Detergents and cleaning agents containing hydroxycarboxylic acid esters and use of hydroxycarboxylic acid esters

Description

[0001] The invention relates to novel detergents and cleaning agents containing hydroxycarboxylic acid esters derived from aliphatic hydroxycarboxylic acids and alkylene glycols. These compounds are excellent complexing agents and can be used in a wide variety of fields, for example, in detergents and cleaning agents, in petroleum production, or for water softening.

[0002] Polymeric hydroxycarboxylic acid esters, such as polymeric citric acid esters, are known from the literature and can be produced by a condensation reaction of hydroxycarboxylic acid with monohydric or polyhydric alcohols. The esterification reaction is carried out by heating the starting components, usually resulting in the formation of oligomers or polymers with undefined chain lengths. There is also a risk of decomposition of the hydroxycarboxylic acid during the reaction, leading to the uncontrolled formation of byproducts, which in turn react with the components of the reaction mixture. For example, citric acid readily decomposes at its melting point, losing a COOH group, making polyesters with reproducible chain lengths difficult to produce.

[0003] WO 2001 / 000463 A2 discloses a process for producing esters of aliphatic carboxylic acids. In this process, a reaction mixture of aliphatic carboxylic acids and monohydric or polyhydric alcohols is heated for a very short time by microwave irradiation to very high temperatures well above 100°C. The process yields almost quantitative yields and virtually no byproducts are formed. Citric acid is cited as an example of an aliphatic carboxylic acid.

[0004] CN 109293505 describes a process for reacting lemon juice and hydrochloric acid under the influence of microwave radiation. This document claims that this process produces ethylene glycol citrate. However, it is not disclosed whether ethylene glycol is present during the reaction, nor when and how ethylene glycol was introduced into the reaction mixture. Furthermore, the acidified lemon juice is exposed to microwave radiation in a closed container for one hour. Under such conditions, partial decomposition or polymerization of the reactants can be expected.

[0005] WO 2019 / 158409 A1 discloses a process for producing surface-active condensates of citric acid. The resulting products contain at least one hydrophobic structural element, which is a hydrocarbon group with at least eight carbon atoms. The condensates can be used as surfactants, emulsifiers, or thickeners in cleaning or care products.

[0006] Polymeric citric acids are already known from the literature for a number of applications.

[0007] Yuzeng Zao et al. describe in Desalination, Vol. 392, pp. 1-7 (2016) (https: / / www.sciencedirect.com / science / article / pii / S0011916416301813) the inhibition of calcium sulfate deposit formation through the use of poly(citric acid) derivatives. The products used exhibit a high degree of polymerization and a large number of citric acid units.

[0008] AT Naeini et al. disclose in Nanomedicine, 6(4), pp. 556-562 (2010) copolymers of poly(citric acid) and poly(ethylene glycol) blocks as biocompatible hybrid materials for nanomedicine.

[0009] In Environmental Science: Processes & Impacts, 2014, 16, 2380-2389, N. Memarizadh et al. describe supramolecular systems of linear dendritic copolymers and indoxacarb as biodegradable and efficient nanopesticides. The copolymers used are dendritic block copolymers of polyethylene glycol and polycitric acid.

[0010] In Biomaterials 31(34), pp. 9092-2108 (2010), D. Gyawali et al. describe in situ crosslinkable biodegradable polymers for the production of cell cultures. The proposed polymers are derived from polyethylene glycol, maleic acid, and citric acid and tend to form hydrogels.

[0011] In J. Polym. Environ (2012), 20: 291-298, B. Tisserat et al. describe analytical methods for characterizing foams made from poly(glycerol citrate) produced by exposure to microwave radiation. Equimolar amounts of citric acid and glycerol are used in the preparation of the polymers, resulting in polymers with high molecular weights.

[0012] In J. of Applied Polymer Science, Vol. 125, 3429-3437 (2012), B. Tisserat et al. describe the synthesis of polyesters derived from citric acid and glycerin. To produce the polyesters, the starting materials are initially introduced in varying proportions and then heated using various heating methods, including microwave radiation. Depending on the heating method used and the proportions of the starting materials, different products are formed, which can be foams, gels, or liquids.

[0013] WO 92 / 16493 A1 describes citric acid esters of polyhydroxy compounds with at least three hydroxy groups, for example, polyglycerol or sugar alcohols, and their use in detergents and cleaning agents. These compounds can enhance the effect of other detergent additives.

[0014] DE 1,617,122 A discloses water-soluble salts of polyesters containing free carboxyl groups, whose acid components consist of a tri- or tetracarboxylic acid residue and whose alcohol components are derived from compounds with two aliphatic hydroxyl groups. For example, polyesters derived from citric acid and ethylene glycol are described. These are high-molecular-weight resins that dissolve in alkaline wash solutions. These agents facilitate the washing process and increase the whiteness of laundry.

[0015] Esters of aliphatic hydroxycarboxylic acids and various alcohols, for example, polyesters derived from citric acid and glycerin or other polyols, are known from the prior art. Molecules with different chain lengths have already been described, which can range from two citric acid units to over one hundred acid units.

[0016] Low molecular weight esters of aliphatic hydroxycarboxylic acids with aliphatic diols have been described, for example, in the following documents.

[0017] Carlier et al. report in J. Org. Chem. 1989, 54, 4016-8 on a study of the mechanism of asymmetric epoxidation. Diglycol esters of tartaric acid are used.

[0018] Newhouse et al. report in JACS (2012) 134, pp. 17354-57 on tetradentate ligands for the enantioselective Ti(IV)-catalyzed oxidation of sulfides to sulfoxides. Among other ligands, diglycol esters of tartaric acid are used.

[0019] Pumpor et al. describe the use of hexafluoroacetone as a protecting group in Monatshefte für Chemie, 135, pp. 1427-43 (2004). Among other things, this article discloses a diester of ethylene glycol and malic acid.

