching and lowering of the pH value for fats - Google Patents

Abstract

Decolorizing and lowering the pH of oleochemicals having at least 6 carbon atoms per molecule comprises contacting the oleochemicals with hydrogen peroxide and magnesium silicate.

Description

The present invention relates to a process for treating fats with silica gel and hydrogen peroxide, the process having a lowering of the pH of the fatty substance, which process has the advantage that both undesirably high pH values of the fatty substances are lowered also that a bleaching effect can be achieved.

Organic substances, especially ingredients for cosmetics, cleaners or pharmaceutical products, should be as colorless as possible for the application, so that they can be incorporated into the respective formulations without contributing to a basic color. For this reason, organic substances, especially for the above applications, subjected to a so-called bleaching process. As part of this bleaching process, the color of the substance is lightened, preferably, the substance is colorless in the visible light. As a bleaching agent z. Bleaching earths used, which are natural magnesium aluminum silicates. In other cases, activated carbons are used for decolorization. Further decolorization methods are, for example, the adsorption on polymeric absorber resins or the distillation. In many cases, peroxo compounds and preferably hydrogen peroxide in aqueous solution is used for decolorization. The degree of decolorization is often insufficient in this application. In addition, hydrogen peroxide is critical in terms of safety, as it easily splits off oxygen. However, it is known from the literature, for example from the DE 41 42 592 in that it is possible to bleach surface-active compounds with hydrogen peroxide and do so in the presence of so-called bleach boosters, namely alkaline earth ions, zinc ions and / or alkali silicates. The DE 41 42 592 names a large number of surface-active compounds which can be bleached by means of peroxygen in the presence of the known bleach boosters, although suitable silicates are exclusively alkali metal silicates. Furthermore, the name DE 41 42 592 also the concomitant use of alkaline earth ions and in particular magnesium ions as suitable bleaching boosters for bleaching surface-active compounds. However, that does DE 41 42 592 There are no statements that magnesium silicates are suitable compounds which can advantageously bleach surface-active compounds in the presence of peroxygen compounds.

In many cases, the organic substances mentioned in the previous paragraph contain alkaline impurities as a result of the preparation, and therefore have an undesirably high pH. For further use, it is usually necessary to lower this undesirably high pH. This requires the addition of acids in many industrial processes to lower an undesirably high pH of a crude product.

The two problems mentioned in the previous paragraphs (undesirably high pH and the need to perform bleaching) occur especially with fatty substances. The term fatty substances is defined more precisely in the present specification. In particular, these two problems occur with fatty substances which, as a result of the preparation, have an undesirably high pH value as crude product. This is especially the case with such fatty substances, in the preparation of bases such. B. hydroxides, such as. B. alkali hydroxides, such as. As NaOH or KOH, are used. These bases are z. B. used as catalysts. For example, in the production of fatty substances containing ethoxyl radicals or propoxyl radicals or oligoethyoxy chains or oligopropoxy chains, catalysts, e.g. As the said hydroxides used. These are z. B. used to convert the starting material ethylene oxide or propylene oxide to said ethoxyl radicals or propoxyl radicals or Oligoethyoxyketten or Oligopropoxyketten.

FR-A 1 216 645 discloses a process for bleaching a vegetable oil with a bleaching agent containing H2O2 and a magnesium silicate. The lowering of the pH of the oil is not disclosed.
US 2006/094894 discloses a process for bleaching a hexalester with a bleaching agent containing H2O2 and a magnesium silicate. The lowering of the pH of the oil is not disclosed.

It is an object of the present invention to provide a process which makes it possible to reduce undesirably high pH values in the case of fatty substances as well as to achieve a bleaching action.

It should preferably be bleached with H ₂ O ₂ , wherein the bleaching effect of H ₂ O _{2 should be} enhanced.

It has been found that the use of magnesium silicates can solve the problem outlined above.

An object of the present technical teaching is therefore a method for lowering the pH and bleaching of fatty substances having at least 6 C atoms in the molecule, characterized in that the fatty substances with a H ₂ O ₂ -containing bleach and with a Brings magnesium silicate into contact until a discoloration has occurred, and then preferably removes the magnesium silicate, wherein in carrying out the process a lowering of the pH of the fatty substance, preferably by at least one unit, preferably by at least 0.5 and in particular by at least 0, 1 takes place. In this case, the fatty substance is preferably heated with stirring to temperatures above the melting point of the fatty substances before carrying out the process.

