Method for co-producing 1, 1, 2-trichloroethane and 1, 1, 2, 2-tetrachloroethane

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a method for co-producing 1, 1, 2-trichloroethane and 1, 1, 2, 2-tetrachloroethane. The method comprises the following steps: enabling a dichloroethane solution containing an initiator to be in contact with chlorine, and carrying out chlorination reaction to generate 1, 1, 2-trichloroethane and 1, 1, 2, 2-tetrachloroethane. The method has the beneficial effects that the dichloroethane is used as the mother liquor, the initiator is dissolved in the dichloroethane to prepare the initiator solution, the chlorine is introduced into the initiator solution, and the trichloroethane and the tetrachloroethane are prepared through liquid-phase chlorination, so that the problems of non-uniform gas-phase feeding distribution, poor reaction effect and low yield are solved; the method is simple in reaction condition, mild and stable in reaction process and easy to control.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane. Background Art

[0002] Trichloroethane is used as a raw material for the production of vinylidene chloride, an intermediate for resins, a fumigant and pesticide in agriculture, a solvent for grease, wax, rubber, and acetate fiber, and an extractant for dyes and spices. It has a good cleaning effect and can be used for ultrasonic cleaning and manual cleaning. It can also be used as a dry cleaning agent and a degreasing agent for metal surfaces.

[0003] At present, there is a big gap between the production process and technical level of trichloroethane at home and abroad. Foreign countries mainly use 1,2-dichloroethane (EDC) chlorination method and ethane chlorination method, and the technical protection is relatively strict. In China, most of them use vinyl chloride (VCM) chlorination method. This process route is mature, but there are many wastes and by-products, resulting in low reaction yield, high production cost, and high waste treatment cost. Summary of the invention

[0004] The present application provides a method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane, aiming to solve the problems of uneven gas phase feed, many by-products, low yield and high cost in the production method of the prior art.

[0005] The present application provides a method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane, comprising the following steps: contacting a dichloroethane solution containing an initiator with chlorine gas to cause a chlorination reaction to generate 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.

[0006] The method described in the present application uses dichloroethane as the mother liquid, dissolves the initiator in dichloroethane to prepare an initiator solution, passes chlorine gas into the initiator solution, and prepares trichloroethane and tetrachloroethane by liquid phase chlorination, thereby solving the problems of uneven distribution of gas phase feed, poor reaction effect and low yield. In addition, the method described in the present application has simple reaction conditions, a mild and stable reaction process, and is easy to control.

[0007] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the initiator includes one or more of azobisisobutyronitrile, azobisisovaleronitrile, tert-butyl hydroperoxide and dibenzoyl peroxide.

[0008] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the mass concentration of the initiator in the dichloroethane solution is 0.2%-1%.

[0009] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the mass concentration of the initiator in the dichloroethane solution is 0.45%-0.55%.

[0010] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the molar ratio of the ethylene dichloride to the chlorine is (1.1-1.5):1.

[0011] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the molar ratio of the ethylene dichloride to the chlorine is (1.3-1.4):1.

[0012] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the temperature of the chlorination reaction is 70-110° C., and the reaction time is 3-5 hours.

[0013] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the temperature of the chlorination reaction is 90-100°C.

[0014] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the pressure of the chlorination reaction is 30-60 KPa.

[0015] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the pressure of the chlorination reaction is 45-55 KPa.

[0016] According to some embodiments of the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in the present application, the method further comprises distilling the chlorination reaction product to obtain 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0018] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0019] The embodiment of the present application provides a method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane, comprising the following steps: contacting a dichloroethane solution containing an initiator with chlorine gas to cause a chlorination reaction to generate 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.

[0020] The method described in the present application uses dichloroethane as the mother liquid, dissolves the initiator in dichloroethane to prepare an initiator solution, passes chlorine gas into the initiator solution, and prepares trichloroethane and tetrachloroethane by liquid phase chlorination, thereby solving the problems of uneven distribution of gas phase feed, poor reaction effect and low yield. In addition, the method described in the present application has simple reaction conditions, a mild and stable reaction process, and is easy to control.

[0021] In some embodiments of the present application, the initiator includes one or more of azobisisobutyronitrile, azobisisovaleronitrile, tert-butyl hydroperoxide and dibenzoyl peroxide.

[0022] In some embodiments of the present application, the mass concentration of the initiator in the dichloroethane solution is 0.2%-1%, for example, 0.2%, 0.45%, 0.5%, 0.55%, 0.6%, 0.7%, 0.9%, 1%, etc.

[0023] In some embodiments of the present application, the mass concentration of the initiator in the dichloroethane solution is 0.45%-0.55%. The initiator within this concentration range is evenly distributed in the reaction system, and will not cause excessively violent local reactions due to excessively high concentrations, nor will it reduce the reaction rate due to excessively low concentrations.

