JPH10158208A - Separation and recovery of cyclohexyl vinyl ether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for separating and recovering cyclohexyl vinyl ether from a mixture of a cyclohexyl vinyl ether and cyclohexanol by a simple distillation operation without causing hydrolysis. SOLUTION: In this method for separating and recovering cyclohexyl vinyl ether by a raw material consisting essentially of a mixture of cyclohexyl vinyl ether and cyclohexanol to extractive distillation, the raw material is introduced into a middle part of an extractive distillation column 1 and the distillation is carried out while introducing at least one or more extractive distillation solvents selected from a 2-5C diol, dimethyl sulfoxide and dimethylformamide from a raw material supply plate to the top of the column.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for separating cyclohexyl vinyl ether, which is useful as a raw material for polymer materials such as paints and synthetic resins, by an extractive distillation operation without using water.
Regarding the method of collecting.

More specifically, a raw material mainly comprising a mixture of cyclohexyl vinyl ether formed by vinylation of cyclohexanol with acetylene and a raw material cyclohexanol is subjected to extractive distillation using a specific extraction solvent to separate cyclohexyl vinyl ether. And how to recover.

[0003]

2. Description of the Related Art Vinyl ethers are generally obtained by a vinylation reaction of an alcohol with acetylene in the presence of an alkali catalyst such as potassium alcoholate. The crude product contains the produced vinyl ether and unreacted alcohol as main components. However, the vinyl ether and the unreacted alcohol may form an azeotropic mixture, and in such a case, it is difficult to separate and recover the vinyl ether by a general distillation method.

Therefore, when such an azeotrope is separated by distillation, a third component is generally added to a two-component distillation system,
A method of eliminating the azeotrope of the two components is used. For example, a method of adding a solvent that preferentially dissolves one of the two components as the third component, subjecting it to extractive distillation and separation, or a method of adding salts or a specific metal to the distillation system to eliminate azeotrope, and the like. Taken.

[0005] In particular, regarding the separation of vinyl ether and raw material alcohol by extractive distillation, US Pat. No. 2,779,720 discloses a method in which water and an organic solvent are used in combination as extractive distillation solvents.
And French Patent No. 1384398.

However, since all of these use water as an extractive distillation solvent together with an organic solvent, vinyl ether is hydrolyzed by heating in the presence of water during distillation, resulting in a decrease in yield. Further, in many cases, there is a disadvantage that moisture remains in the product, and this must be removed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to separate and recover cyclohexyl vinyl ether from a raw material mainly containing a mixture of cyclohexyl vinyl ether and cyclohexanol forming an azeotrope by extractive distillation. It is to separate and recover high-purity cyclohexyl vinyl ether in a high yield without using or using water as an extractive distillation solvent.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies in view of such circumstances, and as a result, by selecting a specific solvent as an extractive distillation solvent, a high-purity cyclohexyl vinyl ether can be obtained by a simple method involving only a distillation step. Can be separated and recovered in high yield.

That is, the gist of the present invention is to provide a method for extracting and distilling a raw material mainly composed of a mixture of cyclohexyl vinyl ether and cyclohexanol to separate and recover cyclohexyl vinyl ether, wherein the raw material is introduced into an intermediate portion of an extractive distillation column. Wherein at least one extractive distillation solvent selected from diols having 2 to 5 carbon atoms, dimethylsulfoxide and dimethylformamide is introduced into the upper part of the tower from a raw material supply stage while separating and recovering the cyclohexyl vinyl ether. Exists.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As the raw material mainly containing a mixture of cyclohexyl vinyl ether and cyclohexanol, any material can be used.However, usually, in the presence of a catalyst composed of alkali metal alcoholate or the like obtained by previously reacting caustic potash or caustic soda with alcohol. , Acetylene and cyclohexanol at a temperature of 120 to 180 ° C and a pressure of 0 to 3
The product mixture obtained at 0 kg / cm ² is used as is. Alternatively, a product obtained by previously removing a catalyst component from this product mixture is applied.

