Preparation method of methylallyl alcohol

Abstract

The invention discloses a preparation method of methylallyl alcohol, which comprises the following steps: adding tricarboxylate into a reaction kettle, adding water for dissolving, heating and refluxing; dropwise adding methyl allyl chloride, and controlling the reaction temperature; cooling and filtering to obtain tricarboxylate solid and filtrate for later use; adding the tricarboxylate solid into a sodium hydroxide aqueous solution for reflux hydrolysis, cooling and layering to obtain methylallyl alcohol and tricarboxylate, and after separation, combining the tricarboxylate with the filtrate for recycling. The polycarboxylate obtained after esterification of the ternary carboxylate has small solubility in a solution, and an esterification product is a precipitate and can be naturally separated out; the esterification reaction can be carried out even under the condition of no catalyst, and the reaction is simple and rapid; then, the polybasic carboxylic ester can be separated through simple filtration, so that the emulsification phenomenon of the carboxylic ester in a water layer is overcome; and hydrolyzing the polybasic carboxylic ester to obtain corresponding alcohol and tricarboxylate, rectifying the alcohol to obtain the product methylallyl alcohol, and recycling the tricarboxylate.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis, and specifically to a method for preparing methyl allyl alcohol. Background Technology

[0002] Methyl allyl alcohol is an important organic compound, an unsaturated alcohol, mainly used as an intermediate in organic synthesis for the production of fragrances, resins, etc. There are numerous methods for preparing methyl allyl alcohol.

[0003] One method is to directly hydrolyze methyl allyl chloride under alkaline aqueous conditions. This method is direct and simple, but it produces a relatively high amount of ether byproducts. These byproducts are generated by the reaction of the alcohol obtained from hydrolysis with the unhydrolyzed halogenated hydrocarbons. The content of byproducts is generally more than 20%.

[0004] Another common hydrolysis method involves reacting methyl allyl chloride with a carboxylate, typically a relatively inexpensive acetate or formate, to obtain a carboxylic ester. This carboxylic ester is then hydrolyzed in an alkaline aqueous solution. This two-step process avoids the ether byproducts produced during the direct hydrolysis of haloalkanes. However, this method also has disadvantages: (a) the reaction of haloalkanes with carboxylates requires a relatively expensive monovalent copper catalyst; (b) the resulting carboxylic ester must be separated from the aqueous solution in the reaction system, and the carboxylic ester and aqueous layer are prone to emulsification during this separation process, leading to difficult and time-consuming separation; (c) the recovery and reuse of the carboxylic acid salt is difficult and results in significant losses. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing methyl allyl alcohol, namely, a reaction of a haloalkane with a tricarboxylic acid salt to prepare a tricarboxylic acid ester, followed by hydrolysis to prepare an alcohol.

[0006] This method involves esterifying methyl allyl chloride with a tricarboxylic acid salt to obtain an organic ester compound. The organic ester compound is then separated by precipitation. The organic ester compound is then hydrolyzed with sodium hydroxide solution to obtain an alcohol and a tricarboxylic acid salt. After obtaining the alcohol product, the tricarboxylic acid salt is recovered and reused.

[0007] The characteristics of this method are: the polycarboxylic acid ester obtained after esterification of the tricarboxylic acid salt has low solubility in solution; the esterification product is a precipitate that will naturally precipitate out, affected by the rightward shift of the equilibrium; the esterification reaction can even proceed without a catalyst, and the reaction is simple and rapid; the polycarboxylic acid ester can then be separated by simple filtration, overcoming the emulsification phenomenon of carboxylic acid esters in aqueous layers. Subsequently, the polycarboxylic acid ester is hydrolyzed to obtain the corresponding alcohol and tricarboxylic acid salt; the alcohol is distilled to obtain the product, and the tricarboxylic acid salt is recovered and reused, resulting in a high recovery and reuse rate and low loss of the obtained tricarboxylic acid salt.

[0008] The technical solution of the present invention is as follows: A method for preparing methyl allyl alcohol, the method comprising: 1) Add a tricarboxylate to the reaction vessel, dissolve it in water, and heat under reflux; the tricarboxylate is sodium benzoate or potassium benzoate. 2) Slowly add the haloalkane dropwise while controlling the reaction temperature; the haloalkane is methyl allyl chloride; 3) Cool and filter to obtain a tricarboxylic acid ester solid; keep the filtrate for later use. 4) The solid tricarboxylic acid ester is directly added to an aqueous sodium hydroxide solution, refluxed at 100°C for hydrolysis, and after cooling, it separates into layers to obtain the methyl allyl alcohol and the tricarboxylic acid salt. The tricarboxylic acid salt is then combined with the filtrate for recycling.

