JP2009263338A - Novel manufacturing method of epichlorohydrin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of epichlorohydrin, by dechlorohydrogenation of a dichlorohydrin mainly composed of 1,3-dichloro-2-propanol, which is excellent in the light of yield, waste water load, and energy used in its manufacturing. <P>SOLUTION: In a process in which epichlorohydrin is generated by dechlorohydrogenation of a dichlorohydrin mainly composed of 1,3-dichloro-2-propanol, it was found that the reaction liquid after dechlorohydrogenation of dichlorohydrin can be separated by the difference of specific gravities of an oil layer and a water layer, and that the property of liquid separation can be controlled by limiting the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol of the dichlorohydrin to be dechlorohydrogenated within 87:13-100:0. Optionally, the resultant oil layer and the water layer are treated intermediately. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing epichlorohydrin by dehydrochlorinating dichlorohydrin with a base.

  Epichlorohydrin is used in large amounts as a starting material for epoxy resins and synthetic rubbers, glycidyl ethers, glycidyl esters, amine adducts and the like.

  Epichlorohydrin can be produced by synthesizing allyl chloride by chlorination of propylene, synthesizing dichlorohydrin by chlorohydrination reaction of allyl chloride, and epichlorohydrin by dehydrochlorination of dichlorohydrin. A method based on a synthesis process is well known. However, this conventional method has been regarded as a problem that unnecessary chlorinated substances such as trichloropropane are by-produced and a large amount of waste water is generated, and a new production method has been desired.

  As another production method for producing dichlorohydrin, a method for obtaining dichlorohydrin by reacting glycerin with hydrogen chloride gas in the presence of a catalyst such as formic acid or acetic acid is known. This method is preferable in that dichlorohydrin can be produced without generating unnecessary chlorinated substances such as trichloropropane.

  In addition, glycerin as a raw material is a low-cost renewable resource, and is a desirable raw material from an economic or environmental point of view because it is produced as a by-product by reaction using vegetable oil or animal oil or production of biodiesel. I can say that.

  For the above reasons, research on production methods for obtaining dichlorohydrin from glycerin has been actively carried out in recent years, and production processes have been studied together with screening for effective catalysts for the reaction (see Patent Documents 1 to 4).

A method for producing chlorohydrins in which glycerin and hydrogen chloride gas are reacted in the presence of a catalyst is represented by the following formula (1).

  When dichlorohydrin is produced from glycerin, dichlorohydrin mainly produces 1,3-dichloro-2-propanol, and 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol Is approximately 90:10 to 99: 1. On the other hand, when dichlorohydrin is produced from allyl chloride, which is a conventional method, the production ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol is approximately 30:70. . The reaction rate of dehydrochlorination of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol is greatly different, and 1,3-dichloro-2-propanol is 2,3-dichloro-1-propanol. The reaction rate of dehydrochlorination is higher, and 1,3-dichloro-2-propanol proceeds even at a relatively low temperature, but 2,3-dichloro-1-propanol does not proceed unless the temperature is increased. However, a high reaction temperature is not preferable because the decomposition reaction is accelerated.

In view of efficient synthesis of epichlorohydrin, dehydrochlorination of 1,3-dichloro-2-propanol, which has a high reaction rate, is generally considered to be preferable. However, in order to improve the yield of epichlorohydrin, it is necessary to suppress the decomposition reaction of the synthesized epichlorohydrin when dehydrochlorinating dichlorohydrin to synthesize epichlorohydrin. The synthesized epichlorohydrin can be converted to monochlorohydrin under base excess conditions. Monochlorohydrin can also react with a base to produce glycidol (see Formula 2 below). When monochlorohydrin reacts with the base used for the dehydrochlorination reaction to produce glycidol, the base used for the production of epichlorohydrin from dichlorohydrin is also consumed, making efficient production impossible. Moreover, since the COD load in wastewater also increases, it is not preferable.

  At present, various attempts have been made for the dehydrochlorination reaction of dichlorohydrin mainly composed of 2,3-dichloro-1-propanol. For example, there is a method of stripping epichlorohydrin produced by the reaction with water vapor (see Patent Documents 5 and 6). Also, the present applicant distills optically active epichlorohydrin produced by reacting optically active 2,3-dichloro-1-propanol and an aqueous alkali solution with stirring under reduced pressure out of the reaction system. Has been made (see Patent Document 7). However, as described above, a method for producing dichlorohydrin containing 1,3-dichloro-2-propanol as a main component, which is greatly different in the reaction rate of the dehydrochlorination reaction, is being established. Investigate efficient dehydrochlorination of dichlorohydrin based on 1,3-dichloro-2-propanol as well as dehydrochlorination of dichlorohydrin based on -1-propanol It became necessary.

WO2005 / 021476 WO2005 / 054167 WO2006 / 020234 WO2006 / 110810 JP-A-60-258171 JP 6-25196 JP-A-6-21822

  In the production of epichlorohydrin for dehydrochlorinating dichlorohydrin containing 1,3-dichloro-2-propanol as a main component, an excellent production method in terms of yield, wastewater load, and energy used for production Is to provide.

  As a result of various studies to solve the above problems, the present inventors have surprisingly found that dichlorohydrin containing 1,3-dichloro-2-propanol as a main component is dehydrochlorinated with a base. In the process of producing epichlorohydrin, the molar ratio of 1,3-dichloro-2-propanol to 2,3-dichloro-1-propanol in the dichlorohydrin used, that is, the unreacted content contained after the dehydrochlorination reaction. It has been found that the liquid separation of the oil layer and the aqueous layer varies depending on the amount of 2,3-dichloro-1-propanol in the reaction. As a result of extensive studies, the molar ratio of 1,3-dichloro-2-propanol to 2,3-dichloro-1-propanol in dichlorohydrin to be dehydrochlorinated is limited to 87:13 to 100: 0. Thus, it has been found that the oil layer and the aqueous layer in the dehydrochlorination step can be separated without becoming emulsion.

That is, the present invention comprises a step of dehydrochlorinating dichlorohydrin having a molar ratio of 1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 87: 13 to 100: 0 with a base; ,
It is a manufacturing method of epichlorohydrin including the process of liquid-separating the produced | generated reaction liquid containing epichlorohydrin into an oil layer and a water layer.

  The method for producing epichlorohydrin of the present invention preferably further includes a step of recovering epichlorohydrin from the obtained oil layer by distillation. Moreover, you may include the process of dehydrochlorinating the distillation residue produced by distillation.

  Further, a step of recovering epichlorohydrin from the obtained aqueous layer by distillation, or further, adding a base to the obtained aqueous layer and producing epichlorohydrin by dehydrochlorination of unreacted dichlorohydrin. It is preferable to include a step of distilling off, preferably a step of distilling off by stripping using water vapor.

