JPH0725796A - Purification of 2,3-dichloro-1-propanol - Google Patents

Abstract

PURPOSE:To efficiently purify the 2,3-dichloro-1-propanol by reacting allyl alcohol with chlorine in the presence of a hydrohloric acid aqueous solution and distilling the produced 2,3-dichloro-1-propanol with a distillation tower. CONSTITUTION:Allyl alcohol is reacted with chlorine in a hydrochloric acid aqueous solution, and the reaction product is fed into an evaporation tower to evaporate the hydrogen chloride. The residual solution is cooled to separate a water layer from an oily layer. The water layer is returned into the reactor, and 2,3-dichloro-1-propanol (referred to as DCH) is obtained from the oil layer. Therein, the oil layer is fed into the first distillation tower, and 1,2,3- trichloropropane as an entrainer is also fed from the overhead of the first distillation tower. Substances having lower boiling points than that of DCH are distilled off, while the distillation of the DCH is prevented, and the bottom solution is fed into a treating installation otherwise disposed to purify the DCH. Since the azeotropic distillation using the reaction by-product as the entrainer and the two liquid phase separation utilizing the mutual solubility difference are performed, the distillation process is simplified and the volume of the treated waste solution is reduced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to 2,3-dichloro-1
-Propanol (hereinafter referred to as CH ₂ ClCHClCH ₂ OH or DCH), 1,2,3-trichloropropane (hereinafter referred to as CH ₂ ClCHClCH ₂ Cl or TCP), 2-chloroacrolein (hereinafter referred to as CH ₂ = CClC)
(Referred to as HO or CAC) and a hydrochloric acid aqueous solution, and efficiently purifying the DCH using a distillation column.

[0002]

2. Description of the Related Art Conventionally, as a method for separating and purifying a target substance from a mixed liquid of the target substance and a substance having a lower boiling point than the target substance, the mixed liquid is introduced into a distillation column and the boiling point of the target substance is lower than that of the target substance It is a general method to distill the substance having the above and to withdraw the target substance from the bottom of the column. Further, a method of refluxing a part of the distillate to the distillation column is used in order to improve the separation efficiency. Chlorine and allyl alcohol (hereinafter referred to as CH ₂ ═CHCH ₂ OH or AAL) are reacted in the presence of an aqueous hydrochloric acid solution, hydrogen chloride is recovered from the reaction solution by a diffusion tower, and the residual solution is cooled to separate water-oil two layers. In this case, in the oil layer, in addition to DCH as a main component, HCl, H ₂ O as main components having a lower boiling point than DCH, and TCP and CAC as by-products having a lower boiling point than DCH are contained.

As a method for separating and removing these low boiling components from the oil layer by using the above-mentioned separation method, JP-A-4-77 is known.
The method shown in 443 is mentioned. In this way, D
A large amount of CH is distilled at the top of the column, the overhead distillate is condensed and cooled, and a large amount of DCH is dissolved in the water layer after water-oil separation. This is because CAC, TCP and DCH form the lowest azeotrope with H ₂ O and the normal boiling point of the azeotrope is C
_{AC-H 2 O <TCP-} H 2 O <DCH-H 2 O (<H
For a ₂ O), when the removal of H ₂ O, H ₂ O is distilled in the form of the azeotrope, the majority of which is distilled in the form of an azeotropic mixture with DCH, further water-oil D when separated
This is because the solubility of CH in the water layer is large. The water layer needs to be extracted out of the system due to the balance with H ₂ O in the reaction process raw material. At that time, DCH loss is large and equipment for discarding it is also required so as not to adversely affect the environment. It has the drawback of

[0004]

The problem to be solved is that, when distilling and separating a low boiling point component from DCH, a large amount of DCH is also distilled out due to the formation of an azeotropic mixture with H ₂ O, and its recovery and treatment Therefore, the process is complicated and the efficiency is low.

[0005]

In the present invention, hydrogen chloride is recovered in a stripping tower from a reaction solution in which DCH is produced from chlorine and AAL in the presence of an aqueous hydrochloric acid solution, and the residual liquid is cooled to obtain a water oil. Separate into two liquid layers and introduce the oil layer into the first distillation column. Furthermore, DCH-H ₂ O from the lower boiling H ₂
The O azeotrope formed, small solubility in H ₂ O, and the also the reaction byproducts TCP fed from the column top as entrainer, H ₂ as a TCP-H ₂ O azeotrope
O is distilled out at the top of the tower to suppress DCH.

The overhead distillate is condensed and cooled, and separated into a water layer containing a small amount of organic matter and an oil layer containing an entrainer as a main component. The bottom liquid of the first distillation column is introduced into a separate purification facility. The top water layer of the first distillation column is introduced into the treatment facility for disposal, and the oil layer is introduced into the second distillation column in order to recover the entrainer. In the second distillation column, a substance having a lower boiling point than TCP is distilled from the top of the column and introduced into a separately provided treatment facility to obtain a liquid containing TCP as the main component from the bottom of the column.
Return to the first distillation column as an entrainer for the first distillation column.
Further, by suppressing the distillation of TCP from the bottom of the first distillation column and the top of the second distillation column, the above operation can be performed with only the reaction by-product amount of TCP without supplementing TCP from the outside.

[0007]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples. Example 1 FIG. 1 is a diagram showing an example of a method for purifying DCH according to the present invention. In the figure, reference numeral 1 is a first distillation column, 2 and 6 are total compactors, 3 is a liquid-liquid separator, 4 , 7 is a reboiler, and 5 is a second distillation column. First distillation of an oil layer 11 obtained by recovering hydrogen chloride in a stripping tower from a reaction liquid in which DCH is produced from chlorine and AAL in the presence of an aqueous hydrochloric acid solution, cooling the residual liquid, and separating the water-oil two-liquid layer. Introduced to the tower, T from the top of the tower as an entrainer
Supply CP.

