JPH0643353B2 - Continuous production method of 2,3-dichloro-1-propanol and its apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used for a method for continuously producing 2,3-dichloro-1-propanol by adding chlorine to allyl alcohol in a hydrochloric acid medium, and to be used for the method. Regarding the device.

[Conventional technology]

Addition of chlorine to allyl alcohol in hydrochloric acid medium 2,3
The method for producing -dichloro-1-propanol is described in, for example, JP-B-37-17206, JP-A-59-128340,
JP-A-59-128341, JP-A-60-25817
No. 1 and the like. In particular, it is known that a high yield of 2,3-dichloro-1-propanol can be obtained by reacting in hydrochloric acid of high concentration, and it is clear that the concentration of hydrochloric acid is one of the important factors. However, it does not provide a specific strategy for continuous commercial scale production.

The present applicant has previously proposed a method in which allyl alcohol, chlorine and hydrogen chloride are simultaneously introduced and reacted in a hydrochloric acid medium to suppress the by-product of allyl chloride and a compound having an ether bond, and to obtain a high yield of 2. It was shown that 3-dichloro-1-propanol can be produced (JP-A Nos. 62-19544 and 26243). However, when attempting to continuously produce 2,3-dichloro-1-propanol using the information obtained from the batch-wise or semi-batch method, a by-product is produced by a sequential reaction or a parallel reaction, and 2,3- Dichloro-1-
The yield of propanol was inevitably reduced by around 5%.

To avoid this, it is usually possible to use a tumbler type or multi-tank type reactor, but as is well known, the addition reaction of chlorine to allyl alcohol involves a large amount of heat generation, so it is necessary to devise heat removal. . Further, although this reaction can obtain a high yield at a lower temperature, the viscosity of the reaction mixture is high, and for this reason, it is necessary to increase the linear velocity in order to improve the efficiency of the heat exchanger, for example, in the ordinary tumbler system. ,
It requires a long reaction tube and is not always practical. On the other hand, the addition reaction of chlorine to allyl alcohol is also known to be fast, and therefore, if the heat removal method is appropriate, such a long residence time is not necessary. Therefore, the multi-tank system using a plurality of stirring tanks is not efficient because the heat removal rate is limited. A method of combining a stirring tank and an external cooler is generally known, but the above reaction has not been provided as a viable method.

[Problems to be Solved by the Invention]

In view of the above points, the present invention has a high concentration of 2, 2 by the reaction of allyl alcohol and chlorine in a hydrochloric acid medium on an industrial scale,
An object of the present invention is to provide a method and an apparatus for continuously producing 3-dichloro-1-propanol in a high yield.

[Means for Solving the Problems]

That is, the present invention provides a method for producing 2,3-dichloro-1-propanol by reacting allyl alcohol and chlorine in a hydrochloric acid medium using a tubular reactor formed into a ring, which comprises: A reaction mixture containing a chlorine medium is cooled and circulated, and allyl alcohol and a mixed gas of chlorine and hydrogen chloride are continuously introduced into the circulating liquid from positions close to each other to cause a reaction in the above-mentioned conduit path and supply. The reaction mixture containing the product corresponding to the total number of moles of allyl alcohol was taken out, hydrogen chloride gas and / or hydrochloric acid was added to the rest, and the reaction heat and the heat of dissolution of hydrogen chloride gas were sensible heat of this circulating liquid. A continuous process for producing 2,3-dichloro-1-propanol (hereinafter abbreviated as DCH), which is characterized by absorption, and a device used for the same.

The method of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an apparatus suitable for carrying out the method of the present invention. In Fig. 1, the circulation pump (2) is installed in the path formed by the conduit (reaction tube) (1).
The reaction mixture containing the hydrochloric acid medium is circulated while being cooled by the heat exchanger (3). Allyl alcohol was introduced into the circulating liquid through the pipe (4), chlorine gas was introduced through the chlorine introduction pipe (5), and hydrogen chloride gas was introduced through the hydrogen chloride gas introduction pipe (6) at a predetermined molar ratio. Tubes as gas mixture (7)
Will be introduced more. A suitable mixer may be provided to improve the mixing of the gases. The mixed gas introduction pipe (7) and the allyl alcohol introduction pipe are arranged close to each other, and the supplied allyl alcohol, chlorine and hydrogen chloride gases are introduced into the static mixer (8) together with the circulating liquid and mixed. From the reaction mixture exiting the mixer (8), a reaction mixture containing at least the DCH product corresponding to the total molar amount of allyl alcohol fed was withdrawn from the pipe (9), the remainder being the gas-liquid separator (1
0), the exhaust gas mixed in the circulating fluid by the partial pressure is separated from the pipe (11), and is recirculated by the circulation pump (2) together with the adjusted water introduced from the pipe (12). To be done. On this occasion,
Hydrochloric acid is introduced through the pipe (13) in order to supplement the hydrogen chloride discharged from the system together with the product.

