Process for producing dipropylene glycol isomers

Abstract

The present invention relates to a process for producing a novel mixture of dipropylene glycol isomers and to the use of said mixture in various fields.

Description

[Technical Field]

[0001] The present invention relates to a novel process for producing a mixture of dipropylene glycol isomers, to this novel mixture, and to the use of the latter in various fields. [Background technology]

[0002] Dipropylene glycol, also known as oxydipropanol, is usually a mixture of isomers. In fact, dipropylene glycols currently available commercially are typically: 40-60% by weight of 2-(2-hydroxypropoxy)-1-propanol; 30-45% by weight of 1,1'-oxydi-2-propanol; less than 10% by weight of 2,2'-oxydipropanol; wherein the weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0003] Today, dipropylene glycol is obtained industrially as a by-product of monopropylene glycol production by hydrolysis of propylene oxide. This process is energy intensive, as it is typically carried out at 200°C and 15 bar (1500 kPa) pressure. Propylene oxide is a toxic chemical and highly volatile (boiling point 35°C).

[0004] Patent application WO2012 / 154460 discloses a method for producing bio-based dipropylene glycol and tripropylene glycol by acid-catalyzed condensation of bio-based propylene glycol at elevated temperatures. In addition to dipropylene glycol and tripropylene glycol, other chemicals such as 4-methyl-2-ethyl-1,3-dioxolane and propanal are also formed. In the examples, the dipropylene glycol content is up to 12.35% by weight of the reaction product mixture. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need for an improved process for producing dipropylene glycol.

[0006] Applicants have developed a novel process for producing dipropylene glycol that consumes less energy, does not require the use of toxic raw materials, and provides good yields. [Means for solving the problem]

[0007] Accordingly, the present invention relates to a method for producing a mixture of dipropylene glycol isomers, comprising the step of reacting 4-methyl-1,3-dioxolan-2-one with propane-1,2-diol.

[0008] To overcome the drawbacks of the prior art, the process according to the present invention is advantageously carried out without the use of propylene oxide. DETAILED DESCRIPTION OF THE INVENTION

[0009] The mixture of dipropylene glycol isomers includes 1,1'-oxydi-2-propanol, 2-(2-hydroxypropoxy)-1-propanol, and optionally 2,2'-oxydipropanol.

[0010] 1,1'-Oxydi-2-propanol (CAS-No.: 110-98-5), also called 2,2'-dihydroxypropyl ether, is of formula I: [ka]

[0011] 2-(2-hydroxypropoxy)-1-propanol (CAS-No.: 106-62-7), also called 2-hydroxypropyl-2'-hydroxyisopropyl ether, is of formula II: [ka]

[0012] 2,2'-oxydipropanol (CAS-No.: 108-61-2) is of formula (III): [ka]

[0013] 4-Methyl-1,3-dioxolan-2-one is also known as propylene carbonate.

[0014] Propane-1,2-diol is also called propylene glycol or monopropylene glycol.

[0015] Preferably, the molar ratio propane-1,2-diol / 4-methyl-1,3-dioxolan-2-one is at least 1.

[0016] In particular, the molar ratio propane-1,2-diol / 4-methyl-1,3-dioxolan-2-one is between 1 and 5, preferably between 1 and 3.

[0017] In this application, all ranges of values ​​used should be understood to be inclusive limits unless otherwise indicated.

[0018] Advantageously, in the process according to the invention, the reaction is carried out in the presence of a basic catalyst.

[0019] The basic catalyst may be homogeneous or heterogeneous.

[0020] In particular, the basic catalyst is an alkali metal hydroxide, an alkali metal methoxide, an alkali metal carbonate, an alkali metal hydrogen carbonate, sodium aluminate or magnesium oxide.

[0021] More specifically, the alkali metal hydroxide is sodium hydroxide, lithium hydroxide, potassium hydroxide, barium hydroxide and / or magnesium hydroxide.

[0022] More specifically, the alkali metal methoxide is sodium methoxide.

[0023] More specifically, the alkali metal carbonate is potassium carbonate, sodium carbonate, lithium carbonate, barium carbonate or calcium carbonate.

