Separation of water from betaines

Abstract

The present invention relates to a gentle method for separating water from betaines.

Description

[0001] The present invention relates to a gentle method for separating water from betaines.

[0002] Betaines, such as cocamidopropyl betaine, are widely used as (co)surfactants in cosmetics and household chemicals, especially in shower gels, shampoos and liquid soaps, but also in fabric softeners or dishwashing liquids.

[0003] Cocoamidopropyl betaines are generally produced first by reacting coconut fatty acids, predominantly C8 to C18 fatty acids, or their triglycerides with dimethylaminopropylamine ((H3C)2N-CH2-CH2-CH2-NH2, DMAPA) to form the corresponding amides, and then reacting these with chloroacetic acid (Cl-CH2-COOH), usually in the presence of a base. If an alkali metal hydroxide is used as the base, the alkali metal halide is formed in addition to the zwitterionic betaine; if sodium hydroxide is used as the base, sodium chloride is formed.

[0004] For the above applications as a (co)surfactant, the betaine is used in aqueous solution; the water and alkali metal halide content is not detrimental. Foaming by the cocamidopropyl betaines is desirable in these applications.

[0005] However, there are also other applications where the content of alkali metal halide and / or water is disruptive and must be largely removed.

[0006] One such application is the use of betaines in fuels: WO 2014 / 202425 describes the use of betaines as additives in fuels, for example as a detergent additive in diesel or to reduce deposits in direct-injection diesel engines. Applications in gasoline or jet fuels are also described.

[0007] A betaine obtained according to the above manufacturing process contains, according to WO 2014 / 202425, 10 to 30 wt% sodium chloride, which can be largely removed by desalination processes, for example, treatment with ion exchangers, precipitation, or membrane filtration. Membrane filtration can reduce the sodium chloride content to as low as 5 wt%, preferably 2.5 wt%, particularly preferably 1.0 wt%, and most preferably to as low as 0.5 wt%.

[0008] A disadvantage is that before membrane filtration, the betaine must be treated with a solvent, usually water, in a quantity of 0.1 to 10 times the amount of the reaction mixture.

[0009] Therefore, the betaine obtained in this way contains at least 10% water.

[0010] Another application of betaines in combination with C6-C15 alcohol ethoxylates for the dispersion of water in liquid hydrocarbon fuels by generating a water-in-oil microemulsion is described in WO 2011 / 045334. In particular, in jet fuels, water would otherwise settle in the fuel tanks and, at low temperatures, for example during flight, form ice crystals that can block or clog fuel filters and thus impair engine performance.

[0011] Since the function of betaine in this application is to distribute water in fuels, the betaine should ideally contain as little water as possible from the outset. However, the removal of sodium chloride according to WO 2014 / 202425 actually increases the water content in the betaine.

[0012] However, simple separation of water by distillation at normal pressure leads to significant losses of betaine due to the reactivity of the zwitterion (see comparative example), probably due to Hoffmann eliminations at the quaternary ammonium ion, transmethylations and / or transesterifications.

[0013] Furthermore, aqueous solutions of cocamidopropyl betaines can only be concentrated to an active component content of approximately 40%, as the solutions tend to foam and gel strongly at higher concentrations.

[0014] The object of the present invention was therefore to provide highly concentrated compositions of betaine with a low water content and to minimize losses of betaine.

[0015] The problem was solved by a method for producing low-water solutions of betaines of formula (I) R 1< -CO-NH-XN(R 2< R 3< ) 2 +< -Y-COO- (I), whereinR1< a linear or branched alkyl or alkenyl group having 5 to 21, preferably 7 to 19, particularly preferably 9 to 17 and particularly 11 to 15 carbon atoms, R2< and R3< each independently of each other C1 to C4 alkyl groups, preferably methyl or ethyl groups, X a divalent alkylene group having 1 to 12, preferably 2 to 8, particularly preferably 2 to 6 and particularly 2 to 4 carbon atoms and Y a linear or branched C1 to C4 alkylene group, preferably methylene, 1,2-ethylene or 1,3-propylene, by combining an aqueous solution containing at least one betaine of formula (I) with at least one ethoxylate of formula (II) R2< -O-[-CH2-CH2-O-]n-H (II) wherein R2< a linear or branched alkyl or alkenyl group, preferably linear alkyl group with 6 to 15, preferably 8 to 14, particularly preferably 8 to 13, most preferably 9 to 13 and particularly 9 to 11 carbon atoms and n a rational number from 1 to 12,preferably 1 to 10, particularly preferably 1 to 5 and most preferably 1 to 3, are mixed and water is distilled off from this mixture at reduced pressure and a temperature below 100 °C for no more than 4 hours, so that the water content is no more than 5 wt%.

[0016] Another object of the present invention is the above method in which the alkali metal halide salt contained is at least partially removed from the betaine of formula (I).

[0017] Another object of the present invention is the use of such water- and optionally alkali metal halide-depleted betaines of formula (I) as an additive in fuels, fuels containing such betaines and a method for distributing water in fuels in which such water- and optionally alkali metal halide-depleted betaines of formula (I) are used as an additive.

[0018] The betaines have the formula (I) R 1< -CO-NH-XN(R 2< R 3< ) 2 +< -Y-COO -< (I). This means:

[0019] R 1< a linear or branched alkyl or alkenyl group with 5 to 21, preferably 7 to 19, particularly preferably 9 to 17 and particularly 11 to 15 carbon atoms. Linear alkyl or alkylene groups are preferred, linear alkyl groups are particularly preferred.

