Organotin-free catalysts for transesterification with monofunctional and polyfunctional alcohols
Lithium hydroxide and magnesium oxide catalysts in transesterification processes address the environmental and efficiency issues of organotin catalysts by achieving high yields and stable esters at lower temperatures, simplifying catalyst removal and reducing energy consumption.
Patent Information
- Application Number
- JP2025544666
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-03
- Filing Date
- 2024-01-25
- Publication Date
- 2026-02-10
AI Technical Summary
Existing transesterification processes using organotin and alkyl titanate catalysts are environmentally harmful, difficult to remove, require high temperatures, and result in undesirable by-products, leading to costly purification processes and high energy consumption.
The use of lithium hydroxide and magnesium oxide catalysts, optionally with sodium hypophosphite, at lower temperatures (below 100°C) to achieve high yields and simplify catalyst removal through precipitation and filtration, resulting in a clear, colorless, and stable reaction product.
This approach reduces energy consumption, simplifies catalyst separation, and produces esters with improved stability and purity, meeting cosmetic and pharmaceutical specifications without the need for additional purification steps.
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Abstract
Description
[Background technology]
[0001] Process technology today is moving towards environmentally friendly catalysts and processes, particularly for the chemical synthesis of raw materials for use in cosmetics and pharmaceuticals. Many processes established with traditional catalysts are now being converted to more environmentally friendly catalysts. Thereby, it is of great concern that the products resulting from the converted process will meet the specifications of the products resulting from the original process and that as few process control changes as possible are required.
[0002] Organotin catalysts, such as dibutyltin diacetate or tetrabutyldiacetoxydistannoxane, are well-established transesterification catalysts in the chemical industry. Nevertheless, as early as 2003, the EU banned tributyltin in marine antifouling coatings, followed in 2010 by a ban on tributyltin in consumer products in Germany due to its adverse effects on genetics and fertility. Therefore, the risk of organotin residues in cosmetics is an increasing threat to customer and consumer acceptance. Additionally, organotin catalysts are difficult to remove from the esterification product, which results in costly and energy-intensive purification processes. Common catalysts active above 180°C, such as organotin compounds, must be separated from the raw product by oxidation to tin oxide, breaking the carbon-tin bond, aqueous precipitation, and filtration using filter aids.
[0003] European Patent Application No. 1858480 describes esters of 2-propylheptanol with linear or branched, saturated or unsaturated C4-C36 carboxylic acids or C4-C36 dicarboxylic acids, which are used as emollients in cosmetic and / or pharmaceutical formulations. These esters are prepared by reacting 2-propylheptanol with the corresponding carboxylic acid at temperatures between 100 and 300°C using sodium methylate and a tetraalkyl titanate as catalysts. Alkyl titanates are also undesirable by-products in cosmetics and personal care products. Furthermore, the use of alkyl titanates results in undesirable by-products due to their reaction with the alkyl ester educt. This catalyst provides an additional hydrolysis step for removal from the reaction product after transesterification. In addition, some of these catalysts require very high temperatures to develop their catalytic effect. Therefore, high energy consumption is another drawback of this process, which should be avoided when developing new manufacturing processes.
[0004] US Patent Application Publication No. 20100197955 discloses a process for preparing butanediol dimethacrylate, which involves the transesterification of an ester of methacrylic acid with butanediol in the presence of a catalyst containing lithium hydroxide and calcium oxide. The use of this catalyst combination to prepare alkyl fatty acid esters did not result in a sufficiently stable, colorless and transparent esterification product for the fatty acid ester due to the formation of a slurry during storage. Summary of the Invention [Problem to be solved by the invention]
[0005] Therefore, the object of the present invention is to provide a tin- and titanate-free catalyst that is selective and highly active under conditions similar to or even milder than those of organotin catalysts. In particular, lower reaction temperatures (at least below 190°C) and even lower reaction initiation temperatures should be explored. In addition, simple separation and removal of the new catalyst (by a combination of precipitation and filtration) is desirable. The resulting reaction product should have the required specifications in terms of catalyst removal and sufficient stability compared to those prepared with previous catalysts. Implementation in production operations should be possible with little effort. In addition to using a catalyst with a better toxicological profile, a reduction in energy consumption should also contribute to achieving a more environmentally friendly manufacturing process. [Means for solving the problem]
[0006] Surprisingly, the transesterification process of formula 1a or 1b R 1 -C(O)OR 2 (Formula 1a) R 2 -O(O)CR 3 -C(O)OR 2 (Formula 1b) (In the formula, R 1 and R 3 is a saturated or unsaturated branched or straight chain aliphatic or aromatic residue, and R 2 is selected from the group consisting of methyl, ethyl, propyl, isopropyl and n-butyl An alkyl ester (a) of a carboxylic acid of formula 2 R 4 -OH (Formula 2) (In the formula, R 4 is a linear or branched, saturated or unsaturated or alkoxylated alkyl, alkenyl or alkoxy residue or a monofunctional alcohol (b1) of the formula (b2) a polyfunctional alcohol selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butanediol, 1,4-butanediol, and 2,3-butanediol; in the presence of catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite, resulted in a clear, colorless, and stable reaction product.
