JP2879356B2 - Purification method of alkylene glycol monovinyl ethers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to functional fluids such as insulating coating materials for electric wires and the like, lubricating oils by copolymerizing with unsaturated compounds such as ethylene, vinyl chloride or methacrylic acid. Body, polyol component for high-performance urethane, coagulant, modifier for polymer material, photo-curable composition for printed circuit board, etc. The present invention relates to a method for purifying alkylene glycol monovinyl ethers that can be used as a monomer.

"Prior art" Alkylene glycol monovinyl ethers can be prepared, for example, by hydrolysis of haloalkyl vinyl ether, dehydrohalogenation of alkylene glycol haloethyl ether, addition of acetylene to alkylene glycol (see German Patent No. 1,116,214), mercury By exchange reaction with alkylene glycol with vinyl acetate, t-butyl vinyl ether or the like in the presence of a system catalyst (see U.S. Pat. No. 2,579,411), and vinyl etherification of alkylene glycol with ethylene in the presence of oxygen using a palladium catalyst system (See U.S. Pat. No. 4,057,575).

However, the reaction solution synthesized by such a method forms an azeotrope with the target alkylene glycol monovinyl ethers in addition to the target alkylene glycol monovinyl ethers, or alkylene glycol divinyl ethers or alkylene glycols which are difficult to separate by distillation because of their close boiling points. And it is very difficult to purify it because it contains cyclic alkylene acetal and the like.

Conventionally, for example, in U.S. Patent No. 2,836,546,
Alkylene glycol monovinyl ether and alkylene glycol are distilled off from the reaction solution synthesized with alkylene glycol and acetylene by steam distillation as an azeotropic composition, and potassium hydroxide is added thereto and distilled, and triethylamine is contained from the distillate. A complicated process is required such that alkylene glycol monovinyl ether is extracted with diethyl ether, dried, and then distilled again to obtain alkylene glycol monovinyl ether.

In addition, the present inventors have found that the alkylene glycol monovinyl ether obtained by such a method shows coloring and a decrease in purity with the passage of time, and furthermore, remarkable coloring particularly when an alkali substance is added as a stabilizer. Have been found to have significant disadvantages.

"Problems to be Solved by the Invention" The need for complicated purification steps as described above in obtaining high-purity alkylene glycol monovinyl ethers is a serious drawback in industrially producing the present compound. In addition, the alkylene glycol monovinyl ether obtained as a product overcoming such difficulties shows a remarkable coloring and a decrease in purity over time.
It can be said to be a fatal defect in view of its use.

"Means for Solving the Problems" In order to overcome these problems, the present inventors have eagerly pursued a method for purifying alkylene glycol monovinyl ethers which has a simple process and does not show any coloration or decrease in purity even after a lapse of time. As a result of the research, it was surprisingly found that if distillation is performed in the presence of a compound exhibiting basicity and reducing ability, alkylene glycol monovinyl ethers can be obtained with a simple purification process and without any coloration or reduction in purity. Heading, and led to the present invention.

That is, polymerization occurs during distillation due to the low stability of the alkylene glycol monovir ethers, and a cyclic acetal or a chain polymer is generated by a reaction of a vinyl group and a hydroxyl group within and between molecules, and thus the purification step is performed. We knew that it was complicated and found that by making the solution basic in a reducing atmosphere, we could suppress those by-products and make it easier to purify them, and could overcome the first problem. . In addition, surprisingly, they have found that the obtained alkylene glycol monovinyl ethers are extremely stable and do not show any coloring or deterioration in purity even after being left for several months. Was completed.

That is, in the present invention, when distilling and purifying an alkylene glycol monovinyl ether represented by the following general formula [1], CH ₂ CHOCHO (RO) nH [1] “where n represents an integer of 1 or 2, R when n is 1
Represents an alkylene group having 2 to 6 carbon atoms, and when n is 2, R represents an alkylene group having 2 carbon atoms. It is a method for purifying alkylene glycol monovinyl ethers, which comprises distilling in the presence of a compound having basicity and reducing ability.

