JPH0725711B2 - Purification method of 2,3-dichloro-1-propanol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to chlorination of allyl alcohol (hereinafter referred to as AAL) with chlorine in hydrochloric acid to form 2,3-dichloro-1-propanol (hereinafter referred to as 2,3DCP). 2) 3D from this
The present invention relates to a method for purifying 2,3DCP that efficiently recovers CP.

[Conventional technology]

2,3DCP is a useful compound used in large quantities as an intermediate for the production of epichlorohydrin used as a solvent, an epoxy resin raw material, a synthetic rubber raw material, a chlorinated rubber stabilizer and the like.

Conventionally, in order to produce 2,3DCP, hydrochloric acid (HClaq) and AAL are introduced into a reactor 1 having a stirrer 1a to prepare an HClaq solution of AAL as shown in FIG. 5, and the reaction temperature is kept constant by cooling. While maintaining, Cl ₂ was blown in to chlorinate to generate 2,3DCP, and this reaction liquid was introduced into the degassing tower 2 to release HCl gas, which was returned to the reactor 1 and the liquid from which gas was released. Is introduced into the first decanter 3 and cooled to 40 ° C or lower to form an aqueous layer 3
a, oil layer 3b, and water layer 3a returned to the reactor 1
3b is directly used as a raw material for other compounds, or these 2,3DCPs are recovered.

In the oil layer 3b where the reaction solution is separated into two layers, 2,3DCP is 72
~ 75wt%, glycerin monochlorohydrin, by-products such as oligomers 3 ~ 6wt%, azeotropic component (20%) HClaq 20wt%
% Is contained.

For example, when producing epichlorohydrin, 2,3DCP is recovered from the oil layer 3b and subjected to a saponification reaction in which it reacts with lime water, or the oil layer 3b is subjected to the saponification reaction as it is.

[Problems to be Solved by the Invention]

However, the method of refining the above oil layer into each component is costly for separating each component and detoxifying unnecessary components.

Also, the method of saponifying the oil layer as it is is that byproducts such as glycerin monochlorohydrin are mixed in the saponified wastewater,
By-products cannot be collected and used. Further, the contained HClaq is also neutralized by the lime, and not only is the lime wasted wastefully, but it is also uneconomical to replenish the reactor with the HClaq component which is discharged from the chlorination step and is not recovered.

The present invention has been made in view of the above circumstances, when 2,3DCP is recovered and used as a raw material for epichlorohydrin, lime is not wastefully consumed, and by-products can be recovered if necessary, It is an object to provide a method for purifying 2,3DCP in which the amount of HClaq supplied to the reactor is suppressed.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the method for purifying 2,3DCP of the present invention uses a reactor to degas a solution of 2,3-dichloro-1-propanol obtained by chlorinating allyl alcohol in hydrochloric acid. Was introduced into the reactor to disperse hydrogen chloride and returned to the reactor, the residual liquid was cooled, separated into an aqueous layer and an oil layer, and the aqueous layer was returned to the reactor, and 2,3-dichloro-1-
In the purification method of 2,3-dichloro-1-propanol for recovering propanol, the above oil layer is introduced into the first distillation column, and hydrogen chloride contained in the oil layer, a part of 2,3-dichloro-1-propanol and other A low-boiling fraction was distilled from the top of the column, cooled to separate into an aqueous layer and an oil layer, and the aqueous layer was returned to the reactor. From this oil layer and the high-boiling fraction of the first distillation column, 2,3 -Recover dichloro-1-propanol.

Alternatively, the oil layer of the first distillation column is further introduced into the second distillation column, the low-boiling components are distilled off from the top of the column, and the bottom of the column is 2,3-
2,3-Dichloro-1-propanol is recovered from the high-boiling fraction mainly containing dichloro-1-propanol and the high-boiling fraction of the first distillation column.

Alternatively, the high boiling components of the first distillation column and the high boiling components of the second distillation column are introduced into the third distillation column, and 2,3-dichloro-1-
Distill off propanol.

[Action]

Since the 2,3DCP purification method of the present invention has the above constitution, for example, HClaq in the raw material components sent to the saponification step
Is significantly reduced, and unnecessary consumption of Ca (OH) ₂ in the saponification process is eliminated. Furthermore, it becomes possible to separate low-boiling components and high-boiling components into each component as needed, and high-concentration 2,
3DCP can be used as a raw material for saponification.

〔Example〕

FIG. 1 shows a first embodiment of the present invention, in which a first distillation column 4 is provided and an oil layer of the first decanter 3 is introduced to
The low boiling point below the boiling point of CP is led to the second decanter 5, and the water layer
5a and oil layer 5b are separated, the water layer 5a is returned to the reactor 1, and the oil layer 5b
And the high-boiling components of the first distillation column 4 are supplied to the 2,3DCP recovery step or the saponification step. By this operation, the amount of HClaq in the liquid sent to the saponification step and the like is significantly reduced, the amount of HClaq supplied to the reactor 1 is suppressed, and when sent to the saponification step, Ca (OH) ₂ Useless consumption is reduced.

