Catalyst free of organic tin for transesterification with monofunctional and polyfunctional alcohols

Abstract

The present invention relates to a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a or 1b (R1-C (O) O-R2 (formula 1a) R2-O (O) C-R3-C (O) O-R2 (formula 1b) wherein R1 and R3 are saturated or unsaturated, branched or linear aliphatic or aromatic or alkoxylated residues, and R2 is selected from the group consisting of methyl, ethyl, propyl, isopropyl and n-butyl) with a monofunctional alcohol (b1) having formula 2 (R4-OH (formula 2) wherein R4 is a linear or branched, saturated or unsaturated alkyl group) or a monofunctional alcohol (b2) selected from the group consisting of glycerol, 1, 3-propanediol, 1, 2-propanediol, ethylene glycol, 1, 2-butanediol, 1, 4-butanediol, 2, 4-butanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3-propanediol, 1, 3- A polyfunctional alcohol (b2) comprising 1, 3-butanediol is treated in the presence of catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite. The use of specific catalyst compositions enables a more efficient energy saving process compared to standard prior art transesterification processes.

Description

[0001] Current process technologies are aimed at environmentally friendly catalysts and processes for chemical synthesis, particularly for raw materials used in cosmetic and pharmaceutical products. Many processes established with conventional catalysts are currently being converted to more environmentally friendly catalysts. Consequently, a primary concern is that the product derived from the conversion process will meet the specifications of the product produced by the original process, and that as few process control changes as possible are necessary.

[0002] Organotin catalysts (such as dibutyltin diacetate or tetrabutyldiacetoxydistannoxane) are well-established transesterification catalysts in the chemical industry. However, the European Union banned tributyltin in marine antifouling coatings in 2003, followed by Germany in 2010 in consumer products due to its damaging effects on genetics and fertility. Therefore, the risk of organotin residues in cosmetic products poses a growing threat to customer and consumer acceptance. Furthermore, organotin catalysts are difficult to remove from the esterification products, leading to expensive and energy-intensive purification methods. Common catalysts (such as organotin compounds) that are active above 180°C must be separated from the crude product by oxidation to tin oxide to break the carbon-tin bond, aqueous precipitation, and filtration with a filter aid.

[0003] European patent application EP 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 acids using sodium methoxide and tetraalkyl titanates as catalysts at temperatures between 100°C and 300°C. Alkyl titanates are also unwanted byproducts in cosmetics and personal care products. In addition, the use of alkyl titanates can produce unwanted byproducts by reacting with alkyl ester educts. These catalysts provide an additional hydrolysis step to remove them from the reaction product after transesterification. In addition, some of these catalysts require very high temperatures to exert their catalytic effect. Therefore, high energy consumption is another disadvantage of this method, which should be avoided when developing new manufacturing methods.

[0004] US Patent No. 20100197955 discloses a method for producing butanediol dimethacrylate, comprising transesterifying a methacrylic acid ester with butanediol in the presence of a catalyst comprising lithium hydroxide and calcium oxide. This catalyst combination, when used to produce alkyl fatty acid esters, did not produce sufficiently stable and transparent fatty acid ester esters due to the formation of slurry during storage.

[0005] Therefore, the object of the present invention is to provide a catalyst that does not contain tin and titanate, and this catalyst has selectivity and high activity under conditions similar to or even milder than organotin catalyst.In particular, should seek lower reaction temperature (at least≤190 ℃) and start reaction at even lower temperature.In addition, it is desirable to simply separate and remove new catalyst (by a combination of precipitation and filtration).Compared with the reaction product prepared with previous catalyst, the obtained reaction product should have the required specification and sufficient stability in terms of catalyst removal.Implementation in production operation should be effortless.In addition to using the catalyst with better toxicological characteristics, the reduction of energy consumption should also help to achieve a more environmentally friendly production method. Summary of the Invention

[0006] Surprisingly, a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a or 1b with

[0007] R 1 -C(O)OR 2 (Formula 1a)

[0008] R 2 -O(O)CR 3 -C(O)OR 2 (Formula 1b)

[0009] where R 1 and R 3 is a saturated or unsaturated, branched or linear aliphatic or aromatic residue, and R 2 is selected from the group consisting of methyl, ethyl, propyl, isopropyl and n-butyl,

[0010] Using a monofunctional alcohol (b1) having formula 2,

[0011] R 4 -OH (Formula 2),

[0012] where R 4 is a linear or branched, saturated or unsaturated or alkoxylated alkyl-, alkenyl- or alkoxy residue, or

[0013] a polyfunctional alcohol (b2) selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, and 2,3-butylene glycol;

[0014] Treatment in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO), and optionally sodium hypophosphite, produces a clear and stable reaction product.