[0020] Examples of fatty acids underlying the R1<-CO- substructure are octanoic acid (caprylic acid), pelargonic acid (nonanoic acid), decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), nonadecanoic acid, arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), as well as palmitoleic acid [(9Z)-hexadec-9-enoic acid], oleic acid [(9Z)-octadec-9-enoic acid], elaidic acid [(9E)-octadec-9-enoic acid], erucic acid [(13Z)-docos-13-enoic acid], linoleic acid [(9Z,12Z)-octadeca-9,12-dienoic acid], and linolenic acid. [(9Z,12Z,15Z)-Octadeca-9,12,15-trienic acid] and elaeostearic acid [(9Z,11E,13E)-Octadeca-9,11,13-trienic acid].

[0021] Preferably, the fatty acids underlying the substructure R 1< -CO- are mixtures of fatty acids from fats or oils of vegetable or animal origin.

[0022] Technically common fatty acid mixtures are preferably tallow fatty acids, coconut oil fatty acids, trans fat fatty acids, coconut palm kernel oil fatty acids, soybean oil fatty acids, rapeseed oil fatty acids, peanut oil fatty acids, or palm oil fatty acids, which contain lauric acid, myristic acid, oleic acid, and / or palmitic acid as their main components. Palm oil fatty acids or coconut oil fatty acids are particularly preferred, and those with acid numbers of 251–262 mg KOH / g according to AOCS Te 1a-64, 5t h< edition are especially preferred.

[0023] Such mixtures contain, for example, as their main components... Caprylic acid 4 - 10 wt% Capric acid 5 - 7 wt% Lauric acid 45 - 55 wt% Myristic acid 15 - 22 wt% Palmitic acid 7 - 11 wt% Stearic acid 2 - 4 wt% Oleic acid 5 - 10 wt% and optionally in quantities up to 5 wt% caproic acid, linoleic acid and linolenic acid.

[0024] R2< and R3< each independently represent C1 to C4 alkyl groups, preferably methyl or ethyl groups, particularly preferably methyl. Preferably, R2< and R3< are the same.

[0025] The C1 to C4 alkyl groups include methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl and tert- Butyl understood.

[0026] X represents a divalent, linear or branched, preferably linear alkylene residue with 1 to 12, preferably 2 to 8, particularly preferably 2 to 6 and particularly 2 to 4 carbon atoms.

[0027] Examples of such dicoordinate residues X are 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,8-octylene, 1,10-decylene and 1,12-dodecylene, preferably 1,2-ethylene, 1,3-propylene, 1,4-butylene and 1,6-hexylene, particularly preferably 1,2-ethylene and 1,3-propylene and most particularly preferably 1,3-propylene.

[0028] Y means a divalent, linear or branched, preferably linear C 1 to C 4 alkylene group, preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, preferably methylene, 1,2-ethylene or 1,3-propylene, particularly preferably methylene or 1,2-ethylene and most particularly preferably methylene.

[0029] Betaines of formula (I) are particularly preferred, in which R 1< C 11 - to C 15 -alkyl, R 2< and R 3< are each methyl, X 1,3-propylene and Y methylene.

[0030] The betaines of formula (I) are generally present as a dilute aqueous solution with a betaine content of 10 to 40, preferably 15 to 40, particularly preferably 20 to 35, most particularly preferably 25 to 35 wt%.

[0031] The betaines of formula (I) used in the process according to the invention are preferably obtained by first proceeding at least one fatty acid of the formula R1<-COOH or its ester, preferably C1 to C4 alkyl esters, reacts with at least one amine of the formula H2NXN(R2<R3<) to form the amide, and in a second step reacts this with at least one haloalkanecarboxylic acid of the formula Hal-Y-COOH or Hal-Y-COO-Alk+<, where Hal represents chlorine, bromine, or iodine, preferably chlorine or bromine, and Alk+< represents an alkali metal cation, preferably sodium or potassium, particularly preferably sodium, in the presence of at least one alkali metal hydroxide, carbonate, or hydrogen carbonate, preferably an alkali metal hydroxide, to form the betaine of formula (I) with simultaneous formation of an alkali metal halide salt, and from the reaction mixture thus obtained, the alkali metal halide salt is obtained by extraction with at least one solvent, treatment with ion exchangers, precipitation, and / or membrane filtration. depleted.

[0032] The alkali metal is selected from the group consisting of lithium, sodium and potassium, preferably sodium and potassium and particularly preferably sodium.

[0033] Separation methods for the alkali metal halide salt are known, for example, from WO 14 / 202425.

[0034] In principle, all relevant desalination processes for removing inorganic salts from polar low- and high-molecular-weight organic compounds are suitable for removing the alkali metal halide salt from the betaine compound. However, ion exchange processes, membrane filtration processes, and precipitation are of particular importance for this purpose. Ultrafiltration, nanofiltration, and reverse osmosis processes are especially suitable for membrane filtration. The membranes used have the property of retaining certain substances (such as organic compounds) while allowing others (such as inorganic salts) to pass through.