The allyl alcohol used above may be anhydrous or may contain up to about 40% by weight water. The chlorine gas may be vaporized liquefied chlorine, or may be a so-called gas containing hydrogen, air and the like in an amount of 1 to 3%. The hydrogen chloride gas can be used by separating and recovering the hydrogen chloride gas contained in the reaction mixture taken out from the pipe (9) as described later. It is desirable to adjust the molar ratio of chlorine to hydrogen chloride in the mixed gas in the range of 0.1 to 9. Further, the molar ratio of chlorine to allyl alcohol supplied is appropriately in the range of 1 to 1.1. The introduction pipes for allyl alcohol and the introduction pipes for the mixed gas may be arranged at plural places respectively, and the hydrogen chloride gas may be introduced separately from chlorine, but at least a part thereof is introduced as a mixed gas with chlorine. To do. The concentration of hydrochloric acid flowing in the reaction tube is at least 15 to 45% by weight, preferably 25 to 45% by weight in the reaction mixture in the reaction region from the first introduction pipe (7) of the mixed gas to the product removal pipe (9). % By weight. If it is less than 15% by weight, the production ratio of 3-chloro-1,2-propanediol, which is a by-product, increases, and the yield of DCH decreases, which is not preferable. If it exceeds 45% by weight, large-scale cooling and / or
Or it is uneconomical because it requires pressurizing equipment. The residence time in the reaction zone is 5 to 30 seconds, which is necessary and sufficient. Within this residence time, the concentration of allyl alcohol at the product outlet can be made substantially zero, and the newly formed product does not stay in the reaction tube longer than necessary, limiting the actual reaction region. It will be possible.

The reaction temperature is preferably 10 ° C or lower in the reaction region. Ten
When the temperature exceeds ℃, by-products such as allyl chloride, trichlorobutane bread and ether increase, and the yield of DCH decreases. On the other hand, if the temperature is lower than -20 ° C, it is advantageous for improving the yield, but it is not preferable from the viewpoint of the cost required for cooling or the fear of freezing the reaction mixture. Since the reaction region in the present invention functions as a kind of adiabatic reactor, a temperature gradient is generated in the reaction tube in the axial direction. In this case, it is suitable that the temperature of the portion where chlorine and allyl alcohol first come into contact is -20 to 0 ° C and the temperature at the product outlet is -10 to 10 ° C. For other parts of the reactor, less -20 to 10 ° C
It is desirable to keep

In the present invention, a circulation system using a reaction tube as described above is adopted, allyl alcohol and chlorine are reacted under adiabatic conditions, and a large amount of reaction heat and heat of dissolution of hydrogen chloride are sensible heat of the cooled circulating liquid. To remove. Therefore mixing of the reaction mixture is important and static mixers are employed. A linear velocity of the reaction mixture in the reaction tube of at least 0.5 m / sec is required to enhance the mixing effect. The static mixer is a static mixer having no driving part and is commercially available under the names of static mixer, high mixer, ISG mixer, LPD mixer and the like. The number of elements is determined in consideration of the linear velocity of the mixed solution, pressure loss, etc., but 4 to 20 elements are sufficient per reaction region.

As the regulated water introduced into the gas-liquid separator (10) through the pipe (12) in FIG. 1, an aqueous phase separated from the reaction mixture taken out through the product take-out pipe (9) is used. That is, in the subsequent step of the present invention, hydrogen chloride gas generated by heating the reaction mixture taken out is recovered, and the residual liquid is cooled to separate into a DCH phase (lower layer) and a hydrochloric acid aqueous solution phase (upper layer). However, this upper layer can be circulated and used as control water. This control water takes into consideration other components supplied to the reaction tube, and also makes the total amount of the liquid flowing in the reaction tube constant and makes the concentrations of DCH and hydrochloric acid in the reaction mixture predetermined values. Adjust the flow rate to introduce into the circulating fluid. The introduction location is not limited to the location shown in the drawings, and may be any location in the reaction tube.