[0015] Surprisingly, the catalyst combination of lithium hydroxide and magnesium oxide reacts at temperatures well below 100°C, while transesterification with other catalysts (especially tin-containing catalysts) begins at around 150°C. The use of lithium hydroxide and magnesium oxide, which already has higher yields at lower temperatures, is advantageous for operating an energy-efficient process. The transesterification reaction usually stalls at a yield of around 90%, but this yield is then reached earlier with less energy consumption. Despite the lower reaction temperature (which puts less stress on the product and is more energy-efficient), the reaction time is comparable to one of the previous standard methods.

[0016] Furthermore, the further processing of the ester is simplified since the effort to remove the catalyst and the phosphorus as phosphates is much lower. The salts can already be separated very well during the filtration, so that a simple filtration step may be sufficient to purify the product.

[0017] Component a) - Alkyl ester of carboxylic acid

[0018] The part R of the alkyl ester of the monocarboxylic acid according to formula 1a 1 It is a linear, branched, saturated or unsaturated C1 to C36 alkyl group, preferably a linear, branched, saturated or unsaturated C4 to C30 alkyl group, particularly C6 to C24, more particularly C6 to C22, still more particularly C6 to C18, most particularly C8 to C18, preferably C8 to C16, more preferably C8 to C12 and still more preferably C6 to C10 alkyl group.

[0019] 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 selected from the group consisting of methyl, ethyl and isopropyl, and most preferably R 2 It's methyl.

[0020] The moiety R of the alkyl ester having 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, still more particularly C6 to C18, most particularly C8 to C18, preferably C8 to C16, more preferably C8 to C12 and still more preferably C6 to C10 alkyl group. 3 It can also be produced from dimerized fatty acids, polycarboxylic acids obtained by polymerization of unsaturated fatty acids (mainly oleic acid or tall oil fatty acid), so that R 3 Contains an alkyl moiety derived from a C36 dicarboxylic acid.

[0021] Preferred dicarbonates are esters of phthalic acid, terephthalic acid, sebacic acid, azelaic acid, adipic acid and dodecanedioic acid.

[0022] Component b) - alcohol

[0023] Part R of Formula 2 4 It is a linear or branched, saturated or unsaturated or alkoxylated alkyl-, alkenyl- or alkoxy residue, preferably a linear or branched, saturated or unsaturated C2 to C36 alkyl group, more preferably a linear, branched, saturated or unsaturated C3 to C24 alkyl group, most preferably a linear or branched, saturated C4 to C12 alkyl group.

[0024] Specifically, the monofunctional alcohol (b1) is 2-propylheptanol and the polyfunctional alcohol (b2) is glycerol.

[0025] The glycerides (e.g., mono-, di-, and triglycerides) or 2-propyl-heptanol esters prepared according to the process of the invention are particularly suitable for cosmetic formulations. These esters can be incorporated particularly well into various formulations, including liquid mixtures that can be used as oil components or consistency factors, depending on the chain length, branching, and number of double bonds of these esters.

[0026] Esters of 2-propylheptanol with linear or branched, saturated or unsaturated C5-C36 carboxylic acids or C4-C36 dicarboxylic acids, more preferably esters of 2-propylheptanol with linear or branched, saturated or unsaturated C5-C18 carboxylic acids or C4-C18 dicarboxylic acids, most preferably esters of 2-propylheptanol with linear or branched, saturated or unsaturated C6-C12 carboxylic acids, such as 2-propylheptyl-n-butyrate, 2-propylheptyl-isobutyrate, 2-propylheptyl-n-valerate, 2-propylheptyl-isovalerate, 2-propylheptyl-n-hexanoate, 2-propylheptyl-isohexanoate , 2-propylheptyl-n-heptanoate, 2-propylheptyl-isoheptanoate, 2-propylheptyl-isooctanoate, 2-propylheptyl-n-nonanoate, 2-propylheptyl-isononanoate, 2-propylheptyl-n-decanoate, 2-propylheptyl-isodecanoate, 2-propylheptyl-n-undecanoate, 2-propylheptyl-isoundecanoate, 2-propylheptyl-n-undecenoate, 2-propylheptyl-isoundecenoate, 2-propylheptyl-n-dodecanoate and 2-propylheptyl-isododecanoate are preferred reaction products of 2-propylheptanol using the transesterification method of the present invention.

