Method for preparing dipropylene glycol isomer

Abstract

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

Description

[0001] The present invention relates to a novel method for preparing a dipropylene glycol isomer mixture, the novel mixture and the use thereof in various fields.

[0002] Dipropylene glycol, also known as oxydipropanol, is usually a mixture of isomers. In fact, the dipropylene glycol currently available on the market is a mixture of three isomers, usually containing:

[0003] -40% to 60% by weight of 2-(2-hydroxypropoxy)-1-propanol;

[0004] - 30% to 45% by weight of 1,1'-oxybis-2-propanol;

[0005] - less than 10% by weight of 2,2'-oxybis(propan-1-ol);

[0006] Weight percentages are based on the weight of the dipropylene glycol isomer mixture.

[0007] Today, dipropylene glycol is produced industrially as a byproduct of monopropylene glycol production through the hydrolysis of propylene oxide. This process is energy-intensive and typically operates at 200°C and 15 bar pressure. Propylene oxide is a toxic chemical and highly volatile (boiling point 35°C).

[0008] Patent application WO2012 / 154460 discloses a method for producing bio-derived dipropylene glycol and tripropylene glycol by acid-catalyzed condensation of bio-derived propylene glycol at high temperature. In addition to dipropylene glycol and tripropylene glycol, other chemical substances such as 4-methyl-2-ethyl-1,3-dioxolane and propionaldehyde are also produced. In some examples, the dipropylene glycol content is up to 12.35% by weight of the reaction product mixture.

[0009] Therefore, there is a need for an improved process for preparing dipropylene glycol.

[0010] The applicant has developed a new method for preparing dipropylene glycol, which has low energy consumption, does not require the use of toxic raw materials, and has high yield.

[0011] Therefore, the present invention relates to a method for preparing a dipropylene glycol isomer mixture, comprising the step of reacting 4-methyl-1,3-dioxolane-2-one with 1,2-propylene glycol.

[0012] In order to overcome the disadvantages of the prior art, the process according to the invention is advantageously carried out without the use of propylene oxide.

[0013] The mixture of dipropylene glycol isomers includes 1,1′-oxybis-2-propanol, 2-(2-hydroxypropoxy)-1-propanol, and optionally 2,2′-oxybis(propan-1-ol).

[0014] 1,1'-Oxybis-2-propanol (CAS No. 110-98-5), also known as bis(2-hydroxypropyl) ether, has the chemical formula I:

[0015]

[0016] 2-(2-Hydroxypropoxy)-1-propanol, (CAS No.: 106-62-7), also known as 2-hydroxypropyl-2'-hydroxyisopropyl ether, has the chemical formula II:

[0017]

[0018] 2,2'-Oxybis(propan-1-ol), (CAS No. 108-61-2), chemical formula (III):

[0019]

[0020] 4-Methyl-1,3-dioxolane-2-one is also known as propylene carbonate.

[0021] Propanediol is also known as propylene glycol or monopropylene glycol.

[0022] Preferably, the molar ratio of 1,2-propylene glycol / 4-methyl-1,3-dioxolane-2-one is at least 1.

[0023] Specifically, the molar ratio of 1,2-propylene glycol / 4-methyl-1,3-dioxolane-2-one is between 1 and 5, preferably between 1 and 3.

[0024] In this application, all numerical ranges used are understood to be inclusive unless otherwise stated.

[0025] Advantageously, in the process according to the invention, the reaction is carried out in the presence of a basic catalyst.

[0026] Basic catalysts can be homogeneous or heterogeneous.

[0027] Specifically, 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.

[0028] More specifically, the alkali metal hydroxide is sodium hydroxide, lithium hydroxide, potassium hydroxide, barium hydroxide and / or magnesium hydroxide.

[0029] More specifically, the alkali metal methoxide is sodium methoxide.

[0030] More specifically, the alkali metal carbonate is potassium carbonate, sodium carbonate, lithium carbonate, barium carbonate or calcium carbonate.

[0031] Preferably, the alkaline catalyst is sodium hydroxide, sodium methoxide, potassium carbonate or sodium carbonate, more preferably sodium hydroxide or sodium methoxide.

