Synthesis method of octadecanedioic acid

Abstract

The invention discloses a synthesis method of octadecanedioic acid, and belongs to the field of chemical synthesis. The method comprises the following steps: adding phosphorus tribromide and acetonitrile into a three-neck bottle, and heating in a nitrogen atmosphere; then slowly dropwise adding a mixed solution of 1, 12-dodecanediol and DMF (Dimethyl Formamide), and after dropwise adding is completed, heating the reaction solution again and reacting; and cooling the reaction liquid, dropwise adding water, extracting with petroleum ether, washing a petroleum ether layer with a saturated saline solution, adding anhydrous sodium sulfate into the petroleum ether layer, and drying, filtering and concentrating to obtain a faint yellow solid. By constructing a molecular skeleton step by step, accurate regulation and control of an intermediate are realized, and complex side reactions are avoided. According to the method, mild reaction conditions are adopted, special requirements on equipment are effectively reduced, and meanwhile, energy consumption is reduced. In the aspect of raw material selection, expensive or highly toxic substances are replaced with commercialized reagents easy to obtain, and cost controllability and environment friendliness are both considered.

Description

Technical Field

[0001] This invention relates to chemical synthesis, and more particularly to a method for synthesizing octadecanoic acid. Background Technology

[0002] Octadecanedioic acid, as an important chemical raw material, has wide applications in polymer materials, surfactants, and biodegradable materials. Traditional synthesis methods often employ oxidation or halogenated hydrocarbon hydrolysis, which suffer from lengthy reaction steps, numerous byproducts, high energy consumption, and environmental pollution. For example, the oxidation method using cyclohexane as a starting material requires multiple stages of oxidative cracking, resulting in difficult product separation and low yields; while halogenated hydrocarbon hydrolysis easily causes equipment corrosion due to the use of strong acids and bases and generates large amounts of saline wastewater. In recent years, the combined strategy of free radical addition and esterification hydrolysis has simplified the process to some extent, but still faces technical bottlenecks such as poor intermediate stability and difficulty in controlling regioselectivity. Furthermore, the stringent dependence of existing processes on reaction conditions (such as high temperature and high pressure) also limits the feasibility of industrial production. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a mild, simple, green and efficient method for synthesizing octadecanoic acid.

[0004] Technical solution: A method for synthesizing octadecanoic acid, characterized by comprising the following steps: S1. Phosphorus tribromide and acetonitrile were added to a three-necked flask, and the mixture was heated under a nitrogen atmosphere. Then, a mixture of 1,12-dodecanediol and DMF was slowly added dropwise. After the addition was complete, the reaction mixture was heated again and allowed to react. The reaction mixture was then cooled, water was added dropwise, and the mixture was extracted with petroleum ether. The petroleum ether layer was then washed with saturated brine. Anhydrous sodium sulfate was added to the petroleum ether layer for drying. The mixture was filtered, concentrated, and a pale yellow solid was obtained. The reaction equation is as follows: ; S2. In a three-necked flask, add 1,12-dibromododecane, acetonitrile, and tert-butyl acrylate and stir. Then add AIBN and sodium cyanoborohydride. After refluxing for 1 hour, cool the reaction mixture, add a saturated ammonium chloride aqueous solution and stir. Then add water and extract with dichloromethane. After washing with saturated brine, dry the dichloromethane layer with anhydrous sodium sulfate, filter, and concentrate to obtain a pale yellow solid. The reaction equation is as follows: ; S3. In a three-necked flask, di-tert-butyl octadecanoate and hydrochloric acid were added and stirred, and the mixture was heated to react for 4 hours. Then, the mixture was cooled, filtered, rinsed, and dried under vacuum. Toluene was added and the mixture was heated and stirred. Then, the mixture was cooled, filtered, and dried to obtain a white solid, octadecanoic acid. The reaction equation is as follows: .

[0005] Furthermore, in step S1, 535.1 g of phosphorus tribromide (1.98 mol) and 600 ml of acetonitrile were added; 200 g of 1,12-dodecanediol (0.988 mol) and 600 ml of DMF were added dropwise.

[0006] Furthermore, during the extraction process in step S1, the petroleum ether is used for extraction twice, 600 ml each time; the petroleum ether layer is washed twice with saturated saline solution, 100 ml each time.

[0007] Furthermore, in step S2, 100 g of 1,12-dibromododecane (0.305 mol), 500 ml of acetonitrile, and 117.18 g of tert-butyl acrylate (0.914 mol) were added; 1 g of AIBN (6.1 mol) and 114.9 g of sodium cyanoborohydride (1.83 mol) were added.

[0008] Furthermore, in step S2, the extraction is performed twice with dichloromethane, 500 ml each time. The dichloromethane layers are then combined and washed once with 100 ml of saturated saline solution.

[0009] Furthermore, in step S3, 100g of di-tert-butyl octadecanoate (0.234mol) and 400ml of hydrochloric acid (15% concentration) were added; 800ml of toluene was added.

