A method for synthesizing long-chain fatty acids

Abstract

This invention provides a method for synthesizing long-chain fatty acids, relating to the field of organic synthesis technology. The method involves reacting long-chain fatty alcohols at 0.1 MPa–1.0 MPa and 80–250 °C with the participation of a base and metal oxide. The resulting fatty acids are then dissolved in water, adjusted to acidity, and extracted to obtain the long-chain fatty acids. The raw materials used in this invention are inexpensive, reducing reaction costs. Furthermore, the operation route is simple, quality is controllable, and it is easy to scale up for production. The resulting products also have high purity and yield.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and more particularly to a method for synthesizing long-chain fatty acids. Background Technology

[0002] Some long-chain saturated fatty acids have medicinal value and are also important intermediates in pharmaceutical synthesis. Recent studies have shown that some saturated and unsaturated fatty acids have anti-tumor effects. For example, 13-methyltetradecanoic acid (13-MTD), a long-chain saturated fatty acid extracted from soybean fermentation products, is a natural product. Previous studies have shown that small doses of 13-MTD can specifically induce apoptosis in various tumor cells, including breast cancer, prostate cancer, liver cancer cells, and leukemia cells, while having no significant effect on normal cells.

[0003] In addition to these applications, long-chain fatty acids can also be used in metal extraction and separation, as drying agents, cosmetics and detergents, engine and gear lubricants, fuel additives, surfactants, emulsifiers, and thickeners. Currently, the main industrial methods for synthesizing long-chain fatty acids include: 1) carbonyl synthesis chemistry, primarily involving the catalytic addition of carbon monoxide and hydrogen to olefins, but this produces aldehydes as a byproduct; 2) the synthesis of branched carboxylic acids via air oxidation catalyzed by n-paraffin, typically using potassium permanganate as a catalyst at high temperatures. The mechanism is essentially free radical chemistry, producing a series of oxygen-containing compounds such as alcohols, hydroxy acids, aldehydes, and ketones; 3) the simple alkali fusion process, which involves high reaction temperatures and, for branched fatty alcohols, the elimination to olefins as a byproduct.

[0004] However, the synthesis of long-chain saturated fatty acids currently faces challenges such as demanding reaction conditions, high costs, low yields, complex processes, and low product purity. Furthermore, the longer the chain, the more uncontrollable the reaction conditions become, and branched fatty alcohols can produce byproducts during oxidation, further reducing the reaction yield. Therefore, finding a simple and efficient method to prepare high-purity long-chain fatty acids is a pressing issue that needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing long-chain fatty acids, which uses inexpensive raw materials to reduce reaction costs, while the operation route is simple, the quality is controllable and easy to scale up, and the resulting product has high purity and yield.

[0006] The present invention provides a method for synthesizing long-chain fatty acids. In the presence of alkali and metal oxides, long-chain fatty alcohols are reacted at 0.1MPa-1.0MPa and 80-250℃ to generate fatty acids. After being dissolved in water and adjusted to acidity, the fatty acids are extracted and separated.

[0007] Optionally, the alkali includes one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, copper hydroxide, lithium hydroxide, aluminum hydroxide, zinc hydroxide, and iron hydroxide.

[0008] Optionally, the metal oxide includes one of zinc oxide, calcium oxide, copper oxide, chromium oxide, cerium oxide, praseodymium oxide, lanthanum oxide, samarium oxide, yttrium oxide, iron tetroxide, manganese oxide, cesium oxide, aluminum oxide, and sodium oxide.

[0009] Optionally, the molar ratio of the long-chain fatty alcohol to the base is 1:(1.1-2.0).

[0010] Optionally, the molar ratio of the long-chain fatty alcohol to the metal oxide is 1:(0.04-0.12).

[0011] Optionally, the structure of the long-chain fatty alcohol is shown in the following formula:

[0012] ;

[0013] Where R is a hydrogen or aliphatic carbon chain, and n is any integer from 2 to 10.

[0014] Optionally, the reaction formula of the synthesis method is shown below:

[0015] .

[0016] Optionally, after dissolving in water, an acid is added to adjust the pH of the system to 2-3. The acid includes one of the following: a hydrochloric acid solution with a concentration of 10%-30%, a sulfuric acid solution with a concentration of 3mol / L-6mol / L, and a phosphonic acid solution with a concentration of 1mol / L-6mol / L.

[0017] Optionally, when extracting and separating long-chain fatty acids, the process includes: adding an extraction solvent for extraction and allowing the mixture to stand for separation, removing the organic phase under reduced pressure and recovering the extraction solvent, and then distilling to obtain the long-chain fatty acids.

[0018] Optionally, the extraction solvent includes one of ethyl acetate, dichloromethane, diethyl ether, methyl tert-butyl ether, toluene, cyclohexane, acetone, and 2-methyltetrahydrofuran.