[0032] 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 1,2-propylene glycol.

[0033] The reaction is preferably carried out under stirring and heating conditions.

[0034] Advantageously, in the process according to the invention, the reaction is carried out at a temperature of at least 100°C.

[0035] Preferably, the reaction is carried out at a temperature of at least 120° C., more preferably at least 140° C. Specifically, the reaction is carried out at a temperature of 100 to 200° C., preferably at a temperature of 120 to 180° C.

[0036] Preferably, the reaction mixture contains no water.

[0037] Preferably, the reaction is carried out until 4-methyl-1,3-dioxolane-2-one disappears. The disappearance of 4-methyl-1,3-dioxolane-2-one can be monitored by gas chromatography or infrared spectroscopy.

[0038] Unreacted 1,2-propylene glycol may be recovered, preferably by distillation.

[0039] Unreacted 1,2-propylene glycol can be recycled, for example for reuse in a subsequent implementation of the process according to the invention.

[0040] The process according to the invention is economically viable. In fact, the process according to the invention makes it possible to obtain a reaction product in which the dipropylene glycol isomer mixture represents at least 25% by weight, preferably at least 35% by weight, of the weight of the reaction product.

[0041] Advantageously, the process according to the invention also comprises a step of purifying the dipropylene glycol isomer mixture.

[0042] Preferably, purification is achieved by distillation, for example by molecular distillation, short path distillation or directly from the reactor.

[0043] Before the purification step and after the reaction step, a step of separating the basic catalyst may be included.

[0044] Advantageously, in the process according to the invention, 4-methyl-1,3-dioxolane-2-one is prepared by reacting 1,2-propylene glycol with dimethyl carbonate.

[0045] Preferably, the reaction between 1,2-propylene glycol and dimethyl carbonate is carried out in the presence of a base such as sodium methoxide.

[0046] Preferably, the reaction between 1,2-propylene glycol and 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.

[0047] The methanol formed during the reaction can be removed by distillation.

[0048] Advantageously, in the process according to the invention, 1,2-propanediol is obtained from renewable resources.

[0049] Preferably, the renewable resource is a plant, in particular a plant oil.

[0050] More specifically, 1,2-propylene glycol is obtained from glycerol.

[0051] Thus, the resulting dipropylene glycol isomer mixture may contain at least 50% renewable carbon, as determined by ASTM D 6866.

[0052] In a preferred embodiment of the process according to the invention, 1,2-propanediol obtained from renewable resources is reacted with 4-methyl-1,3-dioxolane-2-one prepared via 1,2-propanediol obtained from renewable resources.

[0053] Thus, the resulting dipropylene glycol isomer mixture contains at least 90% renewable carbon, as determined in accordance with ASTM D 6866.

[0054] The process according to the present invention may be a batch, semi-batch or continuous process.

[0055] Surprisingly, the dipropylene glycol obtained by the process according to the invention has an isomer content that differs from the isomer content typically obtained with other known processes.

[0056] The present invention also relates to a mixture of dipropylene glycol isomers comprising at least 60% by weight of 1,1'-oxybis-2-propanol and 15% to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, the weight percentages being based on the weight of the dipropylene glycol isomer mixture.

[0057] 1,1′-oxybis-2-propanol and 2-(2-hydroxypropoxy)-1-propanol are as described above.

[0058] Preferably, the amount of 1,1'-oxybis-2-propanol is at least 65 wt%, more preferably at least 70 wt%, based on the weight of the dipropylene glycol isomer mixture.

[0059] Preferably, the amount of 1,1'-oxybis-2-propanol is at most 85% by weight, more preferably at most 80% by weight, based on the weight of the dipropylene glycol isomer mixture.

[0060] Preferably, the amount of 2-(2-hydroxypropoxy)-1-propanol is 20 to 40 wt%, more preferably 20 to 35 wt%, even more preferably 20 to 30 wt%, based on the weight of the dipropylene glycol isomer mixture.

[0061] Advantageously, the dipropylene glycol isomer mixture according to the invention also comprises 2,2′-oxybis(propan-1-ol).

[0062] 2,2'-Oxybis(propan-1-ol) is as described above.