[0024] Preferably, the basic catalyst is sodium hydroxide, sodium methoxide, potassium carbonate or sodium carbonate, more preferably sodium hydroxide or sodium methoxide.

[0025] Preferably, the amount of basic catalyst is at least 0.01 wt. %, more preferably at least 0.05 wt. %, even more preferably at least 0.1 wt. %, based on the weight of propane-1,2-diol.

[0026] The reaction is preferably carried out under stirring and heating.

[0027] Advantageously, in the process according to the invention, the reaction is carried out at a temperature of at least 100°C.

[0028] Preferably, the reaction is carried out at a temperature of at least 120° C., even more preferably at least 140° C. In particular, the reaction is carried out at a temperature of 100 to 200° C., preferably 120 to 180° C.

[0029] Preferably, the reaction mixture is free of water.

[0030] Preferably, the reaction is carried out until the disappearance of 4-methyl-1,3-dioxolan-2-one, which can be controlled by gas chromatography or by infrared.

[0031] Unreacted propane-1,2-diol can be recovered, preferably by distillation.

[0032] Unreacted propane-1,2-diol may be recycled, for example in a subsequent performance of the process according to the invention.

[0033] The process according to the invention is an economically viable process, and in fact makes it possible to obtain a reaction product in which the mixture of dipropylene isomers is at least 25% by weight, preferably at least 35% by weight, based on the weight of the reaction product.

[0034] Advantageously, the process according to the invention further comprises a step of purifying the mixture of dipropylene glycol isomers.

[0035] Preferably, purification is achieved by distillation, such as by molecular distillation, short path distillation, or directly from the reactor.

[0036] Before the purification step and after the reaction step, there may be a step of separating the basic catalyst.

[0037] Advantageously, in the process according to the invention, 4-methyl-1,3-dioxolan-2-one is prepared by reacting propane-1,2-diol with dimethyl carbonate.

[0038] Preferably, the reaction of propane-1,2-diol with dimethyl carbonate is carried out in the presence of a base such as sodium methoxide.

[0039] Preferably, the reaction of propane-1,2-diol with dimethyl carbonate is carried out at a temperature of at least 60°C, more preferably at least 70°C, even more preferably at least 80°C.

[0040] The methanol formed during the reaction can be removed by distillation.

[0041] Advantageously, in the process according to the invention, the propane-1,2-diol is obtained from renewable resources.

[0042] Preferably, the renewable resource is a plant, in particular a vegetable oil.

[0043] More specifically, propane-1,2-diol is obtained from glycerol.

[0044] Therefore, the resulting mixture of dipropylene glycol isomers can contain at least 50% renewable carbon. The determination of the percentage renewable carbon is performed according to ASTM D 6866.

[0045] In one preferred embodiment of the process according to the invention, propane-1,2-diol obtained from renewable resources is reacted with 4-methyl-1,3-dioxolan-2-one prepared from propane-1,2-diol obtained from renewable resources.

[0046] Therefore, the resulting mixture of dipropylene glycol isomers can contain at least 90% renewable carbon. The determination of the percentage renewable carbon is performed according to ASTM D 6866.

[0047] The process according to the invention can be a batch process, a semi-batch process or a continuous process.

[0048] Surprisingly, the dipropylene glycol isomer content obtained from the process according to the invention is different from the isomer content usually obtained from other known processes.

[0049] The present invention also relates to a mixture of dipropylene glycol isomers comprising at least 60% by weight of 1,1'-oxydi-2-propanol and 15% to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, wherein the weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0050] 1,1'-oxydi-2-propanol and 2-(2-hydroxypropoxy)-1-propanol are as described above.

[0051] Preferably, the amount of 1,1'-oxydi-2-propanol is at least 65% by weight, more preferably at least 70% by weight, based on the weight of the mixture of dipropylene glycol isomers.

[0052] Preferably, the amount of 1,1'-oxydi-2-propanol is at most 85% by weight, more preferably at most 80% by weight, based on the weight of the mixture of dipropylene glycol isomers.

[0053] Preferably, the amount of 2-(2-hydroxypropoxy)-1-propanol is from 20% to 40% by weight, more preferably from 20% to 35% by weight, and even more preferably from 20% to 30% by weight, based on the weight of the mixture of dipropylene glycol isomers.