[0035] In a preferred embodiment, the alkali metal halide salt is removed by membrane diafiltration. This is typically an ultrafiltration or nanofiltration technique. For this purpose, after the synthesis of the betaine compound from the amide, the halocarboxylic acid, and the alkali metal hydroxide, the reaction mixture is generally washed with a solvent such as water, and the solvent containing the inorganic salt and the betaine compound is then passed through the membrane, retaining and enriching the betaine compound. This process can be carried out batchwise, semi-continuously, or fully continuously.

[0036] The ultrafiltration or nanofiltration membrane used is typically made of a polymer material such as polyethersulfones, polysulfones, polyamides, or polyimides, or of ceramic materials such as aluminum oxide, titanium dioxide, zirconium dioxide, or silicon carbide. They separate suspensions or solutions, typically with a separation limit in the range of 500 to 150,000 Daltons, particularly in the range of 500 to 10,000 Daltons.

[0037] The amount of solvent used, preferably water or ethanol, is generally 0.1 to 10 times, and in particular 1.5 to 7 times, the amount of the reaction mixture. The amount of solvent should be selected such that the viscosity of the solution before entering the membrane is below 200 cP, and in particular below 50 cP. The operating temperature for diafiltration is typically 20 to 120°C, and in particular 20 to 60°C, depending on the type of membrane. After completion of the diafiltration, the solution of the betaine compound can be reconcentrated, for example, by not adding any further solvent to the reaction mixture and continuing to remove the permeate from the membrane.

[0038] The described diafiltration process can also be operated with a solvent exchange process during its execution. For example, the water used at the beginning can be gradually or immediately replaced with an alcohol such as methanol, ethanol, isopropanol, or an alcohol / water mixture. The optimal technique for such solvent exchange depends in particular on the product retention and the achieved flow rates.

[0039] The chlorine content (determined according to DIN 51408-2) of the aqueous solutions thus obtained, based on the active content of betaine, is less than 1000 ppm, preferably less than 100 ppm, particularly preferably less than 10 ppm.

[0040] It is also possible to deplete the alkali metal halide salt by treatment with at least one ion exchanger, preferably an anion and a cation exchanger.

[0041] Furthermore, the alkali metal halide salt can be precipitated by using an organic solvent in which the betaine is soluble, but the alkali metal halide salt is not. This is described, for example, in EP 2674471 B1. Accordingly, the content of alkali metal halide salts, especially sodium chloride, can be reduced by transferring the betaine into the organic phase with heptane and then washing this organic phase several times with water to remove any alkali metal halide that may be present in the organic phase.

[0042] In the ethoxylates of formula (II) R 2< -O-[-CH 2 -CH 2 -O-] n -H (II) mean R 2< a linear or branched alkyl or alkenyl group, preferably a linear alkyl group with 6 to 15, preferably 8 to 14, particularly preferably 8 to 13, very preferably 9 to 13 and particularly 9 to 11 carbon atoms and n a rational number from 1 to 12, preferably 1 to 10, particularly preferably 1 to 5 and very preferably 1 to 3.

[0043] Examples of the underlying alkanols R 2< OH are n-octanol (octyl alcohol, caprylic alcohol), 2-ethylhexanol, nonyl alcohol (pelargonyl alcohol), iso-nonanol, n-decanol, 2-propylheptanol, decyl alcohol (caprylic alcohol), undecyl alcohol, dodecyl alcohol (lauryl alcohol), tridecyl alcohol and tetradecyl alcohol (myristyl alcohol).

[0044] In a preferred embodiment, these are pure substances such as 2-ethylhexanol or 2-propylheptanol.

[0045] In another embodiment, the underlying alkanol R 2< OH can be a mixture of different alkanols, which on average have 8 to 14, preferably 9 to 11, carbon atoms. Since these are mixtures, the number of carbon atoms can also be non-integer values.

[0046] Examples of such mixtures are mixtures of fatty alcohols, e.g., those obtained from coconut oil. Such mixtures are predominantly composed of C8 to C16 alkanols with even numbers of carbon atoms, typically 4.6–10.0 wt% C8 alkanol, 5.0–8.0 wt% C10 alkanol, 45.1–53.2 wt% C12 alkanol, 16.8–21.0 wt% C14 alkanol, and 7.5–10.2 wt% C16 alkanol.

[0047] In a further embodiment, the alcohol R 2< -OH is a mixture of alcohols having about 13 carbon atoms, particularly preferably one that is obtainable by hydroformylation from a C 12 olefin mixture which in turn is obtainable by oligomerization of an olefin mixture containing predominantly four carbon atoms hydrocarbons.

[0048] On average, this olefin mixture has 11 to 16 carbon atoms, preferably 11.1 to 12.9, particularly preferably 11.2 to 12.8, most preferably 11.5 to 12.5 and particularly 11.8 to 12.2. The alcohols obtained from it accordingly have one more carbon atom.

[0049] In a particularly preferred embodiment, this alcohol R 2< -OH has a mean degree of branching, measured as an ISO index, of 1.8 to 2.7.

[0050] Such mixtures are commercially available as tridecanols or iso-tridecanols.