[0007] Surprisingly, the catalytic combination of lithium hydroxide and magnesium oxide reacts well below 100°C, while transesterification with other catalysts, particularly tin-containing catalysts, begins at about 150°C. The higher yields achieved at lower temperatures using lithium hydroxide and magnesium oxide are advantageous for implementing an energy-efficient process. Typically, transesterification plateaus at approximately 90% yield, which is then reached more quickly and with less energy consumption. Despite the lower reaction temperatures, which place less stress on the product and are more energy-efficient, the reaction time is comparable to that of the previous standard process.
[0008] Additionally, further processing of the ester is simplified, since much less effort is required to remove the catalyst and phosphorus as salts of phosphoric acid: the salts can be well separated already during filtration, so that a simple filtration step can be sufficient to purify the product. DETAILED DESCRIPTION OF THE INVENTION
[0009] Component a) - alkyl esters of carboxylic acids the moiety R of an alkyl ester of a monocarboxylic acid according to formula 1a 1 is a straight-chained, branched, saturated or unsaturated C1 to C36 alkyl, preferably a straight-chained, branched, saturated or unsaturated C4 to C30, particularly C6 to C24, more particularly C6 to C22, even more particularly C6 to C18, most particularly C8 to C18, preferably C8 to C16, more preferably C8 to C12, even more preferably C6 to C10 alkyl.
[0010] The alkyl ester moiety R of formula 1a and formula 1b 2 is selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl and 2,2-butyl, preferably from the group consisting of methyl, ethyl and isopropyl, most preferably R 2 is methyl.
[0011] The moiety R of an alkyl ester of a dicarboxylic acid according to formula 1b 3 is a linear, branched, saturated or unsaturated C2 to C54, particularly C4 to C36, more particularly C6 to C22, even more particularly C6 to C18, most particularly C8 to C18, preferably C8 to C16, more preferably C8 to C12, even more preferably C6 to C10 alkyl. 3 Similarly, R 3 contains an alkyl moiety from a C36 dicarboxylic acid, it can arise from dimer fatty acids, polycarboxylic acids obtained by polymerization of unsaturated fatty acids, mainly oleic acid or tall oil fatty acid.
[0012] Preferred dicarboxylic acid esters are the esters of phthalic acid, terephthalic acid, sebacic acid, azelaic acid, adipic acid and dodecanedioic acid.
[0013] Component b) - Alcohol Part R of Equation 2 4 is a linear or branched, saturated or unsaturated or alkoxylated alkyl, alkenyl or alkoxy residue, preferably a linear or branched, saturated, unsaturated C2-C36 alkyl, more preferably a linear, branched, saturated or unsaturated C3-C24 alkyl, most preferably a linear or branched, saturated C4-C12 alkyl.
[0014] Specifically, the monofunctional alcohol (b1) is 2-propylheptanol, and the polyfunctional alcohol (b2) is glycerol.
[0015] The esters of glycerol prepared according to the process of the present invention, such as the mono-, di-, and tri-esters of glycerol or the esters of 2-propyl-heptanol, are particularly suitable for cosmetic formulations. These esters can be particularly well incorporated into various formulations, such as liquid mixtures that can be used as oil components or viscosity agents, depending on the chain length, branching, and number of double bonds of these esters.
