Synthetic method of long-chain fatty acid

Abstract

The invention provides a synthesis method of long-chain fatty acid, and relates to the technical field of organic synthesis. The synthesis method provided by the invention comprises the following steps: in the presence of alkali and metal oxide, reacting long-chain fatty alcohol at the pressure of 0.1-1.0 MPa and the temperature of 80-250 DEG C to generate the long-chain fatty alcohol, adding water to dissolve the long-chain fatty alcohol, adjusting the solution to be acidic, and extracting and separating to obtain the long-chain fatty acid. The used raw materials are cheap, the reaction cost can be reduced, meanwhile, the operation route is simple, the quality is controllable, large-scale production is easy to carry out, and the prepared product is high in purity and yield.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing long-chain fatty acids. Background Art

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

[0003] In addition, long-chain fatty acids can also be used for metal extraction and separation, drying agents, cosmetics and detergents, engine and gear lubricants, fuel additives, surfactants, emulsifiers, and thickeners. At present, the industrial synthesis methods of long-chain fatty acids mainly include: 1) carbonyl synthesis chemistry, the main form of which is the catalytic addition of carbon monoxide and hydrogen to olefins, but aldehydes will be produced as byproducts; 2) The Soviet Union used normal paraffin to catalyze air oxidation to synthesize branched carboxylic acids. In 1970, the country's total production was 500,000 tons. The reaction usually uses potassium permanganate as a catalyst and air oxidation at high temperature. The mechanism is essentially free radical chemistry, which will produce a series of oxygen-containing compounds such as alcohols, hydroxy acids, aldehydes, ketones, etc.; 3) The simple alkali fusion process has a high reaction temperature, and for branched fatty alcohols, there will be byproducts of elimination into olefins.

[0004] However, the synthesis of long-chain saturated fatty acids currently still faces problems such as harsh reaction conditions, high cost, low yield, complex process routes and low product purity. In addition, the longer the chain, the more uncontrollable the reaction conditions are. Fatty alcohols with branches will produce by-products during oxidation, reducing the reaction yield. How to prepare high-purity long-chain fatty acids simply and efficiently is an issue that needs to be improved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing long-chain fatty acids. The raw materials used are cheap and the reaction cost can be reduced. At the same time, the operation route is simple, the quality is controllable, and it is easy to scale up production. The purity and yield of the obtained product are high.

[0006] The 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°C to generate the long-chain fatty acids, which are then dissolved in water and adjusted to acidity before extraction and separation.

[0007] Optionally, the base 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, ferrosoferric oxide, 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 as shown below:

[0012]

[0013] Wherein, R is hydrogen or an 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, and the acid includes one of 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 method includes: adding an extraction solvent for extraction and then standing 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 the present invention has at least one of the following beneficial effects:

[0020] (1) The raw materials used are cheap and the cost is low;

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

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

[0023] (4) The synthesis method is simple, the raw materials are easily available, and the product purity is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the H NMR spectrum of n-octanoic acid synthesized in Example 1 of the present invention;

[0025] Figure 2 This is the H NMR spectrum of n-heptanoic acid synthesized in Example 2 of the present invention;

[0026] Figure 3 This is the H NMR spectrum of n-hexanoic acid synthesized in Example 3 of the present invention; Figure 4 The present invention provides a synthesis reaction formula of a long-chain fatty acid. DETAILED DESCRIPTION

[0027] In order to make the purpose, 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0028] The invention provides a method for synthesizing long-chain fatty acids. The method comprises the following steps: in the presence of alkali and metal oxides, long-chain fatty alcohols are reacted at 0.1MPa-1.0MPa and 80-250°C to generate the long-chain fatty acids, and then water is added to dissolve the long-chain fatty acids and the long-chain fatty acids are extracted and separated after adjusting the acidity.

[0029] In fact, during the reaction process, the long-chain fatty alcohol is first reacted in a solvent-free alkaline environment with a metal oxide as a catalyst to generate an intermediate product, which is then dissolved in water and adjusted to the acid to generate a crude long-chain fatty acid, which is finally purified by extraction and separation to obtain a pure long-chain fatty acid.

[0030] 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 the long-chain fatty alcohol under the action of the metal oxide to generate an intermediate product during the reaction.

[0031] In fact, the structural formula of the long-chain fatty alcohol used in the present invention is shown below:

[0032]

[0033] Wherein, R is hydrogen 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-heptanol, and n-hexanol.

[0034] Specifically, see Figure 4 The reaction formula of the synthesis method provided by the present invention is as follows:

[0035]

[0036] In some embodiments, when sodium hydroxide is added to the reaction system as a base, the reaction formula is as follows:

[0037]

[0038] 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, ferroferric oxide, manganese oxide, cesium oxide, aluminum oxide, and sodium oxide. In practice, the molar ratio of the long-chain fatty alcohol to the base is 1:(1.1-2.0), and the molar ratio of the long-chain fatty alcohol to the metal oxide is 1:(0.04-0.12).

[0039] In some embodiments, after adding water to dissolve, acid is added to adjust the system pH to 2-3. Specifically, the acid used includes one of 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.

[0040] Specifically, when extracting and separating long-chain fatty acids, the method includes: adding an extraction solvent for extraction, standing for separation, removing the organic phase under reduced pressure, recovering the extraction solvent, and then distilling to obtain the long-chain fatty acids. In fact, the extraction solvent used includes one of ethyl acetate, dichloromethane, ethyl ether, methyl tert-butyl ether, toluene, cyclohexane, and acetone.