[0009] Furthermore, the esterification reactions in steps 1) and 2) are carried out without a catalyst.

[0010] Furthermore, a monovalent copper salt catalyst is added to the esterification reaction in steps 1) and 2); the amount of catalyst used is 0.1-5% of the mass of methyl allyl chloride.

[0011] Furthermore, the reaction temperature for the esterification reaction in steps 1) and 2) is 80-100°C.

[0012] Furthermore, the reaction temperature of the esterification reaction is controlled by the dropping rate of the haloalkanes, and the reaction temperature is not lower than 95°C.

[0013] Furthermore, the molar ratio of the halohydrocarbon to the tricarboxylate is 1:0.3-2.

[0014] Furthermore, the molar ratio of the halohydrocarbon to the tricarboxylic acid salt is 1:0.5-1.

[0015] Furthermore, the sodium tricarboxylic acid salt is sodium pyromellitic acid, sodium trimellitic acid, or sodium isotricarboxylate.

[0016] Furthermore, the tricarboxylic acid ester solid obtained in step 3) is mainly composed of diesterization and trimerization products.

[0017] The beneficial effects of this invention are as follows: (1) This invention uses tricarboxylic acid salts as esterification raw materials with halogenated hydrocarbons for the first time, especially sodium benzoate as raw material, to obtain high melting point tricarboxylic acid esters. In the aqueous reaction system, the esters are precipitated in solid form. The separation of solid esters from the aqueous phase is achieved by simple filtration. This solves the problem that when sodium formate or sodium acetate is used as esterification raw material, the formate esters and acetate esters obtained are oily substances floating on the surface of the water layer, forming an emulsion layer in the middle, which is difficult to separate. (2) The esterification product (tricarboxylic acid ester) in the esterification process of the present invention is a solid and the product is obtained by precipitation. Therefore, the reaction efficiency is relatively high. The reaction can even be carried out without a catalyst. The reaction is even faster with a catalyst, which improves the production efficiency. (3) The sodium tricarboxylate obtained after hydrolysis of the esterification product (tricarboxylic acid ester) of this invention has low saturation in the aqueous layer and easily separates from the obtained alcohol, without an emulsion layer. The separated tricarboxylate can be recycled and reused very simply and conveniently. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0019] The esterification reaction in this invention proceeds as follows: A saturated aqueous solution of a tricarboxylic acid salt is added to a reaction vessel, along with a monovalent copper catalyst. The mixture is stirred and heated to reflux. Then, a haloalkane is slowly added dropwise, maintaining the temperature above 95°C. As the haloalkane is added, a white precipitate continuously forms in the reaction system. The reaction is continued at this temperature for 1 hour until the addition of the haloalkane is complete. The mixture is then cooled and filtered.

[0020] The hydrolysis reaction steps in this invention are as follows: The solid obtained by filtration of the above esterification reaction is not dried, but directly added in batches to an aqueous sodium hydroxide solution, refluxed for 1 hour, cooled and allowed to stand to separate into layers. The upper layer is a crude product alcohol solution, and the lower layer is a semi-dissolved system of water and tribasic acid salt. The crude product alcohol is further purified by distillation to obtain the final product.

[0021] The present invention provides a process for the recovery and reuse of sodium tricarboxylic acid salts: the aqueous layer obtained in the hydrolysis reaction is combined with the filtrate obtained from the esterification reaction, the mixture is heated and refluxed, and a haloalkane is added dropwise to repeat the above esterification reaction.

[0022] The structural formula of the halohydrocarbon in the above esterification reaction is as follows: .

[0023] Preferably, the haloalkane is methyl allyl chloride, and the structure of methyl allyl chloride is as follows: .

[0024] The tricarboxylic acid salts in the above esterification reaction are compounds with three carboxyl groups on their carbon chains, preferably sodium benzoate and potassium benzoate, with the following structures: .

[0025] The sodium benzoate salt is sodium pyromelliticate, sodium isotrimethylbenzene, or sodium trimelliticate, or the potassium salt of the corresponding three. Sodium pyromelliticate is preferred.

[0026] Taking sodium isophthalate as an example, the esterification reaction equation in this invention is as follows: ,or .