  According to the present invention, in the dehydrochlorination of dichlorohydrin, waste water or energy used in the dehydrochlorination step can be reduced, and epichlorohydrin can be recovered in a high yield. The present invention relates to the dechlorination of dichlorohydrin produced by chlorinating glycerin in which the molar ratio of 1,3-dichloro-2-propanol to 2,3-dichloro-1-propanol is approximately 90:10 to 99: 1. It is particularly useful for hydrogenation.

Schematic diagram 1 showing an embodiment of the present invention Schematic diagram 2 showing an embodiment of the present invention

  The present invention can be carried out only when the molar ratio of 1,3-dichloro-2-propanol to 2,3-dichloro-1-propanol is 87:13 to 100: 0, Dehydrochlorination such as stripping of epichlorohydrin produced by the reaction with steam or dehydrochlorination of dichlorohydrin under reduced pressure, and distilling of the produced epichlorohydrin with water azeotropically It is greatly different that the method can be carried out even when it is not in the above molar ratio.

Hereinafter, the present invention will be described in detail.
The method for producing epichlorohydrin according to the present invention comprises dichlorohydrin having a molar ratio of 1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 87: 13 to 100: 0 with a base. It includes at least a step of dehydrochlorination and a step of separating a reaction liquid containing epichlorohydrin generated by dehydrochlorination into an oil layer and an aqueous layer.

Dehydrochlorination Step Hereinafter, the dehydrochlorination step of the present invention will be described in detail. In the present invention, there is a liquid separation step for separating the oil layer and the aqueous layer after the dehydrochlorination step, but at least a part of the oil layer and the water layer obtained by the liquid separation step and / or any separation step after the liquid separation step. Since it may include a step of dehydrochlorinating at least a part of the oil layer and the aqueous layer that have been subjected to the intermediate treatment, if it is necessary to distinguish them from those, dechlorination prior to the provision of the liquid separation step described in detail below. In the hydrogenation step, dichlorohydrin having a molar ratio of 1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 87: 13 to 100: 0 is dehydrochlorinated with a base. The process is also referred to as “dehydrochlorination process before liquid separation process”.

  The starting material dichlorohydrin is a generic name for 1,3-dichloro-2-propanol, 2,3-dichloro-1-propanol and mixtures thereof. The production method of the present invention is a production method suitable for 1,3-dichloro-2-propanol having a high dehydrochlorination reaction rate, and the molar ratio is 1,3-dichloro-2-propanol: 2,3-dichloro. Dichlorohydrin in which -1-propanol = 87: 13 to 100: 0 is preferable, 90:10 to 100: 0 is more preferable, 93: 7 to 100: 0 is further preferable, and 95: 5 to 100: 0 is preferable. Particularly preferred is 95: 5 to 99: 1. In addition, when the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol is 100: 0, only 1,3-dichloro-2-propanol exists as dichlorohydrin. Means.

  The method for producing dichlorohydrin used in the dehydrochlorination step is not a problem. Examples of the route for obtaining dichlorohydrin include dichlorohydrin obtained from allyl chloride, dichlorohydrin obtained from allyl alcohol, dichlorohydrin obtained from glycerin, and mixtures thereof. Incidentally, since dichlorohydrin obtained from allyl chloride and dichlorohydrin obtained from allyl alcohol produce 2,3-dichloro-1-propanol as a main product, the above high 1,3-dichloro- It cannot be the molar ratio of 2-propanol. Therefore, the dichlorohydrin used in the present invention is substantially dichlorohydrin obtained from glycerol, dichlorohydrin obtained from glycerol and dichlorohydrin obtained from allyl chloride, or dichlorohydrin obtained from allyl alcohol. It can be said that it is a mixture. The present invention requires a high molar ratio of 1,3-dichloro-2-propanol, and although the main product is 1,3-dichloro-2-propanol, It is particularly preferred to use dichlorohydrin obtained by chlorination of glycerin from which dichloro-1-propanol is produced.

  The dichlorohydrin in the dehydrochlorination step may contain water, an organic compound, a salt, etc. as long as the reaction solution after the dehydrochlorination reaction separates the oil layer and the aqueous layer. For example, a composition containing an alkali metal salt such as water, sodium salt or potassium salt, an alkaline earth metal salt such as magnesium salt or calcium salt, or a composition containing impurities contained in the production of the dichlorohydrin described above. Can be illustrated. When the dichlorohydrin of the present invention is obtained by chlorinating glycerin, various compounds such as hydrogen chloride, water, high-boiling compounds such as monochlorohydrin and diglycerin as intermediates, diglycerin, catalysts, When an acid is used as a catalyst, compounds such as carboxylic acids and carboxylic acid esters may be included, but it is preferable to remove them in advance as much as possible by a separation operation such as distillation.

  The type and amount of base used in the dehydrochlorination step before the liquid separation step in order to suppress the decomposition reaction of epichlorohydrin generated in the liquid separation step and the intermediate treatment step after the liquid separation step described later. Is preferably selected. That is, the pH of the reaction solution in the liquid separation step is preferably 7 to 13, more preferably 7 to 12, and particularly preferably 8 to 11. When the pH of the reaction liquid in the liquid separation process exceeds 13, hydrolysis of the produced epichlorohydrin occurs in the dehydrochlorination process, the liquid separation process, and the intermediate treatment process after the liquid separation process, and the yield is It is not preferable because the waste water load increases with decreasing. When the pH of the reaction solution in the liquid separation step is less than 7, it is not preferable because the reaction time becomes long. In the dehydrochlorination step before the liquid separation step, the kind and amount of the base used for the pH of the reaction solution in the liquid separation step to be 7 to 13 are not particularly limited.

The kind of the base used in the dehydrochlorination step is not particularly limited as long as it can dehydrochlorinate dichlorohydrin. Illustrative examples include slurries and solutions of alkali metal or alkaline earth metal hydroxides, oxides, salts, etc. The bases may be used alone or in admixture of two or more. In addition, when the slurry is used as a base, since the slurry itself is suspended, it is considered inappropriate in the present invention, but the oil layer and the water layer can be separated after the dehydrochlorination step. In the case of practical use, in particular, when the dehydrochlorination process is started and during the middle of implementation, an inexpensive calcium hydroxide is used as a slurry, and an aqueous solution of sodium hydroxide is added from the middle of the implementation. The use is naturally feasible and is also economically preferable.
Examples of the alkali metal or alkaline earth metal hydroxide include sodium hydroxide, calcium hydroxide, and potassium hydroxide.
Examples of the alkali metal or alkaline earth metal oxide include sodium oxide, potassium oxide, and calcium oxide.
Examples of the alkali metal or alkaline earth metal salt include sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like.