[0041] Example 1

[0042] This embodiment 1 provides a method for synthesizing n-octanoic acid, comprising the following steps:

[0043] S1. Add 130 g (1.0 mol) of n-octanol, 42 g (1.05 mol) of sodium hydroxide, 1.68 g (0.03 mol) of calcium oxide, and 2.0 g (0.05 mol) of magnesium oxide into a reaction kettle, heat to 200 °C, stir and react for 4 h, and then cool to room temperature;

[0044] S2. Add 600 mL of deionized water into the reaction system in step S1, stir to dissolve, and then filter to separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3, then add ethyl acetate to extract. After the organic phase is allowed to stand and separate, the ethyl acetate is removed and recovered under reduced pressure, and 125.5 g of pure n-octanoic acid is obtained by distillation under reduced pressure using an oil pump. The purity is detected to be 98%, and the calculated yield is 87%.

[0045] The n-octanoic acid prepared in Example 1 was characterized by H NMR spectroscopy. Figure 1 As shown, the characterization results are: 1 H NMR (CDCl3, 400MHz), δ2.35 (m, J = 7.6Hz, 2H), 1.63 (m, J = 7.3Hz, 2H), 1.40-1.21 (m, 8H), 0.93-0.83 (m, 3H).

[0046] Example 2

[0047] This embodiment 2 provides a method for synthesizing n-heptanoic acid, comprising the following steps:

[0048] S1. Add 116.2 g (1.0 mol) of n-heptanol, 42 g (1.05 mol) of sodium hydroxide, 1.68 g (0.03 mol) of calcium oxide, and 8.6 g (0.05 mol) of cerium oxide into a reaction kettle, heat to 140°C, stir and react for 3 hours, and then cool to room temperature;

[0049] S2. Add 600 mL of deionized water into the reaction system in step S1, stir to dissolve, and then filter to separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3, then add ethyl acetate to extract. After standing to separate the organic phase, remove and recover the ethyl acetate under reduced pressure, and use an oil pump to distill under reduced pressure to obtain 110.6 g of pure heptanoic acid. The purity is detected to be 98%, and the calculated yield is 87%.

[0050] The n-heptanoic acid prepared in Example 2 was characterized by H NMR spectroscopy. Figure 2 As shown, the characterization results are: 1 H NMR (CDCl3, 400MHz), δ2.28 (m, J = 7.6Hz, 2H), 1.56 (m, J = 7.4Hz, 2H), 1.32 -1.17 (m, 6H), 0.87-0.76 (m, 3H).

[0051] Example 3

[0052] This embodiment 3 provides a method for synthesizing n-hexanoic acid, comprising the following steps:

[0053] S1. Add 102 g (1.0 mol) of n-hexanol, 42 g (1.05 mol) of sodium hydroxide, 1.68 g (0.03 mol) of calcium oxide, and 4.0 g (0.05 mol) of zinc oxide into a reaction kettle, heat to 180°C, stir and react for 3 hours, and then cool to room temperature;

[0054] S2. Add 600 mL of deionized water into the reaction system in step S1, stir to dissolve, and then filter to separate. Add 10% hydrochloric acid to the filtrate and adjust the pH of the system to 2-3, then add ethyl acetate for extraction. After standing to separate the organic phase, remove and recover the ethyl acetate under reduced pressure, and use an oil pump to distill under reduced pressure to obtain 104.5 g of pure n-hexanoic acid. The purity is detected to be 98%, and the calculated yield is 90%.

[0055] The n-hexanoic acid prepared in Example 3 was characterized by H NMR spectroscopy. Figure 3 As shown, the characterization results are: 1 H NMR (CDCl3, 400MHz), δ2.35 (m, J = 7.5Hz, 2H), 1.69-1.59 (m, 2H), 1.39-1.26 (m, 4H), 0.95 -0.84 (m, 3H).

[0056] Although the embodiments of the present invention are described in detail above, it is obvious 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 are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for synthesizing long-chain fatty acids, characterized in that: In the presence of alkali and metal oxides, long-chain fatty alcohols are generated by reaction at 0.1MPa-1.0MPa and 80-250°C, and then dissolved in water and adjusted to acidity to obtain long-chain fatty acids through extraction and separation.

2. The synthesis method according to claim 1, characterized in that 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.

3. The synthesis method according to claim 1, characterized in that The metal oxide includes one of zinc oxide, calcium oxide, copper oxide, chromium oxide, cerium oxide, praseodymium oxide, lanthanum oxide, samarium oxide, yttrium oxide, ferrosoferric oxide, manganese oxide, cesium oxide, aluminum oxide, and sodium oxide.

4. The synthesis method according to claim 1, characterized in that: The molar ratio of the long-chain fatty alcohol to the base is 1:(1.1-2.0); the molar ratio of the long-chain fatty alcohol to the metal oxide is 1:(0.04-0.012).

5. The synthesis method according to claim 1, characterized in that The structure of the long-chain fatty alcohol is shown below: Wherein, R is hydrogen or an aliphatic carbon chain, and n is any integer from 2 to 10.

6. The synthesis method according to claim 5, characterized in that The reaction formula of the synthesis method is shown below:

7. The synthesis method according to claim 1, characterized in that After adding water to dissolve, acid is added to adjust the pH of the system to 2-3. The acid includes one of 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.

8. The synthesis method according to claim 1, characterized in that When extracting and separating the long-chain fatty acids, the method includes: adding an extraction solvent for extraction and then standing for separation, removing the organic phase under reduced pressure and recovering the extraction solvent, and then distilling to obtain the long-chain fatty acids.

9. The synthesis method according to claim 8, characterized in that The extraction solvent includes one of ethyl acetate, dichloromethane, ethyl ether, methyl tert-butyl ether, toluene, cyclohexane, acetone, and 2-methyltetrahydrofuran.

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