The pH of the fat can be either immediate if the fat contains enough water. If this is not the case, the pH can be measured by adding a small amount of water.

In a particularly preferred embodiment, in a first step, the heated surface-active compound is treated with the magnesium silicate and then this mixture is bleached with the H ₂ O ₂ -containing bleach. At the end of the bleaching process, the magnesium silicate is removed, for example, by filtration or any other alternative method known to those skilled in the art.

Another likewise suitable variant of the process consists in first heating the surface-active compound, wherein besides the H ₂ O ₂ the magnesium silicate is simultaneously contained. In both cases, excellently bleached substrates are obtained.
The bleaching agents used are preferably aqueous, alkaline H ₂ O ₂ solutions. Typically, these contain up to 30% by weight of H ₂ O ₂ .

Another object of the present invention is the use of a combination of a H ₂ O ₂ -containing bleaching agent and a magnesium silicate for lowering an undesirably high pH and for bleaching fatty substances, preferably in the process according to the invention or in one of its particular or preferred embodiments.

Silicates are generally understood to mean the salts and esters (silicic acid esters) of orthosilicic acid [Si (OH) ₄ ], and their condensation products. According to the degree of dispersion, the silicates can be classified into coarse-disperse (minerals and glasses), colloidal (eg clay minerals) and molecular disperse silicates (eg present in strongly alkaline solution). Special importance is attached to the technical silicates. For the present technical teaching, however, it is essential that magnesium silicates are used and preferably those silicates which are solid and insoluble in water. Magnesium silicates follow the general formula Mg ₂ SiO ₄ , but the concrete molar ratio MgO: SiO _{2 can be} in the range from 1: 4 to 1: 2. Such preferred silicates according to the invention are produced synthetically. A preferred range is from 1: 2.5 to 1: 3.8 and in particular to 1: 2.6. Such silicates are commercially available and are marketed under the brand Magnesol ^® from. Dallas Group. The specific surface area (BET) is typically and preferably between 100 and 600 m ² / g.

The silicate is according to the invention preferably in amounts of 0.001 to 20 wt .-%, in particular from 0.01 to 2.0 wt .-% and most preferably in amounts of 0.1 to 1.0 wt .-%, respectively used on the fatty substances as bleaching amplifiers.

The temperature at which the bleach booster is used is preferably increased from room temperature. It may be particularly preferred to carry out the reaction with the magnesium silicate at temperatures of 60 to 160 ° C and in particular from 80 to 140 ° C.

Fatty substances in the context of the present technical teaching are all compounds which can be derived from fats and oils and which have at least 6 C atoms in the molecule. Examples of fatty substances are linear, branched, cyclic, saturated or unsaturated fatty alcohols, fatty ethers, fatty acid, fatty acid esters, preferably fatty acid esters of glycerol, alkyl (oligo) glycosides, fatty acid amides, fatty acid amines and / or their preferably alkoxylated derivatives. However, other derivatives are also included, for example sulfated, sulfonated or hydroxylated derivatives of the fatty substances described above.

Preferred fatty substances are those which, owing to their production, have an undesirably high pH (for example due to alkaline impurities). For example, preferred are those fatty substances which contain at least one ethoxy group or propoxy group, or contain at least one oligoethoxy or oligopropoxy. The prefix Oligo is here to be interpreted broadly. Oligo can z. From 1 to 1000, in particular from 2 to 1000, to 500, to 100, to 50 or to 10 ethoxy units or propoxy units.

Particularly preferred are those fatty substances which have surface-active properties, ie can act as surfactants. Preferably, the fatty substances in the sense of the technical teaching described here are anionic, nonionic, cationic or amphoteric surfactants. These are listed by way of example in the following table (according to Römpp-Online, Version 2.10, 31.3.2006, keyword: "Surfactants") : class typical representative anion. Surfactants. Soap Alkylbenzenesulfonates, alkanesulfonates alkyl sulfates alkyl ether nonion. surfactants Fatty alcohol polyglycol ethers, alkylphenol polyglycol ethers (ethoxylated) sorbitan fatty acid esters, alkyl polyglucosides, fatty acid glucamides, fatty acid polyglycol esters, ethylene oxide-propylene oxide block polymers, polyglycerol fatty acid esters, fatty acid alkanolamides cation. surfactants quaternary ammonium compound with one or two hydrophobic groups, (eg cetyltrimethylammonium bromide and cetyltrimethylammonium chloride); Salts long-chain prim. amines amphoteric surfactants N - (acylamidoalkyl) betaines N- alkyl-β-aminopropionates or N- alkyl-β-iminopropionates amine- N- oxides