  The amount of base used in the dehydrochlorination step is generally 0.8 to 1.2 equivalents, preferably 0.9 to 1.1 equivalents, based on the total amount of dichlorohydrin. Further, by utilizing the difference in reaction rate between 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol, it is adjusted to the ratio of 1,3-dichloro-2-propanol in dichlorohydrin. The amount of base used may be adjusted. That is, it is preferable that it is 0.9-1.1 equivalent with respect to 1, 3- dichloro-2-propanol in dichlorohydrin, and it is especially preferable that it is 0.95-1.08 equivalent.

  However, even if the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol of dichlorohydrin to be dehydrochlorinated is limited to 87:13 to 100: 0, the oil layer and water If the specific gravity of the layers is the same or nearly the same, it will become milky. Liquid separation is carried out if the specific gravity difference between the oil layer and the water layer is 0.01 or more, but the specific gravity difference is more preferably 0.02 or more, further preferably 0.03 or more, and 0.05 or more. It is particularly preferred.

Considering the specific gravity difference between the oil layer and the water layer, it can be exemplified that the base used in the dehydrochlorination step is an aqueous solution or slurry of about 20% by weight or less. However, in the present invention, since the difference in specific gravity between the oil layer and the water layer after dehydrochlorination becomes a problem, the concentration of the base to be used should be determined by a substantial concentration in the entire reaction process (“substantially Also referred to as “base concentration”). The “substantial base concentration” is obtained by the following formula.
Substantial base concentration (% by weight) = [basic substance (g) / {water (g) present in dehydrochlorination step + basic substance (g)}] × 100
The water present in the dehydrochlorination step is not only water that dissolves or suspends basic substances, but also water that contains dichlorohydrin and water that dissolves or suspends basic substances. Water that is added to the hydrogenation step, for example, water that is produced together with dichlorohydrin when glycerin is chlorinated is included. That is, when the dichlorohydrin to be dehydrochlorinated contains water, it is necessary to set the base concentration including the water, and an aqueous solution of 20% by weight or more as a base to be added to dichlorohydrin. Or, the slurry must not be used. For example, 100 g of dichlorohydrin is dehydrochlorinated by adding 155 g of a 20% by weight aqueous sodium hydroxide solution, and 40% by weight aqueous sodium hydroxide solution is added to a liquid obtained by mixing 100 g of dichlorohydrin and 77.5 g of water. There is no change in dehydrochlorination by adding 5 g. In the above two implementations, in the present invention in which the substantial concentration is determined including the water contained in dichlorohydrin, the substantial base concentration is 20% by weight.

Further, the substantial concentration (“substantial base concentration”) in the entire dehydrochlorination step is not limited to the case where dichlorohydrin contains water as described above, but also when hydrogen chloride is contained. Of course, it is necessary to consider the base consumed by hydrogen chloride and the water produced. In particular, when dehydrochlorinating dichlorohydrin produced by chlorinating glycerin with hydrogen chloride, water produced when dichlorohydrin chlorinates glycerin and when not recovering hydrogen chloride, It also contains unreacted hydrogen chloride. Further, the substantial concentration (“substantial base concentration”) in the entire dehydrochlorination step in the case of containing hydrogen chloride is obtained by the following equation.
Substantial base concentration (% by weight) = [{basic substance (g) -basic substance (g) required to neutralize hydrogen chloride} / {water present in dehydrochlorination step (g) + Water (g) generated by neutralization of hydrogen chloride + basic substance-basic substance (g) required to neutralize hydrogen chloride}] × 100

  In the dehydrochlorination step, sodium hydroxide having a substantial base concentration of 20% by weight or less is used, and the moles of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol are used as dichlorohydrins. When the ratio is limited to 87:10 to 100: 0, the specific gravity of the water layer is about 1.1 to 1.16, the specific gravity of the oil layer is about 1.17 to 1.22, and the liquid separation property is Since it is good, epichlorohydrin can be recovered as an oil layer. Salts such as sodium chloride are mainly dissolved in the aqueous layer and affect the separation of the oil layer and the aqueous layer, but there is no problem as long as the oil layer and aqueous layer after the reaction can be separated. .

  If the substantial concentration (“substantial base concentration”) in the entire dehydrochlorination step is about 20% by weight or less, there is no problem with liquid separation, but if the substantial base concentration is too low, Since the amount increases, it is not preferable, so the substantial base concentration is preferably 5 to 20% by weight, more preferably 10 to 20% by weight, and a decrease in yield due to dissolution of epichlorohydrin in the aqueous layer is considered. Then, 15 to 20% by weight is particularly preferable.

  In addition, it is possible to control the specific gravity of the oil layer and the water layer by adding an inert solvent or adding a solute. From the aspect, it is preferable to use little or no solvent.

  0-60 degreeC is preferable, as for the reaction temperature of the dehydrochlorination reaction of this invention, 5-40 degreeC is more preferable, and 10-30 degreeC is especially preferable. When the reaction temperature is too high, it is not preferable because the decomposition reaction of epichlorohydrin may occur. Further, at these temperatures, 1,3-dichloro-2-propanol is different from 2,3-dichloro-1-propanol. Since dehydrochlorination proceeds rapidly, the reaction is completed in about 1 to 60 minutes.

  Although the dehydrochlorination of 2,3-dichloro-1-propanol can be promoted by setting the reaction temperature to a relatively high temperature, the decomposition of epichlorohydrin under such high reaction temperature conditions By accelerating the reaction, the yield decreases, and further monochlorohydrin and glycidol accompanying the decomposition of epichlorohydrin are produced. As a result, the liquid separation property may be deteriorated. It is economically preferable to perform the dehydrochlorination reaction at the above reaction temperature because not only the suppression of side reactions and the improvement of the liquid separation property but also the energy for increasing the reaction conditions is not required.

Hereinafter, the liquid separation process of the present invention will be described in detail.
In the present invention, the time required for liquid separation is generally allowed to stand for about 1 to 180 minutes, so that the oil layer and the water layer can be separated. No problem. In addition, the temperature at which the solution is allowed to stand for liquid separation is not particularly limited, and is generally 0 to 60 ° C, preferably 5 to 50 ° C, preferably 10 to 45 ° C. It is particularly preferred.

  The apparatus used in the liquid separation step can be used without particular limitation as long as it can ensure a sufficient standing time and an appropriate standing temperature. In the present invention, dechlorination is also possible. It is not always necessary to perform the hydrogenation step and the liquid separation step with separate apparatuses, and the dehydrochlorination step and the liquid separation step can be performed with the same apparatus.

