A method for preparing 1,1,1,2,3-pentachloropropane

Abstract

The invention provides a method for preparing 1,1,1,2,3-pentachloropropane, and belongs to the field of organic synthesis. The method uses 1,1,1,3,3-pentachloropropane as a raw material, and 1,1,1,3,3-pentachloropropane and nitrogen are fed into an isomerization reactor in the form of a mixed gas by a prepared isomerization catalyst, and the crude product of 1,1,1,2,3-pentachloropropane is obtained, and the unreacted product is re-fed for reaction, and 1,1,1,2,3-pentachloropropane is purified. In the present invention, a method for preparing 1,1,1,2,3-pentachloropropane by one-step isomerization of 1,1,1,3,3-pentachloropropane, the catalyst has a long service life, the product is simply separated from the catalyst, and there is no need to use a complex reaction instrument and process, the yield of 1,1,1,2,3-pentachloropropane is improved, and it can be used for a continuous production method, the process is simple, and it is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and in particular relates to a method for preparing 1,1,1,2,3-pentachloropropane. Background Art

[0002] 1,1,1,2,3-pentachloropropane is an important intermediate for the synthesis of 1,1,2,3-tetrachloropropene. 1,1,2,3-tetrachloropropene is the main intermediate for the synthesis of a new generation of environmentally friendly refrigerant HFO-1234yf and the preparation of the pesticide herbicide chlorpyrifos. How to synthesize 1,1,1,2,3-pentachloropropane efficiently and in an environmentally friendly way has attracted widespread attention.

[0003] At present, there are two main routes for preparing 1,1,1,2,3-pentachloropropane depending on the precursor: (1) using trichloropropene (including 1,1,3-trichloropropene or 3,3,3-trichloropropene or a mixture thereof) as the precursor to synthesize 1,1,1,2,3-pentachloropropane through chlorination; (2) using 1,1,1,3-tetrachloropropane as the precursor to synthesize 1,1,1,2,3-pentachloropropane through direct chlorination. At present, the preparation of 1,1,1,2,3-pentachloropropane mainly adopts the traditional kettle or tower reactor for reaction.

[0004] The traditional 1,1,1,2,3-pentachloropropane synthesis process uses dehydrochlorination first, and then adds chlorine to react when the dehydrochlorination reaction is completed or to a certain extent. The reaction temperatures of the two are inconsistent (the dehydrochlorination reaction temperature must be higher than the chlorination temperature), which is difficult to control during actual operation. On the other hand, trichloropropylene is prone to produce high-boiling substances / polymers during the reaction, which deactivates the catalyst, reduces the product yield, and makes subsequent separation and purification difficult, which is not conducive to industrial production and operation.

[0005] Chinese patent CN104058925B discloses a method in which a certain filler is filled in a tubular reactor, and the raw material trichloropropene (1,1,3-trichloropropene or 3,3,3-trichloropropene or a mixture thereof) reacts with chlorine at 25°C and a residence time of 0.5h to produce 1,1,1,2,3-pentachloropropane in a liquid phase chlorination reaction, with a conversion rate of 99.1% and a selectivity of up to 98.5%. The reaction does not require illumination or a catalyst. Although the operating conditions of this method are relatively simple, the reaction residence time is too long, the device occupies a large area, and the production efficiency is low.

[0006] Chinese patent CN104163750A discloses a method for synthesizing 1,1,1,2,3-pentachloropropane, which uses trichloropropylene or 1,1,1,3-tetrachloropropane as a precursor, and introduces oxygen and HCl under the action of an oxychlorination catalyst (main active ingredient CuCl2) to obtain 1,1,1,2,3-pentachloropropane with a selectivity of less than 82%. This method has a low reaction selectivity and a short catalyst life, which is not conducive to environmental protection and industrial production applications.

[0007] Chinese patent CN107001190A discloses a method for preparing a high-purity 1,1,1,2,3-pentachloropropane product. The reaction steps include: a) 1,1,1,3-tetrachloropropane gas phase catalytic dehydrochlorination, collecting the product and purifying and separating it to obtain 1,1,3-trichloropropene; b) liquid-phase chlorination of the obtained 1,1,3-trichloropropene with chlorine under light, 26°C to 31°C, and a residence time of 30min to 300min to obtain high-purity 1,1,1,2,3-pentachloropropane. The operating conditions required for this method are complex, liquid-phase chlorination requires light, and 1,1,3-trichloropropene needs to be separated and purified. At the same time, the reaction residence time is long, and industrial equipment is not used for production.