It may furthermore be preferred to use those fatty substances which have a melting point of more than 21 ° C., ie are solid at room temperature. Since the process described here preferably proceeds at elevated temperature, suitable fatty substances preferably remain stable in the range up to 120 ° C. and in particular up to 140 ° C. without changing chemically. Preference is therefore given to fatty substances which have melting points of greater than 21 ° C., preferably greater than 80 ° C. and particularly preferably greater than 120 ° C. and in particular greater than or equal to 140 ° C.

The bleaching itself, that is, the contacting of the fatty substances with the H ₂ O _{2 also} takes place advantageously and therefore preferably at elevated temperatures. Particularly preferred is such a process procedure in which the fatty substances are treated with the bleaching agent at temperatures of 60 to 100 ° C and preferably at temperatures of 60 to 90 ° C.

However, particularly preferred substrates for the bleaching process described herein are nonionic surfactants and fatty substances, which are described in detail below:

Hydroxymix ether (HME):

These are, for example, commercially available surfactants of the general formula (I)

R ¹ O [CH ₂ CH ₂ O] _x CH ₂ CH (OM) R ² (I)

in which R ^{1 is} a linear or branched alkyl and / or alkenyl radical having 4 to 22 carbon atoms, or a radical R ^{2 is} -CH (OH) CH ₂ , where R ^{2 is} a linear or branched alkyl and / or Alkenyl radical having 8 to 16 carbon atoms, x represents a number from 40 to 80, and M represents a hydrogen atom or a saturated alkyl radical having 1 to 18 carbon atoms.

Advantageously, those compounds of general formula (I) are used which contain at least one free hydroxyl group (= -OH). Preferred for the purposes of the invention are those hydroxy mixed ethers which are derived from ethoxylates of monohydric alcohols of the formula R ¹ -OH having 6 to 18 carbon atoms, preferably 6 to 16 and especially 8 to 10 carbon atoms, where R ^{1 is} a linear alkyl radical and x for 40 to 60. Furthermore, in the mixtures according to the invention, such compounds are of the general formula (I) in which the index x stands for a number from 40 to 70, preferably 40 to 60 and in particular from 40 to 50. M is then a hydrogen atom. Very particular preference is given to hydroxy mixed ethers of the formula (I) where R ^{1 is} an alkyl radical having 8 to 10 carbon atoms, in particular based on a native fatty alcohol, R ^{2 is} an alkyl radical having 10 carbon atoms, in particular a linear alkyl radical and x is 40 to 60 stands. Preference is furthermore given to mixtures which contain as surface-active compound a compound of the general formula (I) in which R ^{1 is} an alkyl and / or alkenyl radical having 8 to 10 carbon atoms and R ^{2 is} an alkyl or alkenyl radical having 8 to 10 carbon atoms and x is a number from 40 to 50, wherein also here M stands for a hydrogen atom. Also suitable are those compounds of the formula (I) in which R ^{1 is} an alkyl or alkenyl radical having 8 to 10 carbon atoms, R ^{2 is} a radical having 8 to 12 carbon atoms and M is a saturated alkyl radical having 1 to 6, preferably 1 to 4 carbon atoms. The latter compound contains no free hydroxyl groups - rather, the hydroxyl functions were alkylated with suitable reagents, for example alkyl halides.