[0020] In addition, WO 2019 / 157350 A2 and DE 10 2009 002 097 A1 disclose various esters of hydroxycarboxylic acids, such as citric acid, with different glycols.

[0021] To produce esters of aliphatic hydroxycarboxylic acids, condensation reactions were carried out in various solvents, such as water, glycerol, propylene glycol, and ethylene glycol. Surprisingly, it was found that esters of hydroxycarboxylic acids with alkylene glycols or with polyalkylene glycols with a low degree of condensation, prepared by exposure to a high temperature pulse, are excellent complexing agents for various cations. For example, an ester derived from ethylene glycol and citric acid, which has a total of few citric acid units, exhibits an excellent tendency toward complex formation, while an ester derived from glycerol and citric acid, which also has a total of few citric acid units, exhibits no tendency toward complex formation.

[0022] The object of the present invention is to provide chemical compounds which are derived from easily accessible starting materials, preferably from starting materials of biological origin, which have an excellent complex formation tendency and which can preferably be used in washing and cleaning agents.

[0023] The present invention relates to washing and cleaning agents containing compounds of the formula (I) (R 1< OOC) a -R 2< (OH) c -COO-(C n H 2n -O) m -OC-R 3< (OH) d (COOR 4< ) b (I) wherein R 1< and R 4< are independently hydrogen, a cation of a metal, an ammonium cation, C 1 -C 6 -alkyl, cycloalkyl having three to nine ring carbon atoms, aryl having five to ten ring carbon atoms, aryl which is substituted by one or two alkyl groups, aryl which is bonded to the carboxyl group via an alkylene group, -(C n H 2n -O) m -H or -OR 2< (COOR 1< ) a+1, R 2< and R 3< are independently aliphatic hydrocarbon radicals having one to eight, preferably two to four carbon atoms, a and b are independently integers from 1 to 4, preferably 1 to 3, c is an integer from 0 to 4, preferably 1 to 4, in particular 1 or 2 and very particularly preferably 1, d is an integer from 1 to 4, preferably 1 or 2 and most preferably 1, n is 2, 3 or 4, preferably 2 or 3 and especially 2, and m is 1, 2, 3 or 4, with the proviso thatthat R 1< and R 4< can be different within a molecule within the given definitions. ,

[0024] The compounds of formula (I) can also be represented in the form of formula (Ia) where R 1< , R 2< , R 3< , R 4< , a, b, c, d, m, and n have the meanings defined above. NMR analysis suggests that the condensation reaction mediated by pulsed temperature increases, for example, by microwave radiation, forms molecules with a few hydroxycarboxylic acid units, for example, with 2 or 3 citric acid units. The hydroxycarboxylic acid units, for example, the citric acid units, are bonded via ester bonds to units derived from alkylene glycols or di- to trialkylene glycols as the solvent used. This results in low-molecular-weight compounds, not polymers.

[0025] Hydroxycarboxylic acids showed a very high solution viscosity or a brown color when reacted with alcohols other than (poly)alkylene glycols, for example when reacted with glycerol, and moreover, the resulting products showed no or only a slight tendency to form complexes.

[0026] Polyesters containing a large number of hydroxycarboxylic acid units and alcohol units often have excessive viscosity and are therefore not free-flowing and not pumpable. These products are usually produced by heating with conventional sources and are not suitable as complexing agents.

[0027] The compounds of formula (I) used according to the invention are frequently in the form of liquids, in particular transparent liquids having a viscosity at 25°C of at least 100 mPas, measured using a rotational viscometer (Brookfield viscometer).

[0028] The compounds of formula (I) used according to the invention are generally present as mixtures of substances. The preferred mixtures derived from citric acid and ethylene glycol contain, for example, ethylene glycol dicitric acid esters of the following formula

[0029] This ester is excellent for complexing with metal ions, especially alkaline earth metal ions. A complex with calcium is shown below.

[0030] However, other citric acid esters are also present in the mixture, for example compounds with a free carboxyl group instead of the ethylene glycol ester group -COO-CH 2 -CH 2 -OH or compounds in which further citric acid units are bonded to the hydroxyl group of the alkylene glycol unit via their carboxyl group.

[0031] In addition, the mixtures may also contain small amounts of unreacted starting materials, i.e. free diols and / or hydroxycarboxylic acids or, where appropriate, carboxylic acids.

[0032] The mixtures containing different polyesters of formula (I) are generally liquid at 25 °C. The viscosity of these mixtures is preferably 0.1 to 10,000 mPa*s at 20 °C, measured with a Brookfield viscometer (spindles 1 to 7, depending on the viscosity range; shear rate 5 revolutions / minute), preferably 1 to 7500 mPa*s, and most preferably 100 to 2000 mPas.

[0033] The polyesters used according to the invention are prepared by reacting aliphatic hydroxycarboxylic acids with selected aliphatic (poly)alkylene glycols. The latter are alkylene glycols having two, three, or four carbon atoms or polyalkylene glycols having two, three, or four repeating units thereof. These compounds generally have the following structure: HO-(C n H 2n -O) m -H, where n and m are as defined above.

[0034] Ethylene glycols or propylene glycols are preferably used, i.e. compounds of the above formula in which n is 2 or 3.

[0035] Particularly preferred are (poly)ethylene glycols, i.e. compounds of the above formula in which n is 2.

[0036] Ethylene glycol or diethylene glycol are particularly preferably used, i.e. compounds of the above formula in which n=2 and m=1 or 2.

[0037] Ethylene glycol is most preferably used, i.e. a compound of the above formula in which n=2 and m=1.

[0038] Preference is given to using compounds of formula (I) in which n=2 or 3 and m=1 or 2. These compounds are derived from ethylene glycol, propylene glycol, diethylene glycol or dipropylene glycol.

[0039] Particular preference is given to using compounds of formula (I) in which n=2 and m=1. These compounds are derived from ethylene glycol.