[0008] Chinese patent CN103601612A discloses a chlorination reactor for preparing 1,1,1,2,3-pentachloropropane. It includes the following steps: a) 1,1,1,3-tetrachloropropane is dehydrochlorinated at 0℃~120℃ in liquid phase by FeCl3 / C catalyst to obtain crude trichloropropene; b) the above crude liquid phase is directly chlorinated with chlorine by FeCl3 / C catalyst to obtain 1,1,1,2,3-pentachloropropane. The patent does not have detailed data such as reaction selectivity, and it is impossible to judge the quality of the reaction, but judging from the catalyst FeCl3 / C used, the catalyst is very easy to deactivate under liquid phase conditions and is not suitable for industrialization.

[0009] Chinese patent CN104130100A discloses a method for preparing 1,1,1,2,3-pentachloropropane, comprising the following steps: using a semi-batch or continuous method, 1,1,1,3-tetrachloropropane at 40°C to 120°C, catalyzed by FeCl3, to directly obtain 1,1,1,2,3-pentachloropropane, with a selectivity of no more than 90%. This method has a low reaction selectivity and a large amount of "three wastes", which is not conducive to large-scale production.

[0010] Chinese patent CN105164091A discloses a method for preparing 1,1,1,2,3-pentachloropropane, comprising the following steps: reacting 1,1,1,3-tetrachloropropane with a chlorine source (selected from chlorine, sulfonyl chloride and a combination thereof) under liquid phase conditions in the presence of a polyvalent antimony compound containing a pentavalent antimony compound. Reaction conditions: avoid light, reaction temperature 40°C to 200°C, catalyst volume ratio 0.05 to 2%, pressure above 1 psi, and selectivity up to 99.1%. The catalyst used in this method contains heavy metal antimony, and the "three wastes" produced are extremely harmful to the environment, especially after scaled-up production, the environment is difficult to bear.

[0011] Japanese Patent Laid-Open No. 2010-248104 and World Patent WO2010123148 ​​report on the preparation method of 1,1,1,2,3-pentachloropropane, using 1,1,1,3-tetrachloropropane as raw material to obtain a mixture of trichloropropenes by alkali dehydrochlorination, and the product is not separated and chlorine is passed through under UV light to obtain 1,1,1,2,3-pentachloropropane, the selectivity of 1,1,1,2,3-pentachloropropane is 93%, the conversion rate of olefins is 97%, and high-purity 1,1,1,2,3-pentachloropropane can be obtained by vacuum distillation. The chlorination reaction of this method must be carried out under UV light irradiation. In addition to the complex structure of the photochemical reactor, it is easy to produce chlorine free radicals for chlorine substitution reaction to lead to the formation of polychlorinated propanes, which reduces the selectivity of the target product.

[0012] World patent WO2010150835 reports a method for preparing 1,1,1,2,3-pentachloropropane, which uses 1,1,1,3-tetrachloropropane as a raw material to undergo gas phase dehydrochlorination, and then reacts with chlorine in a gas phase or liquid phase to prepare 1,1,1,2,3-pentachloropropane. Using nitrogen as a diluent, gasify 1,1,1,3-tetrachloropropane, and undergo dehydrochlorination at a reaction temperature of 350-550°C to prepare a mixture of trichloropropylenes, and then undergo chlorination reaction with chlorine at a temperature below 300°C, or use liquid phase chlorination at a reaction temperature below 120°C under ultraviolet light to prepare 1,1,1,2,3-pentachloropropane. For example, the olefin gas generated by dehydrochlorination of 1,1,1,3-tetrachloropropane at 500°C is cooled to 150°C and mixed with chlorine to pass through a reaction tube with a residence time of 1.24 seconds. The conversion rate of olefin is 99.0%, and the selectivity of 1,1,1,2,3-pentachloropropane is 95.0%. This method dehydrochlorinates 1,1,1,3-tetrachloropropane at 500°C. The reaction temperature is too high and the product is complex. On the other hand, the chlorination reaction temperature of olefin and chlorine is too high, which is easy to produce chlorine substitution reaction to generate polychloropropane.