Furthermore, HME compounds of the formula (II) are suitable substrates:

R ³ O [CH ₂ CHCH ₃ O] _z [CH ₂ CH ₂ O] _y CH ₂ CH (OH) R ⁴ (II)

in which R ^{3 is} a linear or branched alkyl and / or alkenyl radical having 8 to 22 carbon atoms, R ^{4 is} a linear or branched alkyl and / or alkenyl radical having 8 to 16 carbon atoms, y is a number of 10 and 35, z is zero or must be a number from 1 to 5. It may be advantageous if R ³ = R ¹ and at the same time R ⁴ = R ² those compounds of the formula (II) are selected in which the index z is at least 1. If mixtures of the surface-active compounds of the type of the formula (I) with those of the formula (II) are used, only those mixtures within the meaning of the present technical teaching in which the molecules structurally differ from one another. So there must always be different structure connections side by side. Particularly preferred compounds are, for example, those in which, in the formula (II), the index y is a number from 20 to 30, preferably from 20 to 25. Preference is furthermore given to those compounds in which R ³ in the formula (II) represents an alkyl radical having 8 to 12, preferably 8 to 10, carbon atoms, R ^{4 is} an alkyl radical having 10 to 12, preferably 10 carbon atoms, y is a number of 15 to 35, preferably 20 to 30 and z is a number from 1 to 3, preferably 1 means. Preference is also given to mixtures which contain as surface-active compounds those of the general formula (II) in which R ^{3 is} an alkyl and / or alkenyl radical having 11 to 18 carbon atoms and R ^{4 is} an alkyl or alkenyl radical having 8 to 10 Carbon atoms and y is a number from 20 to 35. Also preferred are mixtures containing as the surface active compound of the general formula (II), in which R ^{3 is} an alkyl and / or alkenyl radical having 8 to 12 carbon atoms and R ^{4 is} an alkyl or alkenyl radical having 8 to 10 carbon atoms and y is a number from 20 to 35 and z is a number from 1 to 3. The compounds of type (II) are also hydroxy mixed ether derivatives which can be prepared by reacting propoxylated and / or ethoxylated fatty alcohols with Alkylepoxiden by ring opening in an alkaline medium. It is in derivatives of the type (II) as well as in all other mixed alkoxylates listed in this description, ie both a propylene oxide CH ₂ CHCH ₃ O (PO) and an ethylene oxide CH ₂ CH ₂ O (EO ), it is possible that from the direction of the C atom with the free hydroxyl group first the EO residues and then the PO residues are arranged in blocks, wherein the sequence first PO, then EO is possible. Furthermore, the alkoxide groups can also be randomly distributed (randomized) in the molecule. It is also possible to use both block and random alkoxylates side by side.

fatty alcohol ethoxylates

Compounds are known per se fatty alcohol ethoxylates of the general formula (III) R ⁵ - (OC ₂ H ₄ ) _z -OH in which R ^{5 is} linear or branched alkyl and / or alkenyl radicals having 8 to 22 carbon atoms and z is an integer from 1 to 20 and preferably from 1 to 15, and especially from 1 to 10. Typical examples are the adducts of on average 1 to 20 moles of caproic alcohol, caprylic alcohol, 2-ethylhexyl alcohol, capric alcohol, lauryl alcohol, isotridecyl 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 Brassidyl alcohol and their technical mixtures, for example, in the high pressure hydrogenation of technical methyl esters based on fats and oils or aldehydes from the Roelen oxo synthesis and as a monomer fraction in the dimerization of unsaturated fatty alcohols incurred. Preferred are adducts of 10 to 40 moles of ethylene oxide with technical fatty alcohols having 12 to 18 carbon atoms, such as Coconut, palm, palm kernel or preferably tallow fatty alcohol. Particularly preferred fatty alcohol ethoxylates are based on tallow alcohols ethoxylated with 2 to 10 and preferably 2 to 5 moles of ethylene oxide per mole of alcohol.

Glykolester

These compounds are mono- and / or preferably diesters of glycol and especially polyglycols and are also known and commercially available. They can be described by the formula R ⁶ CO- (OC ₂ H ₄ ) _m -OR ⁷ , where R ^{6 is} an alkyl and / or alkenyl radical having 7 to 21 carbon atoms and m is a number from 11 to 100, and R ^{7 represents} a hydrogen atom or a radical CO-R ⁶ . In this case, symmetrical (R ⁶ = R ⁷ ) and unbalanced connections (R ⁶ ≠ R ⁷ ) are included.