[0016] Esters of 2-propylheptanol with linear or branched saturated or unsaturated C5 to C36 carboxylic acids or C4 to C36 dicarboxylic acids, more preferably esters of 2-propylheptanol with linear or branched saturated or unsaturated C5 to C18 carboxylic acids or C4 to C18 dicarboxylic acids, most preferably esters of 2-propylheptanol with linear or branched saturated or unsaturated C6 to C12 carboxylic acids, such as 2-propylheptyl-n-butanoic acid ester, 2-propylheptyl-i-butanoic acid ester, 2-propylheptyl-n-pentanoic acid ester, 2-propylheptyl-i-pentanoic acid ester, 2-propylheptyl-n-hexanoic acid ester, 2-propylheptyl-i-hexanoic acid ester, 2-propylheptyl-n-heptanoic acid ester, tanoate, 2-propylheptyl-i-heptanoate, 2-propylheptyl-i-octanoate, 2-propylheptyl-n-nonanoate, 2-propylheptyl-i-nonanoate, 2-propylheptyl-n-decanoate, 2-propylheptyl-i-decanoate, 2-propylheptyl-n-undecanoate, 2-propylheptyl-i-undecanoate, 2-propylheptyl-n-undecenoate, 2-propylheptyl-i-undecenoate, 2-propylheptyl-n-dodecanoate, and the like are preferred reaction products of 2-propylheptanol using the transesterification process of the present invention.
[0017] Catalysts and other additives Lithium hydroxide is preferably used as the monohydrate (LiOH*H2O). The monohydrate is available in solid powder form and is therefore easy to handle depending on the equipment of the reaction plant, especially if water is to be avoided during the reaction. Therefore, in order to avoid an additional drying step, it is possible to add lithium hydroxide powder to the reaction and keep the amount of water in the reactor to a minimum.
[0018] On the other hand, lithium hydroxide monohydrate has good solubility in water and can also be added as an aqueous solution depending on the reaction plant and the capacity of the raw materials to be loaded into the reaction vessel. Addition of lithium monohydroxide in the form of an aqueous solution avoids the appearance of dangerous lithium monohydroxide dust if the required drying step is acceptable.
[0019] It has been shown that using an aqueous solution of lithium hydroxide monohydrate at 5-13 wt%, preferably 8-12 wt%, and more preferably 10 wt% ± 1 wt%, based on the weight of the aqueous solution of lithium hydroxide monohydrate, does not make the process inefficient if the "reaction mixture" is dried prior to transesterification.
[0020] The amount of lithium hydroxide depends on the alcohol used. For transesterification with a monofunctional alcohol, 0.01 to 0.001 mol of lithium hydroxide is used per mole of monofunctional alcohol b1. Since lithium hydroxide is a reactant, this amount is calculated for the lithium hydroxide and not for the respective hydrate. Preferably, 0.008 to 0.002 mol of lithium hydroxide is used per mole of monofunctional alcohol b1, more preferably 0.005 to 0.003 mol of lithium hydroxide per mole of monofunctional alcohol b1.
[0021] For transesterification using polyfunctional alcohols, 0.08 to 0.001 mol of lithium hydroxide is used per mole of polyfunctional alcohol b1, preferably 0.04 to 0.001 mol of lithium hydroxide per mole of polyfunctional alcohol b1, more preferably 0.02 to 0.005 mol of lithium hydroxide per mole of polyfunctional alcohol b1.
[0022] Magnesium oxide is added to the reactants in an amount of 0.02 to 0.001 moles of magnesium oxide per mole of alkyl ester, preferably 0.007 to 0.003 moles of magnesium oxide per mole of alkyl ester, and more preferably 0.006 to 0.004 moles of magnesium oxide per mole of alkyl ester to achieve an optimized transesterification rate.
[0023] From the prior art, calcium oxide was known to be more soluble in organic environments and to be an effective catalyst. The use of magnesium oxide was expected to be disadvantageous in view of its catalytic activity due to its low solubility. Surprisingly, magnesium oxide works well in combination with lithium hydroxide, despite its low solubility in organic environments. In addition, it did not develop any precipitates during storage, resulting in a more stable transesterification reaction product.
[0024] Apart from these catalysts, sodium hypophosphite could be optionally added to the reaction to improve product quality. In a preferred embodiment of the present invention, the process is carried out in the presence of sodium hypophosphite monohydrate to improve the color of the resulting reaction product and achieve better peroxide numbers.