Further, FIG. 2 shows a second embodiment of the present invention, in which a second distillation column 6 is further provided after the apparatus of FIG. The oil layer 5b of the second decanter 5 is introduced into the second distillation column 6 to remove the low boiling point having a lower boiling point than 2,3DCP, and the high boiling point of the first distillation column 4 and the high boiling point of the second distillation column 4 are removed. And are sent to the recovery process of 2,3DCP or the saponification process. In this device, since HClaq is hardly contained in the bottom liquid of the first and second distillation columns 4 and 6, Ca (OH) ₂ is not wasted in saponification. Further, HCl is hardly present in the low boiling point of the second distillation column 6, and the usable low boiling point component can be recovered by this, and most of HCl is returned to the reactor 1, so that the reaction The amount of HClaq replenished in the vessel 1 is very small because it is discharged along with the low boiling point.

FIG. 3 shows a third embodiment of the present invention. The apparatus of FIG. 2 is further provided with a third distillation column 7, and the bottom liquids of the first and second distillation columns are introduced for distillation. It is the one.
The bottom liquid has almost no low-boiling components for 2,3DCP, and 2,3DCP is distilled from the column top and high-boiling components are extracted from the column bottom. Thus, high boiling, low boiling and 2,3D
CP is taken out separately, and 2,3DCP is used as a raw material for each synthesis. For example, if this is introduced into the saponification column 8 shown in FIG. 4, epichlorohydrin can be efficiently synthesized.

Also, since the low boiling point and high boiling point are taken out separately,
By purifying as necessary, useful components such as glycerin monochlorohydrin can be recovered.

Furthermore, since low boiling point and high boiling point are organic chlorinated compounds,
When the components are not collected, steam can be generated as a fuel or the by-product HCl can be collected by combustion.

Example 1 Table 1 shows an example of material balance when 2,3DCP was manufactured and purified using the apparatus shown in FIG. In the table (a)
(H) shows respective positions in FIG.

(Effects of the Invention) As described above, the method for purifying 2,3DCP of the present invention significantly reduces the supply of HClaq in the reactor, and when it is used as a raw material for epiclohydrin, the saponification reaction Improves the basic unit of Ca (OH) ₂ . Two more
Since 3DCP, high-boiling components, and low-boiling components can be separated and recovered, it is convenient not only as a saponification raw material but also for other purposes, and useful by-products can be recovered if necessary. When a detoxification treatment is required, it is discharged as a low-boiling component and a high-boiling component, which has an advantage that the treatment becomes easy.

[Brief description of drawings]

1 to 3 show the first to third aspects of the present invention, respectively.
The figure which shows a 3rd Example, FIG. 4 is a figure which shows an example of a saponification column, and FIG. 5 is a figure which shows the conventional flow. 1 ... Reactor, 1a ... Stirrer, 2 ... Degassing tower, 3 ...
1st decanter, 3a ... water layer, 3b ... oil layer, 4 ... first
Distillation column, 5 ... Second decanter, 5a ... Water layer, 5b ... Oil layer, 6 ... Second distillation column, 7 ... Third distillation column, 8 ... Saponification column.

Claims (3)

[Claims] 1. A solution of 2,3-dichloro-1-propanol obtained by chlorinating allyl alcohol in hydrochloric acid using a reactor is introduced into a degassing column to dissipate hydrogen chloride and then returned to the reactor. The residual liquid is cooled and separated into an aqueous layer and an oil layer, the aqueous layer is returned to the reactor, and 2,3-dichloro-1-propanol is recovered from the oil layer 2,3-dichloro-1.
-In the method for purifying propanol, the above oil layer is introduced into a first distillation column, and hydrogen chloride, a part of 2,3-dichloro-1-propanol and other low-boiling components contained in the oil layer are distilled from the top of the column, This was cooled to separate it into an aqueous layer and an oil layer, the aqueous layer was returned to the reactor, and 2,3-dichloro-1-propanol was recovered from this oil layer and the high boiling point of the first distillation column. Characteristic 2,3-dichloro-1
-Propanol purification method. 2. The oil layer of the first distillation column according to claim (1) is further introduced into a second distillation column, low-boiling fraction is distilled off from the top of the column, and 2.3-dichloro-1- A method for purifying 2,3-dichloro-1-propanol, which comprises recovering 2,3-dichloro-1-propanol from the high-boiling fraction mainly containing propanol and the high-boiling fraction of the first distillation column. 3. The high boiling fraction of the first distillation column and the high boiling fraction of the second distillation column according to claim (2) are introduced into a third distillation column, and 2,3-dichloro-1-propanol is introduced from the top of the column. A method for purifying 2,3-dichloro-1-propanol, which comprises distilling.