[0013] World patent WO2009085862 and Chinese patent CN102199071 describe the preparation method of 1,1,1,2,3-pentachloropropane. Crude 1,1,1,3-tetrachloropropane prepared by polymerization of ethylene and carbon tetrachloride contains 3-30% carbon tetrachloride, and 2.5% or less of anhydrous ferric chloride is added as a catalyst, and chlorine is introduced into the reaction to obtain 1,1,1,2,3-pentachloropropane with a yield of 89.1%. This method uses Lewis acid catalyst ferric chloride, which is easy to cause chlorine substitution reaction. In addition, due to the high solubility of ferric chloride in halogenated hydrocarbons, the post-reaction treatment is relatively complicated.

[0014] The existing preparation technology has the following shortcomings: On the one hand, the catalyst is unstable. The most widely used is the anhydrous FeCl3 Lewis acid catalyst, which is very easy to deactivate. Under liquid phase conditions, it is difficult to separate the product from the catalyst, which is not conducive to industrial production. On the other hand, the raw material / intermediate trichloropropylene for preparing 1,1,1,2,3-pentachloropropane is prone to self-polymerization during the reaction, resulting in an increase in by-products and a decrease in product yield, making the subsequent separation and purification system complicated.

[0015] In view of various deficiencies in the prior art, the inventors have found a method for preparing 1,1,1,2,3-pentachloropropane by one-step isomerization of 1,1,1,3,3-pentachloropropane through long-term experiments and explorations. Summary of the invention

[0016] The object of the present invention is to provide a method for preparing 1,1,1,2,3-pentachloropropane with low raw material cost, few by-products and high yield.

[0017] To achieve the purpose of the invention, the technical solution adopted by the present invention is: a method for preparing 1,1,1,2,3-pentachloropropane, which is a method for isomerizing 1,1,1,3,3-pentachloropropane into 1,1,1,2,3-pentachloropropane under the action of an isomerization catalyst.

[0018] The synthetic route of the present invention is:

[0019] .

[0020] Specifically, a method for preparing 1,1,1,2,3-pentachloropropane comprises the following steps:

[0021] 1) dissolving a soluble salt containing Ru, a soluble salt containing Ga and a soluble salt containing Ti in a solution containing a surfactant to obtain a mixed solution; under stirring conditions, dropping a precipitant solution into the mixed solution to obtain a suspension containing a precipitate; subjecting the suspension containing the precipitate to a hydrothermal reaction, and after the hydrothermal reaction is completed, washing, filtering and drying to obtain a precursor; impregnating the precursor with perchloric acid, drying and calcining the precursor; impregnating the obtained calcined product with a solution containing a soluble salt containing Ni, drying and calcining to obtain an isomerization catalyst;

[0022] 2) under the action of the isomerization catalyst prepared in step 1), 1,1,1,3,3-pentachloropropane and nitrogen are fed into an isomerization reactor in the form of a mixed gas to isomerize 1,1,1,3,3-pentachloropropane to 1,1,1,2,3-pentachloropropane, which is then separated to obtain a crude 1,1,1,2,3-pentachloropropane, and the unreacted raw materials are continuously fed into the reactor for reaction;

[0023] 3) Purifying the crude 1,1,1,2,3-pentachloropropane prepared in step 2) to obtain 1,1,1,2,3-pentachloropropane.

[0024] Specifically, in the solution containing a surfactant in step 1), the content of the surfactant is 0.01% to 1.0% by weight, and the solvent is water and ethanol. Preferably, the surfactant is polyethylene glycol. The surfactant can reduce the interfacial tension in the solution, promote the uniform dispersion of metal ions, and prevent the aggregation of precipitation, thereby helping to form uniform catalyst particles. The selection range of the content ensures that the surfactant can play a role without excessively affecting the properties of the solution.

[0025] Specifically, the precipitant in step 1) is at least one of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate and potassium carbonate.

[0026] Specifically, the hydrothermal reaction conditions described in step 1) above include: temperature of 60°C to 200°C and time of 4h-48h. The hydrothermal reaction is carried out in a closed system, and high temperature and high pressure contribute to the uniform distribution of metal ions and the formation of a crystal lattice. The selection of temperature and time ensures that the precipitate can be fully crystallized to form a catalyst precursor with a high specific surface area and a good pore structure.