[0027] Among them, the esterification reaction products are mainly diesterization products and trimerization products, and both types of products precipitate in the reaction system in the form of precipitates.

[0028] In the above esterification reaction, the molar ratio of methyl allyl chloride to tricarboxylate is 1:0.3-2, preferably 1:0.5-1; During the above esterification reaction, the reaction temperature is 80-100°C, preferably 95-100°C. In the above esterification reaction, the raw material haloalkanes (methyl allyl chloride) are added dropwise to the aqueous solution system of the tricarboxylate. The dropping rate affects the reaction temperature, and the optimal reaction temperature is preferably maintained by the dropping rate. In the above esterification reaction, the reaction system can be without a catalyst; Alternatively, during the above esterification reaction, a catalyst can be added to the reaction system to increase the reaction rate. The catalyst is a Cu salt catalyst, preferably a monovalent Cu salt catalyst. The amount of catalyst used is 0.1-5% of the mass of methyl allyl chloride, preferably 0.5%.

[0029] Esterides (I) and (II) are hydrolyzed to yield an alcohol product (A) and a recyclable sodium carboxylate feedstock (B). The hydrolysis reaction equations are as follows: ,or .

[0030] The alcohol product (A) obtained after hydrolysis is preferably methyl allyl alcohol, and the structure of methyl allyl alcohol is as follows: .

[0031] Example 1 Add 1.38 kg (2 mol) of 40% sodium pyromellitic acid solution to the reactor, add 1.0 g of cuprous chloride, stir and heat to reflux at 100°C.

[0032] 0.27 kg (3.0 mol) of methyl allyl chloride was slowly added dropwise into the reactor. During the dropwise addition, the temperature of the reactor would decrease as methyl allyl chloride was added. The dropwise addition rate was controlled to keep the reaction temperature above 95°C. The dropwise addition was completed in about 1 hour. The reaction was then maintained at 100°C for 1 hour. After cooling and filtration, about 1.25 kg of wet solid and about 0.4 kg of filtrate were obtained.

[0033] 1.25 kg of wet solid was transferred to a new reactor, and 1.2 kg of 10% sodium hydroxide solution was added. The mixture was refluxed for 1 hour, cooled, and separated into layers. The upper layer of crude methyl allyl alcohol, containing approximately 16% water, was separated. The crude product was further purified by distillation to obtain methyl allyl alcohol with a purity greater than 99.5%. Physicochemical characterization of the product: 1H NMR spectroscopy: 1.7 ppm 3H, 4.2 ppm 2H, 4.9 ppm 1H, 5.0 ppm 1H, 2.0 ppm 1H. Example 2

[0034] Add 2.76 kg (4 mol) of sodium trimellitate solution with a mass concentration of 40% to the reactor, add 1.0 g of cuprous chloride, stir and heat to reflux at a temperature of 100°C.

[0035] 0.54 kg (6.0 mol) of methyl allyl chloride was slowly added dropwise into the reactor. During the dropwise addition, the temperature of the reactor would decrease as methyl allyl chloride was added. The dropwise addition rate was controlled to keep the reaction temperature above 95°C. The dropwise addition was completed in about 1 hour. The reaction was then maintained at 100°C for 1 hour. After cooling and filtration, about 2.52 kg of wet solid and about 0.8 kg of filtrate were obtained.

[0036] 2.52 kg of wet solid product was transferred to a new reactor, and 2.5 kg of 10% sodium hydroxide solution was added. The mixture was refluxed for 1 hour, cooled, and separated into layers. The upper layer, containing approximately 15% water, yielded 0.50 kg of crude methyl allyl alcohol. The crude product was further purified by distillation to obtain methyl allyl alcohol with a purity greater than 99.5%. Physicochemical characterization of the product: 1H NMR spectroscopy: 1.7 ppm 3H, 4.2 ppm 2H, 4.9 ppm 1H, 5.0 ppm 1H, 2.0 ppm 1H. Example 3

[0037] Add 2.76 kg (4.0 mol) of 40% sodium pyromellitic acid solution to the reactor, add 0.5 g of cuprous chloride, stir and heat to reflux at 100°C.

[0038] 0.54 kg (6.0 mol) of methyl allyl chloride was slowly added dropwise into the reactor. During the dropwise addition, the temperature of the reactor would decrease as methyl allyl chloride was added. The dropwise addition rate was controlled to keep the reaction temperature above 95°C. The dropwise addition was completed in about 1 hour. The reaction was then maintained at 100°C for 1 hour. After cooling and filtration, about 2.55 kg of wet solid and about 0.8 kg of filtrate were obtained.