[0010] Beneficial Effects: This invention provides a novel synthetic process for octadecanoic acid, significantly improving synthesis efficiency and product quality. By constructing the molecular skeleton stepwise, precise control of intermediates is achieved, avoiding complex side reactions. The method employs mild reaction conditions, effectively reducing the special requirements for equipment and minimizing energy consumption. In terms of raw material selection, readily available commercial reagents are used instead of expensive or highly toxic substances, balancing cost control and environmental friendliness. Furthermore, the post-processing is rationally designed; high-purity target products can be obtained through simple extraction and crystallization operations, significantly shortening the production cycle. The overall process route is simple and efficient, possessing both scalability and economic viability for industrial production, providing a new technical pathway for green chemical synthesis. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0012] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] Example like Figure 1As shown, a method for synthesizing octadecanoic acid includes: Step 1 In a 2L three-necked flask, phosphorus tribromide (535.1g, 1.98mol) and acetonitrile (600ml) were added. The mixture was stirred, protected under nitrogen, and heated to 50-55℃. A mixture of 1,12-dodecanediol (200g, 0.988mol) and DMF (600ml) was added dropwise, maintaining a temperature of 50-70℃. The reaction was exothermic, so the addition was slow. After the addition was complete, the reaction mixture was heated to 80-85℃ and reacted for 2-3 hours. Samples were taken to monitor the reaction, indicating complete reaction of the starting material. The reaction mixture was cooled to 20-30℃, and 2kg of water was added dropwise, maintaining a temperature of 20-30℃. The mixture was extracted twice with petroleum ether (600ml each time). The petroleum ether layer was then washed twice with saturated brine (100ml each time). The petroleum ether layer was dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 304.8g of a pale yellow solid, with a yield of 94%.

[0014] Step Two In a 2L three-necked flask, 1,12-dibromododecane (100g, 0.305mol), acetonitrile (500ml), and tert-butyl acrylate (117.18g, 0.914mol) were added and stirred. Then, AIBN (1g, 6.1mmol) and sodium cyanoborohydride (114.9g, 1.83mol) were added. The mixture was then refluxed for 1 hour, and samples were taken for monitoring until the reaction was complete. The reaction solution was cooled to 20-25°C, and 300ml of saturated ammonium chloride aqueous solution was added. The mixture was stirred for 30 minutes, and then 500ml of water was added. The mixture was extracted twice with 500ml of dichloromethane each time. The dichloromethane layers were combined, washed once with 100ml of saturated brine, and then dried over anhydrous sodium sulfate. The mixture was filtered, concentrated, and yielded 105g of a pale yellow solid, with a yield of 81%.

[0015] Step 3 In a 1L three-necked flask, add 100g (0.234mol) of di-tert-butyl octadecanoate and 400ml of 15% hydrochloric acid. Stir and heat the reaction mixture to 70-80℃ for 4 hours. Sampling is performed to monitor the reaction; once complete, the reaction proceeds. Cool to 20-25℃, filter the solid, wash three times with water, and dry under vacuum. Then add 800ml of toluene, heat to 100-105℃, stir for 30 minutes, cool to 20-25℃, filter, and dry at 40-50℃ to obtain 64.9g of white solid octadecanoic acid, yield 88%. 1H-NMR (400 MHz, DMSO-d6)δ(ppm):11.98 (s, 2H), 2.29 (t, J = 7.5 Hz, 4H), 1.58 (q, J = 7.0 Hz, 4H), 1.36-1.15 (m, 24H).

[0016] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for synthesizing octadecanoic acid, characterized in that, Includes the following steps: S1. Phosphorus tribromide and acetonitrile were added to a three-necked flask, and the mixture was heated under a nitrogen atmosphere. Then, a mixture of 1,12-dodecanediol and DMF was slowly added dropwise. After the addition was complete, the reaction mixture was heated again and allowed to react. The reaction mixture was then cooled, water was added dropwise, and the mixture was extracted with petroleum ether. The petroleum ether layer was then washed with saturated brine. Anhydrous sodium sulfate was added to the petroleum ether layer for drying. The mixture was filtered, concentrated, and a pale yellow solid was obtained. The reaction equation is as follows: ； S2. In a three-necked flask, add 1,12-dibromododecane, acetonitrile, and tert-butyl acrylate and stir. Then add AIBN and sodium cyanoborohydride. After refluxing for 1 hour, cool the reaction mixture, add a saturated ammonium chloride aqueous solution and stir. Then add water and extract with dichloromethane. After washing with saturated brine, dry the dichloromethane layer with anhydrous sodium sulfate, filter, and concentrate to obtain a pale yellow solid. The reaction equation is as follows: ； S3. In a three-necked flask, di-tert-butyl octadecanoate and hydrochloric acid were added and stirred, and the mixture was heated to react for 4 hours. Then, the mixture was cooled, filtered, rinsed, and dried under vacuum. Toluene was added and the mixture was heated and stirred. Then, the mixture was cooled, filtered, and dried to obtain a white solid, octadecanoic acid. The reaction equation is as follows: 。 2. The method for synthesizing octadecanoic acid according to claim 1, characterized in that, In step S1, 535.1 g of phosphorus tribromide (1.98 mol) and 600 ml of acetonitrile were added; 200 g of 1,12-dodecanediol (0.988 mol) and 600 ml of DMF were added dropwise.

3. The method for synthesizing octadecanoic acid according to claim 1, characterized in that, In step S1, the extraction was performed twice with petroleum ether, 600 ml each time; the petroleum ether layer was washed twice with saturated saline solution, 100 ml each time.

4. The method for synthesizing octadecanoic acid according to claim 1, characterized in that, In step S2, 100 g of 1,12-dibromododecane (0.305 mol), 500 ml of acetonitrile, and 117.18 g of tert-butyl acrylate (0.914 mol) were added; 1 g of AIBN (6.1 mol) and 114.9 g of sodium cyanoborohydride (1.83 mol) were added.

5. The method for synthesizing octadecanoic acid according to claim 1, characterized in that, In step S2, the extraction is performed twice with 500 ml of dichloromethane each time. The dichloromethane layers are then combined and washed once with 100 ml of saturated saline solution.

6. The method for synthesizing octadecanoic acid according to claim 1, characterized in that, In step S3, 100g of di-tert-butyl octadecanoate (0.234mol) and 400ml of hydrochloric acid (15% concentration) were added; 800ml of toluene was added.

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