Alkylene glycol monovir ethers that can be used in the present invention are any of the known production methods as described above,
For example, hydrolysis of haloalkyl vinyl ether, method by dehydrohalogenation of alkylene glycol haloethyl ether, method of adding acetylene to alkylene glycol, exchange with alkylene glycol by vinyl acetate, t-butyl vinyl ether, etc. in the presence of a mercury-based catalyst A reaction solution produced by any reaction such as a reaction method, a method of vinyl etherifying alkylene glycol with ethylene in the presence of oxygen using a palladium catalyst system, or a colored product of alkylene glycol monovinyl ether may be used. As alkylene glycols to be used, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3 Butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, can be diethylene glycol and the like.

The compound which is added to the thus obtained alkylene glycol monovinyl ether-containing liquid and exerts its effects is not particularly limited as long as it has a basic liquidity and further has a reducing ability, and is a compound having the two functions. For example, sodium hydride, potassium hydride, sodium borohydride as alkali borohydride, lithium aluminum hydride, sodium bis (2-methoxyethoxy) aluminum hydride as alkali hydride, etc. Yes, these compounds can be used alone or as a mixture of two or more.

In performing the purification by distillation using the compound as described above, in the present invention, first, a compound having basicity and reducing ability is added to a liquid containing alkylene glycol monovinyl ether. The amount of addition is not particularly limited, but is preferably 0.03 to 15% by weight based on the liquid containing the alkylene glycol monovinyl ethers. 15% by weight
It is not preferable to use the amount exceeding 3 from the viewpoint of economy and considering that undesired by-products may be newly generated. If the amount is less than 0.03% by weight, the effect is small and it cannot be said that it is preferable. A more preferred addition amount is 0.1 to 5% by weight.

Then, the above-mentioned mixture is distilled. In many cases, when these compounds having a reducing ability are added to a liquid containing alkylene glycol monovinyl ether, foaming is observed, and this may sometimes be severe. In such a case, the method of the present invention may be carried out by previously distilling low-boiling substances from the alkylene glycol monovinyl ether-containing liquid by distillation or once purifying by a usual method. The distillation method of the present invention may be carried out by a known method without the need for a special method.However, in consideration of the thermal stability of alkylene glycol monovinyl ethers, it is usually 30.
It should be performed in a temperature range of ~ 200 ° C.

Thus, in the conventional method, only alkylene glycol monovinyl ethers that were colored or decreased in purity with the passage of time were obtained, but according to the present invention, a complicated purification step was not required, and even after long-term storage. It is possible to obtain alkylene glycol monovinyl-ethers which are stable without being colored and having a reduced purity.

"Example" The method of the present invention will be described in more detail with reference to examples and comparative examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

Example 1 (Production Example of Ethylene Glycol Monovinyl Ether) In the same manner as in the method described in US Pat. No. 1,959,927,
A metal reactor was charged with 1,000 parts of ethylene glycol and 5 parts of KOH, and 200 parts of acetylene was introduced at about 120 ° C. for 36 hours. The composition after expulsion of low-boiling substances is as follows: ethylene glycol monovinyl ether 28.5%, ethylene glycol divinyl ether 8.7%, 2-methyl-1,3-dioxolane 3.5%
And ethylene glycol 56.7%.

(Distillation purification) After completion of the above reaction, distillation was carried out using a simple distillation apparatus, and the ethylene glycol monovinyl ether-containing liquid 1000
Got a part. The composition was 33% ethylene glycol monovinyl ether, 10% ethylene glycol divinyl ether, 4% 2-methyl-1,3-dioxolane and 50% ethylene glycol.

