Synthetic method for co-production of 3-chloropropyne and p-chlorobenzaldehyde

Abstract

The invention relates to the technical field of synthesis of fine chemical products, in particular to a synthesis method for co-production of 3-chloropropyne and p-chlorobenzaldehyde, which comprises the following steps: mixing and heating propargyl alcohol, a solvent, an ionic liquid catalyst, a cocatalyst DMF and a polymerization inhibitor p-tert-butylcatechol, slowly dropwise adding p-chlorobenzylidene dichloride into the mixture, and carrying out heat preservation and stirring, collecting a generated 3-chloropropyne crude product at a tail gas port, cooling after the reaction is finished, and sequentially rectifying the 3-chloropropyne, the residual propargyl alcohol, the residual solvent and a p-chlorobenzaldehyde finished product under reduced pressure through a rectifying tower. The method solves the problems that a toxic and dangerous chemical chlorinating agent is used in the existing 3-chloropropyne production, and a large amount of toxic waste acid gas or low-added-value byproducts are generated; and the problem of low chlorine atom utilization rate of the existing p-chlorobenzaldehyde direct hydrolysis method is solved, and the environmental pollution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical product synthesis, and particularly relates to a synthesis method for co-producing 3-chloropropyne and p-chlorobenzaldehyde. Background Art

[0002] 3-Chloropropyne is an important chemical raw material, mainly used for synthesizing electroplating intermediates, intermediates for pharmaceuticals and pesticides, and can be used to synthesize pharmaceuticals such as eudralazine and pesticides such as prallethrin, and is also an excellent metal corrosion inhibitor and rust inhibitor. p-Chlorobenzaldehyde is mainly used as an intermediate for pharmaceuticals, pesticides, and dyes. In the pharmaceutical aspect, it is used to manufacture phenaglycodol, aminobutyric acid, etc. In the pesticide aspect, it can be used for the synthesis of fungicide tebuconazole, plant growth regulator uniconazole, and insecticide chlorfenapyr.

[0003] The propynol chlorination method is the main production method for 3-chloropropyne, and the chlorinating agents used mainly include thionyl chloride, phosphorus chloride, and phosgene, etc. CN202849284 mentions that phosphorus trichloride reacts with propynol under the condition of using pyridine as an acid-binding agent, and the yield is 85%. This method has defects such as pyridine being a malodorous liquid and being difficult to recover under acidic conditions; CN99802124.5 mentions that propynol is prepared with phosgene under the action of an amide catalyst, and the yield is only about 65%. Moreover, phosgene is a highly toxic substance, with high equipment requirements and relatively complex operations. CN 107473930 B mentions a method of using phosphorus trichloride for chlorination in a tubular reactor, and the yield is only 90%, and there may also be problems such as low-quality by-product phosphorous acid.

[0004] The preparation methods for p-chlorobenzaldehyde mainly include gas-phase oxidation method, liquid-phase oxidation method, electrochemical oxidation method, and chlorination hydrolysis method of p-chlorotoluene. The oxidation method has low conversion rate and selectivity of p-chlorotoluene, and it is difficult to control the degree of oxidation. Currently, the chlorination hydrolysis method of p-chlorotoluene is mainly used in industrial production in China. Under the action of light or initiator, the side-chain methyl of p-chlorotoluene is chlorinated, and then the chlorination product is hydrolyzed in the presence of a catalyst to obtain p-chlorobenzaldehyde. The hydrolysis reaction commonly uses metal halides such as FeCl 3 、CuCl 2 、SnCl 2 or zinc salts as catalysts. The catalyst dosage is large and there is residue in the product, affecting the product color. And the amount of wastewater generated by the process is large, and the safety and environmental protection pressure of the process is large.

[0005] It can be seen from the above production processes of 3-chloropropyne and p-chlorobenzaldehyde that the two products are produced by different production processes respectively, the atomic economy of the reaction is low, and both have low-value by-products or a large amount of waste acid gas generated, which is easy to cause environmental pollution.

