JP5610917B2 - Method for producing chloropropane - Google Patents

Description

  The present invention relates to a method for producing chloropropane. More specifically, the present invention relates to a method for producing high-efficiency and high-purity chloropropane by suppressing the decomposition of chloropropane when crude chloropropane synthesized from chloropropene and chlorine is purified by distillation.

  Chloropropane is an important chlorine compound as an intermediate of various industrial products including an intermediate of agricultural chemical raw materials. For example, 1,1,2,3-tetrachloropropene produced from 1,1,1,2,3-pentachloropropane is an important chemical intermediate in the production of trichloroallyldiisopropylthiocarbamate herbicides. Are known. Another specific application of the chloropropane includes an application as an intermediate for obtaining chlorofluorocarbon having a low global warming potential depending on its structure.

  Conventionally, as a typical production method of the chloropropane, carbon tetrachloride and ethylene are reacted to produce chloropropane, and the produced chloropropane is produced by using a phase transfer catalyst such as an alkaline aqueous solution and a quaternary ammonium salt. There is known a method for producing a desired chloropropane by chlorinating the produced chloropropene (see Patent Document 1).

  However, Patent Document 1 does not mention a purification method of chloropropane, which is the final object.

On the other hand, when heating polychlorinated alkanes such as 1,1,1,2,3-pentachloropropane in the presence of iron, a method of adding phenols, particularly alkoxy-substituted phenols as a stabilizer is known. (See Patent Document 2)
In addition, as a method for improving the storage stability of a chloroalkane having 1 carbon, it is known to add phenols in combination with other compounds such as alcohol, amine and / or epoxide (for example, Patent Document 3). ~ 5).

Japanese Examined Patent Publication No. 2-47969 Special table 2004-534060 gazette JP-A-62-158228 JP-A-57-018636 JP-A-53-050106

  In order to prevent undesired side reactions and contamination of harmful substances not only in the final product but also in various intermediates, it is preferable that the purity of the compound is high, and the chloropropane is no exception. Distillation can be considered as a purification method of chloropropane, but there is a problem that chloropropane is decomposed by heating during the distillation and yield (yield) is lowered.

  When the alkoxy-substituted phenols described in Patent Document 2 are added, decomposition of polychlorinated alkanes such as 1,1,1,2,3-pentachloropropane by heating is suppressed to about 1/3 to 1/4. However, there was still room for improvement.

  Accordingly, an object of the present invention is to provide a highly efficient process with less decomposition in the purification of chloropropane by distillation.

  The present inventors have intensively studied in view of the above problems. As a result, the present inventors have found that the phenol substituted with an allyl group is more effective in inhibiting decomposition than the phenol substituted with an alkoxy group, and thus completed the present invention.

  That is, in the present invention, a chloropropene represented by the following general formula (1) is reacted with chlorine to chlorinate to obtain a chloropropane represented by the following general formula (2), and then to the crude chloropropane obtained by the reaction, A method for producing a purified chloropropane, comprising adding a phenol compound substituted with an allyl group and then distilling the phenol compound.

_{CCl 2 = CCl (2-m} ) H (m-1) -CCl (3-n) H n (1)
_{CCl 3 -CCl (3-m)} H (m-1) -CCl (3-n) H n (2)
(In the above formula, m is 1 or 2, and when m is 1, n is an integer from 0 to 2, and when m is 2, n is an integer from 0 to 3).
In this invention, it is preferable that the addition amount of the phenol compound substituted by the said allyl group shall be 0.0020-1.0 mass part with respect to 100 mass parts of crude chloropropane.

  According to the production method of the present invention, the thermal decomposition of the chloropropane represented by the above formula (2) is further suppressed to about 1/3 as compared with the conventionally known alkoxy-substituted phenol.

  This is because hydrogen chloride generated by thermal decomposition of the chloroalkane represented by the above formula (2) becomes a catalyst for further decomposition reaction, and the allyl group of the phenol compound captures the hydrogen chloride. I guess that is to prevent it.

  In the present invention, first, chloropropene represented by the following general formula (1) (hereinafter, simply referred to as “chloropropene” unless otherwise specified) is chlorinated by reacting with chlorine, and chloropropane represented by the following general formula (2). (Hereinafter simply referred to as “chloropropane” unless otherwise specified).