Next, 1000 parts of the above mixture and 30 parts of sodium borohydride were placed in a distillation apparatus corresponding to four theoretical plates, and the mixture was separated by distillation. Ethylene glycol monovinyl ether 297 having a purity of 99.6% and a boiling point of 56 ° C. under a pressure of 30 mmHg was distilled.
Got a part. Its recovery was 90%.

Comparative Example 1 (Distillation Purification) Purification was performed according to the method described in U.S. Pat. No. 2,836,546.

1158 parts of the reaction solution obtained in Example 1, 760 parts of water and KOH2
The mixture was placed in a still and separated by distillation to obtain 830 parts of an azeotropic composition of ethylene glycol monovinyl ether and water, which was extracted with 4 parts of triethylamine and 830 parts of ether to obtain an organic layer. This was dried using sodium sulfate. The dried vinyl ether-containing liquid after drying was again subjected to distillation separation using a distillation apparatus corresponding to four theoretical plates. The purity of the obtained vinyl ether was as low as 98.0%, and the recovery rate was as low as 85%.

Comparative Example 2 (Distillation purification) When the method described in Example 1 was repeated using 30 parts of potassium carbonate instead of sodium borohydride, the purity was 98.5.
Only 85% of vinyl ether was recovered.

Example 2 (Example of producing ethylene glycol monovinyl ether) A flask equipped with a stirrer, a thermometer, and a cooler was charged with 523 parts of 2-chloroethyl vinyl ether, 540 parts of sodium formate, and 10 parts of tetraphenylphosphonium bromide.
The reaction was performed at 0 to 120 ° C for 6 hours.

The obtained reaction solution was washed with 1000 parts of water, filtered and the liquid phase was separated to obtain 527 parts of an organic layer. Transfer this to the above flask,
At 20 to 40 ° C., 420 parts of a 50% aqueous sodium hydroxide solution was added dropwise over 2 hours, and the reaction was allowed to proceed for 1 hour.

After completion of the reaction, the mixture was washed with 180 parts of water, and a mixture containing 51% of ethylene glycol monovinyl ether as an organic layer was used.
434 parts were obtained.

Next, 434 parts of the above mixture was placed in a glass simple distillation apparatus and distilled to remove low-boiling substances. Ethylene glycol monovinyl ether 90%, 2-methyl-1,3-dioxolane 6% and 1,4-dioxane 200 parts of a fraction consisting of 2% were obtained.

(Distillation purification) 200 parts of the mixture obtained above and 1.2 parts of VITRIDE (a product of HEXCEL, a 70% toluene solution of sodium bis (2-methoxyethoxy) aluminum hydride) were placed in a distillation apparatus having four theoretical plates. After distillation, 162 parts of ethylene glycol monovinyl ether having a purity of 99.5% were obtained, and the recovery was 90%.

Comparative Example 3 (Distillation purification) Distillation purification described in Example 2 was performed using 0.6 parts of potassium hydroxide instead of VITRIDE.

The purity of the obtained 139 parts of vinyl ether was as low as 98.0%, and the recovery was as low as 77%.

Example 3 (Distillation purification) 1000 parts of ethylene glycol monovinyl ether having a hue of 200 according to the APHA method and a purity of 97% and 1 part of sodium borohydride were placed in a distillation apparatus corresponding to four theoretical plates and subjected to distillation separation. 892 parts of ethylene glycol monovinyl ether having a purity of 99.5% were obtained. This recovery was 92%.

Example 4 (Production example of 1,2-propylene glycol monovinyl ether) When 1,226 parts of 1,2-propylene glycol was used instead of ethylene glycol, the method described in Example 1 was repeated to obtain 1,2-propylene glycol monovinyl ether. Vinyl ether 30
%, 1,2-propylene glycol divinyl ether 10
%, 2,4-dimethyl-1,3-dioxolane 5% and 1,2-
900 parts of a mixture consisting of 52% of propylene glycol were obtained.