[0006] Therefore, there is an urgent need to find a safe and environmentally friendly production method for 3-chloropropyne and p-chlorobenzaldehyde, making it have greater industrial application value. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides a synthesis method for co-producing 3-chloropropyne and p-chlorobenzaldehyde. Using propargyl alcohol as the raw material, under the action of a catalyst, p-chlorobenzal dichloride is chlorinated to obtain 3-chloropropyne and p-chlorobenzaldehyde, solving the problems that toxic and dangerous chemical chlorinating agents are used in the production of existing 3-chloropropyne, and a large amount of toxic waste acid gas or low-value by-products are generated; as well as the problem that the chlorine atom utilization rate of direct hydrolysis of existing p-chlorobenzaldehyde is not high, reducing environmental pollution.

[0008] The present invention is realized through the following technical solutions:

[0009] Provide a synthesis method for co-producing 3-chloropropyne and p-chlorobenzaldehyde. Mix propargyl alcohol, a solvent, an ionic liquid catalyst, a co-catalyst DMF and an inhibitor p-tert-butylcatechol, heat up, and slowly dropwise add p-chlorobenzal dichloride thereto. Keep the temperature and stir, and collect the crude 3-chloropropyne generated at the tail gas port. After the reaction is completed, cool down, and successively distill off 3-chloropropyne, the remaining propargyl alcohol and solvent, and the finished product of p-chlorobenzaldehyde through a rectifying column under reduced pressure.

[0010] In the present invention, the chlorine atom in p-chlorobenzal dichloride undergoes elimination under nucleophilic conditions to generate a carbocation. At the same time, after the hydroxyl group of propargyl alcohol is complexed with the ionic liquid, it attacks the benzyl site to form p-chlorobenzaldehyde and 3-chloropropyne. The nucleophilicity of the lone pair electrons on the oxygen of the co-catalyst DMF can promote the departure of chlorine; the inhibitor p-tert-butylcatechol can inhibit free radical side reactions (such as the polymerization of 3-chloropropyne), avoiding the decomposition of the product.

[0011] Further, during the reduced pressure distillation, the vacuum degree of 3-chloropropyne is 0.07 MPa, and the temperature is 30 - 45 °C; the vacuum degree of the remaining propargyl alcohol and solvent is 0.09 - 0.095 MPa, and the temperature is 60 - 90 °C; the high vacuum of p-chlorobenzaldehyde is 0.098 - 0.1 MPa, and the temperature is about 105 - 125 °C.

[0012] Reaction mixture → First-stage reduced pressure distillation (about 0.07 MPa, temperature 30 - 45 °C) → 3-chloropropyne (product) + remaining components;

[0013] Remaining components → Second-stage reduced pressure distillation (0.09 - 0.095 MPa, temperature 60 - 90 °C) → Solvent and propargyl alcohol mixture + crude p-chlorobenzaldehyde;

[0014] Crude p-chlorobenzaldehyde → Reduced pressure distillation (0.098 - 0.1 MPa, temperature 105 - 125 °C) → p-chlorobenzaldehyde (finished product).

[0015] Preferably, the dropping and heat preservation temperature is 80-90 °C, and heat preservation and stirring are carried out for 2-4 h.

[0016] 80-90 °C is lower than the boiling point of propargyl alcohol, preventing more propargyl alcohol from being carried out by the tail gas during the dropping reaction.

[0017] Furthermore, the molar ratio of propargyl alcohol to p-chlorobenzal dichloride is 1.1-1.5:1.

[0018] Preferably, the molar ratio of propargyl alcohol to p-chlorobenzal dichloride is 1.2-1.3:1.

[0019] Furthermore, the mass ratio of propargyl alcohol to solvent, catalyst, cocatalyst, inhibitor is 1:0.3-0.6:0.05-0.2:0.005-0.01:0.002.

[0020] Preferably, the mass ratio of propargyl alcohol to solvent, catalyst, cocatalyst, inhibitor is 1:0.4-0.5:0.1-0.15:0.01:0.002.

[0021] Furthermore, the solvent is one or more of chlorobenzene, o-dichlorobenzene, xylene.

[0022] The solvent is selected from common and commonly used ones, which play roles such as dilution and uniform mixing, do not participate in the reaction, and the boiling points of the selected solvents are higher than that of propargyl alcohol, so that as little as possible runs away with the tail gas during the reaction process; the raw material ionic liquid has a certain melting point, and the reaction liquid is mixed more uniformly after adding the solvent, and the solvent cannot participate in the reaction; the formed p-aldehyde has a melting point of about 48 °C, which is convenient for the rectification of 3-chloropropyne later.

