JPS6049171B2 - Separation method of cyclohexyl vinyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating cyclohexyl vinyl ether.

Cyclohexyl vinyl ether is mainly produced by the transetherification reaction of lower alkyl vinyl ethers, such as ethyl vinyl ether, with cyclohexanol, or the addition reaction of cyclohexanol to acetylene, but the reaction mixture obtained by these methods contains Cyclohexyl vinyl ether coexists with unreacted cyclohexanol.

Since cyclohexyl vinyl ether forms an azeotrope (weight ratio of approximately 79:21) with cyclohexanol, some measures are required to separate cyclohexyl vinyl ether from the reaction mixture. Conventionally, such separation methods include (1) a method in which cyclohexanol is converted to alcoholade by the action of an alkali metal;

(See US Pat. No. 276,099) (2) A method of carrying out the above-mentioned alcoholade conversion using an alkali metal hydroxide.

(See above specification) (3) Method by steam distillation.

(See US Pat. No. 3,287,235) has been proposed. However, according to the research conducted by the present inventors, in the method (1) above, not only is the operation complicated due to the use of an alkali metal, which is a dangerous chemical, but also hydrogen is produced as a by-product during the conversion to alcoholade. It has the disadvantage of an increased risk of flammability and, furthermore, due to the low solubility of the alcoholade formed, which accumulates on the alkali metal and slows down the progress of the reaction, it is necessary to use such an alcoholade in order to obtain high purity vinyl ethers. It is necessary to repeat the operations of chemical reaction and distillation under reduced pressure several times, which has the disadvantage that the recovery rate of vinyl ether is reduced.Furthermore, there is a disadvantage that the treatment of the distillation residue, which is mainly composed of alcoholade, is complicated.

In addition, in the method (2) above, although the generation of hydrogen during alcoholation can be avoided, the alcoholation reaction takes a long time, and like (1), the recovery rate of vinyl ether is low and the distillation residue is Problems such as complicated processing remain.On the other hand, in method (3) above, no chemicals other than water are required during separation, so problems such as operational risks and residue disposal can be avoided. However, because the boiling points of the water/cyclohexyl vinyl ether azeotrope and the water/cyclohexanol azeotrope are close to each other, it is theoretically difficult to recover high-purity vinyl ether. Since the cyclohexyl vinyl ether is separated into cyclohexanol and acetaldehyde by the action of As a result of repeated studies, we found that by bringing a mixture containing cyclohexanol and cyclohexyl vinyl ether into contact with relatively low-temperature water, cyclohexanol is selectively and efficiently transferred to the aqueous phase, and losses due to decomposition of cyclohexyl vinyl ether are reduced. We have come to the new knowledge that it is possible to minimize the

This finding was exactly expected given the conventional knowledge that the solubility of cyclohexanol in water is only 3 to 5 g/100 g water and that vinyl ethers generally have a tendency to decompose into alcohol and acetaldehyde under the action of water. It should be called something outside. Thus, the present invention has been completed based on the above knowledge, and when separating cyclohexyl vinyl ether from a mixture containing cyclohexanol and cyclohexyl vinyl ether, the mixture is brought into contact with water at a temperature of 0 to 70°C to select cyclohexanol. The object of the present invention is to provide a new method for separating cyclohexyl vinyl ether, which is characterized by comprising the steps of transferring the cyclohexyl vinyl ether to an aqueous phase and separating the aqueous phase and the organic phase.

In the present invention, the mixture containing cyclohexanol and cyclohexyl vinyl ether includes not only a mixture consisting only of these two components, but also a mixture obtained by crude distillation of a reaction mixture of transetherification reaction of ethyl vinyl ether with cyclohexanol. mixture (composition example: cyclohexyl vinyl ether 60wt
%, cyclohexanol 34 Wt. %, ethanol 5
Wt%, trace amounts of ethyl vinyl ether, and trace amounts of high-boiling components) may also contain other components.