  After separating the reaction liquid containing epichlorohydrin obtained by dehydrochlorinating dichlorohydrin, which is one of the features of the present invention, it is purified to at least a part of the oil layer and / or the aqueous layer recovered by the liquid separation. Any intermediate treatment such as can be performed, which is preferable in terms of yield and wastewater load. Specifically, since epichlorohydrin and dichlorohydrin are dissolved in the water layer and the oil layer, it is preferable to recover epichlorohydrin and dehydrochlorinate dichlorohydrin.

Organic layer such as epichlorohydrin and unreacted dichlorohydrin, which are products, may be contained in the aqueous layer after separation in the intermediate treatment step of the aqueous layer after the separation step . In addition, the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol in the aqueous layer after liquid separation is the initial 1,3-dichloro-2-propanol and 2,3-dichloro The molar ratio of -1-propanol is not necessarily the same, and the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol can be in the range of 100: 0 to 0: 100. Therefore, as an intermediate treatment step of the aqueous layer after the liquid separation step, in terms of yield and wastewater load, a step of recovering epichlorohydrin present in the aqueous layer, or an unreacted dichlorohydride present in the aqueous layer A step of recovering epichlorohydrin obtained by dehydrochlorinating phosphorus with a base together with epichlorohydrin present in the aqueous layer is preferable.

  The step of recovering the product epichlorohydrin from the aqueous layer can be recovered by extraction with a solvent or distillation. Epichlorohydrin is preferably recovered by distillation under reduced pressure using azeotropy with water existing in the aqueous layer and / or water newly added from outside the system. In many cases, the distillate containing epichlorohydrin is cooled and separated into an organic layer and an aqueous layer containing epichlorohydrin to recover epichlorohydrin.

  There is no particular limitation on the temperature and pressure in the step of recovering the product epichlorohydrin from the aqueous layer by distillation. In general, the temperature is preferably 20 ° C to 110 ° C, more preferably 30 ° C to 110 ° C, and particularly preferably 40 ° C to 90 ° C. In general, the pressure is preferably 50 to 600 mmHg, more preferably 75 to 450 mmHg, and particularly preferably 100 to 300 mmHg.

In the step of recovering epichlorohydrin obtained by dehydrochlorinating unreacted dichlorohydrin present in the aqueous layer with a base together with epichlorohydrin present in the aqueous layer, unreacted dichlorohydrin is recovered. The base used for dehydrochlorination is not particularly limited as long as it can dehydrochlorinate dichlorohydrin. Illustrative examples include a slurry or solution of an alkali metal or alkaline earth metal hydroxide, oxide or salt.
Examples of the alkali metal or alkaline earth metal hydroxide include sodium hydroxide, calcium hydroxide, and potassium hydroxide.
Examples of the alkali metal or alkaline earth metal oxide include sodium oxide, potassium oxide, and calcium oxide.
Examples of the alkali metal or alkaline earth metal salt include sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like.

  Moreover, it is preferable that it is 0.8-1.2 equivalent with respect to the unreacted dichlorohydrin, and, as for the quantity of the base to be used, it is more preferable that it is 0.9-1.1 equivalent. In addition, a part or all of the base in this step may not be used in the dehydrochlorination step before the liquid separation step and may remain as the base, but the base after controlling the pH of the reaction liquid in the liquid separation step That is, after the organic layer is separated by controlling the pH of the reaction liquid in the liquid separation step to 7 to 13 (more preferably 7 to 12), a base is added to the aqueous layer to add unreacted dichlorohydride. It is more preferable to provide a step of recovering epichlorohydrin obtained by dehydrochlorinating phosphorus.

  In addition, as a step of recovering epichlorohydrin obtained by dehydrochlorinating unreacted dichlorohydrin existing in the aqueous layer of the present invention with a base together with epichlorohydrin existing in the aqueous layer, It is preferable to recover by stripping using. Specifically, a base such as an aqueous layer after separation and a slurry of calcium hydroxide is supplied to the distillation tower, and steam is blown into the distillation tower to distill the produced epichlorohydrin. It is preferable that a base such as a calcium hydroxide slurry is added in advance to the aqueous layer after the separation, and the mixed aqueous layer is supplied to the distillation tower.

The temperature of the distillation column is lower than that of 1,3-dichloro-2-propanol, so that 2,3-dichloro-1-propanol undergoes a dehydrochlorination reaction in the present invention. Requires a higher temperature than the conversion process. However, extreme high temperature conditions are not economical in order to suppress decomposition of the produced epichlorohydrin. Accordingly, in general, the temperature is preferably 80 ° C to 120 ° C, more preferably 90 ° C to 110 ° C, and particularly preferably 95 ° C to 105 ° C.
Moreover, the pressure of the distillation column is preferably 400 mmHg to 1500 mmHg, more preferably 500 mmHg to 1150 mmHg, and particularly preferably 650 mmHg to 950 mmHg in terms of absolute pressure at the top of the column.

  The distillation column is not particularly limited and may have a general structure. Specifically, it may have a structure such as irregular packing, ordered packing, and shelf. Since epichlorohydrin is generated inside the tower, the internal liquid may form a two-layer mixture of the oil layer and the water layer. As a countermeasure, the mesh improves the wettability of the packing surface. A regular packing of the type may be used, and when calcium hydroxide is used as the base, since the supply liquid becomes a slurry, a shelf may be used as a measure against the adhering matter.

  Distilled epichlorohydrin and water may contain unreacted dichlorohydrin. In that case, condensate containing dichlorohydrin is separated by a condenser and returned to the distillation column. Then, after condensing uncondensed gas with a full-condenser, the liquid is allowed to stand for separation to obtain epichlorohydrin from the oil layer. It is desirable to return the aqueous layer containing epichlorohydrin to the distillation column in order to improve the yield.

  The oil layer mainly composed of epichlorohydrin recovered by distillation from the aqueous layer after the liquid separation step, and the oil layer mainly composed of epichlorohydrin obtained in the liquid separation step contain water corresponding to the solubility. Yes. These oil layers are commercialized through a distillation step in a post-process, and in that distillation step, the purity is generally increased by using a total of three or more dehydration tower, low boiling cut tower, and high boiling cut tower. . However, this is not the case when a single tower has multiple roles, such as using side cuts or internally divided towers.

  Water such as a step of recovering the product epichlorohydrin from the aqueous layer or a step of recovering epichlorohydrin obtained by adding a base to the aqueous layer to dehydrochlorinate unreacted dichlorohydrin. There is no problem even if the residue after recovery of epichlorohydrin in the intermediate treatment step of the layer is removed from the reaction system, but the residue may contain dichlorohydrin, so a base is added to a part or all of the residue. Then, a step of dehydrochlorinating dichlorohydrin may be provided, or the residue may be collected and added to the dehydrochlorination step before the liquid separation step.