The mixed solution introduced into the extractive distillation column contains cyclohexyl vinyl ether and cyclohexanol as main components, and also contains a very small amount of impurities generated by a side reaction during the reaction. The compositions of cyclohexyl vinyl ether and cyclohexanol are not particularly limited, but those having a low cyclohexanol concentration are generally advantageous. This is because it is possible to reduce the amount of the distillate distilled from the upper part of the ether-based azeotropic distillation column described later and circulated to the intermediate part of the extractive distillation column.

Cyclohexyl vinyl ether and cyclohexanol form an azeotropic mixture. For example, the boiling point and composition at normal pressure are 150 ° C., 78 wt% of cyclohexyl vinyl ether and 22 wt% of cyclohexanol, and the boiling point and composition at 100 mmHg are 84%. ℃, 92% by weight of cyclohexyl vinyl ether, cyclohexanol 8
wt%. The boiling point of cyclohexyl vinyl ether at normal pressure is 152 ° C., and the boiling point of cyclohexanol is 161 ° C.

The extraction solvent used in the extractive distillation of the present invention has a better solubility in cyclohexanol than cyclohexyl vinyl ether, and a solvent having a boiling point difference of not less than 10 ° C. from cyclohexanol is cyclohexyl vinyl ether or the like. In the operation of separating the components,
It is convenient. The present inventors have as extractive distillation solvents that can satisfy these requirements, diols having 2 to 5 carbon atoms,
Dimethyl sulfoxide or dimethylformamide has been found to be preferred. Here, the diols having 2 to 5 carbon atoms include, for example, ethylene glycol, propanediol, diethylene glycol, butanediol, pentanediol, and the like. Examples of propanediol include 1,2-propanediol and 1,3-propanediol, and examples of butanediol include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol. Butanediol and isobutylene glycol. Among the above, the use of ethylene glycol, 1,2-propanediol, diethylene glycol, 1,4-butanediol, dimethylsulfoxide, dimethylformamide or a mixture thereof is preferred.

The extractive distillation solvent is used in a weight ratio of 0.4 to 20, preferably 2 to 20, with respect to cyclohexanol in the mixture.
15 equivalents are brought into countercurrent contact with the heated and rising vapor of cyclohexyl vinyl ether and cyclohexanol. By doing so, cyclohexanol in the mixed solution can be selectively and efficiently extracted and removed.

The distillation separation method of the present invention is, for example, shown in FIG.
Can be performed based on the flow diagram shown in FIG. In FIG. 1, 1 denotes an extractive distillation column, 2 denotes an ether-based azeotropic distillation column, 3 denotes an ether-based purified distillation column, 4 denotes an alcohol-based azeotropic distillation column, and 5 denotes an alcohol-based purified distillation column. In this figure, only the device parts which are indispensable for the description of the process according to the invention are described,
Other auxiliary devices such as a heater, a condenser, a pressure gauge, and a pump are omitted. The solid line is a pipe, and at the same time, indicates the flow of a substance. Further, cyclohexyl vinyl ether (1) represents a fraction comprising cyclohexyl vinyl ether containing a small amount of high-boiling by-products, and cyclohexyl vinyl ether (2) represents high-purity cyclohexyl vinyl ether.

The distillation apparatus used in the method of the present invention is not particularly limited, but usually a rectification column having 1 to 100, preferably 5 to 50 theoretical plates is used. Any structure may be used for the rectification tower. Examples of the tray tower include those using a bubble bell tray, a uniflux tray, a flexi tray, a natter float tray, a ballast tray, a perforated plate tray, and the like. Examples of the packed tower include a ring-type packed tower, a saddle-type packed tower, and a packed tower using a spray pack or the like. The type of the heater, the condenser and the like is not particularly limited, and various types can be used.

The pressure in each distillation column during distillation is not particularly limited. However, in order to maintain the temperature during distillation as low as possible and to suppress the chemical alteration of the produced cyclohexyl vinyl ether, the pressure is lower than normal pressure, especially 10 to 7 times.
60 mmHg is preferred.