[0054] Advantageously, the mixture of dipropylene glycol isomers according to the invention further comprises 2,2'-oxydipropanol.

[0055] 2,2'-oxydipropanol is as described above.

[0056] Preferred mixtures of dipropylene glycol isomers comprise or consist of: - at least 60% by weight of 1,1'-oxydi-2-propanol; - 15% to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, where the weight percentages are based on the weight of the mixture of dipropylene glycol isomers; optionally 2,2'-oxydipropanol; Here, the weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0057] Preferably, the amount of 2,2'-oxydipropanol is at most 5% by weight, more preferably at most 3% by weight, even more preferably at most 2% by weight, based on the weight of the mixture of dipropylene glycol isomers.

[0058] Preferably, the amount of 2,2'-oxydipropanol is at least 0.05% by weight, more preferably at least 0.1% by weight, even more preferably at least 0.2% by weight, based on the weight of the mixture of dipropylene glycol isomers.

[0059] In one preferred embodiment, the mixture of isomers of dipropylene glycol according to the invention comprises or consists of: - 65-80% by weight of 1,1'-oxydi-2-propanol; - 20-35% by weight of 2-(2-hydroxypropoxy)-1-propanol; - maximum 5% by weight of 2,2'-oxydipropanol; Here, the weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0060] In one particularly preferred embodiment, the mixture of isomers of dipropylene glycol according to the invention comprises or consists of: - 70-80% by weight of 1,1'-oxydi-2-propanol; - 20-30% by weight of 2-(2-hydroxypropoxy)-1-propanol; - maximum 2% by weight of 2,2'-oxydipropanol; Here, the weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0061] Advantageously, in the mixture of dipropylene glycol isomers according to the invention, the dipropylene glycol isomers comprise at least 50% renewable carbon. The determination of the percentage of renewable carbon is carried out in accordance with ASTM D 6866.

[0062] Determining the percentage of renewable carbon, also called the degree of renewability or biobased content, can preferably be carried out according to standard ASTM D 6866 by measuring the level of carbon-14 present in the product. Molecules obtained from renewable sources (from plants, animals or algae) contain a characteristic amount of carbon-14, which distinguishes them from products obtained from fossil sources, which do not contain carbon-14.

[0063] Preferably, in the mixture of dipropylene glycol isomers according to the invention, the dipropylene glycol isomers comprise at least 70% renewable carbon, more preferably at least 90% renewable carbon. The determination of the percentage of renewable carbon is carried out in accordance with ASTM D 6866.

[0064] Advantageously, the process according to the invention makes it possible to obtain a mixture of dipropylene glycol isomers according to the invention. Thus, the mixture of dipropylene glycol isomers according to the invention can be obtained by the process according to the invention.

[0065] The present invention also relates to the use of the mixture of dipropylene glycol isomers according to the invention as a solvent.

[0066] More specifically, mixtures of dipropylene glycol isomers are used as solvents in cosmetics, fragrances, pesticides, antifreezes, inks and / or lubricants.

[0067] Because the mixture of dipropylene glycol isomers is odorless and colorless, it can be used in perfumes; diffusers; skin care products such as creams and lotions; deodorants such as roll-on and stick deodorants; hair care products such as shampoos, conditioners, and coloring products; sun care products; shaving products such as foams, gels, and aftershave lotions; and bath and shower products.

[0068] The mixture of dipropylene glycol isomers according to the invention is advantageously used as a solvent in perfumery, in particular in the storage of perfuming agents.

[0069] In fact, currently commercially available dipropylene glycol usually has a melting point of −20 to −40° C., but the melting point of a mixture of dipropylene glycol isomers is 14 to 20° C. as shown in Example 3.

[0070] This unique feature allows for the storage of the mixture of dipropylene glycol isomers according to the invention and / or the storage of compositions comprising the mixture of dipropylene glycol isomers according to the invention and dipropylene glycol-soluble compounds in solid form at temperatures below 14° C., e.g., in a refrigerator. In particular, fragrances soluble in dipropylene glycol can be stored in solid form at temperatures between 2 and 10° C., e.g., between 4 and 8° C., thus limiting the evaporation of the fragrance. Energy consumption is also limited compared to storage in solid form, which requires the use of a freezer or deep freezer, as with currently commercialized dipropylene glycol, which has a melting point between −40° C. and −20° C.