The oil layer after the liquid separation step after the liquid separation step may contain organic substances such as dichlorohydrin and monochlorohydrin in addition to the target epichlorohydrin. In addition, the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol in the oil layer after liquid separation was such that the initial 1,3-dichloro-2-propanol and 2,3-dichloro- The molar ratio of 1-propanol is not necessarily the same, and the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol can range from 100: 0 to 0: 100.

  There are no particular limitations on the temperature and pressure in the step of recovering the product epichlorohydrin from the oil layer by distillation. In general, the temperature is preferably 20 ° C to 110 ° C, more preferably 30 ° C to 110 ° C, and particularly preferably 40 ° C to 90 ° C. In general, the pressure is preferably 50 to 600 mmHg, more preferably 75 to 450 mmHg, and particularly preferably 100 to 300 mmHg.

  Since the distillation residue after the recovery of the product epichlorohydrin from the oil layer by distillation contains unreacted dichlorohydrin, a base is added to the distillation residue to dechlorinate dichlorohydrin. It is more preferable to recover epichlorohydrin produced after hydrogenation. Further, the distillation residue is added to the step of recovering epichlorohydrin obtained by adding a base to the above-mentioned aqueous layer to dehydrochlorinate unreacted dichlorohydrin, and is simultaneously contained in the aqueous layer. It may be dehydrochlorinated together with unreacted dichlorohydrin or may be added to the dehydrochlorination step before the liquid separation step.

  By the method for producing epichlorohydrin including the dehydrochlorination step and the liquid separation step of the present invention, waste water or energy to be used can be reduced, and a high yield can be expected. In particular, in the present invention, by providing an intermediate treatment step for the water layer and / or oil layer after the liquid separation step, epichlorohydrin can be obtained with a higher yield, and the waste water load can be further reduced. Can be realized.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In addition, embodiment in drawing is only the preferable aspect of this invention, and this invention is not limited to these.
FIG. 1 shows a flowchart of the method for producing epichlorohydrin of the present invention. A liquid stream containing dichlorohydrin is introduced into reaction vessel 1 through tube 2 and a base is introduced through tube 3. In the reaction tank 1, a dehydrochlorination reaction is performed to obtain a reaction liquid containing epichlorohydrin and water. The obtained reaction solution is introduced into the separation tank 5 through the tube 4. The reaction solution is separated into a water layer and an oil layer in a separation tank 5. The aqueous layer obtained by separation in the separation tank 5 is introduced into the distillation column 7 through the pipe 6, epichlorohydrin is recovered through the pipe 8 by azeotropic distillation with water, and the distillation residue is passed through the pipe 9. Discharged. The oil layer obtained by separation in the separation tank 5 is introduced into the distillation column 11 through the pipe 10, epichlorohydrin is recovered through the pipe 12 by distillation, and the distillation residue containing dichlorohydrin is discharged through the pipe 13. Is done.

  In FIG. 1, the distillation residue of the water layer and the oil layer may be discharged out of the reaction system through the pipe 9 or the pipe 13. However, since the distillation residue of these water layer and oil layer may contain dichlorohydrin, In order to improve the recovery rate of chlorohydrin, it is preferable to provide a step of recovering epichlorohydrin after adding a base to the distillation residue and dehydrochlorinating. The distillation residue in the aqueous layer is introduced into the reaction tank 14 through the pipe 9. A base is introduced through a tube 15 into the reaction vessel 14 into which the distillation residue has been introduced, and a dehydrochlorination reaction is performed. The obtained distillation residue of the aqueous layer containing epichlorohydrin is introduced into the distillation column 17 through the pipe 16. Epichlorohydrin is recovered through the pipe 18 by distillation in the distillation column 17, and the distillation residue is discharged out of the reaction system through the pipe 19. The distillation residue of the oil layer is introduced into the reaction tank 20 through the pipe 13. A base is introduced into the reaction vessel 20 into which the distillation residue has been introduced through a tube 21 to perform a dehydrochlorination reaction. The obtained oil layer distillation residue containing epichlorohydrin is introduced into a distillation column 23 through a pipe 22. Epichlorohydrin is recovered through the pipe 24 by distillation in the distillation column 23, and the distillation residue is discharged out of the reaction system through the pipe 25. Moreover, a part or all of the distillation residues of these oil layer and water layer can be dehydrochlorinated in the same reaction tank 26, which is preferable in that the reaction process is simplified. The distillation residue of the water layer and the distillation residue of the oil layer are introduced into the reaction tank 26 through the pipe 27 and the pipe 28. A base is introduced through a tube 29 into the reaction vessel 26 into which the distillation residue has been introduced, and a dehydrochlorination reaction is performed. The obtained distillation residue containing epichlorohydrin is introduced into a distillation column 31 through a pipe 30. By distillation in the distillation column 31, epichlorohydrin is recovered through the pipe 32, and the distillation residue is discharged out of the reaction system through the pipe 33. The distillation residue discharged from the tube 19, the tube 25, and the tube 33 may be reused in a reaction vessel such as the reaction vessel 1, the reaction vessel 14, the reaction vessel 20, and the reaction vessel 26 (not shown). Further, since the water recovered together with the epichlorohydrin recovered in the tube 8, the tube 12, the tube 18, the tube 24, and the tube 32 may contain dichlorohydrin, the reaction tank 1, the reaction tank 14, the reaction tank 20, You may reuse in reaction tanks, such as the reaction tank 26 (not shown).

  FIG. 2 shows a flowchart of the method for producing epichlorohydrin of the present invention. A liquid stream containing dichlorohydrin is introduced into the reaction vessel 34 through a tube 35 and a base is introduced through a tube 36. In the reaction tank 34, a dehydrochlorination reaction is performed to obtain a reaction liquid containing epichlorohydrin and water. The obtained reaction solution is introduced into a separation tank 38 through a tube 37. The reaction solution is separated into a water layer and an oil layer in a separation tank 38. The aqueous layer obtained by separation in the separation tank 38 is introduced into the storage tank 40 through the pipe 39. The aqueous layer is introduced into the storage tank 40 through a tube 41 and stirred, and then introduced into a distillation column 43 through a tube 42. Steam is blown into the distillation column 43, and the produced epichlorohydrin is distilled from the pipe 44. The distillation residue is discharged through the pipe 45 to the outside of the reaction system. Moreover, although the storage tank 40 is used in the figure of FIG. 2, the form which mixes the water layer obtained by separating with the base and the liquid separation tank 38 just before the reaction tank 43, without using a storage tank. You may take