In the present invention, the mixture and water are brought into contact at a relatively low temperature, i.e. from 0 to 70'C, preferably from 5 to 50'C.
It is important to do so.

If the temperature is too high, losses due to decomposition of cyclohexyl vinyl ether will increase, which is disadvantageous. The amount of water in contact depends on the amount of cyclohexanol in the mixture,
Although it can be changed as appropriate depending on the desired purity of cyclohexyl vinyl ether, usually 3
A double amount or more may be adopted, and there may be cases where an amount of about 3CPi is adopted. It is also possible to dissolve inorganic salts such as sodium chloride and potassium sulfate in the water for the purpose of facilitating the separation operation between the aqueous phase and the organic phase, which will be described later. Cyclohexyl vinyl ether hardly dissolves in pure water, but tends to dissolve in water containing a large amount of lower alcohols such as ethanol, so the method of the present invention is applied to mixtures containing lower alcohols. In this case, it is desirable to suppress the elution of hexyl vinyl ether by using water in an amount equal to or more than the amount of lower alcohol in the mixture. In the present invention, the mixture can be brought into contact with water in various ways, and various conventionally known methods can be employed for liquid-liquid extraction.

Examples include a method in which both liquids are charged batchwise into a container and stirred or shaken, and a method in which both liquids are brought into countercurrent contact with each other continuously with or without stirring. In the present invention, separation of the aqueous phase and the organic phase can be carried out in various ways,
A method of separating the liquids using the difference in specific gravity between the two liquids, for example, a method of stirring or shaking in batches and then separating the liquids, a method of separating the liquids after continuous countercurrent contact, or a method of separating the liquids after continuous countercurrent contact, or a method of separating the liquids after continuous countercurrent contact. It is possible to adopt a method of separating the liquid using a hydrophobic porous membrane made of polytetrafluoroethylene or the like by utilizing the difference in tension. In addition, when carrying out the present invention batchwise, it is possible to carry out the liquid-liquid contact and the liquid-liquid separation in multiple steps.

For example, the above mixture and about 2 to 1 volume of water are placed in a container, soaked for a predetermined period of time, then allowed to stand still, the lower aqueous phase is drained, and then about 1 to 5 times the amount of water is added and soaked for a predetermined period of time. After shaking, the aqueous phase is separated and this operation is repeated a predetermined number of times. By employing such an operation, it is possible to promote a reduction in the cyclohexanol concentration in the organic phase. According to the present invention, there is no need to use dangerous chemicals such as alkali metals or alkali metal hydroxides, so the safety of the operation is increased, the recovery rate of cyclohexyl vinyl ether is extremely high, and the time required for separation is increased. In addition to the advantages of being short, cyclohexanol is separated as it is in the form of an aqueous solution, so there is also the advantage that it is easy to recover and reuse as a raw material for cyclohexyl vinyl ether. Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Cyclohexyl vinyl ether (79.0Wt
%) and cyclohexanol (21.0 Wt%) and 400 g of water were loaded into a liquid separation load with an internal volume of 1e, shaken vigorously for 3 minutes at a liquid temperature of 21°C, and then allowed to stand still for 1 min to remove the lower layer. The aqueous phase was drained.

By this operation, the cyclohexanol concentration in the organic phase was reduced to 5.
．． It decreased to 0 Wt%. By repeating the same operation four times in total, 77.0 g of cyclohexyl vinyl ether with a purity of 99.7 wt% was obtained. The recovery rate of cyclohexyl vinyl ether was 97.2%. Example 2 100 g of a mixture of cyclohexyl vinyl ether (50.0 Wt%) and cyclohexanol (50.0 Wt%) and 500 g of water
The mixture was loaded into a stirring tank with an internal volume of 2e, the temperature was maintained at 50 to 45 °C, and the mixture was stirred vigorously for 5 minutes, then transferred to a separation load, left to stand, and the aqueous phase was discharged, followed by the same operation. By repeating the process four times, 47.9 g of cyclohexyl vinyl ether with a purity of 99.5 wt% or more was obtained.