[0040] The aliphatic hydroxycarboxylic acids used in the preparation of the compounds of formula (I) employed according to the invention include any type. They can be aliphatic hydroxycarboxylic acids with two, three, four, or five carboxyl groups. The aliphatic hydroxycarboxylic acids can have one to four hydroxyl groups. A hydroxyl group can be located on a common carbon atom with a carboxyl group, or the hydroxyl group can be in an alpha, beta, or other position relative to a carboxyl group. The carboxyl groups are generally located on different carbon atoms of the aliphatic radical. If multiple hydroxyl groups are present, they are located on different carbon atoms of the aliphatic radical. The aliphatic radical generally has one to eight, preferably two to four, carbon atoms.

[0041] Preferably, compounds of formula (I) are derived from malic acid, lactic acid, tartronic acid, tartaric acid, isocitric acid, citric acid, acetylcitric acid, tartaric acid or mucic acid, in particular from isocitric acid or citric acid, and most preferably from citric acid.

[0042] In the preparation of the compounds of formula (I), aliphatic hydroxycarboxylic acids can also be used, optionally in combination with aliphatic carboxylic acids. Instead of the aliphatic hydroxycarboxylic acids or the aliphatic carboxylic acids, their ester-forming derivatives, such as esters, anhydrides, halides, or their salts, can also be used.

[0043] Preferably, in the preparation of the compounds of formula (I) exclusively one or more aliphatic hydroxycarboxylic acids and / or their reactive derivatives and / or their salts are used.

[0044] The aliphatic carboxylic acids optionally used in the preparation of the compounds of formula (I) used according to the invention include any desired type. They can be aliphatic carboxylic acids with two, three, four, or five carboxyl groups. The carboxyl groups are generally located on different carbon atoms of the aliphatic radical. The aliphatic radical generally has one to eight, preferably two to four, carbon atoms.

[0045] Examples of aliphatic carboxylic acids are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, carballylic acid, butane-1,2,4-tricarboxylic acid, or octric acid. In the preparation of the compounds of formula (I), various aliphatic carboxylic acids can also be used in combination with aliphatic hydroxycarboxylic acids or with derivatives of aliphatic hydroxycarboxylic acids, such as their esters or their salts.

[0046] The radicals R 1 and R 4 can be alkyl. These are alkyl groups with one to six carbon atoms, which can be straight-chain or branched. Methyl and ethyl are preferred.

[0047] The radicals R 1 and R 4 can be cycloalkyl. These are cycloalkyl groups with three to nine ring carbon atoms, preferably five to seven ring carbon atoms. Cyclohexyl is particularly preferred.

[0048] The radicals R 1 and R 4 can be aryl. These are aromatic hydrocarbon radicals with five to ten ring carbon atoms. Phenyl is preferred.

[0049] The radicals R 1 and R 4 can be alkylaryl. These are aryl groups substituted by one or two alkyl groups. Tolyl is preferred.

[0050] The radicals R 1 and R 4 can be aralkyl. These are aryl groups linked to the carboxyl group via an alkylene group. Benzyl is preferred.

[0051] Preferred radicals R 1< and R 4< are hydrogen, metal cations, ammonium cations or radicals of the formula -(C n H 2n -O) m -H.

[0052] Particularly preferred radicals R 1< and R 4< are hydrogen, cations of alkali metals, cations of alkaline earth metals, quaternary ammonium cations or radicals of the formula -(C n H 2n -O) m -H, in particular radicals of the formula -C 2 H 4 -OH.

[0053] The radicals R 2< and R 3< are aliphatic hydrocarbon radicals having one to eight, preferably two to four, carbon atoms. R 2< and R 3< can be straight-chain or branched. The valence of a radical R 2< , i.e. the number of covalent bonds connecting this radical to the other groups of the molecule, is a + c + 1. Depending on the size of the indices a and c, the valence of R 2< can therefore be between 2 and 9. The valence of a radical R 3< is b + d + 1. Depending on the size of the indices b and d, the valence of R 3< can therefore be between 3 and 9. Not all of the theoretically possible R 2< or R 3< radicals can have a valence in the range from 2 to 9 or from 3 to 9, since the number of free possible valences may be smaller in individual cases due to the tetravalent nature of carbon. A radical R 2< with, for example, only one carbon atom can therefore only assume valences in the range from 2 to 4.These connections are known to the expert.

[0054] Preferred are divalent radicals R 2< with the formula -C o H 2o - or trivalent radicals R 2< with the formula -C p H 2p-1 < or tetravalent radicals R 2< with the formula >C q H 2q-2 <, wherein o is an integer from 2 to 4, preferably from 2 to 3 and particularly preferably 2, p is an integer from 1 to 4, preferably from 1 to 3 and particularly preferably 1 or 2, and q is an integer from 2 to 4, preferably from 2 to 3 and particularly preferably 3.

[0055] Particularly preferred compounds of formula (I) are those in which R 2< and R 3< are radicals derived from malic acid, lactic acid, tartronic acid, tartaric acid, isocitric acid or citric acid after removal of the carboxyl groups and the hydroxy group.

[0056] These particularly preferred radicals R 2< and R 3< have the structures of the formulas (Ib), (Ic), (Id), (Ie), (If) or (Ig)

[0057] Very particular preference is given to using compounds of the formula (I) in which a and b are 2, R 2< and R 3< are aliphatic hydrocarbon radicals having three carbon atoms, in particular aliphatic hydrocarbon radicals derived from citric acid, and R 1< and R 4< are hydrogen, cations of alkali metals, cations of alkaline earth metals, quaternary ammonium cations or radicals of the formula -(C n H 2n -O) m -H.

[0058] Very particular preference is given to using the compound of the following formula (II) or its alkali or alkaline earth salts or partial neutralizates thereof HO-C(CH 2 -COOH) 2 -COO-C 2 H 4 -OOC-COH-(CH 2 COOH) 2 (II).