CAC and TCP in the oil layer 11 are distilled to the top of the column in the form of an azeotropic mixture with H ₂ O, and the remaining H ₂ O is a TCP and DCH-H ₂ O azeotrope supplied from the top of the column. A lower boiling point TCP-H ₂ O azeotrope mixture is formed and distilled at the top of the column to obtain a top distillate fraction 13. Therefore, in order to distill the majority of H ₂ O in the form of TCP-H ₂ O azeotrope, DC
Distillation of H to the top of the tower is suppressed. The bottom liquid 12 is introduced into a separately provided purification facility. The overhead distillate 13 is condensed and cooled, and separated into a water layer 14 and an oil layer 15. Although the water layer 14 is sent to a separately provided treatment facility, the amount of DCH distilled at the top of the tower is small and the solubility of TCP, which is the main component of the oil layer 15, in the water layer is small, so the loss of DCH in the water layer is small. It is small and the processing equipment is small. The oil layer 15 is introduced into the second distillation column, TCP is recovered as the column bottom liquid 17, and returned to the first distillation column as an entrainer for the first distillation column. The overhead distillate 16 is introduced into a treatment facility provided separately. In the flow of FIG. 1, Table 1 shows the flow rate of each part when the weight% of the component in each part and the amount of the oil layer 11 are 100.

[0009]

[Table 1]

Comparative Example 1 FIG. 2 is a diagram showing an example of a conventional DCH refining method. In the figure, reference numeral 1 is a first distillation column, 2 and 6 are total compactors, and 3 is a liquid-liquid separator. , 4, 7 are reboilers and 5 is a second distillation column. First distillation of an oil layer 11 obtained by recovering hydrogen chloride in a stripping tower from a reaction liquid in which DCH is produced from chlorine and AAL in the presence of an aqueous hydrochloric acid solution, cooling the residual liquid, and separating the water-oil two-liquid layer. It is introduced into the column, and as the overhead distillate 13, CAC, TCP, HCl, and H ₂ O, which have a lower boiling point than DCH, are distilled over the column.

[0011] In this case, CAC, TCP is distilled as the lowest azeotropic mixture of H ₂ O is a lower boiling point than the H ₂ O.
CAC, distills no H ₂ O as TCP and azeotrope distills as DCH-H ₂ O azeotrope is lower boiling than the H ₂ O. The bottom liquid 12 is led to a separately provided purification facility.
The overhead distillate 13 is condensed and cooled, and the water layer 14 and the oil layer 15 are condensed.
To separate. A large amount of DCH is dissolved in the water layer 14, and this is introduced into a treatment facility provided separately for detoxification treatment, so that DCH loss is large and a large-scale treatment facility is required. The oil layer 15 is introduced into the second distillation column, DCH is recovered as the column bottom liquid 17, and is introduced into a separately provided purification facility, like the first distillation column column bottom liquid. The overhead distillate 16 has a low boiling point component as compared with DCH as a main component and is introduced into a separately provided treatment facility. In the flow of FIG. 2, Table 2 shows the flow rate of each part when the weight% of the component in each part and the amount of the oil layer 11 are 100.

[0012]

[Table 2]

[0013]

As described above, the DC according to the present invention
In the conventional purification method of H, the DCH loss rate and the amount of waste liquid treated are increased, while azeotropic distillation using a reaction by-product as an entrainer and two-liquid phase separation utilizing mutual solubility difference are performed. Therefore, the distillation process is simplified, and there are advantages such as reduction of the amount of waste liquid treated.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a method for purifying DCH of the present invention.

FIG. 2 is a diagram showing a flow of a conventional technique.

[Explanation of symbols]

 1 First Distillation Tower 2 Total Compressor 3 Liquid-Liquid Separator 4 Reboiler 5 Second Distillation Tower 6 Total Compressor 7 Reboiler 11 Emission Tower Outlet Oil Layer 12 First Distillation Tower Bottom Liquid 13 First Distillation Tower Top Distillation Product 14 Top water layer 15 Top oil layer 16 Second distillation column overhead distillate 17 Second distillation column bottom liquid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toshio Oi, 5-1, Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko KK, Kawasaki Plant (72) Isao Ouchi, 5-1, Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa No. Showa Denko Co., Ltd.Kawasaki Factory

Claims (2)

[Claims] 1. A reactor is used to react allyl alcohol with chlorine in the presence of an aqueous hydrochloric acid solution, the reaction solution is introduced into a stripping tower, hydrogen chloride is stripped off and returned to the reactor, and the residual liquid is cooled. The water layer is separated into an oil layer, the water layer is returned to the reactor, and the oil layer is separated into 2,3-dichloro-1-propanol. 2,3-trichloropropane is supplied from the top of the tower, while suppressing the distillation of 2,3-dichloro-1-propanol, HCl, H ₂ O, 2-chloroacrolein, 1,2,3-trichloropropane and the like, 2,3-
A method for purifying 2,3-dichloro-1-propanol in which a substance having a boiling point lower than that of dichloro-1-propanol is distilled off from the top of the column and removed, and the bottom liquid is introduced into a separately provided purification facility. 2. The first distillation column overhead distillate is condensed and cooled to separate into a water layer and an oil layer, the water layer is introduced into a separate treatment facility, and the oil layer is introduced into a second distillation column. 1,2 from the top of the tower
The method according to claim 1, wherein a substance having a lower boiling point than 3-trichloropropane is distilled off, 1,2,3-trichloropropane is recovered from the bottom of the column and used as an entrainer for the first distillation column.