[0027] Catalysts and other additives

[0028] Lithium hydroxide is preferably used as a monohydrate (LiOH*H2O). This monohydrate is available in solid powder form and is therefore easy to handle, depending on the equipment of the reaction apparatus, especially when water should be avoided during the reaction. Therefore, lithium hydroxide powder can be added to the reactants and the amount of water in the reactor is kept to a minimum in order to avoid further drying steps.

[0029] 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 apparatus and the ability to load the raw materials into the reaction vessel. If the necessary drying step is acceptable, adding lithium hydroxide as an aqueous solution avoids the generation of hazardous lithium hydroxide dust.

[0030] It has been shown that when the "reaction mixture" is dried before transesterification, the use of an aqueous solution of lithium hydroxide monohydrate in an amount of 5 to 13 wt%, preferably 8 to 12 wt%, more preferably 10 wt% ± 1 wt%, based on the weight of the aqueous solution of lithium hydroxide monohydrate does not render the process ineffective.

[0031] The amount of lithium hydroxide depends on the alcohol used. For transesterification with monofunctional alcohols, 0.01 to 0.001 mol of lithium hydroxide is used per mol of monofunctional alcohol b1. Since lithium hydroxide is the reactant, this amount is calculated based on the lithium hydroxide rather than the corresponding hydrate. Preferably, 0.008 to 0.002 mol of lithium hydroxide is used per mol of monofunctional alcohol b1, and more preferably 0.005 to 0.003 mol of lithium hydroxide is used per mol of monofunctional alcohol b1.

[0032] For the transesterification with polyfunctional alcohols, 0.08 to 0.001 mol of lithium hydroxide per mol of polyfunctional alcohol b1, preferably 0.04 to 0.001 mol of lithium hydroxide per mol of polyfunctional alcohol b1, more preferably 0.02 to 0.005 mol of lithium hydroxide per mol of polyfunctional alcohol b1 are used.

[0033] Magnesium oxide is added to the reactants in an amount of 0.02 to 0.001 mol magnesium oxide / mol alkyl ester, preferably 0.007 to 0.003 mol magnesium oxide / mol alkyl ester, more preferably 0.006 to 0.004 mol magnesium oxide / mol alkyl ester, in order to achieve an optimal transesterification rate.

[0034] Calcium oxide is known from the prior art to dissolve better in organic environments and to be an effective catalyst. Due to its low solubility, magnesium oxide's use would be disadvantageous in view of its catalytic activity. Surprisingly, despite its low solubility in organic environments, the combination of magnesium oxide and lithium hydroxide works well. Furthermore, it produces a more stable transesterification product that does not produce any precipitation during storage.

[0035] In addition to the catalyst, sodium hypophosphite may optionally be added to the reactants to improve product quality. In a preferred embodiment of the present invention, the process is carried out in the presence of sodium hypophosphite monohydrate in order to improve the color of the resulting reaction product and to achieve a better peroxide value.

[0036] Sodium hypophosphite monohydrate is added in an amount of 0.01 to 0.3 wt.-%, based on the total weight of all educts without catalyst (which is the total weight of the reactants a) alkyl ester of carboxylic acid and b) alcohol (including additionally added raw materials such as inert ingredients, if added), preferably, sodium hypophosphite monohydrate is added in an amount of 0.02 to 0.2 wt.-%, based on the total weight of all educts without catalyst, more preferably in an amount of 0.04 to 0.1 wt.-%, based on the total weight of all educts without catalyst, and most preferably in an amount of 0.04 to 0.06 wt.-%, based on the total weight of all educts without catalyst.

[0037] Therefore, 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).