[0025] Sodium hypophosphite monohydrate is added in an amount of 0.01 to 0.3% by weight based on the total weight of all educts without the catalyst (which is the total weight of the reactants a) alkyl ester of a carboxylic acid and b) alcohol, including further added raw materials such as inert components, if added); preferably, sodium hypophosphite monohydrate is added in an amount of 0.02 to 0.2% by weight based on the total weight of all educts without the catalyst, more preferably, in an amount of 0.04 to 0.1% by weight based on the total weight of all educts without the catalyst, and most preferably, in an amount of 0.04 to 0.06% by weight based on the total weight of all educts without the catalyst.
[0026] For this reason, preferably the transesterification process is carried out in the presence of sodium hypophosphite monohydrate (NaH2PO2*H2O) and the catalysts lithium hydroxide monohydrate (LiOH*H2O) and magnesium oxide (MgO).
[0027] Another object of the present invention is a catalyst composition comprising two single catalysts selected from lithium hydroxide and magnesium oxide (MgO), preferably lithium hydroxide monohydrate and magnesium oxide (MgO). Suitably, both catalysts are used as physically separate components, so that doping of the alkaline earth metal—magnesium oxide—with the strong base lithium hydroxide is precluded, as this composition would not adequately catalyze the transesterification process.
[0028] For base-catalyzed reactions, MgO is often doped with alkali metal cations, especially lithium hydroxide, before adding it to the reaction mixture as the sole catalyst; this doping process provides a combination not achieved by simply mixing lithium hydroxide with magnesium oxide.
[0029] The transesterification of the present invention requires more strongly basic active sites, and as a result, doping of MgO with lithium ions is avoided and is explicitly excluded for the process of the present invention. The catalysts lithium hydroxide and magnesium oxide are added separately to the transesterification process. They do not undergo a pretreatment step of doping magnesium oxide with lithium hydroxide, as this would result in catalysts with different activities.
[0030] A preferred catalyst composition comprises lithium hydroxide and magnesium oxide (MgO) as a pure mixture in a molar ratio of 1:3 to 3:1, more preferably 1:2 to 2:1.
[0031] Reaction conditions Generally, after drying the raw materials in a reactor, alkyl ester a) and alcohol b) are catalytically transesterified at elevated temperatures up to 190° C., first at atmospheric pressure and then under vacuum. During the reaction, the alcohol formed is continuously removed. At the end of the reaction, excess alkyl ester is distilled off.
[0032] The transesterification is carried out at a temperature of 70°C to 240°C, preferably below 195°C, specifically 70°C to 195°C, with the most preferred range being 70°C to 190°C, to reduce energy costs and avoid exposing the product to temperature stress.
[0033] In a preferred embodiment, the process is carried out in the absence of a solvent, preferably in a substantially water-free educt. The respective catalysts can be used in water-free form or in the form of their hydrates. If they are added to the educt in aqueous solution, the mixture is dried before the transesterification reaction is initiated.
[0034] In another preferred embodiment, the interesterification is carried out in the presence of an inactive ingredient, characterized in that it is not interesterified and is an oil of natural origin. Preferably, the inactive ingredient is selected from the group consisting of: oil of guinea palm (elaeis guiineensis) oil, passion flower (passiflora incarnata) seed oil, olive oil, vegetable oil, shea (butyrospermum parkii) butter, coconut (cocos nucifera) oil, shorea stenoptera seed butter, almond oil, avocado oil, borage oil, canola oil, castor oil, chamomile, palm oil, corn oil, cottonseed oil, jojoba oil, evening primrose oil, papaya oil, palm oil, hazelnut oil, peanut oil, walnut oil, safflower oil, sesame oil, soybean oil, sunflower oil, sweet almond, rice bran / wheat germ oil, rosehip oil, castor bean oil, and ricinus communis. communis oil, macauba oil, andiroba oil, Euphorbia vegetable oil, and mixtures thereof. More preferably, the inactive ingredients are selected from the group consisting of olive oil, almond oil, avocado oil, borage oil, canola oil, castor oil, coconut oil, corn oil, cottonseed oil, jojoba oil, palm oil, safflower oil, sesame oil, soybean oil, sunflower oil, macauba oil, and mixtures thereof. Most preferably, the inactive ingredients are selected from the group consisting of coconut oil, and / or sunflower oil, and / or macauba oil.