[0023] Furthermore, the ionic liquid catalyst is one or more of 1-butyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-2,3-dimethylimidazolium bromide.

[0024] Ionic liquid has the property of Lewis acid, can accept the electrons on the chloride ion to form a negatively charged proton, promote the formation of the carbocation of p-chlorobenzal dichloride, and complex with propargyl alcohol; moreover, its oxidizing property is smaller than that of conventional inorganic Lewis acids, preventing the over-oxidation of p-chlorobenzaldehyde.

[0025] Preferably, the ionic liquid catalyst is 1-butyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium bromide.

[0026] Furthermore, the ionic liquid catalyst remaining at the bottom of the rectification still can be recycled for the next batch of synthesis.

[0027] The remaining ionic liquid catalyst after rectification can be recycled 5-12 times to achieve recycling and reduce waste.

[0028] Advantages of the present invention:

[0029] The process of the present invention is clean. Low-toxic solvents and catalysts are used. p-Chlorobenzal chloride is used to avoid the use of dangerous chlorinating agents such as thionyl chloride, phosphorus chloride, and phosgene, reducing the health risks to operators. The ionic liquid has a high biodegradation rate. The reaction is carried out in an acidic environment of the ionic liquid, and Cl- directly participates in the substitution, completely converting p-chlorobenzal chloride into p-chlorobenzaldehyde, avoiding the residue of persistent organic pollutants (POPs). The solvent can be recycled within the circulation system, achieving zero emissions. The catalyst can be recycled 5 to 12 times with its activity remaining >95%, reducing the generation of waste and meeting the requirements of green chemistry and sustainable development. In terms of economy, co-production can reduce raw material consumption. The preparation of p-chlorobenzaldehyde is completed synchronously when synthesizing 3-chloropropyne. Since two products are produced simultaneously in the same reaction step, the atom utilization rate is improved. The efficient use and recycling of the catalyst reduce production costs. By optimizing the separation process, not only high-purity p-chlorobenzaldehyde and 3-chloropropyne are obtained, but also the yields of p-chlorobenzaldehyde and 3-chloropropyne obtained from the reaction are high, making it have greater industrial application value.

[0030] The present invention solves the problems in the prior art that toxic and dangerous chemical chlorinating agents are used in the production of 3-chloropropyne, and a large amount of toxic waste acid gas or low-value by-products are generated; it solves the problem that the chlorine atom utilization rate of direct hydrolysis of p-chlorobenzaldehyde in the prior art is not high, and at the same time reduces environmental pollution; compared with the mainstream industrial production processes of 3-chloropropyne and p-chlorobenzaldehyde in the prior art, the emission reduction of waste acid gas is more than 75%.

[0031] The synthesis method of the present invention realizes zero emission of toxic chlorinating agent waste gas through green solvents, efficient ionic liquid catalysis, and co-production design; the chlorine atom utilization rate is significantly improved compared with the traditional hydrolysis method; all by-products are recycled in a closed loop (propargyl alcohol recycling, solvent recovery, catalyst reuse), achieving the triple goals of efficient resource utilization, environmentally friendly emission, and significant economic benefit improvement. Brief Description of the Drawings

[0032] Figure 1 It is the process flow diagram of the present invention.

[0033] Figure 2 It is the yield table of 3-chloropropyne and p-chlorobenzaldehyde corresponding to different ionic liquid catalysts in Example 2 of the present invention. Detailed Embodiments

[0034] To clearly illustrate the technical features of the present solution, the present solution will be described below through specific embodiments.

[0035] The test materials used in each embodiment of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0036] Embodiment 1:

[0037] To a 1000 ml reaction bottle, add 184.8 g of propargyl alcohol, 56 g of chlorobenzene, 9.3 g of 1-butyl-3-methylimidazolium chloride, 1.8 g of DMF, and 0.37 g of p-tert-butylcatechol. Stir and heat to 80°C. Slowly add 586.5 g of p-chlorobenzylidene chloride dropwise. After the addition is complete, stir at 80°C until the reaction of p-chlorobenzylidene chloride is complete.