[0038] Another object of the present invention is a catalyst composition comprising two single catalysts chosen from lithium hydroxide and magnesium oxide (MgO), preferably lithium hydroxide monohydrate and magnesium oxide (MgO). It is relevant that both catalysts are physically separate components, so that doping of the alkaline earth metal-magnesium oxide with the strong base lithium hydroxide is excluded, since such a composition would not properly catalyze the transesterification process.

[0039] For base-catalyzed reactions, MgO is typically doped with alkali metal cations, particularly lithium hydroxide, before adding the catalyst as the sole catalyst to the reaction mixture. This doping process provides formulations that cannot be achieved by simply mixing lithium hydroxide and magnesium oxide.

[0040] For the transesterification of the present invention, more strongly basic active sites are required, so doping MgO with lithium ions is avoided and explicitly excluded from 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 produce catalysts with different activities.

[0041] Preferred catalyst compositions comprise 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.

[0042] Reaction conditions

[0043] Typically, after drying the starting materials in the reactor, the alkyl ester a) and the alcohol b) are transesterified with a catalyst at elevated temperatures up to 190° C., initially at atmospheric pressure and subsequently under vacuum. During the reaction, the alcohol formed is continuously removed. At the end of the reaction, the excess alkyl ester is distilled off.

[0044] The transesterification is carried out at a temperature of 70 to 240°C, preferably below 195°C, specifically 70 to 195°C, in order to reduce energy costs and avoid exposing the product to temperature stress, the most preferred range is 70 to 190°C.

[0045] In a preferred embodiment, the process is carried out in the absence of a solvent, preferably with an essentially water-free educt. The corresponding catalysts can be used in anhydrous form or in the form of their hydrates. When they are added to the educt in the form of an aqueous solution, the mixture is dried before starting the transesterification reaction.

[0046] In another preferred embodiment, the transesterification is carried out in the presence of an inert ingredient, characterized in that it does not undergo transesterification and is an oil of natural origin. Preferably, the inert ingredient is selected from the group consisting of: oil palm (elaeis guiineensis) oil, passionflower (passiflora incarnata) seed oil, olive oil, olus oil, shea butter (butyrospermum parkii), coconut (cocos nucifera) oil, shorea stenoptera 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 oil, rice bran / wheat germ oil, rosehip oil, castor oil (ricinus communis oil), macaba oil, neem oil, Euphorbia oil, and mixtures thereof. More preferably, the inert ingredient is 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, macaba oil, and mixtures thereof. Most preferably, the inert ingredient is selected from the group consisting of coconut oil and / or sunflower oil and / or macaba oil.

[0047] The inert ingredient improves mixing of components a) (alkyl ester) and b) (alcohol), resulting in improved emulsification or solubilization of at least one component. The inert ingredient is not removed during or after the transesterification so that it will be part of the final esterification product.

[0048] A preferred object of the present invention is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0049] R 1-C(O)O-CH3 (Formula 1a),

[0050] where R 1 is a saturated or unsaturated, branched or linear aliphatic residue having C4 to C18 carbon atoms; a monofunctional alcohol (b1) having the formula 2,

[0051] R 4 -OH (Formula 2),

[0052] where R 4 It is a straight chain or branched, saturated or unsaturated alkyl group

[0053] The treatment is carried out in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0054] Another preferred object of the present invention is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1b) with

[0055] H3C-O(O)CR 3 -C(O)O-CH3 (Formula 1b) (Formula 1b)

[0056] where R 3 is a saturated or unsaturated, branched or linear aliphatic residue having C4 to C18 carbon atoms, with a monofunctional alcohol (b1) having formula 2,

[0057] R 4 -OH (Formula 2),

[0058] where R 4 It is a straight chain or branched, saturated or unsaturated alkyl group

[0059] The treatment is carried out in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0060] More preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0061] R 1 -C(O)O-CH3 (Formula 1a),

[0062] where R 1 is a saturated or unsaturated, branched or straight-chain aliphatic residue having C4 to C18 carbon atoms, treated with propylheptanol in the presence of a catalyst of lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0063] Particularly preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0064] R1 -C(O)O-CH3 (Formula 1a),

[0065] where R 1 It is a saturated or unsaturated, branched or straight-chain aliphatic residue having C4 to C18 carbon atoms, treated with propylheptanol in the presence of a catalyst of lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.