[0024] In some embodiments of the present application, the molar ratio of the ethylene dichloride to the chlorine is (1.1-1.5):1, for example, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, etc.

[0025] In some embodiments of the present application, the molar ratio of the ethylene dichloride to the chlorine is (1.3-1.4): 1. The purity of ethylene dichloride is 99.9%, the purity of chlorine is 98%, and the theoretical molar ratio of the chemical reaction formula is 1:1. Considering the toxicity of chlorine, the raw material ethylene dichloride is fed in a slightly excessive amount to increase the degree of reaction.

[0026] In some embodiments of the present application, the temperature of the chlorination reaction is 70-110° C., such as 70° C., 80° C., 90° C., 100° C., 110° C., etc. The reaction time is 3-5 h, such as 3 h, 4 h, 5 h, etc.

[0027] In some embodiments of the present application, the temperature of the chlorination reaction is 90-100° C. For example, azo initiators will decompose to form isobutyronitrile radicals at above 60° C. These free radicals are highly reactive; at 100° C., the half-life of azo initiators is 8 minutes, and the activity is relatively strong.

[0028] In some embodiments of the present application, the pressure of the chlorination reaction is 30-60 KPa, for example, 30 KPa, 40 KPa, 45 KPa, 50 KPa, 55 KPa, 58 KPa, 60 KPa, etc.

[0029] In some embodiments of the present application, the pressure of the chlorination reaction is 45-55 KPa. The boiling point of ethylene dichloride is 100° C. at a pressure of 50 kPa; high pressure control can reduce the volatilization amount of ethylene dichloride and prolong the residence time of chlorine.

[0030] In some embodiments of the present application, the method further comprises distilling the chlorination reaction product to obtain 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.

[0031] In some embodiments of the present application, the method further includes treating the tail gas, and the tail gas treatment includes water absorption and liquid alkali absorption, and the byproducts obtained from the tail gas treatment are hydrochloric acid and sodium hypochlorite aqueous solution. Specifically, the tail gas is sequentially subjected to condensation treatment, water absorption, and liquid alkali absorption, wherein the organic matter is condensed and recovered, the hydrogen chloride gas is absorbed by water to form hydrochloric acid, and the chlorine gas is absorbed by liquid alkali to form sodium hypochlorite aqueous solution. That is, the method described in the present application improves the utilization rate of raw materials and reduces the difficulty of tail gas treatment.

[0032] The technical solution of this application is further analyzed below in conjunction with specific implementation cases.

[0033] Example 1

[0034] A method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane comprises the following steps:

[0035] The initiator azobisisobutyronitrile and dichloroethane were mixed and stirred at room temperature of 25°C for 5 hours to obtain a dichloroethane solution containing an initiator with a mass concentration of 0.5% (initiator solution). According to the molar ratio of dichloroethane to chlorine gas of 1.4:1, 2Nm 3 Chlorine gas was introduced at a flow rate of / h, so that the initiator solution and chlorine gas were in contact at a temperature of 95°C and a pressure of 50kPa for chlorination reaction. The reaction time was 3h. The chlorination reaction product was distilled to obtain 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and by-product 1,1,1,2-tetrachloroethane.

[0036] The tail gas generated by the chlorination reaction is condensed and then absorbed by water and an 8% mass concentration sodium hydroxide aqueous solution in sequence.

[0037] Example 2

[0038] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 2 is different from that in Example 1 only in the temperature of the chlorination reaction.

[0039] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 2, the temperature of the chlorination reaction is 70° C., and the remaining operating steps are the same as in Example 1.

[0040] Example 3

[0041] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 3 is different from that in Example 1 only in the temperature of the chlorination reaction.

[0042] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 3, the temperature of the chlorination reaction is 90° C., and the remaining operating steps are the same as those in Example 1.

[0043] Example 4

[0044] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 4 is different from that in Example 1 only in the temperature of the chlorination reaction.

[0045] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 4, the temperature of the chlorination reaction is 100° C., and the remaining operating steps are the same as those in Example 1.

[0046] Example 5

[0047] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 5 is different from that in Example 1 only in the temperature of the chlorination reaction.

[0048] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 5, the temperature of the chlorination reaction is 110° C., and the remaining operating steps are the same as in Example 1.

[0049] Example 6

[0050] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 6 is different from that in Example 1 only in the molar ratio of dichloroethane to chlorine.

[0051] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 6, the molar ratio of dichloroethane to chlorine is 1.1:1, and the remaining operating steps are the same as those in Example 1.

[0052] Example 7

[0053] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 7 is different from that in Example 1 only in the molar ratio of dichloroethane to chlorine.

[0054] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 7, the molar ratio of dichloroethane to chlorine is 1.3:1, and the remaining operating steps are the same as those in Example 1.

[0055] Example 8

[0056] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 8 is different from that in Example 1 only in the molar ratio of dichloroethane to chlorine.