[0019] The preparation method provided by this invention has at least one of the following beneficial effects:

[0020] (1) The raw materials used are inexpensive, resulting in low costs;

[0021] (2) The route is simple to operate, the quality is controllable, and it is suitable for large-scale production;

[0022] (3) Organic solvents can be recycled, reducing cost losses;

[0023] (4) The synthesis method is simple, the raw materials are readily available, and the product has high purity. Attached Figure Description

[0024] Figure 1 The above is the 1H NMR spectrum of octanoic acid synthesized in Example 1 of this invention;

[0025] Figure 2 The above is the 1H NMR spectrum of the n-heptanoic acid synthesized in Example 2 of this invention;

[0026] Figure 3 The above is the 1H NMR spectrum of the hexanoic acid synthesized in Example 3 of this invention;

[0027] Figure 4 This invention provides a synthetic reaction formula for long-chain fatty acids. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0029] This invention provides a method for synthesizing long-chain fatty acids. The method involves reacting long-chain fatty alcohols at 0.1 MPa-1.0 MPa and 80-250 °C with the participation of alkali and metal oxides to generate the fatty acids. The fatty acids are then dissolved in water, adjusted to acidity, and extracted to obtain the long-chain fatty acids.

[0030] In fact, during the reaction process, long-chain fatty alcohols are first reacted in a solvent-free alkaline environment with metal oxides as catalysts to generate intermediate products. Then, after dissolving in water and adjusting the acidity, crude long-chain fatty acids are generated. Finally, pure long-chain fatty acids are obtained by extraction and separation.

[0031] In some embodiments, the base used includes one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, copper hydroxide, lithium hydroxide, aluminum hydroxide, zinc hydroxide, and iron hydroxide. In fact, the base can react with long-chain fatty alcohols in the presence of metal oxides during the reaction to generate intermediate products.

[0032] In fact, the structural formula of the long-chain fatty alcohol used in this invention is shown below:

[0033] ;

[0034] Where R is a hydrogen atom or an aliphatic carbon chain, and n is any integer from 2 to 10. Specifically, the long-chain aliphatic alcohol can be one of n-octanol, n-heptol, or n-hexanol.

[0035] Specifically, see Figure 4 The reaction formula of the synthesis method provided by the present invention is as follows:

[0036] .

[0037] In some embodiments, when sodium hydroxide is added as a base to the reaction system, the reaction formula is as follows:

[0038] ;

[0039] .

[0040] In some embodiments, the metal oxide used includes one of zinc oxide, calcium oxide, copper oxide, chromium oxide, cerium oxide, praseodymium oxide, lanthanum oxide, samarium oxide, yttrium oxide, iron oxide, manganese oxide, cesium oxide, aluminum oxide, and sodium oxide. In practice, the molar ratio of long-chain fatty alcohol to base is 1:(1.1-2.0), and the molar ratio of long-chain fatty alcohol to metal oxide is 1:(0.04-0.12).

[0041] In some embodiments, after dissolving in water, acid is added to adjust the pH of the system to 2-3. Specifically, the acid used includes one of the following: a hydrochloric acid solution with a concentration of 10%-30%, a sulfuric acid solution with a concentration of 3 mol / L-6 mol / L, or a phosphonic acid solution with a concentration of 1 mol / L-6 mol / L.

[0042] Specifically, the extraction and separation of long-chain fatty acids includes: adding an extraction solvent for extraction, allowing the mixture to stand for separation, removing the organic phase under reduced pressure and recovering the extraction solvent, and then distilling to obtain the long-chain fatty acids. In practice, the extraction solvents used include one of ethyl acetate, dichloromethane, diethyl ether, methyl tert-butyl ether, toluene, cyclohexane, and acetone.

[0043] Example 1

[0044] This embodiment 1 provides a method for synthesizing octanoic acid, including the following steps:

[0045] S1. Add 130g (1.0mol) n-octanol, 42g (1.05mol) sodium hydroxide, 1.68g (0.03mol) calcium oxide, and 2.0g (0.05mol) magnesium oxide to the reaction vessel, heat to 200℃ and stir for 4h, then cool to room temperature;

[0046] S2. Add 600 mL of deionized water to the reaction system in step S1, stir to dissolve, filter and separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3. Add ethyl acetate for extraction. After standing to separate the organic phase, remove and recover ethyl acetate under reduced pressure. Use an oil pump to distill under reduced pressure to obtain 125.5 g of pure n-octanoic acid. The purity was tested to be 98%, and the yield was calculated to be 87%.

[0047] The octanoic acid obtained in Example 1 was characterized by 1H NMR spectroscopy as follows: Figure 1 As shown, the characterization results are as follows: 1 H NMR (CDCl3, 400 MHz), δ2.35 (m, J = 7.6 Hz, 2H), 1.63 (m, J = 7.3 Hz, 2H), 1.40-1.21 (m, 8H), 0.93-0.83 (m, 3H).