_{CCl 2 = CCl (2-m} ) H (m-1) -CCl (3-n) H n (1)
_{CCl 3 -CCl (3-m)} H (m-1) -CCl (3-n) H n (2)
In the above formula, m is 1 or 2, and when m is 1, n is an integer from 0 to 2, and when m is 2, n is an integer from 0 to 3. The present invention is characterized in that, during distillation described later, hydrogen chloride generated by thermal decomposition is captured by a phenol compound substituted with an allyl group to be added (hereinafter referred to as “allyl-substituted phenol” unless otherwise specified). . Therefore, when the compound represented by the general formula (2) as a product has at least one hydrogen atom, the essential effect is exhibited. Therefore, when m is 1, n must be an integer from 0 to 2, and when m is 2, n must be an integer from 0 to 3.

  Therefore, the compound represented by the formula (1) which is a corresponding raw material compound is also a compound having at least one hydrogen atom. Examples of the chloropropene include 1,1-dichloropropene, 1,1,2-trichloropropene, 1,1,3-trichloropropene, 1,1,2,2-tetrachloropropene, 1,1,2,3. -Tetrachloropropene, 1,1,3,3-tetrachloropropene, 1,1,2,3,3-pentachloropropene, 1,1,3,3,3-pentachloropropene, 1,1,2 , 3,3,3-hexachloropropene and the like.

  Among these compounds, a compound in which m is 2 is preferable in that dehydrochlorination from the generated compound represented by the formula (2) occurs relatively easily. Furthermore, 1,1,3-trichloropropene is most preferable from the viewpoint of the usefulness of the product compound.

  This chlorination reaction may be performed in a gas phase or in a liquid phase of chloropropene.

  The temperature in the gas phase reaction is not particularly limited as long as it is at or above the temperature at which chloropropene does not condense, but in order to reduce by-products, a temperature of not less than the boiling point of chloropropene and not more than 300 ° C. is preferable. The amount of chlorine to be supplied is preferably in the range of 0.9 to 2.0 in terms of molar ratio with respect to chloropropane in that the conversion rate and selectivity can be maintained high. Furthermore, the reaction residence time with chlorine may be appropriately determined depending on the reaction temperature or the like so as to reduce by-products, but generally 1 to 60 seconds is sufficient.

  On the other hand, in the chlorination reaction, the temperature in the case of reacting chloropropene in the liquid phase may be not higher than the temperature at which chloropropene does not vaporize, but preferably chlorinated at 120 ° C. or lower in order to reduce by-products. It is good to do. Further, the amount of chlorine to be supplied is preferably in the range of 0.9 to 2.0 in terms of molar ratio with respect to chloropropane, since the conversion rate and selectivity can be maintained high. Furthermore, the reaction residence time with chlorine may be appropriately determined depending on the reaction temperature or the like so as to reduce by-products, but 1 to 10 hours is generally sufficient.

  As a method for accelerating the reaction, a method in which chlorine is blown into fine bubbles and irradiation with ultraviolet light are also suitable.

In chlorinating the chloropropene of the present invention, it is generally better not to have iron in the chloropropene. This is because the decomposition of chloropropane produced by chlorination is promoted by iron. Therefore, in the present invention, the chloropropene is represented by the following formula (3):
_{CCl 3 -CCl (2-m)} H m -CCl (3-n) H n (3)
It is preferable that it is obtained by dehydrochlorinating chloropropane represented by the following by thermal decomposition. According to this method, iron is hardly mixed in the produced chloropropene. The thermal decomposition method will be described later.

  By such a chlorination reaction, chloropropane corresponding to the structure of chloropropene used as a raw material is produced. Usually, if it carries out on the said conditions, the conversion rate on the basis of chloropropene will be 95-100%, and the selectivity will be 90-99%, and the chloropropane shown by Formula (2) will be obtained.

  In the present invention, the crude chloropropane obtained by performing the chlorination reaction in this manner is distilled to obtain purified chloropropane. The feature of the present invention is that distillation (heating) is performed after adding a phenol compound substituted with an allyl group (allyl-substituted phenol) to the crude chloropropane during the distillation.

  The allyl-substituted phenol is not particularly limited as long as it has at least one allyl group as a substituent. Substituents other than allyl groups such as lower alkyl groups, halogen atoms, and lower alkoxy groups are further substituted. You may have as a group. Further, the substitution position of the allyl group may be any of ortho, meta and / or para positions.

  A suitable allyl-substituted phenol is represented by the following formula (4).

(Wherein R is a hydrocarbon group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, and n is an integer of 0 to 4).

  Specific examples of the compound include o-allylphenol, m-allylphenol, p-allylphenol, 4-allyl-2-methoxyphenol (eugenol), 2-methoxy-4- (1-propenyl) phenol (iso Eugenol) and the like. These allyl-substituted phenols may be used alone or in combination.