Alkyl (oligo) glycosides

These compounds are also known as alky (oligo) glycosides. Alkyl and alkenyl oligoglycosides are known nonionic surfactants which follow the formula R ⁸ O- [G] _p in which R ^{8 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 stands for numbers from 1 to 10. They can be obtained by the relevant methods of preparative organic chemistry. The alkyl and / or alkenyl oligoglycosides can be derived from aldoses or ketoses having 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 indicates the degree of oligomerization (DP), ie the distribution of monoglycerides and oligoglycosides, and stands for a number between 1 and 10. While p in a given compound must always be an integer, and above all the values p = 1 to 6, the value p for a given alkyloligoglycoside is an analytically determined arithmetic size, which is usually a fractional number. Preference is given to using alkyl and / or alkenyl oligoglycosides having an average degree of oligomerization p of from 1.1 to 3.0. From an application point of view, those alkyl and / or alkenyl oligoglycosides whose degree of oligomerization is less than 1.7 and in particular between 1.2 and 1.4 are preferred. The alkyl or alkenyl radical R ⁸ can be derived from primary alcohols having 4 to 11, preferably 8 to 10 carbon atoms. Typical examples are butanol, caproic alcohol, caprylic alcohol, capric alcohol and undecyl alcohol and their technical mixtures, as for example in the hydrogenation of technical fatty acid methyl esters or in the course of the hydrogenation of aldehydes of Roelen's oxosynthesis. Preference is given to alkyl oligoglucosides of the chain length C ₈ -C ₁₀ (DP = 1 to 3) which are obtained as a feedstock in the distillative separation of technical C ₈ -C ₁₈ coconut fatty alcohol and in a proportion of less than 6% by weight C ₁₂ - Alcohol may be contaminated as well as alkyl oligoglucosides based on technical C _9/11 oxo alcohols (DP = 1 to 3). The alkyl or alkenyl radical R ⁸ 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, brassidyl alcohol and technical mixtures thereof which can be obtained as described above. Preference is given to alkyl oligoglucosides based on hydrogenated C _12/14 coconut alcohol having a DP of 1 to 3.

Betaine

in der R^I für Alkyl- und/oder Alkenylreste mit 6 bis 22 Kohlenstoffatomen, R^II für Wasserstoff oder Alkylreste mit 1 bis 4 Kohlenstoffatomen, R^III für Alkylreste mit 1 bis 4 Kohlenstoffatomen, n für Zahlen von 1 bis 6 und X für ein Alkali- und/oder Erdalkalimetall oder Ammonium steht. Typische Beispiele sind die Carboxymethylierungsprodukte von Hexylmethylamin, Hexyldimethylamin, Octyldimethylamin, Decyldimethylamin, Dodecylmethylamin, Dodecyldimethylamin, Dodecylethylmethylamin, C_12/14-Kokosalkyldimethylamin, Myristyldimethylamin, Cetyldimethylamin, Stearyldimethylamin, Stearylethylmethylamin, Oleyldimethylamin, C_16/18-Talgalkyldimethylamin sowie deren technische Gemische.Betaines are known surfactants which are predominantly produced by carboxyalkylation, preferably carboxymethylation of aminic compounds. Preferably, the starting materials are condensed with halocarboxylic acids or their salts, in particular with sodium chloroacetate, wherein one mole of salt is formed per mole of betaine. Furthermore, the addition of unsaturated carboxylic acids, such as acrylic acid is possible. Examples of suitable betaines are the carboxyalkylation products of secondary and in particular tertiary amines, which follow the formula:

in the R ^I for alkyl and / or alkenyl radicals having 6 to 22 carbon atoms, R ^{II is} hydrogen or alkyl radicals having 1 to 4 carbon atoms, R ^{III is} alkyl radicals having 1 to 4 carbon atoms, n is from 1 to 6, and X is a Alkali and / or alkaline earth metal or ammonium. Typical examples are the carboxymethylation products of hexylmethylamine, hexyldimethylamine, octyldimethylamine, decyldimethylamine, dodecylmethylamine, dodecyldimethylamine, dodecylethylmethylamine, C _12/14 cocoalkyldimethylamine, Myristyldimethylamine, cetyldimethylamine, stearyldimethylamine, stearylethylmethylamine, oleyldimethylamine, C _16/18 tallowalkyldimethylamine and technical mixtures thereof.