[0035] The inert ingredient improves mixing with components a) (the alkyl ester) and b) (the alcohol), resulting in improved emulsification or dissolution of at least one of the ingredients. It is not removed during or after the transesterification, so that it will be part of the final esterified product.
[0036] A preferred object of the present invention is a transesterification process comprising the steps of: R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The alkyl ester (a) of a carboxylic acid represented by the formula 2 R 4 -OH (Formula 2) (In the formula, R 4 is a linear or branched, saturated or unsaturated alkyl in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
[0037] Another preferred object of the present invention is a steric exchange process, H3C-O(O)CR 3 -C(O)O-CH3 (Formula 1b) (Formula 1b) (In the formula, R 3 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The alkyl ester (a) of a carboxylic acid represented by the formula 2 R 4 -OH (Formula 2) (In the formula, R 4 is a linear or branched, saturated or unsaturated alkyl in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
[0038] More preferred is a transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The transesterification process comprises treating an alkyl ester of a carboxylic acid (a) of the formula (I) with propylheptanol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
[0039] Particularly preferred is the transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The transesterification process involves treating an alkyl ester of a carboxylic acid (a) of the formula (I) with propylheptanol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.
[0040] Another preferred object of the present invention is a transesterification process comprising the steps of: R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms with a polyfunctional alcohol (b2) selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butanediol, 1,4-butanediol, and 2,3-butanediol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and, optionally, sodium hypophosphite.
[0041] Another preferred object of the present invention is a transesterification process comprising the steps of: H3C-O(O)CR 3 -C(O)O-CH3 (Formula 1b) (In the formula, R 3 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms with a polyfunctional alcohol (b2) selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butanediol, 1,4-butanediol, and 2,3-butanediol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and, optionally, sodium hypophosphite.
[0042] More preferred is a transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The transesterification process comprises treating an alkyl ester (a) of a carboxylic acid of formula (I) with glycerol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
[0043] Preferred is a transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms with glycerol in the presence of a naturally occurring fatty oil and in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
[0044] Particularly preferred is the transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms The transesterification process involves treating an alkyl ester of a carboxylic acid (a) with glycerol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.
[0045] Particularly preferred is the transesterification process, R 1 -C(O)O-CH3 (Formula 1a) (In the formula, R 1 is a saturated or unsaturated, branched or straight chain aliphatic residue having C4 to C18 carbon atoms It is also a transesterification process comprising treating an alkyl ester of a carboxylic acid (a) of the formula (I) with glycerol in the presence of a natural fatty oil and in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.
[0046] The crude reaction product has a basic pH and must be neutralized for stability reasons and for use in personal care or cosmetic compositions.
[0047] The transesterification process is preferably characterized in that the crude alkaline reaction mixture is neutralized with phosphoric or phosphorous acid (H3PO4, H3PO3), preferably phosphoric acid, to a pH of 6.8±0.2, which converts the dissolved lithium and magnesium cations to their respective phosphorus salts, which are insoluble in the organic reaction mixture and can then be more easily separated from the reaction product by filtration.
[0048] The further processing of the obtained ester is simplified because the effort required to remove the catalyst as a phosphoric acid salt is much less.These salts can be easily separated during filtration, so that a simple filtration step can be sufficient to purify the product.It is possible to almost completely remove the catalyst by simple filtration, so that the reaction product that cannot be distilled also does not contain much catalyst residue after filtration alone. [Example]
[0049] Example 1 - Preparation of glycerol-C8 / C10-esters in palm oil Example 1a - Using lithium hydroxide in aqueous solution Manufacturing raw materials for Example 1a:
[0050] [Table 1]
[0051] Palm oil was charged to a reactor at atmospheric pressure and heated to 75° C. The methyl ester was added, followed by pumping 10 wt % lithium hydroxide solution (LiOH) into the reactor.
[0052] The mixture was dried for 30 minutes at 50 mbar or full pump vacuum and 70-85° C. Glycerol was charged to the reaction vessel with a water content of less than 1000 ppm.
[0053] Magnesium oxide (MgO) and sodium hypophosphite were added via a catalock. After heating to 190° C., the reaction was carried out at atmospheric pressure by distillation of methanol.