  The oil layer obtained by separation in the separation tank 38 is introduced into the distillation column 47 through the pipe 46, epichlorohydrin is recovered through the pipe 48 by distillation, and the distillation residue containing dichlorohydrin is passed through the pipe 49. It is introduced into the reaction vessel 50. A base is introduced through a tube 51 into the reaction vessel 50 into which the distillation residue has been introduced, and a dehydrochlorination reaction is performed. The obtained distillation residue containing epichlorohydrin is introduced into a distillation column 53 through a pipe 52. By distillation in the distillation column 53, epichlorohydrin is recovered through the pipe 54, and the distillation residue is discharged out of the reaction system through the pipe 55. The distillation residue discharged from the pipe 45 and the pipe 55 may be reused in a reaction tank such as the reaction tank 34, the reaction tank 40, and the reaction tank 50 (not shown). In addition, since the water recovered together with the epichlorohydrin recovered in the tubes 44, 48 and 54 can contain dichlorohydrin, it can be reused in the reaction tanks such as the reaction tank 34, the reaction tank 40, and the reaction tank 50. (Not shown).

  In FIG. 2, the distillation residue of the water layer separated in the separation tank 38 and the oil layer separated in the separation tank 38 may be separately subjected to dehydrochlorination reaction through a pipe 39 or a pipe 49. However, in order to simplify the reaction process, part or all of the distillation residue of the oil layer may be introduced into the storage tank 40 through the pipe 56, which is preferable in that the reaction process is simplified.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples without departing from the gist thereof.

Example 1
The flask was charged with 257.999 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 98.7: 1.3, 2.0 mol), 15% aqueous sodium hydroxide solution (533). .33 g, 2.0 mol) was reacted at an internal temperature of 30 ° C. with stirring for 20 minutes. Therefore, the substantial base concentration of Example 1 is 15%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 5 minutes. After confirming good separation, the solution was separated. 173.20 g was obtained as an oil layer, and 614.74 g was obtained as an aqueous layer. The lower oil layer contains 94.0% by weight of epichlorohydrin, 2.2% by weight of 1,3-dichloro-2-propanol, and 2.3% by weight of 2,3-dichloro-1-propanol. It was. In the upper water layer, 1.9% by weight of epichlorohydrin, 0.1% by weight of 1,3-dichloro-2-propanol, and 0.1% by weight of 2,3-dichloro-1-propanol It was included. Epichlorohydrin contained in the aqueous layer was recovered by distillation under reduced pressure. The distilled epichlorohydrin was recovered by separating it from the aqueous layer as an oil layer (11.45 g). The oil layer contained 96.9% by weight of epichlorohydrin, 1,3-dichloro-2-propanol and 2 , 3-dichloro-1-propanol was 0.8% by weight. The total yield of recovered epichlorohydrin was 96.4%.

Example 2
Into the flask was added 258 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 97.5: 2.5, 2.0 mol), 15% aqueous sodium hydroxide solution (533.33 g). , 2.0 mol) was reacted at an internal temperature of 30 ° C. with stirring for 20 minutes. Thus, the substantial base concentration of Example 2 is 15%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 5 minutes. After confirming good separation, the solution was separated. 172.46 g was obtained as an oil layer, and 615.72 g was obtained as an aqueous layer. The lower oil layer contains 93.7% by weight of epichlorohydrin, 0.3% by weight of 1,3-dichloro-2-propanol, and 4.5% by weight of 2,3-dichloro-1-propanol. It was. The upper water layer contained 1.8% by weight of epichlorohydrin. Epichlorohydrin contained in the aqueous layer was recovered by distillation under reduced pressure. The distilled epichlorohydrin was recovered by separating it from the aqueous layer as an oil layer (11.45 g). The oil layer contained 98.4% by weight of epichlorohydrin, 1,3-dichloro-2-propanol and 2 , 3-dichloro-1-propanol was 0.1% by weight or less. The total yield of recovered epichlorohydrin was 93.4%.

Example 3
The flask was charged with 257.999 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 90.1: 9.9,2000 mmol), 15% aqueous sodium hydroxide solution (533.32 g). , 2000 mmol) was reacted at an internal temperature of 30 ° C. with stirring for 20 minutes. Therefore, the substantial base concentration of Example 3 is 15%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 10 minutes. After confirming good separation, the solution was separated. 170.30 g was obtained as an oil layer, and 617.87 g was obtained as an aqueous layer. The lower oil layer contained 87.5 wt% epichlorohydrin and 10.4 wt% 2,3-dichloro-1-propanol. The upper water layer contained 1.7% by weight of epichlorohydrin. Epichlorohydrin contained in the aqueous layer was recovered by distillation under reduced pressure. The distilled epichlorohydrin was recovered by separating it from the aqueous layer as an oil layer (10.02 g). In the oil layer, 98.1% by weight of epichlorohydrin, 1,3-dichloro-2-propanol and 2 , 3-dichloro-1-propanol was 0.1% by weight or less. The total yield of recovered epichlorohydrin was 85.8%.

Comparative Example 1
The flask was charged with 257.999 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 85.5: 14.5,2000 mmol) and a 15% aqueous sodium hydroxide solution (533.33 g). , 2000 mmol) was reacted at an internal temperature of 30 ° C. with stirring for 20 minutes. Therefore, the substantial base concentration of Comparative Example 1 is 15%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 30 minutes. However, the mixture solution was emulsified and could not be separated.

Comparative Example 2
Into the flask was 257.98 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 95.5: 4.5,2000 mmol), 22% aqueous sodium hydroxide solution (363.64 g). , 2000 mmol) was reacted at an internal temperature of 30 ° C. with stirring for 20 minutes. Therefore, the substantial base concentration of Comparative Example 2 is 22%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 30 minutes, but the mixed solution became milky and could not be separated.

Example 4
In a 2 L flask, 412.7 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 96.4: 3.6, 3.20 mol), 3.3 g of monochlorohydrin ( 0.03 mol), 201.0 g of water and 284.0 g of an aqueous solution containing 83.0 g of hydrogen chloride were added, and 1417 g (5.31 mol) of a 15% aqueous sodium hydroxide solution was added dropwise. At this time, the neutralization reaction between hydrogen chloride and sodium hydroxide generated heat at the beginning of the dropping, but the dropwise addition was carried out while adjusting the reaction temperature so that the internal temperature did not exceed 20 ° C. Thus, the substantial base concentration of Example 4 is 7.69%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 10 minutes. After confirming good separation, the solution was separated to obtain 252.5 g as an oil layer. According to GC analysis, the amount of epichlorohydrin in the oil layer was 220.8 g, and the yield of epichlorohydrin was 74.7%. From the COD measurement of the aqueous layer, the wastewater load per kg of produced epichlorohydrin was 150 g.