[0066] Another preferred object of the present invention is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0067] R 1 -C(O)O-CH3 (Formula 1a),

[0068] where R 1 is a saturated or unsaturated, branched or straight-chain aliphatic residue having C4 to C18 carbon atoms

[0069] A polyfunctional alcohol (b2) is used, the polyfunctional alcohol being selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butylene glycol, 1,4-butylene glycol and 2,3-butylene glycol.

[0070] The treatment is carried out in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0071] Another preferred object of the present invention is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1b) with

[0072] H3C-O(O)CR 3 -C(O)O-CH3 (Formula 1b)

[0073] where R 3 is a saturated or unsaturated, branched or linear 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-butylene glycol, 1,4-butylene glycol and 2,3-butylene glycol

[0074] The treatment is carried out in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0075] More preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0076] R 1 -C(O)O-CH3 (Formula 1a),

[0077] where R 1It is a saturated or unsaturated, branched or linear aliphatic residue having C4 to C18 carbon atoms, treated with glycerol in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0078] Also preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0079] R 1 -C(O)O-CH3 (Formula 1a),

[0080] where R 1 It is a saturated or unsaturated, branched or straight-chain aliphatic residue having C4 to C18 carbon atoms, treated with glycerol in the presence of natural fatty oils and in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

[0081] Particularly preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0082] R 1 -C(O)O-CH3 (Formula 1a),

[0083] where R 1 It is a saturated or unsaturated, branched or linear aliphatic residue having C4 to C18 carbon atoms, treated with glycerol in the presence of a catalyst of lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.

[0084] Also particularly preferred is a transesterification process comprising reacting an alkyl ester (a) of a carboxylic acid of formula 1a) with

[0085] R 1 -C(O)O-CH3 (Formula 1a),

[0086] where R 1 It is a saturated or unsaturated, branched or linear aliphatic residue having C4 to C18 carbon atoms, treated with glycerol in the presence of natural fatty oils and in the presence of catalysts lithium hydroxide and magnesium oxide (MgO) and sodium hypophosphite.

[0087] The crude reaction product has an alkaline pH and must be neutralized for stability reasons and for use in personal care or cosmetic compositions.

[0088] The transesterification process is preferably characterized in that the crude alkaline reaction mixture is neutralized with phosphoric acid or phosphorous acid (H3PO4, H3PO3), preferably with phosphoric acid, to a pH of 6.8±0.2. In the case of phosphoric acid or phosphorous acid (H3PO4, H3PO3), the dissolved lithium and magnesium cations are transferred to the corresponding phosphonium salts, which are insoluble salts in the organic reaction mixture and can then be more easily separated from the reaction product by filtration.

[0089] The further processing of the esters obtained is simplified since the effort to remove the catalyst as phosphate salts is much lower. The salts can already be separated very well during filtration, so that a simple filtration step may be sufficient to purify the product.

[0090] By simple filtration, the catalyst can be removed almost completely, so that the reaction product which cannot be distilled is also substantially free of catalyst residues after filtration alone.

[0091] Examples

[0092] Example 1 - Production of Glycerol-C8 / C10-Ester in Coconut Oil

[0093] Example 1a - Lithium hydroxide in aqueous solution

[0094] Raw materials for Example 1a:

[0095]

[0096] Coconut oil was charged into a reaction vessel at atmospheric pressure and heated to 75° C. Methyl ester was added and then 10 wt % lithium hydroxide solution (LiOH) was pumped into the reactor.

[0097] The mixture was dried for 30 min at 50 mbar or under full pump vacuum at 70-85° C. The reaction vessel was filled with glycerol at a water content of less than 1000 ppm.

[0098] Magnesium oxide (MgO) and sodium hypophosphite were added via a catalock.

[0099] After heating to 190° C., the reaction takes place at atmospheric pressure by distillation of methanol.

[0100] When methanol accumulation ceased, a vacuum ramp was started (ramp start = normal pressure, ramp time = 3 h, full scale = 350 mbar).

[0101] When more than 2000 kg of methanol has accumulated, the distillate yield is reduced and the OHZ (hydroxyl number) and SZ (acid number) are measured every 60 minutes from the start of the vacuum. The distillation of methyl ester (component a1) begins at an OHZ of 50.