(Distillation purification) 900 parts of the mixture obtained above and an ether solution of lithium aluminum hydride (1) were placed in a distillation apparatus equivalent to four theoretical plates.
8 parts were added and the mixture was separated by distillation to obtain 243 parts of propylene glycol monovinyl ether having a purity of 99.2%. This recovery was 90%.

Example 5 (Production example of 1,4-butanediol monovinyl ether) Complex prepared from 180 parts of 1,4-butanediol, palladium acetate and 1,10-phenanthroline in a reaction flask
0.8 ° C and 20.1 parts of isobutyl vinyl ether
After 4 hours of reaction, simple distillation was performed to remove low-boiling substances. Then, 1,4-butanediol monovinyl ether 34%, 1,4
57 parts of a mixture consisting of 3% of butanediol divinyl ether and 62% of 1,4-butanediol were obtained.

(Distillation purification) In a distillation apparatus corresponding to four theoretical plates, 57 parts of the mixture obtained above and a liquid paraffin mixture of sodium hydride 1.3
Then, 17 parts of 1,4-butanediol monovinyl ether having a purity of 99.0% was obtained at a recovery of 88%.

Example 6 (Production Example of Diethylene Glycol Monovinyl Ether) A reaction flask was charged with 1200 parts of 1,4-dioxane and 112 parts of potassium t-butoxide, and 169 parts of diethylene glycol mono (2-chloroethyl) ether was added at room temperature to 1 part.
The mixture was added dropwise over a period of time, and the reaction was further performed for 1 hour after the completion of the addition.

After the reaction solution was filtered off, 1,4-dioxane was distilled off from the liquid part under reduced pressure to obtain diethylene glycol monovinyl ether 80.
% Of diethylene glycol (2-chloroethyl) ether 15% was obtained.

(Distillation purification) 63 parts of the mixture obtained above and 0.3 part of sodium borohydride were placed in a distillation apparatus corresponding to four theoretical plates, and the mixture was separated by distillation. 44 parts of diethylene glycol monovinyl ether having a purity of 98.5% was recovered. Obtained at a rate of 87%.

Example 7 200 g of the purified vinyl ethers obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were put in a test glass bottle, 0.2 g of potassium hydroxide was further added as a stabilizer, and the mixture was heated at room temperature in a room. The sample was allowed to stand for a predetermined time, and the change in hue and change in purity were tracked. The results are shown in Tables 1 and 2.

Some of the nine samples were colored immediately after the addition of the stabilizer, and are shown in the rightmost column of Table 1.

As is clear from the above table, the vinyl ether purified using the method of the present invention did not show any coloration or decrease in purity even after 3 months, and showed good hue. The product was colored after only one month, and the purity was significantly reduced. That is, the excellent characteristics of the method of the present invention were remarkably exhibited.

[Effects of the Invention] The method of the present invention is a novel purification method in which alkylation glycol monovinyl ethers which can simplify the purification step and obtain stable properties by distillative purification in the presence of a compound exhibiting basicity and having a reducing ability. Is the way.

────────────────────────────────────────────────── (5) References US Pat. No. 4,057,575 (US, A) US Pat. No. 3,657,360 (US, A) US Pat. No. 2,836,546 (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) C07C 43/178 C07C 41/42 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] (1) When distilling and purifying an alkylene glycol monovinyl ether represented by the following general formula [1], CH ₂ CHOCHO (RO) nH [1] wherein n represents an integer of 1 or 2, R when n is 1
Represents an alkylene group having 2 to 6 carbon atoms, and when n is 2, R represents an alkylene group having 2 carbon atoms. A method for purifying alkylene glycol monovinyl ethers, wherein the distillation is carried out in the presence of a compound having basicity and reducing ability. 2. The substance having a basic property and a reducing ability,
2. The method according to claim 1, wherein the compound is at least one compound selected from the group consisting of alkali hydride, alkali borohydride, and alkali aluminum hydride.