  Although the usage-amount of allyl substituted phenol should just be determined suitably, generally it is 0.0020-0.1 mass part with respect to 100 mass parts of crude chloropropane, Preferably it is 0.005-0.05 mass part.

  In distillation, phenol other than allyl-substituted phenol may be used in combination as a decomposition inhibitor. Furthermore, linear, branched, or cyclic unsaturated hydrocarbons having a double bond in the molecule, specifically amylene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, etc. are also preferably used as a decomposition inhibitor. it can.

In the present invention, crude chloropropane can be distilled by a known method.
Specifically, a plate column or a packed column can be mentioned as a preferable one.

  As the column tower, for example, a cross flow tray, a shower tray, or the like can be used. Specific examples of these include cross-flow trays such as a perforated plate tray, bubble bell tray, valve tray, and turbo grid tray, and shower trays such as a turbo grid tray and a ripple tray. Of these, it is preferable to use a cross flow tray.

  As the packed column, a distillation column packed with an ordered packing or an irregular packing can be used. Examples of the irregular packing include Raschig rings, Bersaddles, McMahons, Nutter rings, polling, cascade mini rings, and helipacks. Among these, it is preferable to use a distillation column packed with a regular packing or a cascade mini-ring because the distillation efficiency can be increased.

  While higher distillation temperature can increase the pressure during distillation, chloropropane is likely to be decomposed, but according to the present invention, allyl-substituted phenol is added to crude chloropropane and then distilled. Can be distilled at a good yield even at a temperature of about 180 ° C., where the decomposition is severe and the yield is significantly reduced. The distillation temperature is preferably 60 to 140 ° C, more preferably 80 to 130 ° C.

  The distillation pressure is preferably set at a pressure capable of maintaining the distillation operation at the preferred temperature, and can be set to 1 to 20 kPa, for example.

  As described above, the chloropropene used as a raw material in the present invention is preferably obtained by thermally decomposing chloropropane represented by the formula (3). The thermal decomposition method will be described below.

  The thermal decomposition reaction can be performed by a method in which the chloropropane represented by the formula (3) is heated at a temperature equal to or higher than the thermal decomposition temperature.

  This thermal decomposition reaction is preferably performed in the gas phase, and the reaction method may be either a distribution method or a batch method. However, since the thermal decomposition reaction can achieve a high reaction conversion rate in a short reaction time, it is preferable from the viewpoint of reaction efficiency to use a flow system.

  The heating temperature is preferably 300 to 600 ° C, more preferably 350 to 550 ° C. The heating time (staying time) is, for example, preferably 1 to 10 seconds, more preferably 1 to 5 seconds, and further preferably 1 to 3 seconds. Here, if the heating temperature is less than 300 ° C. or the heating time is less than 1 second, thermal decomposition becomes difficult. On the other hand, if the heating temperature exceeds 600 ° C. or the heating time exceeds 10 seconds, the reaction selectivity May be lower.

  The heating for the thermal decomposition can be performed by a known method. As the reactor, a reaction tube (decomposition furnace) provided with a heating device on the outer wall is suitable. Examples of the material constituting the reactor include quartz, ceramic, and metal. As the heating device, for example, a burner, an electric heater, a high-frequency heating device or the like can be used.

  In this reaction, as a method for supplying the chloropropane represented by the formula (3) to the reactor, for example, a method of vaporizing the compound by a vaporizer and introducing it into the reactor as a gas, or a reaction by spraying a liquid compound It is possible to adopt a method of introducing into a vessel. At this time, only the chloropropane represented by the formula (3) may be supplied to the reactor, or a mixture of the chloropropane represented by the formula (3) and an appropriate dilution gas may be introduced. As the dilution gas used here, it is preferable to use an inert gas, for example, nitrogen, argon, helium, etc. can be preferably used, but nitrogen is particularly used from the viewpoint of the cost required for the dilution gas. preferable. Moreover, it is preferable to adjust the oxygen concentration in the gas to be subjected to thermal decomposition (in the case of using a dilution gas, a mixed gas with the dilution gas) to 1 wt% or less.

  If the product obtained by dehydrochlorination by pyrolysis (chloropropane represented by the above formula (3)) contains water, an extra purification step is required for its removal, which is an economic disadvantage. . In order to avoid this, it is preferable to set the water concentration in the gas (mixed gas with the dilution gas when the dilution gas is used) to 1000 ppm by weight or less before subjecting to thermal decomposition.

  The reaction pressure at the time of dehydrochlorination by this thermal decomposition is not particularly limited, and it can be carried out under normal pressure, reduced pressure or increased pressure. The pressure can be reduced to make the reactor smaller, but the higher the reaction pressure, the more likely the precipitation of carbon in the piping tends to occur. Considering the apparatus cost, reaction efficiency, etc., it is most preferable to carry out at normal pressure.