[0102] Methyl ester distillation and product filtration:

[0103] The methyl ester distillation was started at 150° C. to 190° C. with a second vacuum ramp (ramp start value = 300 mbar, full scale = 0 mbar (optimum vacuum), ramp time = 1.0 hour).

[0104] After the vacuum ramp is terminated, distillation is continued under full vacuum until no more methyl esters are produced. The vacuum pump is then turned off and the vacuum is released with nitrogen. The color and OHZ are measured.

[0105] The reaction mixture was cooled to 60-75°C and pumped to a finishing vessel. Phosphoric acid (10% in water) was added at 60-75°C while stirring and the pH was measured to reach pH 6.9 ± 0.2.

[0106] The batch was then filtered through activated coal and filter aid (Dicalite Speedplus, (source?)) and bleaching earth (Tonsil Standard 310FF).

[0107] The yield of final product (after filtration) was 12500 kg with a density of 0.909 kg / l.

[0108] The transesterified esters are subsequently deodorized with steam in a countercurrent column.

[0109] Example 1b - Using lithium hydroxide monohydrate in powder form

[0110] Raw materials for Example 1b:

[0111] raw material quantity Refined coconut oil (Charles Daudruy van Cauwenberghe) 7090kg C8-C10M methyl ester (BASF) 7800kg Glycerol 99.5% (BASF) 1335kg Lithium hydroxide monohydrate (Rockwood Lithium Co., Ltd.) 3.25kg Magnesium oxide (Luvomag M072 – Leman Fuss) 9.74kg Sodium hypophosphite monohydrate (Bruntag International) 16.23kg

[0112] The reaction of Example 1a was repeated by adding solid lithium hydroxide monohydrate to the reaction mixture:

[0113] 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 under vacuum until the water content was below 300 ppm.

[0114] Lithium hydroxide monohydrate, magnesium oxide and NaH2PO2 monohydrate were then added in powder form. The transesterification was started at atmospheric pressure by increasing the temperature from 70° C. to 190° C. while distilling off the methanol released.

[0115] The product was further processed according to Example 1a.

[0116] Example 2-2-propyl heptanol octyl ester production

[0117] Example 2a - Lithium hydroxide in 10 wt% aqueous solution

[0118] Raw materials for Example 2a:

[0119]

[0120]

[0121] The reaction vessel was filled with 2-propylheptanol, methyl octanoate and lithium hydroxide solution (LiOH) and dried at 50 mbar and 70-85° C. to a target value of less than 1000 ppm water (<0.1 wt %). The vacuum was released and magnesium oxide (MgO) and sodium hypophosphite monohydrate were added via a catalock.

[0122] Subsequently, the reaction was started at atmospheric pressure by heating the reactor from 70° C. to 190° C. (fractionator 50° C.) while distilling off the released methanol.

[0123] When the methanol accumulation decreased, a vacuum ramp was started (ramp start value = normal pressure, ramp time = 3 h, ramp end value = 350 mbar). The OHZ (hydroxyl number) and SZ (acid number) were measured every 60 minutes from the start of the vacuum.

[0124] After reaching 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 value was below 55 mg KOH / g. The heating was then stopped, the temperature was allowed to drop to 85°C, and methyl ester distillation was started at an OHZ of 50 mg KOH / g.

[0125] refined:

[0126] When the temperature dropped to 65°C, 10 wt% phosphoric acid aqueous solution (85% phosphoric acid was diluted to 10 wt% aqueous solution with demineralized water) was added.

[0127] Add to the reaction mixture and stir for one hour to produce a pH below 7 (6.8 ± 0.2).

[0128] The neutralized product was dried (at 70-85° C. under vacuum). After a residual water content of less than 0.10% (1000 ppm) was reached, the mixture was cooled to 50° C. and filtered using diatomaceous earth and Tonsil Optimum (Clariant) as filter aids.

[0129] The yield obtained was 12.555 kg of 2-propylheptanol octyl ester, which had a density of 0.855.

[0130] Fractionation and deodorization:

[0131] The resulting filtered transesterification product is fractionated, removing unreacted 2-propylheptanol and methyl esters as distillate in a first step and distilling the transesterification product in a second step.