in der R^IV CO für einen aliphatischen Acylrest mit 6 bis 22 Kohlenstoffatomen und 0 oder 1 bis 3 Doppelbindungen, m für Zahlen von 1 bis 3 steht und R^II, R^III, n und X die oben angegebenen Bedeutungen haben. Typische Beispiele sind Umsetzungsprodukte von Fettsäuren mit 6 bis 22 Kohlenstoffatomen, namentlich Capronsäure, Caprylsäure, Caprinsäure, Laurinsäure, Myristinsäure, Palmitinsäure, Palmoleinsäure, Stearinsäure, Isostearinsäure, Ölsäure, Elaidinsäure, Petroselinsäure, Linolsäure, Linolensäure, Elaeostearinsäure, Arachinsäure, Gadoleinsäure, Behensäure und Erucasäure sowie deren technische Gemische, mit N,N-Dimethylaminoethylamin, N,N-Dimethylaminopropylamin, N,N-Diethylaminoethylamin und N,N-Diethylaminopropylamin, die mit Natriumchloracetat kondensiert werden. Bevorzugt ist der Einsatz eines Kondensationsproduktes von C_8/18-Kokosfettsäure-N,N-dimethylaminopropylamid mit Natriumchloracetat.Also suitable are carboxyalkylation products of amidoamines which follow the formula given below,

in which R ^IV CO is an aliphatic acyl radical having 6 to 22 carbon atoms and 0 or 1 to 3 double bonds, m is a number from 1 to 3 and R ^II , R ^III , n and X have the meanings given above. Typical examples are reaction products of fatty acids having 6 to 22 carbon atoms, namely caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid and their technical mixtures, with N, N-dimethylaminoethylamine, N, N-dimethylaminopropylamine, N, N-diethylaminoethylamine and N, N-diethylaminopropylamine, which are condensed with sodium chloroacetate. The use of a condensation product of C _8/18 coconut fatty acid N, N-dimethylaminopropylamide with sodium chloroacetate is preferred.

in der R^V für einen Alkylrest mit 5 bis 21 Kohlenstoffatomen, R⁶ für eine Hydroxylgruppe, einen OCOR^V- oder NHCOR^V-Rest und m für 2 oder 3 steht. Auch bei diesen Substanzen handelt es sich um bekannte Stoffe, die beispielsweise durch cyclisierende Kondensation von 1 oder 2 Mol Fettsäure mit mehrwertigen Aminen, wie beispielsweise Aminoethylethanolamin (AEEA) oder Diethylentriamin erhalten werden können. Die entsprechenden Carboxyalkylierungsprodukte stellen Gemische unterschiedlicher offenkettiger Betaine dar. Typische Beispiele sind Kondensationsprodukte der oben genannten Fettsäuren mit AEEA, vorzugsweise Imidazoline auf Basis von Laurinsäure oder wiederum C_12/14-Kokosfettsäure, die anschließend mit Natriumchloracetat betainisiert werden.Furthermore, suitable starting materials for the betaines to be used in the context of the invention are also imidazolines which follow this formula,

in which R ^{V is} an alkyl radical having 5 to 21 carbon atoms, R ^{6 is} a hydroxyl group, an OCOR ^V or NHCOR ^V radical and m is 2 or 3. Even with these substances These are known substances which can be obtained, for example, by cyclizing condensation of 1 or 2 moles of fatty acid with polyhydric amines, such as, for example, aminoethylethanolamine (AEEA) or diethylenetriamine. The corresponding carboxyalkylation products are mixtures of different open-chain betaines. Typical examples are condensation products of the abovementioned fatty acids with AEEA, preferably imidazolines based on lauric acid or again C _12/14 coconut fatty acid, which are subsequently betainized with sodium chloroacetate.

epoxides

in der R⁹ für einen linearen oder verzweigten Alkyl- und/oder Alkenylrest mit 4 bis 22 Kohlenstoffatomen und o für eine Zahl von 1 bis 20 und der Index p für Null oder Zahlen von 1 bis 20 steht.
Diese ebenfalls als Hydroxymischether zu bezeichnenden Verbindungen folgen der allgemeinen Formel (V):