[0027] Specifically, the calcination temperature in the above step 1) is 500°C to 800°C, and the calcination time is 4h to 10h. The calcination process helps to remove organic impurities in the catalyst, enhance the crystallinity of the metal oxide, and improve the thermal stability and activity of the catalyst. The selection of temperature and time ensures the structural stability of the catalyst while avoiding excessive sintering.

[0028] Specifically, the molar ratio of 1,1,1,2,3-pentachloropropane to nitrogen in the above step 2) is 1:1-20.

[0029] Specifically, the isomerization temperature in the above step 2) is 200°C to 300°C.

[0030] Specifically, the isomerization reactor in step 2) above is a fixed bed reactor. In a fixed bed reactor, the catalyst is fixed in the reactor, and reactants and products can pass through continuously, which helps to improve the reaction efficiency and the utilization rate of the catalyst.

[0031] Specifically, the crude 1,1,1,2,3-pentachloropropane in the above step 3) is purified by continuous distillation.

[0032] The reaction principle used in this method lies in the action of the catalyst and the control of the reaction conditions. The catalyst is used to provide an alternative activation path to reduce the activation energy of the reaction, and the chemical bonds in the molecules are broken and reformed. At the molecular level, the catalyst adsorbs 1,1,1,3,3-pentachloropropane molecules to reduce the bond energy between one chlorine atom and the adjacent carbon atom, thereby promoting the migration of the chlorine atom to form 1,1,1,2,3-pentachloropropane.

[0033] Compared with the prior art, the method for preparing 1,1,1,2,3-pentachloropropane of the present invention has the following beneficial effects:

[0034] 1. A method for synthesizing 1,1,1,2,3-pentachloropropane by isomerization of 1,1,1,3,3-pentachloropropane;

[0035] 2. No need to use a reactor with a complex structure;

[0036] 3. The catalyst has a long service life and the separation of the product and the catalyst is simple;

[0037] 4. The raw material 1,1,1,3,3-pentachloropropane is easily available and has low synthesis cost. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0039] Experimental process:

[0040] 450mL water, 150mL ethanol and 1.81g polyethylene glycol (PEG400) were stirred evenly to obtain a solution containing a surfactant; 130.0g titanium trichloride, 1.85g ruthenium trichloride and 6.0g gallium nitrate were dissolved in the above solution containing a surfactant to obtain a mixed solution; under stirring, 1 mol / L sodium hydroxide was dropped into the mixed solution to hydrolyze it to generate a precipitate to obtain a suspension containing a precipitate; the suspension containing the precipitate was placed in a hydrothermal kettle and hydrothermaled at 150°C for 24h, the suspension in the hydrothermal kettle was taken out, filtered, the precipitate was washed with ethanol, and dried at 120°C for 12h to obtain a precursor, and the precursor was immersed in 150ml , 1.0 mol / L perchloric acid, dried at 120°C for 24 h, and calcined at 700°C for 6 h; finally, the calcined product was impregnated with an aqueous solution of nickel perchlorate, then dried at 120°C for 12 h, and calcined at 600°C for 6 h to obtain an isomerization catalyst.

[0041] Example 1

[0042] 60 ml of isomerization catalyst was loaded into a tubular reactor with an inner diameter of 38 mm and a sintered bottom, and a temperature sensor was inserted and exited in the middle of the catalyst.

[0043] The reactor was slowly heated to 350°C in a 30L / h nitrogen flow. The catalyst was first treated with HCl, and the catalyst bed temperature change was strictly controlled to ≤±5°C. The catalyst bed temperature change was controlled by adjusting the nitrogen and HCl flow rates. The HCl flow was maintained for 120 hours, and the HCl was purged with a nitrogen flow.

[0044] Temperature 300 ℃, N2:1,1,1,3,3-pentachloropropane = 20:1 (mol), space velocity 330 / h, after half an hour of reaction, samples were taken at the reactor outlet to detect the content of each component. The sampling frequency was 4h / time.

[0045] Example 2

[0046] On the basis of Example 1, the reaction temperature was changed to 250° C., N2:1,1,1,3,3-pentachloropropane=10:1 (mol), and the space velocity was 330 / h. After the reaction, samples were taken at the reactor outlet to detect the content of each component.

[0047] Example 3

[0048] On the basis of Example 1, the reaction temperature was changed to 200°C, N2:1,1,1,3,3-pentachloropropane=5:1 (mol), and the space velocity was 330 / h. After the reaction, samples were taken at the reactor outlet to detect the content of each component. The reaction results are shown in Table 1.