[0051] Particularly preferred are mixtures of linear alcohols having 9, 10, and 11 carbon atoms. In a most preferred embodiment, the alkanol R₂OH is a mixture of primary alcohols with the composition of 15–20 wt% C₉, 40–45 wt% C₁₀, and 35–40 wt% C₁₁ alcohols, wherein the proportion of alcohols with 8 or fewer or with 12 or more carbon atoms is not more than 1 wt% in each case. Particularly preferred are highly linear alkanols having a degree of branching, measured as an ISO index, of not more than 0.5, preferably not more than 0.3, particularly preferably not more than 0.2, and most preferably not more than 0.1. The average molecular weight of such an alcohol mixture is from 158 to 164 g / mol. The OH number ranges from 342 to 355 mg KOH / g.

[0052] The degree of ethoxylation m of the ethoxylated alkanols is a rational number from 1 to 3, preferably 1.5 to 3, particularly preferably 1.75 to 3, very preferably 1.75 to 2.75 and particularly 2 to 2.75.

[0053] The degree of ethoxylation m is an arithmetic mean, therefore m can also take on non-integer values.

[0054] Optionally and preferably, at least one ethylene glycol of formula (III) HO-[-CH 2 -CH 2 -O] m -H (III) can be added to the mixture of betaine of formula (I) and ethoxylate of formula (II). wherein m is a rational number of at least 1, preferably from 1 to 4, particularly preferably from 1 to 3, most preferably from 1 to 2 and particularly 1.

[0055] Examples of such mono- or oligoethylene glycols are monoethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol, as well as mixtures thereof, preferably monoethylene glycol or diethylene glycol or technical mixtures of triethylene glycol and tetraethylene glycol.

[0056] Monoethylene glycol is particularly preferred.

[0057] Possible, though less preferred, are mono-C1-C4 alkyl ethers of the aforementioned mono- or oligoethylene glycols, especially the mono-methyl, -ethyl or -n-butyl ethers of these mono- or oligoethylene glycols, particularly preferably the mono-methyl or -n-butyl ethers and most preferably the mono-methyl ethers of these mono- or oligoethylene glycols, especially the di-, tri- or tetraethylene glycols.

[0058] Examples include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-butyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether and tetraethylene glycol mono-n-butyl ether.

[0059] Diethylene glycol monoethyl ether is particularly preferred.

[0060] Optionally, at least one C 1 -C 8 -alkanol, preferably C 2 -C 6 -alkanol, particularly preferably C 2 -C 4 -alkanol and most preferably ethanol can be added to the mixture of betaine of formula (I) and ethoxylate of formula (II) and optionally ethylene glycol of formula (III).

[0061] Examples include methanol, ethanol, isopropanol, n-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol, 2-ethylhexanol, n-octanol, preferably ethanol, n-butanol and 2-ethylhexanol, particularly preferred is ethanol.

[0062] To dehydrate the aqueous solution of betaine of formula (I) with only minimal losses of betaine or even essentially without loss, the invention requires the addition of at least one ethoxylate of formula (II) to the aqueous solution of betaine before and / or during, preferably before, the water removal. The addition of the ethoxylate of formula (II) to the betaine stabilizes it during the distillative removal of water. The mere presence of the ethoxylate of formula (II) during water removal significantly reduces the losses of betaine (see comparative example B) compared to water removal without its presence.

[0063] For this purpose, 1 to 100 times the amount of ethoxylate, preferably 2 to 75, particularly preferably 3 to 65, most preferably 4 to 60, particularly 5 to 55 and especially 10 to 50 times the amount of ethoxylate, is added to the aqueous solution of betaine before and / or during, preferably before, the distillative water separation.

[0064] It is also conceivable to add the ethoxylate partly before and partly during the separation of the water; however, it is preferable to add the desired amount completely before the separation.

[0065] Furthermore, it is essential to the invention to keep the thermal stress on the betaine during the distillation of water as low as possible by carrying out the distillation for no more than 4 hours at a temperature of no more than 100 °C and at reduced pressure.

[0066] Preferably, the distillation is carried out in less than 4 hours, particularly preferably in no more than 3h45min, most particularly preferably in no more than 3h30min.

[0067] The temperature during distillation should not exceed 100 °C, preferably not more than 98 °C and particularly preferably not more than 95 °C.

[0068] Distillation is carried out at reduced pressure, i.e., at ambient pressure, preferably at no more than 750 mbar, particularly preferably at no more than 500 mbar, most preferably at no more than 250 mbar, particularly preferably at no more than 200 mbar, and especially at no more than 150 mbar. A pressure of 50 mbar should not be undercut.

[0069] The combination of duration, temperature, and pressure is selected such that, after distillation, the water content in the mixture of betaine, ethoxylate of formula (II), and optionally ethylene glycol of formula (III) is no more than 5 wt%, preferably no more than 4 wt%, particularly preferably no more than 3 wt%, most preferably no more than 2 wt%, and particularly no more than 1 wt%. Specifically, levels of no more than 0.75 wt%, and even no more than 0.5 wt%, 0.25 wt%, or 0.1 wt%, can be targeted.

[0070] Distillation can be carried out continuously or discontinuously in any manner. Preferably, the distillative separation of water takes place in a stirred tank with double-wall heating and / or internal heating coils under reduced pressure.

[0071] Of course, distillation can also be carried out by passing the mixture through a falling-film, thin-film, or wiper-blade evaporator one or more times. For this, the aqueous mixture is passed through the apparatus continuously or discontinuously under reduced pressure. To minimize the thermal stress on the distillation residue, the effluent is preferably cooled after passing through the evaporator.