         R¹⁰CH(OR¹¹)CH₂-OR¹¹     (V)

in der R¹⁰ für einen gesättigten oder ungesättigten, verzweigten oder unverzweigten Alkyl- oder Alkenylrest mit 8 bis 16 Kohlenstoffatomen steht, und R¹¹ jeweils unabhängig voneinander einen Rest (CH₂CH₂O)_rCH₂CH(OH)R¹² symbolisieren, wobei r in jedem Rest R¹¹ unabhängig für Null oder eine Zahl von 1 bis 50 steht und R¹² einen gesättigten oder ungesättigten, verzweigten oder unverzweigten Alkyl- oder Alkenylrest mit 8 bis 16 Kohlenstoffatomen steht.These nonionic compounds, which are also known, are prepared, for example, by reacting alkyl epoxides with ethylene glycol and then with further ethylene oxide. These are also commercially available substances. They follow the general formula (IV)

in which R ^{9 is} a linear or branched alkyl and / or alkenyl radical having 4 to 22 carbon atoms and o is a number from 1 to 20 and the subscript p is zero or numbers from 1 to 20.
These compounds, which are also to be referred to as hydroxy mixed ethers, follow the general formula (V):

R ¹⁰ CH (OR ¹¹ ) CH ₂ -OR ¹¹ (V)

in which R ^{10 is} a saturated or unsaturated, branched or unbranched alkyl or alkenyl radical having 8 to 16 carbon atoms, and R ¹¹ each independently of one another symbolize a radical (CH ₂ CH ₂ O) _r CH ₂ CH (OH) R ¹² , wherein r in each radical R ^{11 is} independently zero or a number from 1 to 50 and R ^{12 is} a saturated or unsaturated, branched or unbranched alkyl or alkenyl radical having 8 to 16 carbon atoms.

amines

These are nitrogen-containing compounds of the general formula (VI):

NR ¹³ ₃ (VI)

wherein R ¹³ independently of one another is a radical (CH ₂ CH ₂ O) _s -CH ₂ CH (OH) R ¹⁴ or an alkyl radical having 8 to 16 carbon atoms and s is independently zero for each individual radical R ¹³ , or a number from 1 to 50. Compounds of type b8) are obtainable, for example, by ethoxylation of alkylamines or of triethanolamine and subsequent reaction with alkylene oxides with alkyl chains having 8 to 18 carbon atoms under conditions of alkaline catalysis.

fatty alcohols

In addition to the surface-active compounds described above, it may be advantageous to use further surface-active compounds as substrates. Pure fatty alcohols in particular come into question here. Fatty alcohols are primary aliphatic alcohols of the formula R ¹⁴ -OH in which R is an aliphatic, linear or branched hydrocarbon radical having 6 to 22 carbon atoms and 0 and / or 1, 2 or 3 double bonds. Typical examples are caproic alcohol, caprylic alcohol, 2-ethylhexyl alcohol, capric alcohol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linolyl alcohol, linolenyl alcohol, elaeostearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and brassidyl alcohol and the like technical mixtures which are obtained, for example, in the high-pressure hydrogenation of technical methyl esters based on fats and oils or aldehydes from Roelen's oxosynthesis and as a monomer fraction in the dimerization of unsaturated fatty alcohols. Preferred are technical fatty alcohols having 12 to 18 carbon atoms, such as coconut, palm, palm kernel or tallow fatty alcohol.

fatty acids

By fatty acids are meant aliphatic carboxylic acids of the formula (VII)

R ¹⁵ CO-OH (VII)

in which R ¹⁵ CO is an aliphatic, linear or branched acyl radical having 6 to 22 carbon atoms and 0 and / or 1, 2 or 3 double bonds. Typical examples are caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, elaeostearic acid, arachidic acid, gadoleic acid, behenic acid and erucic acid, and technical mixtures thereof , which occur, for example, in the pressure splitting of natural fats and oils, in the reduction of aldehydes from the Roelen oxo synthesis or the dimerization of unsaturated fatty acids. Preference is given to technical fatty acids having 12 to 18 carbon atoms, such as, for example, coconut, palm, palm kernel or tallow fatty acid.

The hydroxy mixed ethers of the above description of the formulas (I) and (II) are particularly preferred substrates in the context of the present technical teaching.