[0054] When the methanol accumulation plateaued, a vacuum ramp was initiated (ramp start value = standard pressure, ramp time = 3 h, full scale = 350 mbar).
[0055] When more than 2000 kg of methanol accumulated, distillate production decreased and OHZ (hydroxyl number) and SZ (acid number) were measured every 60 minutes from the start of vacuum. Methyl ester (component a1) distillation began at 50 OHZ.
[0056] Methyl ester distillation and product filtration: Methyl ester distillation was initiated at 150-190°C with a second vacuum ramp (ramp start value = 300 mbar, full scale = 0 mbar (best vacuum), ramp time = 1.0 hour).
[0057] After the vacuum lamp expired, distillation at full vacuum was continued until no more methyl esters were produced. The vacuum pump was then turned off and the vacuum was quenched with nitrogen. Color and OHZ were measured.
[0058] The reaction mixture was cooled to 60-75°C and pumped to a purification vessel. Phosphoric acid (10% aqueous solution) was added at 60-75°C with stirring until the pH reached 6.9±0.2.
[0059] The batch was then filtered using activated carbon and filter aid (Dicalite Speedplus, (supplier?)) and bleaching earth (Tonsil Standard 310 FF).
[0060] The yield of the final product (after filtration) was 12500 kg with a density of 0.909 kg / l. The transesterified ester was subsequently deodorized with steam in a countercurrent column.
[0061] Example 1b - Using lithium hydroxide monohydrate in powder form Manufacturing raw materials for Example 1b:
[0062] [Table 2]
[0063] The reaction of Example 1a was repeated by adding solid lithium hydroxide monohydrate to the reaction mixture: C8-C10 methyl esters, coconut oil (preheated to 70°C), and glycerol (99.5 wt%) were added to a reaction vessel and dried at 70°C and vacuum to a water content of less than 300 ppm. Lithium hydroxide monohydrate, magnesium oxide, and NaH2PO2 monohydrate were then added in powder form. The transesterification was initiated at atmospheric pressure, and the temperature was increased from 70°C to 190°C while the released methanol was distilled. The product was further processed according to Example 1a.
[0064] Example 2 - Preparation of 2-propylheptanol octyl ester Example 2a - Using a 10% by weight aqueous solution of lithium hydroxide Manufacturing raw materials for Example 2a:
[0065] [Table 3]
[0066] A reaction vessel was charged with 2-propylheptanol, octanoic acid methyl ester, and lithium hydroxide solution (LiOH) and dried at 50 mbar and 70-85°C to a target value of less than 1000 ppm water (less than 0.1 wt%). The vacuum was released, and then magnesium oxide (MgO) and sodium hypophosphite monohydrate were added via a catalok.
[0067] The reaction was then initiated at atmospheric pressure by heating the reactor from 70° C. to 190° C. (dephlegmator 50° C.) while distilling off the released methanol.
[0068] When the methanol accumulation decreased, a vacuum ramp was initiated (ramp start value = standard pressure, ramp time = 3 h, ramp end value = 350 mbar). OHZ (hydroxyl number) and SZ (acid number) were measured every 60 min from the start of the vacuum.
[0069] After reaching the full vacuum ramp value, GC analysis was performed every hour and the reaction was continued until the methyl ester and alcohol content no longer decreased and the hydroxyl number was less than 55 mg KOH / g. Then, heating was stopped so that the temperature decreased to 85°C, and methyl ester distillation was started at 50 mg KOH / g OHZ.
[0070] purification: When the temperature dropped to 65°C, an aqueous solution of 10% by weight phosphoric acid (85% phosphoric acid diluted with demineralized water to a 10% by weight solution) was added to the reaction mixture and stirred for 1 hour to achieve a pH of less than 7 (6.8±0.2). The resulting neutralized product was dried (70-85°C and vacuum). After reaching a water residue of less than 0.10% (1000 ppm), the mixture was cooled to 50°C and filtered using diatomaceous earth and Tonsil Optimum (Clariant) as filter aids.
[0071] The yield obtained was 12.555 kg of 2-propylheptanol octyl ester with a density of 0.855.