In addition, the hydrogen chloride gas recovered in the above post-process is
Normally, as shown in the drawing, it is introduced into the conduit (1) through the pipes (6) and (7), but when excess is generated, for example, the branch pipe (1) of the pipe (6)
4) may be introduced into the gas-liquid separator (10) or a heat exchanger
(3) It may be installed at a position before entering.

FIG. 2 shows an example in which the apparatus shown in FIG. 1 is combined into a two-stage type. The numbers of the piping and equipment of the first-stage reaction device on the left side of the drawing are the same as those in FIG. 1, and the reaction containing the product taken out from the product take-out pipe (9) is shown in the second-stage device on the right side. The mixture is introduced and circulates in a conduit (reaction tube) (101) as a circulating liquid by a pump (102). Further, the hydrogen chloride gas is branched from the first-stage introduction pipe (6), and then the second-stage introduction pipe (106).
Is mixed with chlorine introduced through the pipe (105) and introduced into the conduit (101) through the pipe (107). Allyl alcohol introduction tube
(104), static mixer (108), product extraction pipe (109), gas-liquid separator (110), exhaust gas discharge pipe (111), heat exchanger (103),
The replenishing hydrochloric acid introducing pipe (113) and the hydrogen chloride gas introducing pipe (114) are the same as those explained in FIG.

The ratio of the reaction amounts in the first step and the second step can be easily determined by considering reaction engineering, but in the present invention, the ratio is 1 :.
A value of 1 is suitable. And with the product withdrawal tube (9)
The allyl alcohol concentration at (109) should be substantially zero. Similarly, if the two-stage type is changed to a three-stage type or a multi-stage type of more than that, it is advantageous in yield.
It may be determined as appropriate in consideration of economy.

[Action]

 The basic reaction mechanism of the method of the present invention is shown by the following formula.

(Main reaction) (Side reaction) However, in the above formula, AA: allyl alcohol MCH: 3-chloro-1,2-propanediol AA ^* : representative of compounds having a hydroxy group such as AA, DCH, MCH ETH: ethers k ₁ , k ₂ , k ₃ : reaction rate constant of the equations (i) (ii) (iii) From this, the following reaction rate equation can be obtained.

d [DCH] / dt = k 1 [AA] [Cl 2] [Cl -] (iv) d [MCH] / dt = k 2 [AA] [Cl 2] [H 2 O] (v) d [ETH ] / Dt = k ₃ [AA] [Cl ₂ ] [AA ^* ] (vi) However, in the above equation, [] represents the concentration of the component.

From the formulas (iv) (v) (vi), the production ratio of MCH or ETH is d [DCH] / d [MCH] = k ₁ [Cl ⁻ ] / k ₂ [H ₂ O] (vii) d [DCH] / D [ETH] = k ₁ [Cl ⁻ ] / k ₃ [AA ^* ] (viii).

According to the above formula (vii), the higher the Cl ⁻ concentration in the reaction field, the higher the D
This is advantageous because the production ratio of CH becomes high, and it is preferable that the concentration of hydrochloric acid serving as a medium be large enough to be industrially inconvenient as in the present invention.

Further, although the present invention employs a circulation system using a reaction tube as described above, the average residence time can be shortened in comparison with a continuous system using a stirring tank in view of a part of newly generated products. In addition, since a reactor similar to a tumbler reactor is formed in the reaction region and the mixing of the reaction mixture in the axial direction of the tube is suppressed, the chance of successive reactions is reduced, and by-products mainly consisting of ether are produced. It can be suppressed. Further, according to the above formula (iii), AA ^* and Cl ₂ are A
Since it is considered to be involved in the production of ETH together with A, A
The contribution of A ^{* to} the reaction rate can be approximately represented by the initial concentration of AA. From such a point, if multiple introduction pipes for allyl alcohol and chlorine are arranged,
Since the initial concentration of allyl alcohol can be brought close to infinity, [AA ^* ] in the formula (viii) becomes small, which is effective in further reducing the ether formation ratio. In this way, a continuous reaction similar to a batch method can be performed.