The vapor distilled from the upper part of each distillation column is condensed and a part or most of the vapor is returned to the column from which it was distilled as reflux. The reflux ratio at this time is not particularly limited, but is selected in the range of 1 to 50 depending on the performance of the rectification column and the purity required for the substance to be separated and recovered. The reflux ratio of the extractive distillation column, the ether-based azeotropic distillation column, and the ether-based purified distillation column affects the purity and recovery of the target cyclohexylvinyl ether, and the reflux ratio of the alcohol-based azeotropic distillation column and the alcohol-based purified distillation column. The ratio affects the purity of the recovered cyclohexanol and extractive distillation solvent as well as the recovery. The higher the reflux ratio, the better the separation.

Hereinafter, the separation and recovery method of the present invention will be described more specifically with reference to the drawings. First, a mixture containing cyclohexyl vinyl ether and cyclohexanol as main components is supplied to an intermediate portion of the extractive distillation column 1. At the same time, the extractive distillation solvent is introduced from an arbitrary portion higher than the supply portion, usually from a portion near the top of the column. In the extractive distillation column 1, a fraction mainly composed of cyclohexyl vinyl ether is distilled off from the upper portion, usually the top portion, and a fraction mainly composed of cyclohexanol and the extractive distillation solvent is separated from the lower portion, usually the bottom portion. You. The pressure of the extractive distillation column 1 is not particularly limited. However, the lower the pressure, the greater the relative volatility of cyclohexyl vinyl ether with other components to be separated, and the side reaction of ether can be suppressed.
Normal pressure, preferably in the range of 10 to 500 mmHg, is employed. When the pressure is 10 mmHg or less, although the temperature setting during distillation can be lowered and the ratio of side reactions can be reduced, the distillation apparatus becomes more expensive because the degree of pressure reduction is extremely high. On the other hand, when the pressure is equal to or higher than the normal pressure, the temperature setting at the time of distillation becomes too high, and the ratio of side reactions increases. At this point, the purity of cyclohexyl vinyl ether is quite high, but when further purification is carried out as follows.

That is, the distillate from the upper part of the extractive distillation column 1 is led to the middle part of the ether azeotropic distillation column 2 and subjected to distillation,
To separate. In this case, an azeotropic mixture of cyclohexyl vinyl ether and cyclohexanol is removed from the upper part of the ether-based azeotropic distillation column 2, usually from the top, and a high-boiling component is removed from the lower part, usually from the bottom, respectively.
A one-stage method in which a more purified cyclohexyl vinyl ether is recovered as a side stream from a suitable intermediate part other than the part where the fraction from the top of the column is introduced, or the upper part of the ether azeotropic distillation column 2, usually The low-boiling components are removed from the top, and the withdrawn liquid from the lower part of the column, usually the bottom, is led to the middle part of the ether-based purification distillation column 3, where the high-boiling components are removed from the lower part of the purification distillation column 3, usually from the bottom. Then, any of the two-stage methods of recovering high-purity cyclohexyl vinyl ether from the upper part of the column, usually from the top, can be employed. FIG. 1 corresponds to the two-stage method.

In any method, the azeotropic distillate from the upper part of the ether azeotropic distillation column 2 is combined with the raw material to the intermediate part of the extractive distillation column 1 or circulated separately to convert cyclohexyl vinyl ether. It can be collected efficiently. In this case, it is preferable to remove the low-boiling components in the raw materials before using the method of the present invention. The purpose of the ether azeotropic distillation column 2 is to remove cyclohexanol contained in a fraction obtained from the upper part of the extractive distillation column 1. To reduce the amount of the fraction obtained from the top of the azeotropic distillation column 2 circulated to the distillation column 1 and circulated to the extractive distillation column, the higher the better, the higher the pressure, the higher the distillation temperature This is not preferred in that cyclohexyl vinyl ether easily causes side reactions. Therefore, a range of 400 mmHg to normal pressure is usually adopted as the operating pressure.

Ether azeotropic distillation column 2 in two-stage process
The liquid withdrawn from the lower part of the column consists essentially of cyclohexyl vinyl ether and has a sufficiently high purity as it is, and generally shows a purity of 95 to 99 wt%. However, a small amount of by-products during the reaction and low-polymerized products of acetaldehyde dicyclohexyl acetal or cyclohexyl vinyl ether formed by the addition reaction of cyclohexanol with cyclohexanol are mixed into the withdrawn liquid. May be.
So if you need to remove these impurities,
Furthermore, purification is performed by distillation. That is, the distillate obtained from the lower part of the ether azeotropic distillation column 2 is led to the middle part of the ether type purification distillation column 3, and from the lower part, usually the bottom part of this column 3, the high boiling fraction which is a by-product of cyclohexyl vinyl ether. The fractions are separated off and the high purity cyclohexyl vinyl ether is recovered from the top, usually at the top, of the column 3. The pressure of the ether-based purification distillation column 3 is not particularly limited, but it is preferable to operate at a low pressure similarly to the extraction distillation column 1 in order to suppress the side reaction of cyclohexyl vinyl ether and to increase the recovery of cyclohexyl vinyl ether.
A pressure in the range of 0 mmHg to normal pressure, preferably 10 to 300 mmHg is employed.

Although not shown in FIG. 1, cyclohexyl vinyl ether is used as a side stream to form an ether-based azeotropic distillation column 2.
, It is preferable to carry out a stripping operation in order to remove small but entrained light components. In the field of petroleum refining and petrochemicals, stripping is generally performed by using steam, but in the present invention, an inert gas such as nitrogen, carbon dioxide, flue gas or a reboiler is used. Good. Even if an inert gas is used, it must be heated to the temperature required for stripping, and if a flue gas is used, a pretreatment for removing impurities that may interfere with the reaction is necessary. In addition, it is rather easy to use a reboiler. There is no particular limitation on the structure of the stripper,
Known ones can be used. The side stream is withdrawn at an arbitrary position below the portion for supplying the fraction distilled from the upper part of the extractive distillation column 1 and above the portion for extracting the high boiling point component.

On the other hand, a fraction mainly consisting of cyclohexanol and an extractive distillation solvent obtained from the lower part of the extractive distillation column 1, usually from the bottom, is led to the alcohol-based azeotropic distillation column 4, where it is distilled, and the fraction is formed. , A mixture having an azeotropic composition of cyclohexyl vinyl ether and cyclohexanol is recovered, and a mixture containing cyclohexanol and an extractive distillation solvent is recovered from the bottom of the column. The azeotropic mixture of cyclohexyl vinyl ether and cyclohexanol recovered from the upper part of the column is joined to the raw material introduction pipe supplied to the intermediate part of the extractive distillation column 1, or separately from the intermediate part of the extractive distillation column 1. Circulated to The purpose of the alcohol azeotropic distillation column 4 is to remove a small amount of cyclohexyl vinyl ether from the distillate obtained from the lower part of the extractive distillation column 1. It is better to operate at low pressure to reduce the amount circulated. Therefore, it is usually operated at a pressure of 10 mmHg to normal pressure, preferably 10 to 300 mmHg.

Further, the mixture containing cyclohexanol and the extractive distillation solvent withdrawn from the lower part of the azeotropic distillation column is led to the intermediate part of the alcohol-based purification distillation column 5, and cyclohexanol is added from the upper part of the column, usually the top part. Extractive distillation solvent is recovered from the bottom of the column, usually from the bottom. Naturally, the recovered cyclohexanol is used as a raw material for producing cyclohexyl vinyl ether, and the extractive distillation solvent is
It is circulated and reused as the extractive distillation solvent supplied to the extractive distillation column.

The present invention can be carried out by a continuous system or a batch system, but the continuous system is preferable in terms of productivity, operation stability and the like.

[0027]

The present invention will be described in more detail with reference to the following examples. However, these examples are illustrative only, and the present invention is not limited to the following examples. still,
In the experiments described below, as each distillation column, an all-shaw rectification column made of glass having a column diameter of 30 mm and 20 stages was used.

Example 1 (1) Separation and recovery of cyclohexyl vinyl ether A vinylation reaction product of cyclohexanol with acetylene was obtained by removing the catalyst in advance, and 90.1 wt% of cyclohexyl vinyl ether and 8.0 wt% of cyclohexanol. %, And 1.9% by weight of other components, was introduced at the rate of 341 ml / hr from the top of the extractive distillation column to the 16th stage and 1,4-butanediol was used as the extractive distillation solvent at the 11th stage from the top of the extractive distillation column. Was supplied at 142 ml / hr and brought into countercurrent contact. At this time, the supplied 1,4-butanediol corresponded to a weight ratio of 6 to cyclohexanol in the mixture.

When the extractive distillation column was operated under the conditions of 100 mmHg and a reflux ratio of 4, from the top of the column, 303 ml of a distillate containing 97.2% by weight of cyclohexyl vinyl ether and 2.1% by weight of cyclohexanol at 82.5 ° C. Distilled at / hr. Also, at 100 ° C, 18
A 0 ml / hr solution was withdrawn.

The distillate from the top of the extractive distillation column was introduced at the 10th stage from the top of the ether azeotropic distillation column, and was distilled under the conditions of a top temperature of 150 ° C., 760 mmHg, and a reflux ratio of 10. In this azeotropic distillation column, a liquid was extracted from the bottom of the column at 168 ° C. at 285 ml / hr and led to the 10th stage from the top of the ether-based purification distillation column. The distillate from the top of the ether azeotropic distillation column was withdrawn at 18 ml / hr.

Subsequently, the ether-based purification distillation column was set at 100 mm.
Operating under the conditions of Hg and a reflux ratio of 4, a distillate was recovered from the top of the column at 87 ° C. at 277 ml / hr. As a result of analysis, the distillate contained 99.2% by weight of cyclohexyl vinyl ether and 0.1% by weight of cyclohexanol. Also,
The yield of cyclohexyl vinyl ether was 90.0 wt%. Here, the yield is the ratio of recovered cyclohexyl vinyl ether to cyclohexyl vinyl ether in the mixture supplied to the extractive distillation column as a raw material.

(2) Separation and Recovery of Cyclohexanol and Extractive Distillation Solvent The liquid extracted from the bottom of the extractive distillation column in (1) above was cyclohexanol and 1,4-
Since the mixture contains butanediol and a small amount of cyclohexyl vinyl ether, the mixture was further distilled and separated.

That is, the liquid extracted from the bottom of the extractive distillation column was discharged to the 10th stage from the top of the alcohol-based azeotropic distillation column.
It was guided at 0 ml / hr and operated under the conditions of 200 mmHg and a reflux ratio of 10. Then, a distillate was distilled at a rate of 16 ml / hr at 103 ° C. from the top of the azeotropic distillation column, and 1 mL was distilled from the bottom of the column.
The liquid was withdrawn at 13 ° C. at 162 ml / hr. The distillate at the top of the alcohol-based azeotropic distillation column contains cyclohexanol as a main component and a small amount of cyclohexyl vinyl ether, which was extracted out of the system.

On the other hand, the liquid withdrawn at the bottom of the column is mainly composed of cyclohexanol and 1,4-butanediol.
It was introduced at 2 ml / hr. And, this purification distillation column is 300
Distillation was performed at a pressure of 10 mmHg and a reflux ratio of 10.
Cyclohexanol 16 having a purity of 99.5 wt% at
At 141 ° C., 141 ml / hr of a liquid which was substantially 1,4-butanediol was recovered from the bottom of the column.

The top fraction of the ether-based azeotropic distillation column and the top fraction of the alcohol-based azeotropic distillation column are circulated to the raw materials of the extractive distillation column. It is estimated from the above experimental results that the yield of the obtained high-purity cyclohexylvinyl ether is about 95% by weight.

Example 2 The procedure of Example 1 (1) was repeated except that the extractive distillation solvent was ethylene glycol, and the extractive distillation column was operated at a temperature at the top of the column of 85.5 ° C. and a temperature at the bottom of the column of 101.0 ° C. Separation and purification by distillation were performed.

As a result, a distillate containing 99.3 wt% of cyclohexyl vinyl ether and 0.1 wt% of cyclohexanol was obtained from the top of the ether-based purification distillation column.

Example 3 The same procedure as in Example 1 (1) was carried out except that the extractive distillation solvent was dimethyl sulfoxide, and the extractive distillation column was operated at a top temperature of 89.5 ° C. and a bottom temperature of 105.5 ° C. Separated into
Purification was performed.

As a result, a distillate containing 99.0% by weight of cyclohexyl vinyl ether and 0.1% by weight of cyclohexanol was obtained from the top of the ether-based purification distillation column.

COMPARATIVE EXAMPLE 1 The extractive distillation solvent was water, and the extractive distillation column was heated to a top temperature of 48.
Separation and purification were carried out in the same manner as in Example 1 (1) except that the operation was carried out at a temperature of 60 ° C. and a tower bottom temperature of 60 ° C.

As a result, a distillate containing 94.2% by weight of cyclohexyl vinyl ether and 3.3% by weight of cyclohexanol was obtained from the top of the extractive distillation column. At this time, the yield of cyclohexyl vinyl ether was 65.0% by weight.

[0042]

According to the method using extractive distillation of the present invention, by selecting a specific solvent as the extractive distillation solvent, a high-purity cyclohexylvinylether can be obtained in a simple method by distillation without using water. Can be separated and recovered at a high rate. In the method of the present invention, unlike the conventional method, an extractive distillation solvent containing no water is used, and therefore, there is obtained an advantage that hydrolysis of cyclohexyl vinyl ether, which is the target product, does not occur and the target product can be obtained in high yield. Further, it is possible to effectively separate and recover the cyclohexanol and the extractive distillation solvent which are the reaction raw materials.

[Brief description of the drawings]

FIG. 1 is a flow diagram illustrating one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extraction distillation tower 2 Ether azeotropic distillation tower 3 Ether purification distillation tower 4 Alcohol azeotropic distillation tower 5 Alcohol purification distillation tower

Claims (6)

[Claims] 1. A method for extracting and distilling a raw material mainly composed of a mixture of cyclohexyl vinyl ether and cyclohexanol to separate and recover cyclohexyl vinyl ether, wherein the raw material is introduced into an intermediate portion of an extractive distillation column, and has 2 to 5 carbon atoms. Wherein at least one extractive distillation solvent selected from the group consisting of diols, dimethylsulfoxide and dimethylformamide is introduced into the upper part of the tower from a raw material supply stage while distillation is being performed. 2. The diol having 2 to 5 carbon atoms is ethylene glycol, 1,2-propanediol, diethylene glycol or 1,4-butanediol.
Separation and recovery method. 3. A cyclohexyl distilled from the upper portion of the ether azeotropic distillation column, wherein a fraction distilled from the upper portion of the extractive distillation column from the extractive distillation solvent supply stage is introduced into an intermediate portion of the ether azeotropic distillation column. The azeotrope of vinyl ether and cyclohexanol is circulated to the middle part of the extractive distillation column, and cyclohexyl is fed from a portion other than the portion where the distillate from the upper portion of the extractive distillation column is introduced and a portion other than the upper portion of the ether-based azeotropic distillation column. 3. The method according to claim 1, wherein the vinyl ether fraction is recovered from the ether azeotropic distillation column. 4. The cyclohexyl vinyl ether fraction in the ether-based azeotropic distillation column from an arbitrary portion below a portion for supplying a fraction distilled from the upper portion of the extractive distillation column and above a portion for extracting a high boiling point component. 4. The method according to claim 3, wherein the high-boiling component is extracted from the lower part of the column while extracting as a side stream. 5. In the ether-based azeotropic distillation column, a cyclohexyl vinyl ether fraction is withdrawn from a lower portion of the column,
4. The method according to claim 3, wherein the product is further purified by distillation to recover high-purity cyclohexyl vinyl ether. 6. An azeotropic mixture of cyclohexanol and cyclohexyl vinyl ether distilled from the lower portion of the alcoholic azeotropic distillation column by supplying the liquid extracted from the lower portion of the extractive distillation column to the middle portion of the alcoholic azeotropic distillation column. Circulating to the middle part of the extractive distillation column, and separating the liquid extracted from the lower part of the alcohol-based azeotropic distillation column into cyclohexanol and the extractive distillation solvent by distillation.
5. The separation and recovery method of 5.