[0072] Fractional distillation and deodorization: The resulting filtered transesterification product was fractionally distilled to remove unreacted 2-propylheptanol and methyl esters as distillate in a first stage, and the transesterification product was distilled in a second stage, which was subsequently deodorized with steam in a countercurrent column.
[0073] Example 2b - Using lithium hydroxide monohydrate in powder form Manufacturing raw materials for Example 2b:
[0074] [Table 4]
[0075] The preparation of 2-propylheptyl octanoate ester in Example 2a was repeated by adding solid lithium hydroxide monohydrate to the reaction mixture instead of aqueous solution. 2-Propylheptanol and octanoic acid methyl ester were added to the reaction vessel. The mixture was dried at 70°C and vacuum for 30 minutes to a water content of less than 300 ppm. Lithium hydroxide monohydrate, magnesium oxide, and NaH2PO2 monohydrate were then added, and the mixture was heated from 70°C to 190°C under nitrogen while the released methanol was distilled off.
[0076] When the methanol accumulation decreased, a vacuum ramp was initiated (ramp start value = standard pressure, ramp time = 3 h, ramp end value = 350 mbar). OHZ (hydroxyl number) and SZ (acid number) were measured every 60 min from the start of the vacuum.
[0077] After reaching the full vacuum ramp value, GC analysis was performed every hour and the reaction was continued until the methyl ester and alcohol content no longer decreased and the hydroxyl number was less than 55 mg KOH / g. Heating was then stopped so that the temperature decreased to 85°C, and methyl ester distillation was started at 50 mg KOH / g OHZ.
[0078] purification: When the temperature decreased to 65°C, an aqueous solution of 10 wt% phosphoric acid (85% phosphoric acid diluted with demineralized water to a 10 wt% aqueous solution) was added to the reaction mixture and stirred for 1 hour to bring the pH below 7 (6.8±0.2).
[0079] The resulting neutralized product was dried (70-85°C and vacuum). After reaching a water residue of less than 0.10% (1000 ppm), the mixture was cooled to 50°C and filtered using diatomaceous earth and Tonsil Optimum (Clariant) as filter aids. The yield was 12.555 kg of 2-propylheptanol octyl ester with a density of 0.855.
[0080] Fractional distillation and deodorization: The resulting filtered transesterification product was fractionally distilled to remove unreacted 2-propylheptanol and methyl esters as distillate in a first stage, and the transesterification product was distilled in a second stage, which was subsequently deodorized with steam in a countercurrent column.
[0081] Example 3: Storage stability, residual catalyst and evaluation Analytical parameters during and after manufacturing and before and after storage were determined according to the following methods. Acid number: measured according to ISO 4314 Peroxide number: measured according to ISO 3960 Saponification number: measured according to ISO 3681 Hydroxyl number: determined according to DIN 53240 Hazen color scale: measured according to DIN ISO 6271
[0082] 3.1 An 8-month storage test at 40°C was carried out on transesterification products made with lithium hydroxide monohydrate powder and magnesium oxide.
[0083] Cocoglycerides of Example 1b:
[0084] [Table 5]
[0085] Example 2b 2-propylheptyl octanoate:
[0086] [Table 6]
[0087] 3.2 An accelerated 4-week storage test at 50°C was carried out on transesterification products prepared using lithium hydroxide monohydrate - 10 wt% aqueous solution and magnesium oxide.
[0088] Cocoglycerides of Example 1a:
[0089] [Table 7]
[0090] Example 2a 2-propylheptyl octanoate:
[0091] [Table 8]
[0092] 3.3 Measurement of residual catalyst Analytical determination of lithium, magnesium, sodium and total phosphorus (according to DIN EN ISO 11885, Fa. Fueling) in the transesterification products of Examples 1a, b and 2a, b after filtration resulted in values below the quantification level for all ions and all Examples.
[0093] 3.4 Evaluation of results The use of lithium hydroxide and magnesium oxide as a catalyst mixture has been shown to simplify the production process of esters produced by transesterification. The process of the present invention avoids the additional washing step of the transesterification product that would be necessary when using an organotin catalyst, resulting in esters of sufficient purity and stability. The complex precipitation and purification of organotin or titanate catalysts with an additional bleaching step of the reaction product can be avoided, resulting in a much more energy- and resource-efficient production than commonly used transesterification reactions using organotin or titanate catalysts. The catalyst, including lithium hydroxide monohydrate and magnesium oxide, can be easily removed, resulting in no detectable residual catalyst in the transesterification reaction product.