Examples

• Tensid 1 modifizierter Fettalkoholpolyglykolether (Dehypon E127 - Fa. Cognis)
• Tensid 2 Hydroxymischether (Dehypon KE 3697 - Fa. Cognis)
• Tensid 3 modifizierter Fettalkoholpolyglykolether (Dehypon KE 3447 - Fa. Cognis)

To test the process according to the invention, bleaching tests were carried out with and without magnesium silicate on various nonionic surfactants as fatty substances. The following surfactants were investigated:

• Surfactant 1 modified fatty alcohol polyglycol ether (Dehypon E127 - Cognis)
• Surfactant 2 hydroxy mixed ethers (Dehypon KE 3697 - Cognis)
• Surfactant 3 modified fatty alcohol polyglycol ether (Dehypon KE 3447 - Cognis)

example 1

198.8 g of the surfactant were heated to 140 ° C. with stirring. Then, 1 g of synthetic magnesium silicate (Magnesol ^® R60) was added and the mixture stirred at about 80 ° C stirred for an hour. The mixture was then filtered through a heatable filter (T120, Seitz) at 60 ° C. The filtrate (168.4 g) was then added at 60 ° C with 0.48 g of a 35% aqueous H ₂ O ₂ solution and stirred for 5 hours.

Examples 2 and 3 were carried out analogously to Example 1. The color numbers of the starting and end products were determined using a color number determination device from the company Dr. Ing. Lange, model Lico 200 intended. For comparison, values were also measured for bleaching with H ₂ O ₂ but without added magnesium silicate. The results are shown in the following Table 1. <u> Table 1 </ u> attempt 1 2 3 Color number according to Hazen before bleaching 478 567 > 1000 after treatment with magnesium silicate 51 80 91 Bleaching without addition of magnesium silicate 472 213 143

One recognizes the significant improvement in the color of the products after bleaching. However, it is also clear that the addition of magnesium silicate leads to a further, significant improvement in the color number.

pH-reduction:

Trial 1 with another batch of surfactant 1 was repeated. The pH values during the experiment were determined. The following values were obtained. attempt Color number according to Hazen pH before bleaching 610 11 Treatment only with magnesium silicate 339 5.8 Bleaching with H2O2 without addition of magnesium silicate 419 10.9 after treatment with magnesium silicate and H2O2 42 10.3

The surfactants treated in the example were not sales products but crude solutions obtained from the reaction to make the surfactants. Before they are for sale, they must be bleached and the pH must be lowered.

Claims (14)

A method for lowering the pH and for bleaching fatty substances having at least 6 C atoms in the molecule, characterized in that bringing the fatty substances with a H ₂ O ₂ -containing bleach and with a magnesium silicate in contact until a discoloration occurred is, and then preferably the magnesium silicate removed, wherein in the implementation of the method, a lowering of the pH of the fatty substance takes place. The method according to claim 1, characterized in that the fatty substances are selected from linear, branched, cyclic, saturated or unsaturated fatty alcohols, fatty ethers, fatty acids, fatty acid esters, preferably fatty acid esters of glycerol, alkyl (oligo) glycosides, fatty acid amides, fatty acid amines and their alkoxylated derivatives , The method according to one of claims 1 to 2, characterized in that the fatty substances are surface-active compounds. The method according to any one of claims 1 to 3, characterized in that the fatty substances are nonionic, anionic, cationic and / or amphoteric surfactants. The method according to any one of claims 1 to 4, characterized in that the fatty substances are hydroxy mixed ethers. The method according to any one of claims 1 to 5, characterized in that, in a first step, the heated fatty substances are treated with magnesium silicate and then bleach bleached with the H ₂ O ₂ . The method according to one of claims 1 to 6, characterized in that the fatty substances are treated simultaneously with magnesium silicate and the H ₂ O ₂ contained bleach. The process according to any one of claims 1 to 7, characterized in that a bleaching agent containing H ₂ O ₂ is an aqueous alkaline solution of H ₂ O ₂ . The process according to any one of claims 1 to 8, characterized in that the magnesium silicate is used in amounts of from 0.001 to 20% by weight, preferably from 0.01 to 2.0 and in particular from 0.1 to 1.0% by weight. - Based on the amount of fatty substances - is used. The method according to any one of claims 1 to 9, characterized in that the fatty substances are bleached at temperatures of 60 to 160 ° C, preferably at temperatures of 80 to 140 ° C and treated with magnesium silicate. The method according to any one of claims 1 to 10, characterized in that the treatment of the fatty substances with the H ₂ O ₂ -containing bleach at temperatures of 60 to 100 ° C, preferably at 60 to 90 ° C. The method according to any one of claims 1 to 11, characterized in that a solid, water-insoluble magnesium silicate is used. The use of a combination of a H ₂ O ₂ -containing bleaching agent and a magnesium silicate for lowering an undesirably high pH and for bleaching fatty substances. The use of claim 13 in the method of any one of claims 1 to 12.