[0072] Advantageously, an inert gas, preferably argon or a nitrogen-containing gas, particularly preferably argon, nitrogen or a mixture of air and nitrogen (lean air), most preferably nitrogen, can be introduced or passed through the distillation apparatus, for example 0.1 - 1, preferably 0.2 - 0.8 and particularly preferably 0.3 - 0.7 m 3< / m 3< h, based on the volume of the liquid mixture.

[0073] Optionally, a rectification column with up to 10 theoretical trays can be added to the distillation apparatus; however, this is usually not necessary for the simple separation of water and is therefore less preferred.

[0074] Once the desired water content is reached, the distillation is stopped and the distillation residue is cooled, preferably to ambient temperature. This can be done indirectly by cooling the vessel or by passing it through a heat exchanger; preferably, the water-depleted distillation residue can also be cooled directly by introducing it into a solvent, preferably the aforementioned C1-C8 alkanol.

[0075] In this way, formulations of betaines of formula (I) with ethoxylates of formula (II) can be obtained, which may preferably be composed as follows: Betaine of formula (I), preferably with R1< C11- to C15-alkyl, R2< and R3< each methyl, X 1,3-propylene and Y methylene: 0.1-10 wt%, preferably 0.5-5 wt%; ethoxylates of formula (II), preferably with R2<= C9-C13-alkyl and n = 1-3: 30-95 wt%, preferably 45-75 wt%; ethylene glycol of formula (III), preferably monoethylene glycol: 0-20 wt%, 0.5-10 wt%, and C1-C8-alkanol, preferably ethanol: 0-65 wt%, 5-50 wt%. provided that the sum of all components always equals 100% by weight.

[0076] A composition analogous to WO 2011 / 045334 A1 is particularly preferred. 2 parts Cocoamidopropyl betaine, 60 parts of at least one ethoxylate of formula (II), 4 parts ethylene glycol, and 34 parts ethanol.

[0077] These water-depleted betaines or formulations are particularly advantageous when used as a surfactant for the distribution, especially dispersion or emulsification, of water in fuels selected from the group consisting of gasoline, diesel, marine fuels and aviation fuels, preferably diesel or aviation fuels, especially preferably aviation fuels, especially turbine fuels.

[0078] These water-depleted betaines or formulations make it possible to distribute a water content of at least 50 ppm in liquid hydrocarbon fuels within stable microemulsions with a droplet size of no more than 0.25 µm. This is particularly useful for reducing or suppressing the formation of ice particles in the fuel when cooled to minus 50°C. Furthermore, it prevents the formation of a separated water phase at the bottom of aircraft fuel tanks, which can lead to undesirable corrosion due to biofilm formation.

[0079] The dehydrated betaines can be used alone or preferably as formulations.

[0080] Such an application and corresponding mixtures are described in WO 2011 / 045334 A1.

[0081] To reduce ice crystal formation, the following quantities are preferably added to the fuel: from 45 to 4575 ppm, preferably 45 to 500 ppm of at least one ethoxylated alkanol and / or from 0 to 425 ppm, e.g. 1 to 425 ppm, preferably 1 to 5 ppm of at least one (C 8 -C 24 )alkylamido (C 1 -C 6 )alkyl betaine.

[0082] The at least one (C 8 -C 24 )alkylamido (C 1 -C 6 )alkyl betaine may preferably be cocamidopropyl betaine.

[0083] In addition to this surface-active agent or emulsifier, the fuel may also contain one or more of the following additional components: static dissipators, antioxidants, metal deactivators, leak detection additives, corrosion inhibitors, lubricants, alcohols, glycols and other standard products known to those skilled in the art, as well as impurities such as fatty acid methyl esters.

[0084] Turbine fuels contain a primary component of liquid turbine fuel, such as a turbine fuel commonly used in civil or military aviation. Examples include fuels designated Jet Fuel A, Jet Fuel A-1, Jet Fuel B, Jet Fuel JP-4, JP-5, JP-7, JP-8, and JP-8+100. Jet A and Jet A-1 are commercially available, kerosene-based turbine fuel specifications. The relevant standards are ASTM D 1655 and DEF STAN 91-91. Jet B is a more highly refined fuel based on naphtha and kerosene fractions. JP-4 is equivalent to Jet B. JP-5, JP-7, JP-8, and JP-8+100 are military turbine fuels, such as those used by the Navy and Air Force. In some cases, these standards specify formulations that already contain further additives, such as corrosion inhibitors, icing inhibitors, static dissipators, etc.

[0085] Further additives, which are known per se, may be added to the turbine fuel. Suitable additives that may be included in the turbine fuel composition typically include detergents, corrosion inhibitors, sulfur-free antioxidants such as sterically hindered tert-butylphenols, N-butylphenylenediamines or N,N'-diphenylamine and derivatives thereof, metal deactivators such as N,N'-disalicylidene-1,2-diaminopropane, solubilizers, antistatic agents such as Stadis 450, biocides, anti-icing agents such as diethylene glycol methyl ether or triethylene glycol methyl ether, as well as mixtures of the aforementioned additives.

[0086] Specifications for turbine fuel and approved additives with their respective dosages are listed in ASTM D1655-24.

[0087] The microemulsions can be produced by mixing 99,995 to 99,999 parts, e.g., 99,998 parts, of a fuel, e.g., a turbine fuel, and about 0.0001 to about 0.01 parts, e.g., 0.025 parts, of an emulsifier composition, wherein the emulsifier composition comprises: - at least one dehydrated (C8-C24)alkylamido (C1-C6)alkyl betaine, preferably cocamidopropyl betaine, and - at least one ethoxylated alkanol. where the specifications for the parts always refer to the volume.