[0048] Example 2

[0049] This embodiment 2 provides a method for synthesizing n-heptanoic acid, including the following steps:

[0050] S1. Add 116.2g (1.0mol) n-heptanol, 42g (1.05mol) sodium hydroxide, 1.68g (0.03mol) calcium oxide and 8.6g (0.05mol) cerium oxide to the reaction vessel, heat to 140℃ and stir for 3h, then cool to room temperature;

[0051] S2. Add 600 mL of deionized water to the reaction system in step S1, stir to dissolve, filter and separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3. Add ethyl acetate for extraction. After standing to separate the organic phase, remove and recover ethyl acetate under reduced pressure. Use an oil pump to distill under reduced pressure to obtain 110.6 g of pure n-heptanoic acid. The purity was tested to be 98%, and the yield was calculated to be 87%.

[0052] The n-heptanoic acid prepared in Example 2 was characterized by 1H NMR spectroscopy as follows: Figure 2 As shown, the characterization results are as follows: 1 H NMR (CDCl3, 400 MHz), δ2.28 (m, J = 7.6 Hz, 2H), 1.56 (m, J = 7.4 Hz, 2H), 1.32 -1.17 (m, 6H), 0.87 -0.76 (m, 3H).

[0053] Example 3

[0054] This embodiment 3 provides a method for synthesizing hexanoic acid, including the following steps:

[0055] S1. Add 102g (1.0mol) n-hexanol, 42g (1.05mol) sodium hydroxide, 1.68g (0.03mol) calcium oxide, and 4.0g (0.05mol) zinc oxide to the reaction vessel, heat to 180℃ and stir for 3h, then cool to room temperature;

[0056] S2. Add 600 mL of deionized water to the reaction system in step S1, stir to dissolve, filter and separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3. Add ethyl acetate for extraction. After standing to separate the organic phase, remove and recover ethyl acetate under reduced pressure. Use an oil pump to distill under reduced pressure to obtain 104.5 g of pure hexanoic acid. The purity was tested to be 98%, and the yield was calculated to be 90%.

[0057] The hexanoic acid prepared in Example 3 was characterized by 1H NMR spectroscopy as follows: Figure 3 As shown, the characterization results are as follows: 1 H NMR (CDCl3, 400 MHz), δ2.35 (m, J = 7.5 Hz, 2H), 1.69-1.59 (m, 2H), 1.39-1.26 (m,4H), 0.95 -0.84 (m, 3H).

[0058] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for the synthesis of n-octanoic acid, characterized by, Comprising the following steps: S1, 130g n-octanol, 42g sodium hydroxide, 1.68g calcium oxide, 2.0g magnesium oxide were added into the reaction kettle, and the temperature was raised to 200℃ and stirred for 4h, then cooled to room temperature; S2, 600mL deionized water was added into the reaction system in step S1, stirred and dissolved, then filtered and separated, 10% hydrochloric acid was added to the filtrate to adjust the pH to 2-3, then extracted with ethyl acetate, separated the organic phase, then removed and recovered ethyl acetate under reduced pressure, and then distilled under reduced pressure using an oil pump to obtain 125.5g of n-octanoic acid pure product.

2. A method of synthesizing n-heptanoic acid, characterized by, Comprising the following steps: S1, 116.2g n-heptanol, 42g sodium hydroxide, 1.68g calcium oxide, 8.6g cerium oxide were added into the reaction kettle, and the temperature was raised to 140℃ and stirred for 3h, then cooled to room temperature; S2, 600mL deionized water was added into the reaction system in step S1, stirred and dissolved, then filtered and separated, 10% hydrochloric acid was added to the filtrate to adjust the pH to 2-3, then extracted with ethyl acetate, separated the organic phase, then removed and recovered ethyl acetate under reduced pressure, and then distilled under reduced pressure using an oil pump to obtain 110.6g of n-heptanoic acid pure product.

3. A method of synthesizing n-hexanoic acid, characterized by, Comprising the following steps: S1, 102g n-hexanol, 42g sodium hydroxide, 1.68g calcium oxide, 4.0g zinc oxide were added into the reaction kettle, and the temperature was raised to 180℃ and stirred for 3h, then cooled to room temperature; S2, 600mL deionized water was added into the reaction system in step S1, stirred and dissolved, then filtered and separated, 10% hydrochloric acid was added to the filtrate to adjust the pH to 2-3, then extracted with ethyl acetate, separated the organic phase, then removed and recovered ethyl acetate under reduced pressure, and then distilled under reduced pressure using an oil pump to obtain 104.5g of n-hexanoic acid pure product.

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