Example 5
In a 2 L flask, 412.7 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 96.4: 3.6, 3.20 mol), 3.3 g of monochlorohydrin ( 0.03 mol), 201.0 g of water and 284.0 g of an aqueous solution containing 83.0 g of hydrogen chloride were added, and a 15% aqueous sodium hydroxide solution (1417 g, 5.31 mol) was added dropwise. At this time, the neutralization reaction between hydrogen chloride and sodium hydroxide generated heat at the beginning of the dropping, but the dropwise addition was performed while adjusting the reaction temperature so that the internal temperature did not exceed 20 ° C., and the reaction was allowed to stir for 30 minutes. Thus, the substantial base concentration of Example 5 is 7.69%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 10 minutes. After confirming good separation, the solution was separated. 252.5 g was obtained as an oil layer, and 1720.7 g was obtained as an aqueous layer. The lower oil layer contains 87.2% by weight of epichlorohydrin, 5.6% by weight of 1,3-dichloro-2-propanol, and 4.2% by weight of 2,3-dichloro-1-propanol. It was. The upper water layer contains 1.9% by weight of epichlorohydrin, 0.1% by weight of 1,3-dichloro-2-propanol, and 0.1% by weight of 2,3-dichloro-1-propanol. It was. The pH of the aqueous layer was 10.6.

  Epichlorohydrin contained in the oil layer was recovered by distillation by distillation under a reduced pressure of 99 mmHg. The distillate was separated into two layers and separated to obtain 220.0 g of an organic layer and 26.9 g of an aqueous layer. When the organic layer was analyzed by GC, the oil layer was 97.0% by weight of epichlorohydrin, 0.6% by weight of 1,3-dichloro-2-propanol, and 0.2% of 2,3-dichloro-1-propanol. 3% by weight was contained. Further, 24.9 g of a residue obtained by distillation under reduced pressure was obtained. Moreover, the yield of epichlorohydrin obtained in the intermediate treatment step of the oil layer after the liquid separation step in Example 5 was 72.1%.

  A mixture of 1720.7 g of the aqueous layer obtained by liquid separation after dehydrochlorination, 26.9 g of the distilled water layer obtained by vacuum distillation of the oil layer and 24.9 g of distillation residue was mixed with 17.8 g of calcium hydroxide. And stirred well for 5 minutes to obtain a suspension. Water is placed in a packed tower (9 × 9 mm Raschig ring packed) with an inner diameter of 30 mmφ × 124 cm at the top and a 1 L four-necked flask equipped with a water separator and a cooler at the top, and heated and stirred with a 400 W mantle heater. Water was refluxed with a water separator, the suspension was fed from the top of the packed tower with a roller pump, and azeotropic epichlorohydrin was separated with a water separator. A certain amount of the liquid in the four-necked flask at the bottom of the packed tower was extracted so that the liquid level was constant. After the end of feeding, 68.9 g of an oil layer was obtained with a water separator. GC analysis of the oil layer revealed that the oil layer contained 96.6% by weight of epichlorohydrin, 0.1% by weight of 1,3-dichloro-2-propanol, and 0.3% of 2,3-dichloro-1-propanol. It was included by weight. Moreover, the yield of epichlorohydrin obtained in the intermediate treatment step of the aqueous layer after the liquid separation step in Example 5 was 22.5%. Therefore, the total yield of recovered epichlorohydrin in Example 5 was 94.6%. The amount of steam generated by heating the mantle heater was 2.7 kg per kg of all epichlorohydrin. Further, from the COD measurement of the four-necked flask liquid and the flask effluent after completion of the reaction, the wastewater load per kg of produced epichlorohydrin was 25 g.

Example 6
In a 2 L flask, 412.7 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 96.4: 3.6, 3.20 mol), 3.3 g of monochlorohydrin ( 0.03 mol), 201.0 g of water, and 83.0 g of hydrogen chloride were added, and 1545 g (5.79 mol) of a 15% aqueous sodium hydroxide solution was added dropwise. At this time, the neutralization reaction between hydrogen chloride and sodium hydroxide generated heat at the beginning of the dropping, but the dropwise addition was performed while adjusting the reaction temperature so that the internal temperature did not exceed 20 ° C., and the reaction was allowed to stir for 30 minutes. Therefore, the substantial base concentration of Example 6 is 8.19%. After the reaction, the reaction solution was transferred to a separatory funnel and allowed to stand for 10 minutes. After confirming good separation, the solution was separated. 261.2 g was obtained as an oil layer, and 2036.1 g was obtained as an aqueous layer. The lower oil layer contains 93.9% by weight of epichlorohydrin, 0.2% by weight of 1,3-dichloro-2-propanol, and 3.9% by weight of 2,3-dichloro-1-propanol. It was. In the upper water layer, epichlorohydrin is 2.0% by weight, 1,3-dichloro-2-propanol is 0.1% by weight or less, and 2,3-dichloro-1-propanol is 0.1% by weight or less. It was included. The pH of the aqueous layer was 12.5.

  Epichlorohydrin contained in the oil layer was recovered by distillation by distillation under a reduced pressure of 98 mmHg. The distillate was separated into two layers and separated to obtain 210.6 g of an organic layer and 27.8 g of an aqueous layer. GC analysis of the organic layer revealed that the oil layer was 97.5% by weight of epichlorohydrin, 0.1% by weight or less of 1,3-dichloro-2-propanol, and 0% of 2,3-dichloro-1-propanol. Contained 5 wt%. Further, 28.3 g of a residue obtained by distillation under reduced pressure was obtained. Moreover, the yield of epichlorohydrin obtained in the intermediate treatment step of the oil layer after the liquid separation step in Example 6 was 69.3%.

2036.1 g of the aqueous layer obtained by liquid separation after dehydrochlorination, 27.8 g of the distilled water layer obtained by vacuum distillation of the oil layer, and 28.3 g of the distillation residue were mixed. Water is placed in a 1 L four-necked flask equipped with a packed column (9 × 9 mm Raschig ring packed) with an inner diameter of 30 mmφ × 124 cm at the top and a water separator and a cooler at the top, and heated and stirred with a 400 W mantle heater. Water was refluxed with a water separator, and the mixture was fed from the top of the packed tower with a roller pump, and azeotropic epichlorohydrin was separated with a water separator. A certain amount of the liquid in the four-necked flask at the bottom of the packed tower was extracted so that the liquid level was constant. After the end of feeding, 61.0 g of an oil layer was obtained with a water separator. GC analysis of the oil layer revealed that the oil layer contained 97.6% by weight of epichlorohydrin, 0.1% by weight of 1,3-dichloro-2-propanol, and 0.3% of 2,3-dichloro-1-propanol. It was included by weight. Moreover, the yield of epichlorohydrin obtained in the intermediate treatment step of the aqueous layer after the liquid separation step in Example 6 was 20.1%. Therefore, the total yield of recovered epichlorohydrin in Example 6 was 89.4%. The amount of steam generated by heating the mantle heater was 2.7 kg per kg of all epichlorohydrin. Further, from the COD measurement of the liquid in the four-necked flask and the flask distillate after completion of the reaction, the waste water load per kg of the produced epichlorohydrin was 50 g.
Comparative Example 3