[0049] Example 4

[0050] On the basis of Example 1, the reaction temperature was changed to 200° C., N2:1,1,1,3,3-pentachloropropane=10:1 (mol), the space velocity was 660 / h, and the other reaction conditions were the same as in Example 1. The reaction results are shown in Table 1.

[0051] Example 5

[0052] On the basis of Example 4, the reaction temperature was changed to 250°C, N2:1,1,1,3,3-pentachloropropane = 5:1 (mol), the space velocity was 660 / h, and the other reaction conditions were the same as in Example 4. The reaction results are shown in Table 1.

[0053] Example 6

[0054] On the basis of Example 4, the reaction temperature was changed to 300° C., N2:1,1,1,3,3-pentachloropropane=20:1 (mol), the space velocity was 660 / h, and the other reaction conditions were the same as in Example 4. The reaction results are shown in Table 1.

[0055] Example 7

[0056] On the basis of Example 6, the reaction temperature was changed to 200° C., N2:1,1,1,3,3-pentachloropropane=10:1 (mol), the space velocity was 1000 / h, and the other reaction conditions were the same as in Example 1. The reaction results are shown in Table 1.

[0057] Example 8

[0058] On the basis of Example 6, the reaction temperature was changed to 250°C, N2:1,1,1,3,3-pentachloropropane = 20:1 (mol), the space velocity was 1000 / h, and the other reaction conditions were the same as in Example 1. The reaction results are shown in Table 1.

[0059] Example 9

[0060] On the basis of Example 6, the reaction temperature was changed to 300°C, N2:1,1,1,3,3-pentachloropropane = 5:1 (mol), the space velocity was 1000 / h, and the other reaction conditions were the same as in Example 1. The reaction results are shown in Table 1.

[0061] Table 1 Reaction results of various examples

[0062] .

[0063] The reactor outlet material collected in the embodiment can be purified to a product purity of 99.9%, and the unreacted product can be put into the reactor for further reaction.

[0064] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A method for preparing 1,1,1,2,3-pentachloropropane, characterized in that: The following steps are involved: 1) dissolving a soluble salt containing Ru, a soluble salt containing Ga and a soluble salt containing Ti in a solution containing a surfactant to obtain a mixed solution; Under stirring conditions, the precipitant solution is added dropwise to the mixed solution to obtain a suspension containing a precipitate; The suspension containing the precipitate is subjected to a hydrothermal reaction, and after the hydrothermal reaction is completed, the precursor is washed, filtered, and dried to obtain a precursor; the precursor is impregnated with perchloric acid, dried, and calcined; the calcined product is impregnated with a solution containing a soluble salt of Ni, dried, and calcined to obtain an isomerization catalyst; 2) under the action of the isomerization catalyst prepared in step 1), 1,1,1,3,3-pentachloropropane and nitrogen are fed into an isomerization reactor in the form of a mixed gas to isomerize 1,1,1,3,3-pentachloropropane to 1,1,1,2,3-pentachloropropane, which is then separated to obtain a crude 1,1,1,2,3-pentachloropropane, and the unreacted raw materials are continuously fed into the reactor for reaction; 3) Purifying the crude 1,1,1,2,3-pentachloropropane prepared in step 2) to obtain 1,1,1,2,3-pentachloropropane.

2. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: In the solution containing a surfactant in step 1), the mass content of the surfactant is 0.01% to 1.0%, and the solvent is water and ethanol.

3. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The surfactant described in step 1) is polyethylene glycol.

4. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The precipitant in step 1) is at least one of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate and potassium carbonate.

5. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The hydrothermal reaction conditions described in step 1) include: temperature of 60°C to 200°C and time of 4h to 48h.

6. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The calcination temperature in step 1) is 500° C. to 800° C., and the calcination time is 4 h to 10 h.

7. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The molar ratio of 1,1,1,2,3-pentachloropropane to nitrogen in step 2) is 1:1-20.

8. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The isomerization temperature in step 2) is 200°C to 300°C.

9. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: The isomerization reactor described in step 2) is a fixed bed reactor.

10. A method for preparing 1,1,1,2,3-pentachloropropane as claimed in claim 1, characterized in that: In step 3), the crude 1,1,1,2,3-pentachloropropane is purified by continuous distillation.