[0088] Accordingly, a further object of the invention is a method for distributing water in fuels, wherein one an aqueous solution containing at least one betaine of formula (I) is prepared by first reacting at least one fatty acid of formula R 1< -COOH or its ester with at least one amine of formula H 2 NXN(R 2< R 3< ) to form the amide, and in a second step reacting this with at least one haloalkanecarboxylic acid of formula Hal-Y-COOH, where Hal represents chlorine, bromine or iodine, preferably chlorine or bromine and particularly preferably chlorine, in the presence of at least one alkali metal hydroxide to form the betaine of formula (I) with simultaneous formation of an alkali metal halide salt, and from the reaction mixture thus obtained the alkali metal halide salt is removed by extraction with at least one solvent, treatment with ion exchangers, precipitation and / or membrane filtration, and water is distilled off from this mixture at reduced pressure and a temperature below 100 °C for not more than 4 hours.so that the water content is no more than 5 wt%, and the resulting low-water solution of betaines of formula (I) and at least one ethoxylate of formula (II) is mixed with a fuel selected from the group consisting of gasoline, diesel, marine fuels and aviation fuels. Examples Materials and methods

[0089] On average, a 2.5-fold ethoxylated mixture of C 9 -C 11 -alkanols (Synperonic ™< 91 / 2.5 from Croda, CAS 68439-46-3).

[0090] Monoethylene glycol (MEG) fibre grade, ≥ 99.9%, CAS 107-21-1, from BASF SE, Ludwigshafen.

[0091] Cocoamidopropyl betaine (CAPB): Dehyton®< K (CAS 147170-44-3) from BASF SE, Ludwigshafen, 29-32% in water containing 4.5-6.0% NaCl, was desalinated by ultrafiltration according to WO 2014 / 202425. The resulting solutions had CAPB contents of 24.6 to 34.4% and chlorine contents (DIN 51408-2) <50 ppm based on the CAPB content.

[0092] Cocoamidopropyl betaine levels were measured using HPLC-MS.

[0093] Water content was measured using volumetric Karl Fischer titration.

[0094] Initially, the desalination and dehydration of cocamidopropyl betaine by distillation with azeotrope-forming entrainers was investigated. Upon removal of the water and its replacement with the solvent, some of the sodium chloride precipitates and can be separated by filtration. Example 1 (Comparison)

[0095] 500 g of non-desalted, glycerin-free cocamidopropyl betaine (water content: 68.1%, sodium chloride content 14.7% based on the dissolved solids) were mixed with ethanol and water was azeotropically distilled off.

[0096] Water and dissolved sodium chloride content were monitored throughout the dehydration process. After 30 hours, the sodium chloride content was 2.03% based on the dissolved solids, and the water content had decreased to 0.7 g.

[0097] The HPLC of the product showed, in addition to the CAPB peak, a multitude of newly occurring, partly broad signals of lower molecular weight, which suggest decomposition of the cocamidopropyl betaine during distillation. Example 2 (Comparison)

[0098] 500 g of non-desalted, glycerol-free cocamidopropyl betaine (water content: 68.1%, sodium chloride content: 14.7% of dissolved solids) were mixed with butanol and water was azeotropically distilled off. The water and dissolved sodium chloride content were monitored throughout the dehydration process. After 20.75 hours, the sodium chloride content was 1.31% of dissolved solids, and the water content had decreased to 0.3 g.

[0099] The HPLC of the product showed, in addition to the CAPB peak, several newly occurring signals of slightly lower molecular weight, which suggest a decomposition of the cocamidopropyl betaine during distillation.

[0100] These two experiments show that while azeotropic distillation with ethanol or butanol removes water, it decomposes the cocamidopropyl betaine. The distillation process is very lengthy, especially when using ethanol.

[0101] The sodium chloride content can be reduced, but not as much as by ultrafiltration according to WO 2014 / 202425. Example A (comparison)

[0102] 30.0 g of a 24.6% aqueous solution of cocamidopropyl betaine were placed in a 2 L single-necked round-bottom flask. Using a rotary evaporator, the solution was concentrated at a bath temperature of 80°C by slowly applying a vacuum. Strong foaming was observed under these conditions. Care had to be taken to prevent the foam from entering the condenser section of the rotary evaporator. Finally, a reduced pressure of 50 mbar was reached, and the distillation was continued at this pressure for a further 4 hours. The cocamidopropyl betaine solution concentrated to a gel that covered the inner surface of the flask. Ethoxylated C₉-C₁₁₁ alkanol (360 g) and monoethylene glycol (30.0 g) were added, and the mixture was homogenized. The product had a water content of 0.75%.

[0103] It can be seen that aqueous solutions of cocamidopropyl betaine tend to gel upon concentration, even at low temperatures well below 100 °C. Furthermore, distillation is hampered by foaming, as was to be expected for cocamidopropyl betaine, which is used as a foaming agent in personal care products. Example B (Comparison)

[0104] In a double-walled 750 ml reactor equipped with a cross-arm stirrer, thermocouple, and a condenser connected to a vacuum unit, 24.6% aqueous cocamidopropyl betaine (30.0 g) was heated to 80 °C. A vacuum was slowly applied, resulting in strong foaming and the formation of gel particles that covered the inner surface of the reactor.