[0132] The esters are then deodorized with steam in a countercurrent column.

[0133] Example 2b - Using lithium hydroxide monohydrate in powder form

[0134] Raw materials for Example 2b:

[0135] raw material quantity Agnique ME 890-GTTS (95% C8) (BASF) 8250kg 2-Propylheptanol (BASF) 7100kg Lithium hydroxide monohydrate (Rockwood Lithium Co., Ltd.) 3.84kg Magnesium oxide (Luvomag M072 – Levman Fuss). 9.21kg Sodium hypophosphite monohydrate (Bruntag International) 7.68kg

[0136] The production of 2-propylheptyl octanoate from Example 2a was repeated by adding solid lithium hydroxide monohydrate to the reaction mixture instead of an aqueous solution: 2-propylheptyl alcohol and methyl octanoate were added to a reaction vessel. The mixture was dried under vacuum at 70°C for approximately 30 minutes until the water content was below 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 distilling off the released methanol.

[0137] When the methanol accumulation decreased, a vacuum ramp was started (ramp start value = normal pressure, ramp time = 3 h, ramp end value = 350 mbar). The OHZ (hydroxyl number) and SZ (acid number) were measured every 60 minutes from the start of the vacuum.

[0138] After reaching 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 value was below 55 mg KOH / g. The heating was then stopped, the temperature was allowed to drop to 85°C, and methyl ester distillation was started at an OHZ of 50 mg KOH / g.

[0139] refined:

[0140] When the temperature dropped to 65°C, 10 wt% phosphoric acid aqueous solution (85% phosphoric acid was diluted to 10 wt% aqueous solution with demineralized water) was added.

[0141] Add to the reaction mixture and stir for one hour to produce a pH below 7 (6.8 ± 0.2).

[0142] The neutralized product was dried (at 70-85° C. under vacuum). After a residual water content of less than 0.10% (1000 ppm) was reached, the mixture was cooled to 50° C. and filtered using diatomaceous earth and Tonsil Optimum (Clariant) as filter aids.

[0143] The yield obtained was 12.555 kg of 2-propylheptanol octyl ester, which had a density of 0.855.

[0144] Fractionation and deodorization:

[0145] The resulting filtered transesterification product is fractionated, removing unreacted 2-propylheptanol and methyl esters as distillate in a first step and distilling the transesterification product in a second step.

[0146] The esters are then deodorized with steam in a countercurrent column.

[0147] Example 3: Storage stability, residual catalyst and evaluation

[0148] Analytical parameters during and after manufacture and before and after storage have been determined according to the following methods:

[0149] Acid value: measured according to ISO 4314

[0150] Peroxide value: Determined according to ISO 3960

[0151] Saponification value: measured according to ISO 3681

[0152] Hydroxyl value: Determined according to DIN 53240

[0153] Hasen color: determined according to DIN ISO 6271

[0154] 3.1 Storage test of transesterification products made with lithium hydroxide monohydrate powder and magnesium oxide at 40°C for 8 months:

[0155] Coco-glyceride of Example 1b:

[0156] Specification <2.0 <3.0 <150 Months at 40°C Acid value Peroxide value Hassan Color (based on) 1 0.35 1.28 100 3 0.37 0.73 108 8 0.30 0.3. 129

[0157] 2-Propylheptyl octanoate of Example 2b:

[0158] Specification <2.0 <1.0 <15 Months at 40°C Acid value Peroxide value Hassan Color 1 0.06 0.02 3 3 0.10 0.09 2 6 0.02 0.02 7 8 0.06 0.02 1

[0159] 3.2 Accelerated 4-week storage test at 50°C of transesterification products made with lithium hydroxide monohydrate-10 wt% aqueous solution and magnesium oxide:

[0160] Coco-glyceride of Example 1a:

[0161]

[0162] 2-Propylheptyl octanoate of Example 2a:

[0163]

[0164] 3.3 Determination of residual catalyst

[0165] After filtration, analytical determinations of lithium, magnesium, sodium and total phosphorus in the transesterification products of Examples 1a, b and 2a, b (according to DIN EN ISO 11885, Fa. Fülling) resulted in values ​​below the quantitative level for all ions and all examples.