[0038] The boiling points of several products in this scheme are quite different, 3-chloropropyne is 58°C, propargyl alcohol is 114.5°C, solvent is 130-180°C, and p-aldehyde is 213°C, so distillation is relatively easy. 3-Chloropropyne is distilled out of the reaction mixture under the conditions of vacuum degree 0.07MPa and temperature 30-45°C; solvent and remaining propargyl alcohol mixture are distilled out at 0.09MPa and temperature 60-80°C; and p-chlorobenzaldehyde is distilled out at 0.1MPa and temperature 105-125°C.

[0039] During the reaction, 56.4 g of crude 3-chloropropyne with a purity of 91.2% was collected from the tail gas outlet; 179.8 g of 3-chloropropyne with a purity of 99.3% was obtained by vacuum distillation of the reaction liquid; and 416.4 g of p-chlorobenzaldehyde with a purity of 99.4% was obtained by distillation. The total yield of 3-chloropropyne was 93.6%, and the yield of p-chlorobenzaldehyde was 98.2%.

[0040] Embodiment 2:

[0041] The operation steps and feeding amount of this example are the same as those of Example 1, and the ionic liquid catalyst is replaced by 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-2,3-dimethylimidazolium bromide or a combination thereof. Figure 2 shown.

[0042] Embodiment 3:

[0043] The residual catalyst from the distillation in Example 1 was applied, and 184.8g of propargyl alcohol, 56g of chlorobenzene, 1.8g of DMF, and 0.37g of p-tert-butylcatechol were added to a 1000ml reaction bottle, and the temperature was raised to 80°C with stirring, and 586.5g of p-chlorobenzylidene dichloride was slowly added dropwise. After the addition was completed, the mixture was kept warm and stirred until the p-chlorobenzylidene dichloride reacted completely. 53.8g of the generated crude 3-chloropropyne was collected, with a purity of 92.4%; 179.1g of 3-chloropropyne was distilled out of the reaction solution under reduced pressure, with a purity of 99.5%; 418.5g of p-chlorobenzaldehyde was distilled out, with a purity of 99.3%. The total yield of 3-chloropropyne was 92.7%, and the yield of p-chlorobenzaldehyde was 98.6%.

[0044] Certainly, the above description is not limited to the above examples. The technical features not described in the present invention can be implemented by or adopted from the prior art, and will not be elaborated here. The above embodiments and the accompanying drawings are only used to illustrate the technical solutions of the present invention and are not a limitation to the present invention. The present invention has been described in detail with reference to the preferred embodiments. Those of ordinary skill in the art should understand that any changes, modifications, additions or substitutions made by those of ordinary skill in the technical field within the essence of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing 3-chloropropyne to produce p-chlorobenzaldehyde, characterized in that: The mixture of propargyl alcohol, solvent, ionic liquid catalyst, co-catalyst DMF and inhibitor p-tert-butylcatechol is heated, and p-chlorobenzyl dichloride is slowly added dropwise thereto. The mixture is stirred at the temperature, and the generated crude 3-chloropropyne is collected at the tail gas outlet. After the reaction is completed, the mixture is cooled, and 3-chloropropyne, the remaining propargyl alcohol and solvent, and the finished p-chlorobenzaldehyde are successively distilled out under reduced pressure through a distillation tower.

2. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: During vacuum distillation, the vacuum degree of 3-chloropropyne is 0.07MPa, and the temperature is 30-45°C; the vacuum degree of the remaining propargyl alcohol and solvent is 0.09-0.095MPa, and the temperature is 60-90°C; the high vacuum degree of p-chlorobenzaldehyde is 0.098-0.1MPa, and the temperature is about 105-125°C.

3. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The temperature for adding and keeping warm is 80-90°C, and stirring is carried out for 2-4 hours.

4. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The molar ratio of propargyl alcohol to p-chlorobenzyl dichloride is 1.1-1.5:

1.

5. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The mass ratio of propargyl alcohol to solvent, catalyst, co-catalyst and inhibitor is 1: 0.3-0.6: 0.05-0.2: 0.005-0.01: 0.

002.

6. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The solvent is one or more of chlorobenzene, o-dichlorobenzene and xylene.

7. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The ionic liquid catalyst is one or more of 1-butyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium bromide and 1-butyl-2,3-dimethylimidazolium bromide.

8. The method for synthesizing 3-chloropropyne and p-chlorobenzaldehyde according to claim 1, characterized in that: The ionic liquid catalyst remaining at the bottom of the distillation kettle can be used for the next batch of synthesis.

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