[0105] The pressure was maintained above 150 mbar for 45 minutes to prevent foaming in the upper part of the reactor and in the condenser. After 45 minutes, the pressure was slowly reduced to 50 mbar and held at this pressure for 4 hours. Gel particles formed on the inner surface of the reactor. Ethoxylated C₉-C₁₁₁ alkanol (360 g) and monoethylene glycol (30.0 g) were added, and the mixture was homogenized. The product had a water content of 0.19%. Example C (Comparison)

[0106] Ethoxylated C9-C11 alkanol (334.1 g), monoethylene glycol (26.7 g), and 30% aqueous cocamidopropyl betaine (24.9 g) were mixed in an apparatus as in Example B. The mixture had a water content of 4.5%. A vacuum was slowly applied down to 100 mbar, during which slight foaming was observed, which disappeared after about 1 minute. The solution was then heated to 110°C at 100 mbar for 5 hours, and an aqueous distillate was collected. After cooling to room temperature, the product had a water content of 50.1%.

[0107] Quantitative HPLC analyses revealed a betaine content of 71% (based on C12-substituted betaine) and 81% (sum of C12-C18-substituted betaine) for the sample after dehydration compared to the sample before dehydration. Due to the concentration effect during distillation, betaine contents of 105% are expected. This indicates a degradation of 23–32 mol% cocamidopropyl betaine during the distillation process.

[0108] It can be seen that the presence of ethoxylated C9-C11 alkanol suppresses the gel formation of cocamidopropyl betaine, but significant degradation occurs at temperatures above 100 °C. Furthermore, the presence of the ethoxylated C9-C11 alkanol suppresses foaming, which complicates the processing of cocamidopropyl betaine. Example D (according to the invention)

[0109] Ethoxylated C9-C11 alkanol (360 g), monoethylene glycol (30.0 g), and 24.6% aqueous cocamidopropyl betaine (30.0 g) were mixed in an apparatus as in Example B. The mixture had a water content of 5.4%. A vacuum down to 50 mbar was slowly applied, during which slight foaming was observed, which disappeared after about 1 minute. The solution was then heated to 95°C at 50 mbar for 3 hours, collecting an aqueous distillate. After cooling to room temperature, the product had a water content of 50.1%. During the evacuation process from 95°C to 50 mbar, a small foam head briefly formed, which did not exceed the maximum reactor fill level (750 ml) and collapsed after about 2 minutes.

[0110] Quantitative HPLC analysis, as described for example C, showed no decomposition of cocamidopropyl betaine during the distillation process. Example E (according to the invention)

[0111] Ethoxylated C9-C11 alkanol (360 g), monoethylene glycol (30.0 g), and 24.6% aqueous cocamidopropyl betaine (30.0 g) were mixed in an apparatus as in Example B. The mixture had a water content of 5.4%. A vacuum down to 50 mbar was slowly applied, during which slight foaming was observed, which disappeared after about 1 minute. The solution was then heated to 80°C at 50 mbar for 3 hours, collecting an aqueous distillate. After cooling to room temperature, the product had a water content of 50.1%.

[0112] Quantitative HPLC analysis, as described for example C, showed no decomposition of cocamidopropyl betaine during the distillation process. Example F (according to the invention)

[0113] Ethoxylated C9-C11 alkanol (360 g), monoethylene glycol (30.0 g), and 24.6% aqueous cocamidopropyl betaine (30.0 g) were mixed in an apparatus as in Example B. The mixture had a water content of 5.4%. A vacuum down to 50 mbar was slowly applied, during which slight foaming was observed, which disappeared after about 1 minute. The solution was then heated to 95°C at 50 mbar for 4 hours, collecting an aqueous distillate. After cooling to room temperature, the product had a water content of 50.1%.

[0114] Quantitative HPLC analysis, as described for example C, showed no decomposition of cocamidopropyl betaine during the distillation process. Example G (according to the invention)

[0115] Ethoxylated C₉-C₁₁₁ alkanol (375.42 g), monoethylene glycol (29.94 g), and 34.4% aqueous cocamidopropyl betaine (24.42 g) were mixed in an apparatus as in Example B. The mixture had a theoretical water content of 3.7%. A nitrogen stream of 10 L / h was passed over the surface of the mixture. A vacuum of 150 mbar was applied, during which slight foaming was observed, which disappeared after about 1 minute. The mixture was then heated to 80°C at 150 mbar for 3 h 45 min, and an aqueous distillate was collected. After cooling to room temperature, the product had a water content of 50.1%.

[0116] Quantitative HPLC analysis, as described for example C, showed no decomposition of cocamidopropyl betaine during the distillation process.

[0117] A portion of the dehydrated solution obtained in this way (50 g) was mixed with 22.5 g of ethanol. A solution with a kinematic viscosity of 7.52 mm² / s and a density of 0.893 g / cm³ at 20 °C was obtained (ASTM D7042).