[0063] Preferred dipropylene glycol isomer mixtures include or consist of:

[0064] - at least 60% by weight of 1,1'-oxybis-2-propanol;

[0065] - 15 to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, the weight percentages being based on the weight of the dipropylene glycol isomer mixture;

[0066] - Optionally, 2,2'-oxybis(propan-1-ol);

[0067] Weight percentages are based on the weight of the dipropylene glycol isomer mixture.

[0068] Preferably, the amount of 2,2'-oxybis(propan-1-ol) is at most 5 wt%, more preferably at most 3 wt%, even more preferably at most 2 wt%, based on the weight of the dipropylene glycol isomer mixture.

[0069] Preferably, the amount of 2,2'-oxybis(propan-1-ol) is at least 0.05 wt%, more preferably at least 0.1 wt%, even more preferably at least 0.2 wt%, based on the weight of the dipropylene glycol isomer mixture.

[0070] In a preferred embodiment, the mixture of dipropylene glycol isomers according to the present invention comprises or consists of:

[0071] - 65% to 80% by weight of 1,1'-oxybis-2-propanol;

[0072] -20% to 35% by weight of 2-(2-hydroxypropoxy)-1-propanol;

[0073] - up to 5% by weight of 2,2'-oxybis(propan-1-ol);

[0074] Weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0075] In a particularly preferred embodiment, the mixture of dipropylene glycol isomers according to the present invention comprises or consists of:

[0076] -70% to 80% by weight of 1,1'-oxybis-2-propanol;

[0077] -20% to 30% by weight of 2-(2-hydroxypropoxy)-1-propanol;

[0078] - up to 2% by weight of 2,2'-oxybis(propan-1-ol);

[0079] Weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

[0080] Advantageously, in the mixture of dipropylene glycol isomers according to the invention, the dipropylene glycol isomers contain at least 50% renewable carbon, wherein the percentage of renewable carbon is determined according to ASTM D 6866.

[0081] The percentage of renewable carbon (also called the degree of renewableness or biobased content) is preferably determined by measuring the amount of carbon 14 in the product according to ASTM D6866. Molecules obtained from renewable resources (from plants, animals, or algae) contain a characteristic amount of carbon 14, which distinguishes them from products from fossil resources that do not contain carbon 14.

[0082] Preferably, in the mixture of dipropylene glycol isomers according to the present invention, the dipropylene glycol isomers contain at least 70% renewable carbon, more preferably at least 90% renewable carbon, wherein the renewable carbon percentage is determined according to ASTM D6866.

[0083] Advantageously, the process according to the invention makes it possible to obtain a mixture of dipropylene glycol isomers according to the invention.Thus, a mixture of dipropylene glycol isomers according to the invention can be obtained by the process according to the invention.

[0084] The present invention also relates to the use of the mixture of dipropylene glycol isomers according to the invention as solvent.

[0085] More specifically, mixtures of dipropylene glycol isomers are used as solvents in cosmetics, fragrances, pesticides, de-icing agents, inks, and / or lubricants.

[0086] Because the mixture of dipropylene glycol isomers is odorless and colorless, it is 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 shampoo, conditioner, hair color products), sunscreen products, shaving products (such as foams, gels, aftershave lotions), and bath and shower products.

[0087] The mixture of dipropylene glycol isomers according to the invention is advantageously used as solvent in perfumery, in particular in the storage of perfumery.

[0088] In fact, the melting point of currently commercialized dipropylene glycol is generally between -20°C and -40°C, but the melting point of a mixture of dipropylene glycol isomers is between 14°C and 20°C, as shown in Example 3.

[0089] This property enables the dipropylene glycol isomer mixture of the present invention and / or compositions comprising the dipropylene glycol isomer mixture of the present invention and a dipropylene glycol-soluble compound to be stored in solid form at temperatures below 14°C, for example, in a refrigerator. Specifically, flavoring agents soluble in dipropylene glycol can be stored in solid form at temperatures between 2°C and 10°C, for example, between 4°C and 8°C. This limits evaporation of the flavoring agent. Energy consumption is also lower than the storage of currently commercially available dipropylene glycol (melting point between -40°C and -20°C) in solid form, which requires the use of a freezer or deep freezer.