Claims
1. A transesterification process comprising the steps of: R １ -C(O)O-R ２ (Formula 1a) R ２ -O(O)C-R ３ -C(O)O-R ２ (Formula 1b) (In the formula, R １ and R ３ is a saturated or unsaturated branched or straight chain aliphatic or aromatic residue, and R ２ is selected from the group consisting of methyl, ethyl, propyl, isopropyl and n-butyl An alkyl ester (a) of a carboxylic acid represented by the formula Formula 2 R ４ -OH (Equation 2) (In the formula, R ４ is a linear or branched, saturated or unsaturated or alkoxylated alkyl, alkenyl or alkoxy residue or a monofunctional alcohol (b1) of the formula (b2) a polyfunctional alcohol selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butanediol, 1,4-butanediol, and 2,3-butanediol; in the presence of catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.
2. The moiety R in formula 1a １ is a linear, branched, saturated or unsaturated C1-C36 alkyl, and R in formula 1b ３ is a linear, branched, saturated or unsaturated C2 to C54 alkyl.
3. 3. The transesterification process according to claim 1 or 2, wherein the monofunctional alcohol (b1) is 2-propylheptanol and / or the polyfunctional alcohol (b2) is glycerol.
4. The moiety R in formula 1a １ is a linear, branched, saturated or unsaturated C4 to C18 alkyl.
5. The catalyst is lithium hydroxide monohydrate (LiOH*H ２ 5. The transesterification process of claim 1, comprising a catalyst containing magnesium oxide (MgO) and magnesium oxide (MgO) and optionally sodium hypophosphite monohydrate.
6. Sodium hypophosphite monohydrate (NaH ２ P.O. ２ *HO) and the catalyst lithium hydroxide monohydrate (LiOH*H ２ The transesterification process according to any one of claims 1 to 5, wherein the transesterification process is carried out in the presence of methyl methyl acrylate (MMA), ...
7. A transesterification process according to any one of claims 1 to 6, characterized in that it is carried out at a temperature between 70°C and 240°C, preferably between 70°C and 195°C.
8. 8. The transesterification process according to claim 1, wherein 0.01 to 0.001 moles of lithium hydroxide are used per mole of the monofunctional alcohol (b1).
9. 8. The transesterification process according to claim 1, wherein 0.08 to 0.001 moles of lithium hydroxide are used per mole of polyfunctional alcohol (b2).
10. 10. The transesterification process according to any one of claims 1 to 9, characterized in that 0.02 to 0.001 moles of magnesium oxide are used per mole of alkyl ester (a).
11. 11. The transesterification process according to any one of claims 1 to 10, characterized in that 0.01 to 0.3 wt. % of sodium hypophosphite is used, based on the sum of the weights of all reactants without catalyst.
12. 12. The transesterification process according to any one of claims 1 to 11, characterized in that the crude alkaline reaction mixture is neutralized with phosphoric acid.
13. Non-interesterified inactive ingredients include elaeis guiineensis oil, passion flower (passiflora incarnata) seed oil, olive oil, vegetable oil, shea (butyrospermum parkii) butter, coconut (cocos nucifera) oil, shorea stenoptera (shorea) oil, and the like.
13. The interesterification process according to any one of claims 1 to 12, characterized in that it is carried out in the presence of an inert ingredient selected from the group consisting of: laurel wort (Lucirumabensis) seed butter, almond oil, avocado oil, borage oil, canola oil, castor oil, chamomile, coconut oil, corn oil, cottonseed oil, jojoba oil, evening primrose oil, papaya oil, palm oil, hazelnut oil, peanut oil, walnut oil, safflower oil, sesame oil, soybean oil, sunflower oil, sweet almond, rice bran / wheat germ oil, rosehip oil, Ricinus communis oil, macauba oil, andiroba oil, Euphorbia vegetable oil and mixtures thereof.
14. A catalyst composition for use in a transesterification process comprising a mixture of two single catalysts selected from lithium hydroxide and magnesium oxide (MgO).
15. 13. The catalyst composition of claim 12, comprising lithium hydroxide and magnesium oxide (MgO) in a molar ratio of 1:3 to 3:1.