[0057] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 8, the molar ratio of dichloroethane to chlorine is 1.5:1, and the remaining operating steps are the same as those in Example 1.

[0058] Example 9

[0059] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 9 is different from that in Example 1 only in the pressure of the chlorination reaction.

[0060] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 9, the pressure of the chlorination reaction is 30 KPa, and the remaining operating steps are the same as those in Example 1.

[0061] Example 10

[0062] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 10 is different from that in Example 1 only in the pressure of the chlorination reaction.

[0063] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 10, the pressure of the chlorination reaction is 70 KPa, and the remaining operating steps are the same as those in Example 1.

[0064] Embodiment 11

[0065] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 11 is different from that in Example 1 only in the pressure of the chlorination reaction.

[0066] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 11, the pressure of the chlorination reaction is 100 KPa, and the remaining operating steps are the same as those in Example 1.

[0067] Example 12

[0068] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 12 is different from that in Example 1 only in the different mass concentration of the initiator in the dichloroethane solution.

[0069] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 12, the mass concentration of the initiator in the dichloroethane solution is 0.8%, and the remaining operating steps are the same as those in Example 1.

[0070] Embodiment 13

[0071] The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 13 is different from that in Example 1 only in the different mass concentration of the initiator in the dichloroethane solution.

[0072] In the method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane described in Example 13, the mass concentration of the initiator in the dichloroethane solution is 0.3%, and the remaining operating steps are the same as those in Example 1.

[0073] The selectivity analysis of 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and by-product 1,1,1,2-tetrachloroethane obtained by the methods described in Examples 1-13 of the present application is shown in Table 1.

[0074] Table 1

[0075] 1,1,2-Trichloroethane(%) 1,1,2,2-Tetrachloroethane(%) 1,1,1,2-Tetrachloroethane(%) total Example 1 69.93 12.49 12.69 95.11 Example 2 56.23 13.56 14.77 84.56 Example 3 67.16 12.60 12.55 92.31 Example 4 72.00 11.51 11.37 94.88 Example 5 64.80 14.09 14.23 93.12 Example 6 75.89 9.42 9.41 94.72 Example 7 72.19 11.28 11.51 94.98 Example 8 65.59 14.58 14.79 94.96 Example 9 69.23 12.73 12.68 94.64 Example 10 69.29 12.56 13.15 95.00 Embodiment 11 67.46 13.69 13.37 94.52 Example 12 75.59 9.34 9.41 94.34 Embodiment 13 65.46 13.91 14.36 93.73

[0076] It can be seen from Table 1 that the analysis of Examples 1-5 shows that: the higher the temperature, the shorter the half-life of the initiator, the stronger the activity, and the higher the reaction conversion rate; when the temperature is higher than 100°C, the polychlorination reaction of 1,1,2,2-tetrachloroethane and the by-product 1,1,1,2-tetrachloroethane is violent, and the selectivity of trichloroethane becomes smaller.

[0077] The analysis of Examples 1, 6, 7, and 8 shows that the higher the initiator concentration, the more intense the polychlorination reaction of 1,1,2,2-tetrachloroethane and the byproduct 1,1,1,2-tetrachloroethane; and Example 1 has the highest overall product yield.

[0078] The analysis of Examples 1, 9, 10 and 11 shows that the pressure has no significant effect on the conversion rate of the reaction.

[0079] The analysis of Examples 1, 12, and 13 shows that the higher the initiator concentration, the more free radicals are released and the more violent the reaction. When the initiator concentration is too high, the polychlorination side reaction is more violent, and the product 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and the byproduct 1,1,1,2-tetrachloroethane further react to form high boiling products.

[0080] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane, characterized in that: The following steps are involved: The dichloroethane solution containing the initiator is brought into contact with chlorine gas to cause a chlorination reaction to generate 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.

2. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The initiator comprises one or more of azobisisobutyronitrile, azobisisovaleronitrile, tert-butyl hydroperoxide and dibenzoyl peroxide; And / or, the mass concentration of the initiator in the dichloroethane solution is 0.2%-1%.

3. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The mass concentration of the initiator in the dichloroethane solution is 0.45%-0.55%.

4. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The molar ratio of the ethylene dichloride to the chlorine is (1.1-1.5):

1.

5. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The molar ratio of the ethylene dichloride to the chlorine is (1.3-1.4):

1.

6. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The temperature of the chlorination reaction is 70-110° C., and the reaction time is 3-5 hours.

7. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The temperature of the chlorination reaction is 90-100°C.

8. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The pressure of the chlorination reaction is 30-60KPa.

9. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The pressure of the chlorination reaction is 45-55KPa.

10. The method for co-producing 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane according to claim 1, characterized in that: The method further comprises subjecting the chlorination reaction product to distillation treatment to obtain 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane.