JP2002322105A - Preparation method for 2,3-dichloro-1-propanol and epichlorohydrin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation method for 2,3-DCH and epichlorohydrin(ECH) capable of controlling the formation of polymers within a distillation column which distills to remove low-boiling point portions and of a continuous operation for a long period relating to a preparation method for 2,3-dichloro-1-propanol(2,3-DCH). SOLUTION: It relates to the preparation method for 2,3-DCH and ECH. This preparation method represents the following features, respectively. To prepare 2,3-DCH, polymerization inhibitor is added within a distillation column which distils to remove the low-boiling point portions from the top of the distillation column, and the components remaining in the bottom of the column and in the bottom of the first distillation column are led to the third distillation column. From the top of the column, 2,3-DCH is recovered. ECH is prepared by subjecting the recovered 2,3-DCH to a saponification reaction. As polymerization inhibitors hydroquinone monomethylether, 2,5-di-tert-butylhydroquinone and 2,2-methylenebis (4-ethyl-6-tert-butylphenol) are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing 2,3-dichloro-1-propanol, which is an intermediate for producing epichlorohydrin, and to a process for producing epichlorohydrin from 2,3-dichloro-1-propanol. Obtained by chlorinating allyl alcohol with chlorine in
The present invention relates to a method for producing 2,3-dichloro-1-propanol for efficiently recovering 3-dichloro-1-propanol with high purity.

[0002]

2. Description of the Related Art 2,3-Dichloro-1-propanol (hereinafter sometimes abbreviated as 2,3-DCH) is known.
It is a useful compound used as an intermediate in the production of epichlorohydrin (hereinafter sometimes abbreviated as ECH) used as a solvent, an epoxy resin raw material, a synthetic rubber raw material, a chlorinated rubber raw material stabilizer and the like.

The present applicant has previously proposed a method for producing 2,3-dichloro-1-propanol obtained by chlorinating allyl alcohol with chlorine in hydrochloric acid as shown in FIG. No. 25711). That is, using the reactor 1, a solution of 2,3-DCH obtained by chlorinating allyl alcohol (AAL) in a hydrochloric acid solution (HClq) is introduced into the degassing tower (2) to diffuse hydrogen chloride. The hydrogen chloride is returned to the reactor (1), the remaining liquid is cooled in the first liquid-liquid separator (3), and the aqueous layer (3a) and the oil layer (3b)
And returning the aqueous layer (3a) to the reactor (1) and recovering 2,3-DCH from the oil layer,
The oil layer is led to a first distillation column (4), and hydrogen chloride, a part of 2,3-DCH and other low-boiling components contained in the oil layer are distilled off from the top of the column. ) To separate into an aqueous layer (5a) and an oil layer (5b). The aqueous layer (5a) is returned to the reactor (1), and the oil layer is further introduced into the second distillation column (6). The lower boiling components are distilled off, and the high boiling components mainly composed of 2,3-DCH coming out of the bottom and the high boiling components of the first distillation column (4) are led to a third distillation column (7). 2,3-DCH is distilled off and collected from the top of the tower.

According to the above method, the next step (saponification step)
Since the amount of hydrochloric acid sent to the next step is greatly reduced, there is no wasteful consumption of alkali used in the next step, and low-boiling and high-boiling components are separated into each component, so that high-purity 2,3-DCH can be obtained.

[0005] However, when the above-mentioned method is continuously produced by the apparatus shown in Fig. 1, a polymer is produced in the second distillation column (6), the accumulation of which proceeds, and finally the column is clogged. Therefore, it is necessary to periodically stop the operation of the tower to remove the polymer in the tower, and there is a problem that continuous operation cannot be performed for a long time.

[0006]

Accordingly, an object of the present invention is to provide a method for producing 2,3-DCH, which suppresses the production of a polymer in a second distillation column for distilling low boiling components, An object of the present invention is to provide a method for producing 2,3-DCH and ECH capable of long-term continuous operation.

[0007]

Means for Solving the Problems In view of the above problems, the present inventors have made intensive studies and as a result, found that a substance causing a polymer in the second distillation column is 2-chloroacrolein (hereinafter, referred to as "chloroacrolein").
It may be abbreviated as CAC. ), And found that it is effective to add a radical polymerization inhibitor into the second distillation column to suppress the polymerization. Furthermore, as a result of examining various radical polymerization inhibitors, particularly, hydroquinone monomethyl ether, 2,5-di-tert
-Butylhydroquinone, 2,2'-methylenebis (4
-Ethyl-6-tert-butylphenol) was found to be highly effective and inhibited the polymerization of CAC by addition of a small amount, thereby completing the present invention.

That is, the present invention relates to a process for chlorinating allyl alcohol in a hydrochloric acid solution using a reactor.
-A solution of dichloro-1-propanol is introduced into a degassing tower to dissipate the hydrogen chloride, return the hydrogen chloride to the reactor, cool the remaining liquid, separate it into an aqueous layer and an oil layer, and react the aqueous layer. The oil layer was guided to the first distillation column, and a component having a boiling point lower than that of 2,3-dichloro-1-propanol contained in the oil layer and a part of 2,3-dichloro-1-propanol were introduced from the top of the column. The distillate is cooled, the distillate is cooled and separated into an aqueous layer and an oil layer, the aqueous layer is returned to the reactor, the oil layer is introduced into a second distillation column, and a polymerization inhibitor is added to the second distillation column. Low-boiling components are distilled off from the top of the column, and the components coming out of the bottom and the bottom components of the first distillation column are led to a third distillation column, and 2,3-dichloro-1-propanol is recovered from the top. Characterized by the following 2,
The present invention relates to a method for producing 3-dichloro-1-propanol.

In the present invention, as the radical polymerization inhibitor, any one having an action of generally inhibiting radical polymerization can be used, but the primary or growing radical generated from 2-chloroacrolein and 50 ° C. Recombination, disproportionation, electron transfer,
Those which cause a chain transfer reaction or an addition reaction to generate a stable radical are preferred.

As specific examples, catechol, hydroquinone, hydroquinone monomethyl ether, 2,5-di-
tert-butyl hydroquinone (DBH), 2,2 '
-Methylenebis (4-ethyl-6-tert-butylphenol), phenothiazine and the like, but are not limited thereto. The radical polymerization inhibitor can be supplied from any position in the distillation column, but these polymerization inhibitors are 2,3-D
It is a component having a higher boiling point than CH and is preferably added to the reflux liquid at the top in view of exhibiting a polymerization preventing function in the entire distillation column.

When the radical polymerization inhibitor is a solid, it is desirable that the radical polymerization inhibitor be dissolved in a solvent and added in order to quickly mix it with the top solution. As the solvent, a solvent capable of dissolving the radical polymerization inhibitor can be used.
Perform saponification reaction using 3-DCH and alkali as raw materials
Any material can be used as long as it does not react in the process of producing CH, can be easily separated from ECH in the ECH distillation process, and can be easily separated from 2,3-DCH in the 2,3-DCH distillation process. It is.

Specific examples thereof include aliphatic hydrocarbon solvents such as heptane and decane having a boiling point at normal pressure of 50 ° C. or higher and 100 ° C. or lower, or 150 ° C. or higher, such as 1,2-dichloroethane and trichloropropane. Aliphatic halogenated hydrocarbon solvents, benzene, aromatic hydrocarbons such as trimethylbenzene, aliphatic ethers such as isopropyl ether, aromatic ethers such as ethylphenyl ether,
Examples thereof include aliphatic alcohols such as 1-propanol and 1-hexanol, and aromatic alcohols such as benzyl alcohol.

In the present invention, the addition of a radical polymerization inhibitor
The addition amount is 20 ppm or more to the reflux liquid amount of the distillation column.
ppm or less is preferred. Polymerization with less than 20 ppm
Sufficient effect cannot be expected for prevention.
Even if added, the effect of preventing polymerization does not increase further. Ma
Further, the present invention relates to 2,3-dichloro- obtained by the above method.
1-propanol is subjected to a saponification reaction.
And a process for producing epichlorohydrin. Where Ken
The reaction is carried out by the reaction of 2,3-DCH with an alkali.
For producing ECH, for 2,3-DCH
The reaction is carried out using 1.0 to 1.5 equivalents of an alkali. Ken
As the alkali used for the oxidation reaction, for example, Ca (O
H) _Two, NaOH, KOH, Na_TwoCO_Three, K_TwoCO_ThreeEtc.
Can be used as aqueous solution or slurry solution
You. The reaction conditions are not particularly limited.
The reaction should be carried out under reduced or elevated pressure at a temperature of 110 ° C.
Can be. Various methods are used for the reaction mode
It is possible.

[0014]

The present invention will be specifically described below with reference to examples and comparative examples. However, the scope of the invention is not limited by the present embodiment.

Example 1 Using a continuous distillation apparatus, a distillation experiment was conducted on a liquid corresponding to the reflux liquid at the top of the second distillation column (6) in FIG. 1 to confirm whether or not a polymer was formed. The distillation device has an inner diameter of 20 mm
× 3 mm inside diameter × 5 outside diameter in a 200 mm high glass column
It is filled with a porcelain filler of mm × 10 mm in length. A distillation material is continuously supplied to the top using a metering pump. The supplied liquid is 500 attached to the bottom of the tower.
Heated in a ml round bottom flask, the vapor is cooled and condensed by passing through a condenser, and extracted out of the system. The flask at the bottom of the tower is configured to continuously extract high-boiling components from the bottom of the tower with a metering pump so that the liquid amount is maintained at about 250 g. Using the above apparatus, 2-chloroacrolein (C
AC) 48.2% by mass, 1,2,3-trichloropropane (hereinafter abbreviated as TCP) 38.9% by mass, 2,3-DC
0.1% by mass of H, 12.2% by mass of other organic substances, and H ₂ O
Continuous distillation of a liquid obtained by adding 1000 ppm of hydroquinone monomethyl ether (MQ) to a distillation raw material containing 0.5% by mass and 0.1% by mass of HCl was performed under normal pressure. The raw material was supplied at 120 g / hour and withdrawn from the tower at 48 g / hour. At this time, the tower top temperature was 90 to 100 ° C. After continuous distillation for 36 hours, the distillation was stopped, the appearance of the packed material was checked, methanol was flown from the top of the column, and the product was cooked with methanol from the bottom of the column to wash the packed material. The change in weight was determined. After continuous distillation for 36 hours, the amount of polymer attached to the packing after washing with methanol was 0.30 g.

Example 2 Using the apparatus of Example 1, a liquid obtained by adding 200 ppm of MQ to the distillation raw material of Example 1 was subjected to continuous distillation. The raw material was supplied at a rate of 120 g / hour, and was withdrawn from the top of the tower at a rate of 48 g / hour. After distillation for 36 hours continuously, the distillation was stopped, the appearance of the packing was confirmed, and then methanol was flown from the top of the column,
In addition, cook with methanol from the bottom of the tower to wash the packing,
Thereafter, the sample was dried and the change in weight from that before the experiment was determined. The weight of the polymer attached to the filler was 0.36 g.

Example 3 The apparatus of Example 1 was used and 2,5,5
-Di-tert-butylhydroquinone (DBH)
Continuous distillation of the liquid added with 00 ppm was performed. 1 raw material
It was fed at a rate of 20 g / h and withdrawn from the top of the tower at a rate of 48 g / h. After continuous distillation for 36 hours, the distillation was stopped, the appearance of the packing was checked, then methanol was flown from the top of the column, and then the packing was washed with methanol from the bottom of the column, and then the packing was washed and dried. And the change in weight was determined. The weight of the polymer attached to the filler was 0.21 g.

Example 4 The apparatus of Example 1 was used, and
The liquid to which 300 ppm of 2'-methylenebis (4-ethyl-6-tert-butylphenol) had been added was subjected to continuous distillation. The raw material is supplied at 120 g / hour, and 48
g / h. After continuous distillation for 36 hours, the distillation was stopped, the appearance of the packed material was checked, methanol was flown from the top of the column, and the product was cooked with methanol from the bottom of the column to wash the packed material. The change in weight was determined. The weight of the polymer attached to the filler was 0.30 g.

Comparative Example 1 Using the apparatus of Example 1, continuous distillation was carried out using the distillation raw material of Example 1 without adding a polymerization inhibitor. The raw material was supplied at a rate of 120 g / hour, and was withdrawn from the top of the tower at a rate of 48 g / hour. After 36 hours of continuous distillation, stop the distillation,
The appearance of the packing was confirmed, and then methanol was flowed from the top of the tower, and the packing was washed with methanol from the bottom, washed and dried, and the change in weight from that before the experiment was determined. The weight of the polymer attached to the filler was 1.1 g.

Example 5 FIG. 2 is a diagram showing an example of the method for producing 2,3-dichloro-1-propanol (2,3-DCH) according to the present invention. In the figure, reference numeral 6 denotes a distillation column corresponding to the second distillation column in FIG. 1, 8 denotes a full contractor, 9 denotes a reboiler, 10 denotes a polymerization inhibitor dissolving tank, and 11 denotes a polymerization inhibitor supply pump. The polymerization inhibitor is added from the reflux line 12 of the distillation column to the top of the column. The above distillation equipment is equipped with a tower top pressure of 1.6 kPa (absolute pressure), a supply flow rate of 300 kg / hour, a tower top withdrawal flow rate of 60 kg /
Time, tower bottom extraction flow rate 240 kg / hour, tower top reflux flow rate 300 kg / hour, tower top temperature 80 ° C., tower bottom temperature 127
Continuous distillation was carried out under operating conditions of ° C. Hydroquinone monomethyl ether (MQ) was used as a polymerization inhibitor, and 1,2,3-trichloropropane (TCP) was used as a solvent for MQ. A TCP solution of 3% MQ was used so that the addition amount of MQ was 200 ppm with respect to the reflux flow rate. It was fed at a flow rate of 2 kg / hour. Under these conditions, continuous operation was performed for three months.
No polymer accumulation was found in the tower.

Example 6 Continuous distillation was carried out under the same distillation conditions as in Example 5. Hydroquinone monomethyl ether (M
Q), 1,2,3-trichloropropane (TCP) was used as an MQ solvent, and the amount of MQ added was 2 to the reflux flow rate.
2 kg of TCP solution of MQ0.3% to be 0 ppm
/ Hour flow rate. Under these conditions, continuous operation was performed for 100 days, but no accumulation of polymer was observed in the tower.

Comparative Example 2 Continuous distillation was carried out under the same distillation conditions as in Example 5 except that no polymerization inhibitor was added. Under these conditions, continuous operation was performed for 100 days. However, accumulation of the polymer was observed in the concentrated portion of the distillation column, and 50% or more of the cross-sectional area was blocked.

[0023]

As described above, according to the present invention, 2,3-
The method for producing DCH is based on a distillation column for distilling off 2-chloroacrolein (CAC) having a low boiling point.
, The long-term continuous operation of the column becomes possible, and the production of 2,3-dichloro-1-propanol (2,3-DCH) can be carried out more economically. The 2,3-DCH produced according to the present invention is of high purity from which low-boiling and high-boiling components have been separated, and does not waste alkali in the subsequent saponification step and efficiently produces epichlorohydrin. be able to.

[Brief description of the drawings]

FIG. 1 is a flow chart of a method for producing 2,3-dichloro-1-propanol in which allylic alcohol is chlorinated with chlorine in hydrochloric acid.

FIG. 2 is a flow chart of one embodiment of a method for producing 2,3-dichloro-1-propanol (2,3-DCH) according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Degassing tower 3 1st liquid-liquid separator 4 1st distillation tower 5 2nd liquid-liquid separator 6 2nd distillation tower 7 3rd distillation tower 8 Total contractor 9 Reboiler 10 Polymerization inhibitor dissolution tank 11 Polymerization Inhibitor supply pump 12 reflux line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C048 BB04 CC01 UU03 XX02 4H006 AA02 AC30 AD11 AD16 BA94 BB31 BD33 BD40 BD41 BD52 BD60 BE01 BE53 FE11 FE71 FE75

Claims (4)

[Claims] 1. A solution of 2,3-dichloro-1-propanol obtained by chlorinating allyl alcohol in a hydrochloric acid solution using a reactor is introduced into a degassing column to diffuse hydrogen chloride, and the hydrogen chloride is removed. Was returned to the reactor, the remaining liquid was cooled and separated into an aqueous layer and an oil layer, the aqueous layer was returned to the reactor, the oil layer was led to the first distillation column, and the 2,3-dichloro-1 contained in the oil layer was removed.
-Distilling off a component having a lower boiling point than propanol and a part of 2,3-dichloro-1-propanol from the top of the column,
The distillate was cooled and separated into an aqueous layer and an oil layer, the aqueous layer was returned to the reactor, the oil layer was introduced into the second distillation column, a polymerization inhibitor was added to the second distillation column, and the distillate was cooled down from the top. The boiling components are distilled off, and the bottom component and the bottom component of the first distillation column are led to a third distillation column.
A process for producing 2,3-dichloro-1-propanol, comprising recovering 2,3-dichloro-1-propanol from the top of the column. 2. As a polymerization inhibitor, catechol, hydroquinone, hydroquinone monomethyl ether, 2,5
The 2,3-dichloro-1 according to claim 1, wherein a radical polymerization inhibitor selected from -di-tert-butylhydroquinone, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), and phenothiazine is used.
-A method for producing propanol. 3. The method according to claim 1, wherein the polymerization inhibitor is hydroquinone monomethyl ether, 2,5-di-tert-butylhydroquinone, or 2,2′-methylenebis (4-ethyl-6).
The method for producing 2,3-dichloro-1-propanol according to claim 2, which is -tert-butylphenol). 4. A method for producing epichlorohydrin, which comprises subjecting 2,3-dichloro-1-propanol produced by the method according to any one of claims 1 to 3 to a saponification reaction.