[0059] The compounds of formula (II) can also be represented in the form of formula (IIa).

[0060] Particularly preferred are also mixtures containing different compounds of formula (I) which are liquid at 25°C.

[0061] Preference is further given to using compounds of the formula (I) which have a radical of the formula (R 1< OOC) a -R 2< (OH)-COO- and a radical of the formula (R 4< OOC) b -R 3< (OH)-COO-, where these radicals have the same meaning.

[0062] The compounds of formula (I) can be prepared by esterifying aliphatic hydroxycarboxylic acids or their ester-forming derivatives, such as their alkyl esters, with selected diols at elevated temperatures. The temperature increase in the reaction mixture must be pulsed but temperature-controlled. Under these conditions, only small molecules are formed, and no polymerization or decomposition of the components used occurs. Optionally, the reaction mixture may also contain aliphatic carboxylic acids or their ester-forming derivatives.

[0063] The compounds of formula (I) used according to the invention can be prepared by a process comprising the following measures: i) Initial charge of hydroxycarboxylic acids of formula (V) or their ester-forming derivatives, such as their alkyl esters, and optionally of carboxylic acids or hydroxycarboxylic acids of formula (IV) or their ester-forming derivatives, such as their alkyl esters, and of alkylene glycol of formula (VI) (R 1< OOC) a -R 2< (OH) c -COOR 1< (IV) R 4< OOC-R 3< (OH) d (COOR 4< ) b (V) OH-(C n H 2n -O) m -H (VI) wherein R 1< , R 2< , R 3< , R 4< , a, b, c, d, n and m have the meaning defined above, ii) Heating the mixture obtained in step i) to at least 90°C for a period of time from 0.1 milliseconds to 60 minutes, and iii) cooling the product mixture obtained in step ii) to 25 °C or below within a period of 1 second to 60 minutes.

[0064] The required heat can be supplied by any device capable of briefly introducing high amounts of heat into the reaction mixture. It is important to limit the reaction temperature to values that prevent decomposition of the reactants. Examples of suitable devices include heat exchangers, especially recuperators, or electromagnetic radiation in the microwave band.

[0065] Conventional types of recuperators can be used. Examples include plate heat exchangers, capillary heat exchangers, microreactors, spiral heat exchangers, shell-and-tube heat exchangers, U-tube heat exchangers, shell-and-tube heat exchangers, heating registers, or counterflow heat exchangers.

[0066] Preferably, the reaction mixture is subjected to high heating power in the heating zone by heating with electromagnetic radiation in the microwave band or with a heat exchanger.

[0067] Particularly preferably, the heating zone is designed in the form of a pressure-resistant, microwave-transparent tube located in a suitably dimensioned cavity resonator capable of generating an electromagnetic field, preferably in the microwave band, of suitable field strength, with the aid of which the reaction material is heated by dielectric heating mechanisms.

[0068] The electromagnetic radiation used preferably has a frequency in the range of 300 MHz to 30 GHz, in particular a frequency of 915 MHz, 2.45 GHz or 5.8 GHz.

[0069] Due to the brief exposure of the reaction mixture to high temperatures, esterification and transesterification reactions occur very rapidly and simultaneously. The majority of the hydroxycarboxylic acids and diols present are esterified, although in the case of hydroxycarboxylic acids with multiple carboxyl groups, some of the carboxyl groups often remain unesterified.

[0070] A process is preferred in which the heating in step ii) is carried out by irradiation with microwave radiation.

[0071] The reaction temperature in step ii) is generally in the range from 90 to 190 °C, preferably from 120 to 180 °C and most preferably from 140 to 160 °C.

[0072] Most particularly preferred is a process in which the mixture in step ii) is heated to a temperature between 140 and 160°C and in which the heating time is 1 to 120 seconds.

[0073] The process described above can be carried out batchwise or, preferably, continuously.

[0074] When carrying out the process, the alkylene glycols are preferably used in a molar excess to the hydroxycarboxylic acid.

[0075] Typically, the molar ratio of hydroxycarboxylic acid to alkylene glycol is 1:10 to 10:1, preferably 5:1 to 1:5, and particularly preferably 1:1 to 1:3.

[0076] The process can be carried out in various reaction mixtures. Examples include emulsions or solutions. The process is preferably carried out in solution. In the process, the reaction mixture according to process step i) contains compounds of formula (V) and optionally of formula (IV) or their ester-forming derivatives and compounds of formula (VI).

[0077] Any liquid in which the reactants dissolve and which are essentially inert under the reaction conditions can be considered as solvents. Examples include aprotic polar organic solvents.

[0078] In a preferred embodiment, the alkylene glycol used simultaneously serves as a solvent for the resulting oligoester.

[0079] The process can be carried out with or without the use of esterification or transesterification catalysts. Examples of esterification or transesterification catalysts are acidic catalysts or mixtures thereof. These can be inorganic, organometallic, and / or organic acidic compounds. Suitable acidic inorganic catalysts for the purposes of the present invention include mineral acids, for example hydrochloric acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, phosphonic acid, or hypophosphorous acid; acidic salts, such as aluminum sulfate hydrate, alum, acidic silica gel, or acidic aluminum hydroxide, can also be used.Further acidic inorganic catalysts are, for example, aluminum compounds of the general formula Al(OR) 3 and titanates of the general formula Ti(OR) 4 , where the radicals R can each be the same or different and are independently selected from C 1 -C 10 alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neo-pentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl or n-decyl, from C 3 -C 12 cycloalkyl radicals, for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, Cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclododecyl; preferred are cyclopentyl, cyclohexyl, and cycloheptyl. Preferably, the R radicals in Al(OR) 3 and Ti(OR) 4 are each identical and selected from isopropyl, butyl, and 2-ethylhexyl.