[0090] The present invention therefore also relates to a perfuming composition comprising the mixture of dipropylene glycol isomers according to the invention and a perfuming agent.

[0091] The fragrance is liquid at 20°C and atmospheric pressure.

[0092] Fragrances are natural or synthetic.

[0093] A person skilled in the art knows how to select and combine perfuming agents in order to impart odor to a perfuming composition.

[0094] The perfume can be selected from chemicals known in the field of perfumery, such as the following chemical classes: alcohols, esters, ketones, aldehydes, ethers, acetates, nitriles, terpenoids, nitrogen-containing heterocyclic compounds, sulfur-containing heterocyclic compounds, essential oils and mixtures thereof. Preferably, the perfume is soluble in the mixture of dipropylene glycol isomers of the present invention.

[0095] Preferably, the flavoring agent is an oil.

[0096] Advantageously, the perfuming composition according to the invention also comprises a solvent other than dipropylene glycol.

[0097] Preferably, the solvent is water and / or ethanol.

[0098] The perfuming composition may also comprise a surfactant. In fact, when the perfuming agent is an oil, a surfactant may enhance the solubility of the perfuming agent in the perfuming composition.

[0099] Preferably, the surfactant is PEG-40 hydrogenated castor oil or polysorbate 20.

[0100] The invention also relates to the use of the mixture of dipropylene glycol isomers according to the invention as a reaction intermediate in the preparation of plasticizers, polymers and / or resins.

[0101] More specifically, mixtures of dipropylene glycol isomers can be used as polyols, preferably for the preparation of polymers (eg polyurethanes) or resins (eg polyester resins or alkyd resins).

[0102] More specifically, mixtures of dipropylene glycol isomers can be used as replacements for phthalates, preferably in the preparation of plasticizers.

[0103] The following examples will further illustrate the present invention. It should be understood that the present invention is not limited to these examples in any way.

[0104] Example 1: Method for preparing a dipropylene glycol isomer mixture according to the present invention

[0105] The three dipropylene glycol isomer mixtures DPG1, DPG2 and DPG3 of the present invention were prepared using 1,2-propylene glycol and 4-methyl-1,3-dioxolane-2-one.

[0106] 1.1DPG1

[0107] DPG1 was prepared using 1 mol of 1,2-propylene glycol and 1 mol of 4-methyl-1,3-dioxolane-2-one.

[0108] In a five-necked flask equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, and reflux condenser, 1 mol (76.1 g) of 1,2-propylene glycol (Radianol 4710, manufactured by Oleon) and 0.045 mol (1.8 g) of sodium hydroxide were added and dissolved by heating to 70°C. Then, with stirring and nitrogen purging, 1 mol (102.1 g) of 4-methyl-1,3-dioxolane-2-one (Jeffsol propylene carbonate, manufactured by Huntsman) was added dropwise over 5 hours at 140°C. After the addition was complete, the mixture was stirred at the same temperature for an additional 5 hours.

[0109] Gas chromatography analysis was performed using an Agilent CP9106 column (30 m) equipped with an FID detector.

[0110] As a result of gas chromatography analysis of the reaction product, unreacted monopropylene glycol accounted for 31.9%, dipropylene glycol accounted for 53%, and tripropylene glycol accounted for 15.1%, the percentages being based on the total area occupied by the reaction products on the chromatogram.

[0111] The dipropylene glycol was further purified by vacuum distillation.

[0112] 1.2DPG2

[0113] DPG2 was prepared using 3 mol of 1,2-propylene glycol and 1 mol of 4-methyl-1,3-dioxolane-2-one using the same method as above.

[0114] The reaction product was subjected to gas chromatography analysis using the same material as above.

[0115] Unreacted 1,2-propylene glycol accounted for 67.7%, dipropylene glycol accounted for 30.3%, and tripropylene glycol accounted for 2%, the percentages being based on the total area represented by the reaction products on the chromatogram.

[0116] The dipropylene glycol was further purified by vacuum distillation.