[0039] 2.55 kg of wet solid product was transferred to a new reactor, and 2.5 kg of 10% sodium hydroxide solution was added. The mixture was refluxed for 1 hour, cooled, and separated into layers. 0.52 kg of crude methyl allyl alcohol was separated from the upper layer. The crude product was further purified by distillation to obtain methyl allyl alcohol with a purity greater than 99.5%. Physicochemical characterization of the product: 1H NMR spectroscopy: 1.7 ppm 3H, 4.2 ppm 2H, 4.9 ppm 1H, 5.0 ppm 1H, 2.0 ppm 1H. Example 4

[0040] Add 1.38 kg (2 mol) of 40% sodium pyromellitic acid solution to the reactor, stir and heat to reflux at 100°C.

[0041] 0.27 kg (3.0 mol) of methyl allyl chloride was slowly added dropwise into the reactor. During the dropwise addition, the temperature of the reactor would decrease as methyl allyl chloride was added. The dropwise addition rate was controlled to keep the reaction temperature above 95°C. The dropwise addition was completed in about 24 hours. The reaction was then maintained at 100°C for 1 hour. After cooling and filtration, about 1.20 kg of wet solid and about 0.45 kg of filtrate were obtained.

[0042] 1.20 kg of wet solid was transferred to a new reactor, and 1.2 kg of 10% sodium hydroxide solution was added. The mixture was refluxed for 1 hour, cooled, and separated into layers. 0.21 kg of crude methyl allyl alcohol (containing 15% water) was separated from the upper layer. The crude product was further purified by distillation to obtain methyl allyl alcohol with a purity greater than 99.5%. Physicochemical characterization of the product: 1H NMR spectroscopy: 1.7 ppm 3H, 4.2 ppm 2H, 4.9 ppm 1H, 5.0 ppm 1H, 2.0 ppm 1H.

Claims

1. A method for preparing methyl allyl alcohol, characterized in that, The method includes: 1) Add a tricarboxylate to the reaction vessel, dissolve it in water, and heat under reflux; the tricarboxylate is sodium benzoate or potassium benzoate. 2) Slowly add the haloalkane dropwise while controlling the reaction temperature; the haloalkane is methyl allyl chloride; 3) Cool and filter to obtain a tricarboxylic acid ester solid; keep the filtrate for later use. 4) The solid tricarboxylic acid ester is directly added to an aqueous sodium hydroxide solution, refluxed at 100°C for hydrolysis, and after cooling, it separates into layers to obtain the methyl allyl alcohol and the tricarboxylic acid salt. The tricarboxylic acid salt is then combined with the filtrate for recycling.

2. The method for preparing methyl allyl alcohol as described in claim 1, characterized in that, The esterification reactions in steps 1) and 2) are carried out without a catalyst.

3. The method for preparing methyl allyl alcohol as described in claim 1, characterized in that, In steps 1) and 2), a monovalent copper salt catalyst is added to the esterification reaction; the amount of catalyst used is 0.1-5% of the mass of methyl allyl chloride.

4. A method for preparing methyl allyl alcohol according to any one of claims 1-3, characterized in that, The esterification reaction in steps 1) and 2) is carried out at a temperature of 80-100°C.

5. The method for preparing methyl allyl alcohol as described in claim 4, characterized in that, The reaction temperature of the esterification reaction is controlled by the dropping rate of the haloalkane, and the reaction temperature is not lower than 95°C.

6. A method for preparing methyl allyl alcohol according to any one of claims 1-3, characterized in that, The molar ratio of the halohydrocarbon to the tricarboxylic acid salt is 1:0.3-2.

7. The method for preparing methyl allyl alcohol as described in claim 6, characterized in that, The molar ratio of the halohydrocarbon to the tricarboxylic acid salt is 1:0.5-1.

8. A method for preparing methyl allyl alcohol according to any one of claims 1-3, characterized in that, The sodium tricarboxylic acid salt is sodium pyromellitic acid, sodium trimellitic acid, or sodium isotricarboxylic acid.

9. A method for preparing methyl allyl alcohol according to any one of claims 1-3, characterized in that, The tricarboxylic acid ester solids obtained in step 3) are mainly diesterization products and trimerization products.