[0080] Preferred acidic organometallic catalysts are selected from dialkyltin oxides (R 3< ) 2 SnO, where R 3< is as defined above. A particularly preferred representative of acidic organometallic catalysts is di-n-butyltin oxide, which is commercially available as so-called oxotin or as Fascat<(R)> brands.

[0081] Preferred acidic organic catalysts are organic compounds containing acidic groups, for example, phosphate groups, phosphonic acid groups, sulfonic acid groups, sulfate groups, or carboxylic acid groups. Particularly preferred sulfonic acids contain at least one sulfonic acid group and at least one saturated or unsaturated, linear, branched, and / or cyclic hydrocarbon radical having 1 to 40 carbon atoms, preferably 1 to 24 carbon atoms. Particular preference is given to aromatic sulfonic acids, especially alkylaromatic monosulfonic acids having one or more C 1 -C 28 alkyl radicals, and in particular those having C 1 -C 22 alkyl radicals.

[0082] Preferred examples are methanesulfonic acid, butanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, 2-mesitylenesulfonic acid, 4-ethylbenzenesulfonic acid, isopropylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, didodecylbenzenesulfonic acid, naphthalenesulfonic acid.

[0083] Boric acid, phosphoric acid, polyphosphoric acid and polystyrenesulfonic acids are particularly preferred for carrying out the process.

[0084] Particularly preferred are titanates of the general formula Ti(OR) 4 and especially titanium tetrabutylate and titanium tetraisopropylate.

[0085] In another embodiment, acidic, solid catalysts are used in the process. Examples include zeolites, silica gel, acidic phyllosilicates such as montmorillonite, and organic ion exchangers.

[0086] Preferably, the process is carried out without the use of esterification or transesterification catalysts.

[0087] The catalysts are typically used in amounts of up to 10 wt.% based on the total mass of the reaction mixture, preferably in amounts of 0.01 to 10 wt.% and particularly preferably 0.02 to 2 wt.%.

[0088] The reaction mixture is passed through a reactor. The reaction mixture is heated strongly in a heating zone by the addition of heat. This can occur through physical contact with a warmer wall through heat transfer or through the interaction of polar or ionic molecules with electromagnetic fields, for example, with wavelengths in the centimeter range (microwave).

[0089] The reaction mixture is subjected to a sufficiently high heat output in the heating zone for a period of up to 60 minutes, typically from 0.1 milliseconds to 60 minutes, preferably from 1 second to 10 minutes, and most preferably from 1 second to 2 minutes. The reaction mixture experiences a significant temperature increase and, upon leaving the heating zone, has a temperature between 90°C and 190°C, preferably between 120°C and 180°C, and most preferably between 140°C and 160°C, measured using a PT100 temperature sensor immediately after leaving the heating zone.

[0090] The reaction mixture can be present in the reactor under reduced pressure, atmospheric pressure, or, in particular, under superatmospheric pressure. The pressure in the reactor is preferably 0 to 1000 bar absolute, more preferably 1 mbar to 200 bar absolute, most preferably 50 mbar to 20 bar absolute, and most preferably between 1 and 20 bar absolute. The pressure in the reactor should, in particular, be selected such that both the reaction mixture and the condensates formed during the reaction are in the liquid state in the reactor. In this variant, the reaction mixture is efficiently heated in the reaction zone, particularly if electromagnetic radiation, such as microwave radiation, is used for this purpose.

[0091] The residence time in the heating zone is adjusted by selecting a suitable flow rate of the reaction mixture through this zone. Another preferred option for adjusting the residence time within the meaning of the invention is a suitable selection of the apparatus size.

[0092] In one embodiment of the process, the heating zone of the reactor is followed by a residence zone. The product mixture resulting from the reaction mixture can remain in this residence zone after the heating zone for a residence time of up to 60 minutes, preferably from 1 to 600 seconds, particularly preferably from 1 to 120 seconds.

[0093] The required heat output in the heating zone can be supplied by any device capable of briefly introducing high amounts of heat output into the reaction mixture. Examples of suitable devices have already been described above.

[0094] Due to the brief exposure of the reaction mixture to high temperatures and pressures, esterification and, if necessary, transesterification reactions occur very rapidly. In this process, some of the alcohols and carboxylic acids present are converted into carboxylic acid esters with a comparatively low molecular weight, and depending on the starting substance, alcohols and / or water of reaction are released.

[0095] The cooling of the hot product mixture in step iii) can take place in the residence zone and / or in a cooling zone downstream of the residence zone or the reaction zone. Preferably, the hot product mixture is cooled rapidly to avoid further reactions.

[0096] The resulting product mixture can be combined with other substances as such without further processing or it can be processed before further processing.

[0097] After step iii), further processing may include, for example, drying and / or neutralization of the product mixture and / or separation of solid components.

[0098] The product mixture, if required, can be further processed by applying it to a solid support and / or by granulation together with other substances.

[0099] Experiments have shown that the compounds of formula (I) used according to the invention are suitable as extraordinarily good complexing agents for metal cations, in particular for alkaline earth metal cations such as Mg 2+< and Ca 2+< .

[0100] The invention therefore also relates to the use of the compounds of formula (I) as complexing agents in washing and cleaning agents, in oil production or for water softening.

[0101] Detergents and cleaning agents that are particularly suitable for cleaning dishes are those that are suitable for use in automatic dishwashers.

[0102] For use in detergents and cleaning agents, the compounds of formula (I) are usually used in the form of granules in combination with other components of detergents and cleaning agents.

[0103] The performance of bleaching agents in detergents and cleaning agents can be significantly increased when a bleaching agent used as a peroxygen compound is brought into contact with a combination of a bleaching catalyst and bleach activator. The bleaching effect of the catalyst is effectively supported by the peroxycarboxylic acid formed from the activator. At the same time, the peroxycarboxylic acid significantly contributes to killing germs on the items being cleaned, improves the odor of the wash liquor, and prevents the formation of biofilm in the washing machine or dishwasher. The combination of bleaching catalysts and / or bleach activators is therefore useful for increasing the bleaching effect and ensuring hygiene when using bleaching agents in detergents and cleaning agents.