Also, as is well known, the reaction between allyl alcohol and chlorine is extremely fast. Therefore, it is advantageous to bring them into contact with each other quickly, and it is for this purpose to introduce allyl alcohol and chlorine at the same time and at a close position in the reaction tube as in the present invention. Furthermore, as described above, the higher the Cl ^- concentration, the higher the production ratio of DCH. Therefore, it is effective to introduce a part of hydrogen chloride gas as a mixed gas with chlorine at the same time. Hereinafter, Examples and Comparative Examples are shown, but the composition% is in weight unit.

〔Example〕

Comparative Example 1 Allyl alcohol and chlorine were reacted in a hydrochloric acid medium using the apparatus shown in FIG.

Using a glass stirring tank (reaction vessel) (201) with a capacity of 700 ml below the product extraction pipe (203), use allyl alcohol from pipe (206) and chlorine gas (207) hydrogen chloride from pipe (209). gas
(208) mixed gas, hydrochloric acid from pipe (210), cycled controlled water from pipe (211) are supplied, and reaction is performed while exhaust gas is discharged from pipe (212) to continuously generate from pipe (203). The material was discharged into the reaction mixture container (204). The glass stirring tank (201) and the receiver (204) are cooled by cooling baths (213) and (214). Table 1 shows the supply amount of each raw material, the reaction conditions and the results.

Reference Example The product discharge pipe (203) of the apparatus shown in FIG. 3 was closed and used as a semi-batch type apparatus.

Charge 400 g of 37% hydrochloric acid to the reaction vessel (201), and while maintaining the temperature at 0 ° C., stir the mixed gas of allyl alcohol 85 g, chlorine 105 g, and hydrogen chloride 80 g so that allyl alcohol and chlorine are almost equivalent. Supplied in minutes. After the reaction, nitrogen gas was blown in to expel hydrogen chloride, and the reaction mixture was quantified by gas chromatography. As a result, DCH was produced in a yield of 98.0% based on the fed allyl alcohol.

Examples 1 to 5 Comparative Examples 2 and 3 In the apparatus shown in FIG. 1, a heat exchanger (3) made of carbate having a heat transfer area of 10 m ^2, a ceramic static mixer (8) having 20 elements, and a capacity of 100 A gas-liquid separator (10) consisting of a glass-lined container and a circulation pump (2) were annularly connected with a fluororesin lining pipe (1) having a diameter of 25 mm to form a reaction tube. The entire reaction tube was sufficiently kept cool, and the jackets of the heat exchanger and the gas-liquid separator were circulated with a refrigerant to cool it. Mixed gas introduction pipe of chlorine and hydrogen chloride (7) and allyl alcohol introduction pipe (4)
Are placed close to each other, and the distance from this position to the product take-out pipe (9) is set to 20 m. For comparison,
The reaction tube was provided with a bypass that did not pass through the static mixer. Although not shown in the figure, instrumentation equipment such as a thermometer, a flowmeter, and a pressure gauge was equipped in a normal manner. The amount of liquid retained in the reaction tube was about 200.

Table 2 shows the supply amount of each raw material, reaction conditions and test results. The hydrochloric acid concentration was determined by neutralization titration, and the product was determined by gas chromatography. Silicon-based medium-polarity capillary column (length 25
m, Gas Chloro Industrial Co., Ltd. OV-1701) was used to quantify ethylene glycol diethyl ether as an internal standard substance. Controlled water (recycled liquid from the subsequent step) is heated to a reaction mixture containing the product taken out to release hydrogen chloride gas at atmospheric pressure to 1.5 atm, and then cooled to separate into two layers.
The recovered upper layer (aqueous phase) was used.

In Example 5, a two-stage type device as shown in FIG. 2 was used. However, the hydrogen chloride gas introduction pipes (14) (114) were not used.

From the above examples, comparative examples, and reference examples, the following can be understood.
Each of the examples using the method and apparatus of the present invention has a higher target DCH yield than Comparative Example 1 performed by the one-stage continuous method using an ordinary stirring tank shown in FIG. Living things are decreasing. The reference example is a semi-batch method using the apparatus shown in FIG. 3, and a high yield was obtained, but it was carried out in a laboratory volume and is industrially inappropriate. 2 shown in FIG.
In Example 5 using the stepwise apparatus, the yield was remarkably improved, which is close to the reference example performed by the semi-batch method.
Further, in Comparative Example 2 in which the static mixer was omitted, a decrease in yield was recognized as compared with each Example.