[0071] The present invention therefore also relates to a perfuming composition comprising a mixture of dipropylene glycol isomers according to the invention and a perfuming agent.

[0072] The fragrance is liquid at atmospheric pressure and 20°C.

[0073] The fragrances may be of natural or synthetic origin.

[0074] Those skilled in the art know how to select and combine fragrance agents to impart fragrance notes to fragrance compositions.

[0075] The fragrance may be selected from chemicals known in the cosmetic art, such as the following chemical classes: alcohols, esters, ketones, aldehydes, ethers, acetates, nitriles, terpenoids, nitrogen-containing heterocycles, sulfur-containing heterocycles, essential oils, and mixtures thereof. Preferably, the fragrance is soluble in the mixture of dipropylene glycol isomers according to the invention.

[0076] Preferably, the fragrance is an oil.

[0077] Advantageously, the fragrance composition according to the invention further comprises a solvent other than dipropylene glycol.

[0078] Preferably, the solvent is water and / or ethanol.

[0079] The fragrance composition may further comprise a surfactant, which in fact can increase the solubility of the fragrance in the fragrance composition if the fragrance is an oil.

[0080] Preferably, the surfactant is PEG-40 hydrogenated castor oil or polysorbate 20.

[0081] The present invention also relates to the use of the mixture of dipropylene glycol isomers according to the invention as a reactive intermediate in the production of plasticizers, polymers and / or resins.

[0082] More specifically, the mixture of dipropylene glycol isomers can preferably be used as a polyol in the production of polymers, such as polyurethanes, or resins, such as polyester or alkyd resins.

[0083] More specifically, a mixture of dipropylene glycol isomers can be preferably used as a phthalate substitute in the manufacture of plasticizers.

[0084] The present invention is further described in the following examples, it will be understood that the invention as claimed is in no way intended to be limited by these examples. [Example]

[0085] Example 1: Method for producing a mixture of dipropylene glycol isomers according to the present invention Three mixtures of dipropylene glycol isomers according to the invention, DPG1, DPG2 and DPG3, were prepared using propane-1,2-diol and 4-methyl-1,3-dioxolan-2-one.

[0086] 1.1 DPG1 DPG1 was prepared using 1 mole of propane-1,2-diol and 1 mole of 4-methyl-1,3-dioxolan-2-one.

[0087] In a five-neck flask equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet, and reflux condenser, 1 mole (76.1 g) of propane-1,2-diol (Radianol 4710 from Oleon) and 0.045 mole (1.8 g) of sodium hydroxide were dissolved by heating to 70° C. Next, 1 mole (102.1 g) of 4-methyl-1,3-dioxolan-2-one (Jeffsol propylene carbonate from Huntsman) was added dropwise over 5 hours at 140° C. with stirring and nitrogen sparging. After the dropwise addition was complete, the mixture was stirred at the same temperature for an additional 5 hours.

[0088] Gas chromatographic analysis was performed on an Agilent column CP 9106 (30 meters) using an FID detector.

[0089] Gas chromatographic analysis of the reaction product showed 31.9% unreacted monopropylene glycol, 53% dipropylene glycol, and 15.1% tripropylene glycol. The percentages are based on the total area represented by the reaction products on the chromatogram.

[0090] Dipropylene glycol was further purified by distillation under vacuum.

[0091] 1.2 DPG2 DPG2 was prepared using 3 moles of propane-1,2-diol and 1 mole of 4-methyl-1,3-dioxolan-2-one in a similar manner to that described above.

[0092] Gas chromatographic analysis of the reaction product was carried out using the same equipment as above.

[0093] Unreacted propane-1,2-diol was 67.7%, dipropylene glycol was 30.3%, and tripropylene glycol was 2%. The percentages are based on the total area represented by the reaction products on the chromatogram.

[0094] Dipropylene glycol was further purified by distillation under vacuum.

[0095] 1.3 DPG3 DPG3 was prepared using propane-1,2-diol and 4-methyl-1,3-dioxolan-2-one, where the 4-methyl-1,3-dioxolan-2-one was prepared in situ.