[0166] 3.4 Evaluation of results

[0167] It can be confirmed that the use of lithium hydroxide and magnesium oxide as a catalyst mixture simplifies the production process of esters produced by transesterification. The method of the present invention produces esters with sufficient purity and stability, avoiding further washing steps of the transesterification product, which would be necessary when using an organotin-based catalyst. The complicated precipitation and purification of organotin or titanate catalysts and the additional bleaching steps of the reaction product can be avoided, making this production save much more energy and resources compared to the commonly used transesterification with organotin or titanate catalysts. The catalyst comprising lithium hydroxide monohydrate and magnesium oxide can be easily removed, making it impossible to detect residual catalyst in the transesterification reaction product.

Claims

1. A transesterification method, comprising: An alkyl ester of a carboxylic acid of formula 1a or 1b (a) R 1 -C(O)O-R 2 (Formula 1a) R 2 -O(O)C-R 3 -C(O)O-R 2 (Formula 1b) where 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, Using a monofunctional alcohol (b1) having formula 2, R 4 -OH (Formula 2), where R 4 is a linear or branched, saturated or unsaturated or alkoxylated alkyl-, alkenyl- or alkoxy residue, or a polyfunctional alcohol (b2) selected from the group consisting of glycerol, 1,3-propylene glycol, 1,2-propylene glycol, ethylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, and 2,3-butylene glycol; The treatment is carried out in the presence of the catalysts lithium hydroxide and magnesium oxide (MgO) and optionally sodium hypophosphite.

2. The transesterification method according to claim 1, wherein Part R in Formula 1a 1 is a linear, branched, saturated or unsaturated C1-C36 alkyl group, and R in Formula 1b 3 It is a linear, branched, saturated or unsaturated C2-C54 alkyl group.

3. The transesterification method according to claim 1 and / or claim 2, wherein: The monofunctional alcohol (b1) is 2-propylheptanol and / or the polyfunctional alcohol (b2) is glycerol.

4. The transesterification method according to any one of claims 1 to 3, wherein Part R in Formula 1a 1 It is a linear, branched, saturated or unsaturated C4-C18 alkyl group.

5. The transesterification method according to any one of claims 1 to 4, wherein These catalysts contain lithium hydroxide monohydrate (LiOH*H2O) and magnesium oxide (MgO) and optionally sodium hypophosphite monohydrate.

6. The transesterification process according to any one of claims 1 to 5, in the presence of sodium hypophosphite monohydrate (NaH2PO2*H2O) and the catalysts lithium hydroxide monohydrate (LiOH*H2O) and magnesium oxide (MgO).

7. The transesterification method according to any one of claims 1 to 6, characterized in that The transesterification process is carried out at a temperature of 70°C to 240°C, preferably 70°C to 195°C.

8. The transesterification method according to any one of claims 1 to 7, characterized in that 0.01 to 0.001 mol of lithium hydroxide per mol of the monofunctional alcohol (b1) is used.

9. The transesterification method according to any one of claims 1 to 7, characterized in that 0.08 to 0.001 mol of lithium hydroxide is used per mol of the polyfunctional alcohol (b2).

10. The transesterification method according to any one of claims 1 to 9, characterized in that 0.02 to 0.001 mol of magnesium oxide per mol of alkyl ester (a) is used.

11. The transesterification method 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 total weight of all reactants excluding the catalyst.

12. The transesterification method according to any one of claims 1 to 11, characterized in that The crude alkaline reaction mixture was neutralized with phosphoric acid.

13. The transesterification method according to any one of claims 1 to 12, characterized in that The transesterification process is carried out in the presence of an inert ingredient that does not undergo transesterification and is selected from the group consisting of: palm oil, passionflower seed oil, olive oil, orus oil, shea butter, coconut oil, sago palm seed oil, almond oil, avocado oil, borage oil, canola oil, castor oil, chamomile oil, 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 oil, rice bran / wheat germ oil, rosehip oil, castor oil, macaba oil, neem oil, euphorbia oil, and mixtures thereof.

14. A catalyst composition for use in a transesterification process, the catalyst composition comprising a mixture of two single catalysts selected from lithium hydroxide and magnesium oxide (MgO).

15. The catalyst composition of claim 12, comprising lithium hydroxide and magnesium oxide (MgO) in a molar ratio of 1:3 to 3:1.

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