〔The invention's effect〕

As described above, according to the method and apparatus of the present invention, the reaction of allyl alcohol and chlorine in a hydrochloric acid medium causes 2,3-
The step of producing dichloro-1-propanol can be efficiently performed by a continuous method suitable for an industrial scale.
Further, according to the present invention, it is possible to minimize the high yield reduction in the laboratory method, which is inevitable in industrialization, and is extremely useful in industry.

[Brief description of drawings]

1 and 2 show a schematic view of an apparatus for carrying out the method of the present invention. FIG. 1 shows a one-stage type, and FIG. 2 shows a two-stage type. FIG. 3 shows a schematic view of a laboratory scale apparatus for producing 2,3-dichloro-1-propanol used in Comparative Example 1. 1, 101: Conduit (reactor), 2, 102: Circulation pump, 3, 103: Heat exchanger, 4, 104: Allyl alcohol introduction pipe, 7, 107: Chlorine / hydrogen chloride mixed gas introduction pipe, 8, 108 : Static mixer, 9,109: Product take-out pipe

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Claims (6)

[Claims] 1. Allyl alcohol and chlorine are reacted in a hydrochloric acid medium by a tubular reactor formed into a ring to form 2,3
A method for producing dichloro-1-propanol, in which a reaction mixture containing a hydrochloric acid medium is cooled and circulated in a conduit, and allyl alcohol and a mixed gas of chlorine and hydrogen chloride are brought close to each other in the circulating liquid. The reaction mixture is continuously introduced from the position and reacted in the above circulation path, the reaction mixture containing the product corresponding to the total number of moles of allyl alcohol supplied is taken out, and the balance is supplemented with chlorine gas and / or hydrochloric acid. 2,3-dichloro-1-, which absorbs the heat of reaction and the heat of dissolution of hydrogen chloride gas by the sensible heat of the circulating liquid
Continuous production of propanol. 2. The method according to claim 1, wherein the reaction temperature of allyl alcohol and chlorine in the circulating liquid is −20 to + 10 ° C. 3. The process according to claim 1, wherein the reaction residence time of allyl alcohol and chlorine in the circulating liquid is 5 to 30 seconds. 4. The method according to claim 1, wherein chlorine gas recovered from a reaction mixture containing a product taken out through a conduit is used as hydrogen chloride gas. 5. Allyl alcohol and chlorine are reacted in a hydrochloric acid medium by a tubular reactor formed into a ring to form a few
An apparatus for producing dichloro-1-propanol, which comprises a conduit path for circulating a reaction mixture containing a hydrochloric acid medium to carry out the above reaction at least at a part thereof, the conduit comprising an allyl alcohol introduction tube, A mixed gas introduction pipe of chlorine and hydrogen chloride arranged close to the allyl alcohol introduction pipe, a static mixer for mixing the above allyl alcohol and gas, a take-out pipe for reaction products, and a gas-liquid separator for separating and discharging exhaust gas A device provided with a control water introducing pipe, a supplemental hydrogen chloride gas and / or hydrochloric acid introducing pipe, a circulation pump and a circulating liquid heat exchanger. 6. A method for producing 2,3-dichloro-1-propanol by the reaction of allyl alcohol and chlorine in a hydrochloric acid medium, which is used by sequentially connecting the apparatuses according to claim 5 in series. A multi-stage or multi-stage apparatus, which comprises a conduit path for circulating a reaction mixture containing a hydrochloric acid medium to carry out the above-mentioned reaction at least at a part thereof, wherein the conduit is an allyl alcohol introduction tube, the allyl alcohol introduction tube Introducing a mixed gas of chlorine and hydrogen chloride arranged in close proximity to the above, a static mixer for mixing the above allyl alcohol and gas, a take-out pipe for reaction products, a gas-liquid separator for separating and discharging exhaust gas, from the previous stage An apparatus comprising: a pipe for introducing the product, a supplemental hydrogen chloride gas and / or hydrochloric acid introduction pipe, a circulation pump, and a heat exchanger for cooling the circulating liquid.