[0096] 228.3 g of propane-1,2-diol (Radianol 4710 from Oleon) and 135.2 g of dimethyl carbonate were introduced into a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser. 0.228 g of sodium methoxide (Sigma Aldrich) was then added and dissolved by heating to 70 °C. The mixture was stirred and heated to 80 °C until all the dimethyl carbonate had reacted (controlled by gas chromatography). The methanol formed was removed from the mixture by distillation.

[0097] The reaction temperature was increased to 140° C. with stirring and nitrogen bubbling until all the 4-methyl-1,3-dioxolan-2-one had reacted (controlled by gas chromatography).

[0098] Gas chromatographic analysis of the reaction product was carried out using the same equipment as above.

[0099] Unreacted propane-1,2-diol was 36.1%, dipropylene glycol was 49.7%, and tripropylene glycol was 9.4%. The percentages are based on the total area represented by the reaction products on the chromatogram.

[0100] Dipropylene glycol was further purified by distillation under vacuum.

[0101] Example 2: Analysis of a mixture of dipropylene glycol isomers according to the invention The identity and quantity of the dipropylene glycol isomers obtained in Example 1 were determined by gas chromatographic analysis carried out on an Agilent column CP 9106 (30 meters) using an FID detector.

[0102] The results are summarized in Table 1 below.

[0103] [Table 1]

[0104] Example 3: Melting points of mixtures of dipropylene glycol isomers according to the invention To assess the melting point of the mixture of dipropylene glycol isomers according to the invention, a 30 g sample of DPG1 was placed in a closed glass bottle and cooled to −18° C. in a deep freezer for 24 hours.

[0105] A PT100 temperature sensor was then placed into the sample, which became a white solid, and the sample was slowly heated to room temperature.

[0106] At 14°C the sample began to melt, and at 20°C the sample became completely transparent.

Claims

1. A process for producing a mixture of dipropylene glycol isomers, comprising the step of reacting 4-methyl-1,3-dioxolan-2-one with propane-1,2-diol.

2. 10. The method of claim 1, wherein the method is carried out without the use of propylene oxide.

3. 3. The method of claim 1, wherein the reaction is carried out in the presence of a basic catalyst.

4. The method of any one of claims 1 to 3, wherein the reaction is carried out at a temperature of at least 100°C.

5. 5. The method of any one of claims 1 to 4, further comprising purifying the mixture of dipropylene glycol isomers.

6. 6. The method of any one of claims 1 to 5, wherein the 4-methyl-1,3-dioxolan-2-one is prepared by reacting propane-1,2-diol with dimethyl carbonate.

7. 7. The method of any one of claims 1 to 6, wherein the propane-1,2-diol is obtained from renewable resources.

8. A mixture of dipropylene glycol isomers comprising at least 60% by weight of 1,1'-oxydi-2-propanol and 15 to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, wherein the weight percentages are based on the weight of said mixture of dipropylene glycol isomers.

9. 9. The mixture of dipropylene glycol isomers of claim 8, further comprising 2,2'-oxydipropanol.

10. 10. A mixture of dipropylene glycol isomers according to claim 8 or 9, comprising or consisting of: at least 60% by weight of 1,1′-oxydi-2-propanol; - 15% to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, where the weight percentages are based on the weight of said mixture of dipropylene glycol isomers; optionally, 2,2'-oxydipropanol; Here, the weight percentages are based on the weight of said mixture of dipropylene glycol isomers.

11. 11. The mixture of dipropylene glycol isomers according to any one of claims 8 to 10, wherein the dipropylene glycol isomers comprise at least 50% renewable carbon, and the determination of the percentage of renewable carbon is carried out according to ASTM D 6866.

12. Use of the mixture of dipropylene glycol isomers according to any one of claims 8 to 11 as a solvent.

13. A fragrance composition comprising the mixture of dipropylene glycol isomers according to any one of claims 8 to 11 and a fragrance.

14. 14. The fragrance composition of claim 13, further comprising a solvent other than propylene glycol.

15. Use of the mixture of dipropylene glycol isomers according to any one of claims 8 to 11 as a reactive intermediate in the production of plasticizers, polymers and / or resins.

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