Claims

1. Method for the preparation of low-water solutions of betaines of formula (I) R 1 -CO-NH-XN(R 2 R 3 )2 + -Y-COO - (I) wherein R 1 a linear or branched alkyl or alkenyl group having 5 to 21, preferably 7 to 19, particularly preferably 9 to 17 and particularly 11 to 15 carbon atoms, R 2 and R 3 each independently of one another C1 to C4 alkyl groups, preferably methyl or ethyl groups, X a divalent alkylene group with 1 to 12, preferably 2 to 8, particularly preferably 2 to 6 and particularly 2 to 4 carbon atoms and Y a linear or branched C1 to C4 alkylene group, preferably methylene, 1,2-ethylene or 1,3-propylene, by combining an aqueous solution containing at least one betaine of formula (I) with at least one ethoxylate of formula (II) R 2 -O-[-CH2-CH2-O-] n -H (II) wherein R 2a linear or branched alkyl or alkenyl group, preferably a linear alkyl group with 6 to 15, preferably 8 to 14, particularly preferably 8 to 13, most preferably 9 to 13 and particularly 9 to 11 carbon atoms, and n being a rational number from 1 to 12, preferably 1 to 10, most preferably 1 to 5 and most preferably 1 to 3, mixed and water distilled off from this mixture at reduced pressure and a temperature below 100 °C for no more than 4 hours, so that the water content is no more than 5 wt%.

2. Method according to claim 1, characterized by the fact that The aqueous solution containing at least one betaine of formula (I) and at least one ethoxylate of formula (II) is additionally mixed with at least one ethylene glycol of formula (III) HO-[-CH2-CH2-O] m-H (III) wherein m is a rational number of at least 1, preferably of 1 to 4, particularly preferably of 1 to 3, most particularly preferably of 1 to 2 and in particular of 1.

3. Method according to any of the foregoing claims, characterized by the fact that The aqueous solution, containing at least one betaine of formula (I) and at least one ethoxylate of formula (II), is additionally mixed with at least one C1-C8 alkanol, preferably C2-C6 alkanol, particularly preferably C2-C4 alkanol and most preferably ethanol.

4. Method according to any one of the foregoing claims, characterized by the fact that The aqueous solution containing at least one betaine of formula (I) is prepared by first reacting at least one fatty acid of formula R 1 -COOH or its esters with at least one amine of the formula H2N-XN(R 2 R 3) is converted to the amide and this is reacted in a second step - with at least one haloalkanecarboxylic acid of the formula Hal-Y-COOH or Hal-Y-COO - alcohol + wherein Hal is for chlorine, bromine or iodine, preferably chlorine or bromine and particularly preferably chlorine and alcohol + for an alkali metal cation, preferably sodium or potassium, particularly preferably sodium, - reacts in the presence of at least one alkali metal hydroxide, carbonate or hydrogen carbonate, preferably one alkali metal hydroxide, to form the betaine of formula (I) with simultaneous formation of an alkali metal halide salt, and depletes the alkali metal halide salt from the reaction mixture thus obtained by - extraction with at least one solvent, - treatment with ion exchangers, - precipitation and / or - membrane filtration.

5. Method according to claim 4, characterized by the fact thatThe alkali metal is selected from the group consisting of lithium, sodium and potassium, preferably sodium and potassium and particularly preferably sodium.

6. Method according to claim 4 or 5, characterized by the fact that The alkali metal halide salt is depleted by extraction with at least one solvent, the solvent being selected from the group consisting of water and ethanol.

7. Method according to claim 4 or 5, characterized by the fact that The alkali metal halide salt is removed by ultrafiltration, nanofiltration and / or reverse osmosis.

8. Method according to claim 4 or 5, characterized by the fact that The alkali metal halide salt is depleted by treatment with at least one ion exchanger, preferably an anion and a cation exchanger.

9. Method according to claim 4 or 5, characterized by the fact that The alkali metal halide salt is removed by precipitation.

10. Use of low-water solutions of betaines of formula (I) and at least one ethoxylate of formula (II) obtainable by any of the above methods as an additive in fuels.

11. Use according to claim 10 as an additive for distributing water in fuels, especially gasoline, diesel, marine fuels and aviation fuels.

12. Method for distributing water in fuels, wherein an aqueous solution containing at least one betaine of formula (I) is prepared by first preparing at least one fatty acid of formula R 1 -COOH or its esters with at least one amine of the formula H2N-XN(R 2 R 3 ) is converted to the amide and this is reacted in a second step - with at least one haloalkanecarboxylic acid of the formula Hal-Y-COOH or Hal-Y-COO - alcohol + wherein Hal is for chlorine, bromine or iodine, preferably chlorine or bromine and particularly preferably chlorine and alcohol +for an alkali metal cation, preferably sodium or potassium, particularly preferably sodium, - reacts in the presence of at least one alkali metal hydroxide, carbonate or hydrogen carbonate, preferably one alkali metal hydroxide, to give the betaine of formula (I) with simultaneous formation of an alkali metal halide salt, and from the reaction mixture thus obtained the alkali metal halide salt is depleted by - extraction with at least one solvent, - treatment with ion exchangers, - precipitation and / or - membrane filtration, water is distilled off from this mixture at reduced pressure and a temperature below 100 °C for no more than 4 hours, so that the water content is no more than 5 wt%, and the resulting low-water solution of betaines of formula (I) and at least one ethoxylate of formula (II) is mixed with a fuel selected from the group consisting of gasoline, diesel, marine fuels and aviation fuels.

13. Fuel comprising a low-water solution of betaines of formula (I) and at least one ethoxylate of formula (II) according to a method according to any one of claims 1 to 9.

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