The recovery rate was 95.4%. Example 3 The same operation as in Example 1 was repeated seven times, except that a 5% aqueous solution of sodium chloride was used instead of water.

Cyclohexyl vinyl ether with a purity of 99.9% is 75
．． 5g was obtained. The recovery rate is 95.4%. Comparative example 1
500g mixture of cyclohexyl vinyl ether (86.2wt%) and cyclohexanol (13.8wt%)
was charged into a Yotsuro flask with an internal volume of 1e, and 19.0 g of metallic sodium filaments were charged under a nitrogen stream, heated at 80 to 100°C for 42 hours with stirring to perform the alcoholation reaction, and then heated for 3'7 VfI. By distilling under reduced pressure, 398 g of distillate was obtained.

The composition of the distillate is cyclohexyl vinyl ether 99.
0 wt%, and cyclohexanol was 1.0 wt%.
Using the entire amount of the above distillate, 1.1 g of metallic sodium filament was charged, and the same alcoholation reaction as above (6.0 hours) was carried out.
By performing distillation under reduced pressure (3. kimono), the purity level is 9.
390g of 9.6wt% cyclohexyl vinyl ether
I got it. Recovery rate of cyclohexyl vinyl ether is 90
．． Only 3%. Comparative Example 2 Mixture 2 similar to Comparative Example 1
22.2 g of powdered sodium hydroxide was added to 00 g, heated at 80 to 100° C. for 6 hours with stirring, and then distilled under reduced pressure to obtain 179 g of distillate.

The composition of the distillate is cyclohexyl vinyl ether 94.
4 wt%, and cyclohexanol 5.6 wt%.
The same purification operation was repeated one more time (however, the heating time was 1
1 hour), but the purity of cyclohexyl vinyl ether remained at 97.1 wt%, and the recovery rate was 92.0%.
It was a low percentage. Comparative Example 3 8.4 Wt% Na was added to 200 g of the same mixture as Comparative Example 1.
873 g of an OH aqueous solution was added, and steam distillation was performed at normal pressure.

Organic phase 3 of the initial distillate distilled with a boiling point of 89-90'C
The composition of 1.9g is cyclohexyl vinyl ether94.
6 wt% and cyclohexanol 5.4 wt%, but as distillation progressed, the boiling point rose to a new 94°C.
Accordingly, the composition of cyclohexyl vinyl ether in the organic phase of the distillate decreased. The total amount of the organic layer finally distilled was 186.5 g, and its composition was 74.6 wt% cyclohexyl vinyl ether, 2 wt% cyclohexanol.
It was 5.4 wt%. This result shows that about 15 wt% of cyclohexyl vinyl ether was hydrolyzed during the separation operation.
This indicates that it has changed to cyclohexanol. Comparative Example 4 Using 100 g of the same mixture as in Example 1 and 400 g of water, contact and separation at 80 to 90°C were repeated 5 times using the same apparatus as in Example 2, resulting in a purity of 99.7 wt%.
of cyclohexyl vinyl ether was obtained, but the amount recovered was 67.4 g, and the recovery rate of cyclohexyl vinyl ether was considerably reduced to 85.1%.

Example 4 100 g of a mixture obtained by crudely distilling the reaction mixture of the transetherification reaction of cyclohexanol and ethyl biphnyl ether using a mercury catalyst (composition: cyclohexyl vinyl ether 54.2 wt%, cyclohexanol 30.3 Example 1
Repeat the same operation 5 times (however, the amount of water is 500g)
54.0 g of organic phase was recovered.

Claims (1)

[Claims] 1. When separating cyclohexyl vinyl ether from a mixture containing cyclohexanol and cyclohexyl vinyl ether, the mixture is brought into contact with water at a temperature of 0 to 70°C to selectively transfer cyclohexanol to the aqueous phase, and the aqueous phase and organic phase are separated. A method for separating cyclohexyl vinyl ether, the method comprising the step of separating cyclohexyl vinyl ether.