[0117] 1.3 DPG3

[0118] DPG3 was prepared using 1,2-propylene glycol and 4-methyl-1,3-dioxolane-2-one, wherein 4-methyl-1,3-dioxolane-2-one was prepared in situ.

[0119] 228.3 g of 1,2-propylene glycol (Radiano 14710, manufactured by Oleon) and 135.2 g of dimethyl carbonate (Daxsol dimethyl carbonate, manufactured by UBE) were added to a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and reflux condenser. 0.228 g of sodium methoxide (Sigma Aldrich) was then added and heated to 70°C to dissolve. The mixture was stirred and heated to 80°C until all the dimethyl carbonate had reacted (as monitored by gas chromatography). The resulting methanol was removed from the mixture by distillation.

[0120] The reaction temperature was raised to 140° C. while stirring and bubbling nitrogen until all 4-methyl-1,3-dioxolane-2-one had reacted (controlled by gas chromatography).

[0121] The reaction product was subjected to gas chromatography analysis using the same material as above.

[0122] Unreacted 1,2-propylene glycol accounted for 36.1%, dipropylene glycol accounted for 49.7%, and tripropylene glycol accounted for 9.4%, the percentages being based on the total area represented by the reaction products on the chromatogram.

[0123] The dipropylene glycol was further purified by vacuum distillation.

[0124] Example 2: Analysis of a dipropylene glycol isomer mixture according to the present invention

[0125] The dipropylene glycol isomers obtained in Example 1 were identified and quantitatively analyzed by gas chromatography using an Agilent CP9106 column (30 m) equipped with an FID detector.

[0126] The results are summarized in Table 1 below:

[0127]

[0128] Table 1: Content of mixture of dipropylene glycol isomers DPG1 and DPG2

[0129] Example 3: Melting Point of Dipropylene Glycol Isomer Mixture of the Present Invention

[0130] In order to evaluate the melting point of the dipropylene glycol isomer mixture according to the present invention, a 30 g sample of DPG1 was placed in a sealed glass bottle and cooled to -18°C in a deep freezer and stored for 24 hours.

[0131] Then, place the PT 100 temperature sensor into the sample that has turned into a white solid, and allow the sample to slowly heat to room temperature.

[0132] At 14°C the sample began to melt and at 20°C the sample became completely transparent.

Claims

1. A method for preparing a mixture of dipropylene glycol isomers, comprising the step of reacting 4-methyl-1,3-dioxolane-2-one with 1,2-propylene glycol.

2. The process according to claim 1, wherein the process is carried out without using propylene oxide.

3. The method according to claim 1 or 2, wherein the reaction is carried out in the presence of a basic catalyst.

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

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

6. The process according to any one of claims 1 to 5, wherein the 4-methyl-1,3-dioxolane-2-one is prepared by reacting 1,2-propylene glycol with dimethyl carbonate.

7. The process according to any one of claims 1 to 6, wherein the 1,2-propylene glycol is obtained from renewable resources.

8. A mixture of dipropylene glycol isomers comprising at least 60 weight percent 1,1'-oxybis-2-propanol and 15 to 40 weight percent 2-(2-hydroxypropoxy)-1-propanol, the weight percents being based on the weight of the mixture of dipropylene glycol isomers. 9 . The mixture of dipropylene glycol isomers according to claim 8 , further comprising 2,2′-oxybis(propan-1-ol).

10. The mixture of dipropylene glycol isomers according to claim 8 or 9, comprising or consisting of: - at least 60% by weight of 1,1'-oxybis-2-propanol; - 15% to 40% by weight of 2-(2-hydroxypropoxy)-1-propanol, the weight percentages being based on the weight of the mixture of dipropylene glycol isomers; - Optionally, 2,2'-oxybis(propan-1-ol); Weight percentages are based on the weight of the mixture of dipropylene glycol isomers.

11. The mixture of dipropylene glycol isomers according to any one of claims 8 to 10, wherein the dipropylene glycol isomers contain at least 50% renewable carbon, as determined by 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 perfuming composition comprising the mixture of dipropylene glycol isomers according to any one of claims 8 to 11 and a perfuming agent.

14. Perfuming composition according to 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 reaction intermediate in the preparation of plasticizers, polymers and / or resins.

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