[0104] Preferred detergents and cleaning agents according to the invention, in particular those for cleaning dishes, contain the compounds of formula (I) used according to the invention in amounts between 0.1 and 10 wt. %, preferably in amounts between 0.2 and 8 wt. %, and particularly preferably in amounts between 0.5 and 6 wt. %. The percentages are based on the total weight of the detergent and cleaning agent.

[0105] The washing and cleaning agents according to the invention, which can be in the form of granules, powdered or tablet-shaped solids but also in liquid or pasty form, can in principle contain, in addition to the compounds of formula (I) used according to the invention, all known ingredients customary in such agents.

[0106] The detergents and cleaning agents according to the invention may contain, in particular, builders, peroxygen compounds, enzymes, alkali carriers, surface-active surfactants, pH regulators, organic solvents, and other auxiliaries, such as glass corrosion inhibitors, silver corrosion inhibitors, and foam regulators. The granules according to the invention are suitable for use in both phosphate-containing and, in particular, phosphate-free formulations.

[0107] Particularly preferred washing and cleaning agents, especially agents for cleaning dishes, contain i) 5 to 65% by weight, preferably 10 to 60% by weight of a water-soluble builder component, ii) 5 to 20% by weight, preferably 8 to 10% by weight, of a peroxygen compound, iii) 0.5 to 25% by weight of a compound of formula (I), and iv) 0 to 50% by weight of further additives such as enzymes, alkali carriers, surface-active surfactants, pH regulators, organic solvents or further auxiliaries such as glass corrosion inhibitors, silver corrosion inhibitors and foam regulators, in each case based on the total weight of the washing and cleaning agent.

[0108] Such an agent is in particular low alkaline, ie its 1% by weight aqueous solution has a pH in the range from 8 to 11.5 and preferably from 8 to 11.

[0109] Possible ingredients of detergents and cleaning agents are sufficiently described in the patent literature, for example in WO 2018 / 210442 A1.

[0110] Examples of preferred water-soluble builder components in the detergents and cleaning agents according to the invention are organic polymers of native or synthetic origin of the polycarboxylate type, which act as co-builders, particularly in hard water regions. Examples of suitable co-builders are polyacrylic acids and copolymers of maleic anhydride and acrylic acid, as well as the sodium salts of these polymer acids. Commercially available products include Sokalan® CP 5, CP 10, and PA 30 from BASF. Polymers of native origin that can be used as co-builders include, for example, oxidized starch and polyamino acids such as polyglutamic acid or polyaspartic acid. Other possible water-soluble builder components are naturally occurring hydroxycarboxylic acids, such as mono- and dihydroxysuccinic acid, alpha-hydroxypropionic acid, and gluconic acid. Preferred organic water-soluble builder components include the salts of citric acid, particularly sodium citrate.Depending on the pH ultimately established in the detergents and cleaning agents according to the invention, the acids corresponding to the co-builder salts mentioned may also be present. Particularly preferred builder components in phosphate-free formulations are methylglycine diacetate (MDGA, e.g., Trilon®< M, BASF), L-glutamic acid, N,N,(biscarboxymethyl)-tetrasodium salt (GLDA, Dissolvine®< DL, Akzo Nobel), sodium polyaspartate (Baypure®< , Lanxess), or salts of iminodisuccinic acid (Baypure®< , Lanxess).

[0111] Examples of preferred peroxygen compounds in the washing and cleaning agents according to the invention are perborates and percarbonates, in particular the corresponding sodium salts of these compounds.

[0112] The enzymes optionally present in detergents and cleaning agents according to the invention include proteases, amylases, pullulanases, cutinases, and / or lipases. The enzymes used can be adsorbed on carriers and / or embedded in coating substances to protect them against premature inactivation. They are typically present in the detergents and cleaning agents according to the invention in amounts of up to 10 wt.% and preferably in amounts of 0.05 to 5 wt.%, with particular preference being given to using enzymes stabilized against oxidative degradation.

[0113] The detergents and cleaning agents according to the invention, in particular the dishwashing agents, preferably contain conventional alkali carriers such as alkali silicates, alkali carbonates, and / or alkali bicarbonates. Examples of these are mentioned in WO 2018 / 210442 A1. Alkali carriers can be present in the detergents and cleaning agents in an amount of up to 50 wt.% and preferably from 5 to 40 wt.%.

[0114] Examples of preferred surfactants optionally present in the detergents and cleaning agents according to the invention are anionic surfactants, zwitterionic surfactants, and preferably low-foaming nonionic surfactants. Their amount can be up to 20 wt.%, preferably up to 10 wt.%, and particularly preferably in the range from 0.5 to 5 wt.%, based in each case on the total weight of the detergent and cleaning agent. Examples of surfactants are mentioned in WO 2018 / 210442 A1.

[0115] To establish a desired pH value that does not arise automatically from the mixing of the other components, the detergents and cleaning agents according to the invention can contain system- and environmentally compatible acids, in particular citric acid, acetic acid, tartaric acid, malic acid, lactic acid, glycolic acid, succinic acid, glutaric acid, and / or adipic acid, but also mineral acids, in particular sulfuric acid or alkali metal hydrogen sulfates, or bases, in particular ammonium or alkali metal hydroxides. Such pH regulators are present in the detergents and cleaning agents according to the invention, in particular dishwashing agents, preferably in amounts of not more than 10% by weight and particularly preferably in amounts of 0.5 to 6% by weight, based in each case on the total weight of the agent.

[0116] Examples of preferred organic solvents optionally present in the detergents and cleaning agents according to the invention are alcohols having 1 to 4 carbon atoms, in particular methanol, ethanol, isopropanol, and tert-butanol; diols having 2 to 4 carbon atoms, in particular ethylene glycol and propylene glycol; and mixtures thereof and the ethers derivable from the aforementioned classes of compounds. Such water-miscible solvents are typically present in the detergents and cleaning agents according to the invention in an amount of not more than 20% by weight and particularly preferably from 1 to 15% by weight.