  In a 1 L flask, 246.6 g of dichlorohydrin (1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 96.3: 3.7, 1.91 mol), 147.1 g of water, and chloride An aqueous solution containing 49.1 g of hydrogen was added, and 638.8 g (1.724 mol) of a 20% calcium hydroxide slurry solution was added dropwise. At this time, the neutralization reaction between hydrogen chloride and calcium hydroxide generates heat at the beginning of the dropping, but it was dropped while adjusting the reaction temperature so that the internal temperature did not exceed 20 ° C. A suspension was obtained. Therefore, the substantial base concentration of Comparative Example 3 is 10.06%. Water is placed in a 1 L four-necked flask equipped with a packed column (9 × 9 mm Raschig ring packed) with an inner diameter of 30 mmφ × 124 cm at the top and a water separator and a cooler at the top, and heated and stirred with a 400 W mantle heater. Water was refluxed with a water separator, the suspension was fed from the top of the packed tower with a roller pump, and azeotropic epichlorohydrin was separated with a water separator. A certain amount of the liquid in the four-necked flask at the bottom of the packed tower was extracted so that the liquid level was constant. After the end of feeding, 177.7 g of an oil layer was obtained with a water separator. As a result of GC analysis of the oil layer, the oil layer was found to be 95.5% by weight of epichlorohydrin, 0.1% by weight of 1,3-dichloro-2-propanol, and 1.7% of 2,3-dichloro-1-propanol. It was included by weight. The yield of epichlorohydrin was 96.0%. The amount of steam generated by heating the mantle heater was 10.3 kg per kg of all epichlorohydrin, and 3.8 times as much steam as in Example 4 was required. Further, from the COD measurement of the four-necked flask solution and the flask effluent after completion of the reaction, the wastewater load per kg of produced epichlorohydrin was 27 g.

  As shown in Examples 1 to 3, when carried out in the molar ratio of 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol of dichlorohydrin as defined in the present invention, Since the specific gravity difference with the water layer can be controlled and the amount of unreacted 2,3-dichloro-1-propanol that has not been dehydrochlorinated is small, the separation between the oil layer and the water layer is good, It was easy to collect as an oil layer. However, as shown in Comparative Example 1, when the molar ratio of 1,3-dichloro-2-propanol to 2,3-dichloro-1-propanol in dichlorohydrin is not 87:13 to 100: 0, liquid separation is performed. Could not be recovered as an oil layer. In addition, as shown in Comparative Example 2, when the substantial base concentration in the dehydrochlorination is not within the range described in the present specification, the oil layer and the aqueous layer are likely to become emulsified. It was difficult to control the liquid separation.

Table 1 summarizes the yields of Examples 4 to 6 and Comparative Example 3, the required steam volume per kg of epichlorohydrin, and the wastewater load per kg of epichlorohydrin.

From Examples 4 to 6 and Comparative Example 3, compared with the method for producing epichlorohydrin by stripping with water vapor (stripping method), the method for producing epichlorohydrin (liquid separation method) by liquid separation is used. By adopting, it can be seen that the amount of steam is greatly reduced. In addition, by using a separation method and a stripping method together,
A high yield, a small amount of steam, and a low wastewater load can be realized, and more preferable results have been obtained by controlling the pH in the liquid separation process. Furthermore, the combined use of the liquid separation method and the stripping method is preferable in that the equipment used for stripping (stripping tower) can be made smaller than when only the stripping method is employed.

1 Reaction tank 2 Pipe 3 Pipe 4 Pipe 5 Separation tank 6 Pipe 7 Distillation tower 8 Pipe 9 Pipe 10 Pipe 11 Distillation tower 12 Pipe 13 Pipe 14 Reaction tank 15 Pipe 16 Pipe 17 Distillation tower 18 Pipe 19 Pipe 20 Reaction tank 21 Pipe 22 Tube 23 Distillation column 24 Tube 25 Tube 26 Reaction tank 27 Tube 28 Tube 29 Tube 30 Tube 31 Distillation tower 32 Tube 33 Tube 34 Reaction tank 35 Tube 36 Tube 37 Tube 38 Separation tank 39 Tube 40 Storage tank 41 Tube 42 Tube 43 Distillation tower 44 Pipe 45 Pipe 46 Distillation tower 47 Pipe 48 Pipe 49 Pipe 50 Reaction tank 51 Pipe 52 Pipe 53 Distillation tower 54 Pipe 55 Pipe 56 Pipe

  In a method for producing epichlorohydrin by dehydrochlorinating dichlorohydrin with a base, the present invention uses waste water or energy to be used by utilizing the separation of oil and water layers after dehydrochlorination. In addition, the process can be simplified by not using special equipment, and can be carried out particularly under mild conditions. In addition, epichlorohydrin can be recovered in a high yield. It is said. The epichlorohydrin produced and recovered can be used as a starting material for epoxy resins and synthetic rubber raw materials, glycidyl ethers, glycidyl esters, amine adducts and the like.

Claims (6)

Dehydrochlorinating dichlorohydrin having a molar ratio of 1,3-dichloro-2-propanol: 2,3-dichloro-1-propanol = 87: 13 to 100: 0 with a base;
The manufacturing method of epichlorohydrin including the process of liquid-separating the produced | generated reaction liquid containing epichlorohydrin into an oil layer and a water layer.   Furthermore, the manufacturing method of the epichlorohydrin of Claim 1 including the process of collect | recovering epichlorohydrin from the obtained aqueous layer by distillation.   Furthermore, epichlorohydrin obtained by dehydrochlorinating unreacted dichlorohydrin existing in the aqueous layer with a base is distilled by stripping using water vapor together with epichlorohydrin existing in the aqueous layer. The manufacturing method of the epichlorohydrin of Claim 1.   Furthermore, the manufacturing method of the epichlorohydrin in any one of Claims 1-3 including the process of collect | recovering epichlorohydrin by distillation from the obtained oil layer.   Furthermore, the manufacturing method of the epichlorohydrin of Claim 4 including the process of dehydrochlorinating the obtained distillation residue.   The method for producing epichlorohydrin according to claim 1, wherein the reaction solution has a pH of 7 to 13 in the liquid separation step.

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