  EXAMPLES Hereinafter, examples and comparative examples will be shown to specifically describe the present invention, but the present invention is not limited only to these examples.

<Production of compound represented by formula (1)>
The raw material was 1,1,1,3-tetrachloropropane (GC purity about 100%) produced by reacting carbon tetrachloride with ethylene and purified by distillation. The 1,1,1,3-tetrachloropropane is vaporized with a 200 ° C preheater, the flow rate is adjusted so that the residence time is 2.5 seconds based on the inlet gas flow rate, and heated to 500 ° C by an electric furnace. The reaction tube (material SUS316, inner diameter 4.35 mm, length 300 mm) was introduced in the form of a gas, and a thermal decomposition reaction was performed in a gas phase at normal pressure.

  At this time, a part of the product gas obtained was cooled to 0 ° C., liquefied, and analyzed by gas chromatography to obtain the conversion and selectivity. As a result, the conversion was 99.7%, and the selectivity to 1,1,3-trichloropropene was 99.0%.

  After cooling the reaction product gas to 0 ° C., hydrogen chloride gas was separated, and the liquid phase was subjected to the chlorination step in the following Examples and Comparative Examples.

Example 1
9 mol of 1,1,3-trichloropropene was put into a 1000 ml volume flask, chlorine was supplied into the same liquid at a rate of 400 ml / min, and chlorination reaction was carried out at a reaction temperature of 100 ° C. for 8 hours. As a result, the conversion was 95% and the 1,1,1,2,3-pentachloropropane selectivity was 98%.

  In a distillation column with a diameter of 30 mmφ in which 0.01 parts by mass of eugenol was added and 100 ml of Shiba Kagaku's glass packing was packed inside, the distillation pressure was 10 kPa, Batch distillation was performed at a temperature of 135 ° C.

  The purity of the obtained purified 1,1,1,2,3-pentachloropropane was 99.5%, and the yield was 75%. Further, 1,1,1,2,3-pentachloropropane decomposed in the course of the distillation was 1.5% as a result of analyzing the distillation distillate and the distillation residue together.

Comparative Example 1
Purified 1,1,1,2,3-pentachloropropane was produced in the same manner as in Example 1 except that distillation was performed without adding eugenol.

  As a result, the purity of the obtained purified 1,1,1,2,3-pentachloropropane was 98%, and the yield was 70%. Further, 1,1,1,2,3-chloropropane decomposed during the distillation process was 2.6%.

Examples 2, 3 and Comparative Examples 2-6
To 100 parts by mass of crude 1,1,1,2,3-pentachloropropane obtained by the same method as in Example 1, 0.01 parts by mass of various phenol compounds such as eugenol were added. Heated at ˜175 ° C. for 5 hours. Thereafter, the decomposition rate of 1,1,1,2,3-chloropropane was analyzed again by gas chromatography. Table 1 shows the types of added phenolic compounds and the measurement results of the decomposition rate.

Claims (3)

Chloropropene represented by the following general formula (1) is reacted with chlorine to chlorinate to obtain chloropropane represented by the following general formula (2). Next, the crude chloropropane obtained by the reaction is subjected to the following general formula (4 A method for producing purified chloropropane, comprising adding a phenol compound substituted with an allyl group represented by formula (I) and then distilling it.
_{CCl 2 = CCl (2-m} ) H (m-1) -CCl (3-n) H n (1)
_{CCl 3 -CCl (3-m)} H (m-1) -CCl (3-n) H n (2)
(In the above formula, m is 1 or 2, and when m is 1, n is an integer from 0 to 2, and when m is 2, n is an integer from 0 to 3).

(In the formula, R is a hydrocarbon group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, and n is an integer of 0 to 4) The manufacturing method of Claim 1 which makes the addition amount of the phenol compound substituted by the allyl group shown by General formula (4) 0.0020-1.0 mass part with respect to 100 mass parts of crude chloropropane. When purifying chloropropane represented by the following general formula (2) by distillation, a phenol compound substituted with an allyl group represented by the following general formula (4) is added to the composition before distillation, and then distilled. A method for producing purified chloropropane, characterized in that:
_{CCl 3 -CCl (3-m)} H (m-1) -CCl (3-n) H n (2)
(In the above formula, m is 1 or 2, and when m is 1, n is an integer from 0 to 2, and when m is 2, n is an integer from 0 to 3).

(In the formula, R is a hydrocarbon group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, and n is an integer of 0 to 4)