[0117] To suppress glass corrosion during the wash cycle, appropriate inhibitors can be used in the detergents and cleaning agents according to the invention, especially those for cleaning dishes. Crystalline layered silicates and / or zinc salts are particularly advantageous in this regard. Examples of glass corrosion inhibitors are listed in WO 2018 / 210442 A1.

[0118] In a further preferred embodiment, the washing and cleaning agents according to the invention, in particular the agents for cleaning dishes, have an amount of the crystalline layered silicate of 0.1 to 20 wt. %, particularly preferably 0.2 to 15 wt. % and especially preferably 0.4 to 10 wt. % in each case based on the total weight of the agent.

[0119] To provide silver corrosion protection, silver corrosion inhibitors can be used in the detergents and cleaning agents according to the invention, especially in dishwashing agents. Examples of silver corrosion inhibitors are listed in WO 2018 / 210442 A1.

[0120] The washing and cleaning agents according to the invention, in particular the agents for cleaning dishes, can contain as further ingredients, for example sequestering agents, electrolytes, additional peroxygen activators, dyes or fragrances, such as perfume oils, known from the prior art for such agents.

[0121] The production of the solid washing and cleaning agents according to the invention, in particular the agents for cleaning dishes, presents no difficulties and can in principle be carried out in a known manner, for example by spray drying or granulation, wherein the peroxygen compound and the granules according to the invention are optionally added separately later.

[0122] Detergents and cleaning agents according to the invention in the form of aqueous solutions or solutions containing other conventional solvents, in particular corresponding agents for cleaning dishes, are particularly advantageously prepared by simply mixing the ingredients, which can be added in substance or as a solution into an automatic mixer.

[0123] The washing and cleaning agents according to the invention, in particular agents for cleaning dishes, are preferably in the form of powdered, granular or tablet-shaped preparations which can be produced in a manner known per se, for example by mixing, granulating, roller compacting and / or by spray drying of thermally resilient components and admixing the more sensitive components, which include in particular enzymes, bleaching agents and the bleaching catalyst.

[0124] The inventive detergents for machine cleaning of dishes can be used in both domestic and commercial dishwashers. They are added manually or using suitable dosing devices. The application concentrations in the cleaning solution are generally approximately 1 to 8 g / l, preferably 2 to 5 g / l.

[0125] A dishwasher program is conveniently supplemented and completed by several intermediate rinses with clean water and a final rinse with a conventional rinse aid. After drying, the dishwashing detergent according to the invention produces completely clean and hygienically perfect dishes. Examples

[0126] In the following examples, % values are by weight unless explicitly stated otherwise. Manufacturing examples Example 1: Production of oligo-citric acid monoethylene glycol ester

[0127] In a 5 l Büchi stirred autoclave equipped with stirrer, internal thermometer and pressure equalization, 2.5 kg of citric acid (as monohydrate) were placed and mixed with 6.5 kg of monoethylene glycol and 0.05 kg of sulfuric acid.

[0128] The resulting mixture was heated to 80°C, during which all reactants dissolved completely. At a working pressure of 15 bar, the reaction solution was then continuously pumped through the reaction tube at 5 l / h and exposed to a microwave power of 1.5 kW, of which 91% was absorbed by the reaction mixture. The residence time of the reaction mixture in the irradiation zone was approximately 25 seconds. At the end of the reaction tube, the reaction mixture had a temperature of 155°C. Immediately after leaving the reactor, the reaction mixture was cooled to room temperature using an intensive heat exchanger. Example 2 (comparison): Production of oligo-citric acid glyceryl ester

[0129] In a 5 l Büchi stirred autoclave equipped with stirrer, internal thermometer and pressure equalization, 2.5 kg of citric acid (as monohydrate) were placed and mixed with 4.8 kg of glycerol and 0.05 kg of methanesulfonic acid.

[0130] The resulting mixture was heated to 75°C, during which all reactants dissolved completely. At a working pressure of 15 bar, the reaction solution was then continuously pumped through the reaction tube at 5 l / h and exposed to a microwave power of 1.3 kW, of which 94% was absorbed by the reaction mixture. The residence time of the reaction mixture in the irradiation zone was approximately 25 seconds. At the end of the reaction tube, the reaction mixture had a temperature of 160°C. Immediately after leaving the reactor, the reaction mixture was cooled to room temperature using an intensive heat exchanger. Example 3: Preparation of oligo-citric acid monoethylene glycol ester without the use of a reaction-accelerating catalyst

[0131] In a 5-liter Büchi stirred autoclave equipped with a stirrer, internal thermometer, and pressure equalizer, 2.5 kg of citric acid (as monohydrate) were added, followed by 6.5 kg of monoethylene glycol. No catalyst was added at this stage.

[0132] The resulting mixture was heated to 80°C, during which all reactants dissolved completely. At a working pressure of 15 bar, the reaction solution was then continuously pumped through the reaction tube at 5 l / h and exposed to a microwave power of 1.5 kW, of which 90% was absorbed by the reaction mixture. The residence time of the reaction mixture in the irradiation zone was approximately 25 seconds. At the end of the reaction tube, the reaction mixture had a temperature of 155°C. Immediately after leaving the reactor, the reaction mixture was cooled to room temperature using an intensive heat exchanger. Application examples

[0133] The transparent solutions prepared according to Preparation Examples 1, 2, and 3 were tested in a citrate-based dishwashing detergent formulation. It was investigated whether the use of these solutions could prevent the deposition of calcium carbonate on glasses and other tableware.

[0134] The following table describes the composition of dishwashing detergents used in the tests. Table raw material 1 2 3 4 Trisodium citrate 36% 35% 35% 35% Sodium carbonate 30% 30% 30% 30% Percarbonates 15% 15% 15% 15% TAED 5% 5% 5% 5% PEG1500 3% 3% 3% 3% PEG6000 2% 2% 2% 2% Sokalan PA25 5% 5% 5% 5% Lutensol TO 7 1% 1% 1% 1% Protease Blaze 100T 2% 2% 2% 2% Amylase Stainzyme Evity 12T 1% 1% 1% 1% Perfume, dye, etc. 0% 0% 0% 0% Mixture according to manufacturing instruction 1 0% 1% 0% 0% Mixture according to manufacturing instruction 2 0% 0% 1% 0% Mixture according to manufacturing instruction 3 0% 0% 0% 1% sum 100% 100% 100% 100%

[0135] The powder formulations were mixed and dispensed as 20g portions from the dosing chamber. The liquid mixture from Preparation Examples 1, 2, and 3 was dispensed onto the powder via pipettes. The pH, measured as a 1 wt.% solution in water, was 10.2.

[0136] The washing performance was measured in a Miele GSL 2 dishwasher at 55°C using water with a hardness of 21 degrees. Three wash programs were run each. Schott Zwiesel long drink glasses were visually assessed for film and stain formation in a black box. Ratings were assigned from 1 to 10 (1 = worst; 10 = best). The average of all ratings was calculated. The results are shown in the table below. Table formulation 1 2 3 4 Film and stain formation 5,9 6,9 5,1 7,6

[0137] The shine on the glasses had improved significantly when a mixture containing monoethylene glycol di-citric acid ester prepared according to Preparation Examples 1 and 3 was used in the dishwashing detergent formulation.

[0138] The shine on the glasses did not improve when a mixture containing monoglycerol di-citric acid ester prepared according to Preparation Example 2 was used in the dishwashing detergent formulation.

Claims

1. Detergent and cleaning agent containing compounds of the formula (I)         (R1OOC)a-R2(OH)c-COO-(CnH2n-O)m-OC-R3(OH)d(COOR4)b     (I) wherein R1 and R4 independently of one another are hydrogen, a cation of a metal, an ammonium cation, C1-C6-alkyl, cycloalkyl having three to nine ring carbon atoms, aryl having five to ten ring carbon atoms, aryl substituted by one or two alkyl groups, aryl linked to the carboxyl group via an alkylene group, -(CnH2n-O)m-H or -O-R2(COOR1)a+1, R2 and R3 independently of one another are aliphatic hydrocarbon radicals having one to eight carbon atoms, a and b independently of one another are integers from 1 to 4, c is an integer from 0 to 4, d is an integer from 1 to 4, n is 2, 3 or 4, and m is 1, 2, 3 or 4, with the proviso that R1 and R4 may be different within a molecule within the scope of the given definitions.

2. Detergent and cleaming agent according to claim 1, characterized in that n is 2 or 3, and m is 1 or 2.

3. Detergent and cleaning agent according to claim 2, characterized in that n is 2 and m is 1.

4. Detergent and cleaning agent according to at least one of claims 1 to 3, characterized in that c and d are 1.

5. Detergent and cleaning agent according to at least one of claims 1 to 4, characterized in that R2 is a divalent radical of the formula -CoH2o- or a trivalent radical of the formula -CpH2p-1< or a tetravalent radical of the formula >CqH2q-2< in which o is an integer from 2 to 4, preferably from 2 to 3 and particularly preferred 2, p is an integer from 1 to 4, preferably from 1 to 3 and particularly preferred 1 or 2, and q is an integer from 2 to 4, preferably from 2 to 3 and particularly preferred 3.

6. Detergent and cleaning agent according to at least one of claims 1 to 5, characterized in that R2 and R3 are radicals which are derived from malic acid, lactic acid, tartronic acid, tartaric acid, isocitric acid, citric acid, acetyl citric acid, tartaric acid or mucic acid after removal of the carboxyl groups and the hydroxyl groups.

7. Detergent and cleaning agent according to claim 6, characterized in that R2 and R3 are radicals of the formula (Ib), (Ic), (Id), (le), (If) or (Ig) 8. Detergent and cleaning agent according to claim 6, characterized in that R2 and R3 are radicals which are derived from citric acid after removal of the carboxyl groups and the hydroxyl group.

9. Detergent and cleaning agent according to at least one of claims 1 to 8, characterized in that a and b are 2, in that R2 and R3 are aliphatic hydrocarbon radicals having three carbon atoms and in that R1 and R4 are hydrogen, cations of alkali metals, cations of alkaline earth metals, quaternary ammonium cations or radicals of the formula -(CnH2n-O)m-H.

10. Detergent and cleaning agent according to at least one of claims 1 to 9, characterized in that the compounds of formula (I) have the structure of formula (II) or the alkali metal or alkaline earth metal salts or partial neutralizates thereof         HO-C(CH2-COOH)2-COO-C2H4-OOC-COH-(CH2COOH)2     (II).

11. Detergent and cleaning agent according to at least one of claims 1 to 10, characterized in that the compounds of formula (I) are present as mixtures of a plurality of compounds of formula (I) which are liquid at 25°C.

12. Detergent and cleaning agent according to at least one of claims 1 to 11, characterized in that the compounds of the formula (I) have a radical of the formula (R1OOC)a-R2(OH)-COO- and a radical of the formula (R4OOC)b-R3(OH)-COO-, these radicals having the same meaning.

13. Detergent and cleaning agent according to at least one of claims 1 to 12, characterized in that this is an agent for cleaning dishes.

14. Use of compounds of the formula (I)         (R1OOC)a-R2(OH)c-COO-(CnH2n-O)m-OC-R3(OH)d(COOR4)b     (I) wherein R1, R2, R3, R4, a, b, c, d, n and m have the meaning defined in claim 1, as complexing agents in detergents and cleaning agents, in petroleum production or for water softening.