JPS58162544A - Purification of ethers - Google Patents

Abstract

PURPOSE:To obtain a glycol dimethyl ether industrially advatnageously, by reacting a specific ether compound with ethylene oxide to give a crude reaction product, bringing the crude reaction product into contact with water so that coexisting inpurities are hydrolyzed, reacting the by-products with a methylating agent. CONSTITUTION:A compound shown by the formula (n is integer of 0-10) is reacted with ethylene oxide to give a crude reaction product containing a very small amount of by-products, which is brought into contact with water so that acetals comprising mainly the by-products are hydrolyzed into glycol monomethyl ethers, etc. The by-products are methylated with a methylating agent, especially a methyl monohalide and an alkali metal, its hydroxide, oxide or hydride, so that mono polyethylene glycol dimethyl ethers useful as a polar solvent containing no active hydrogen, etc. are obtained in high purity in high yield by converting the by-products into the desired compound by a simple operation without separating the by-products unseparable by a physical means such as distillation, etc. from the crude reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION A crude product obtained by reacting dimethyl ether, mono- or polyethylene glycol dimethyl ethers with ethylene oxide (hereinafter referred to as F).

Abbreviated as crude product. ).

The production of mono- or polyethylene glycol dimethyl ether, which has recently become increasingly useful as a polar solvent without active hydrogen, a dissolving agent for metal or non-metallic hydrides, an acid gas absorber, or a component of various catalysts, has conventionally been carried out using the Quilliamson method and its modifications. It has been produced by the hydrogenolysis method of glycol ether formal. However, these conventional methods 4 are not suitable for industrial use because the reaction itself is complicated and a large amount of by-products are produced. Recently, a method of directly inserting ethylene oxide into dimethyl ether or mono- or polyethylene glycol dimethyl ether in the presence of a catalyst has been proposed as a more rational method (JP-A-53-34709, JP-A-56-8338, JP-A-Sho 56-8338). 56- 16413
Publication No. 1, Publication No. 56-166136, Publication No. 56-1
(See Publication No. 66137). These direct insertion methods can produce the above-mentioned glycol dimethyl ethers in a single reaction, and when using the conventional Williamson method, they can be produced at a stoichiometric (two-handed method) without producing a large amount of by-products such as alkali halides. On the other hand, A cyclic acetals such as 2-methyldioxolane, chain acetals such as methyl hexa(or poly)glycol ether acecool, or mono(or poly)ethylene glycol monomethyl ether have the advantage of not producing any living organisms. The production of small amounts of by-products such as hydroxyl group-containing compounds has been a problem, and the treatment of these by-products has been a problem. If these by-products were to be separated simply by distillation operation C2, it would be necessary to use a rectification column with an extremely high number of plates and a culm that was practically unnecessary. It cannot be recovered well.

Furthermore, it is virtually impossible to separate polyethylene glycol dimethyl ethers such as pentaethylene glycol dimethyl ether, which are useful as acidic gas absorbents, from polyethylene glycol monomethyl ethers by rectification, and a mixture of the two cannot be used for the above purpose. If used for this purpose, it has the disadvantage that its life as a gas absorbent will be significantly shortened.

Other separation methods, such as known physical operations such as extraction and adsorption, are nearly impossible in practice, and even if they were possible, they were extremely complicated.

Based on the above-mentioned theory EI+, the present inventors have determined that a simple and practical method (second method) for purifying mono- or polyethylene glycol ethers by eliminating a small amount of the above-mentioned by-products contained in the crude product. As a result of intensive studies, we found that the aforementioned acetals, which account for most of the by-products, are not separated from the crude product, and if they come into contact with water in the crude product, they can easily be converted into glycol monomethyl ethers or glycols. (ii) If the produced glycol dimethyl ethers or glycols are methylated with a methylating agent without separating them from the desired product glycol dimethyl ethers, the glycol dimethyl ethers can be converted into glycol dimethyl ethers. Due to the contribution of the solvent effect, it is highly selective and rapid (
Therefore, most of the by-products present in the crude product can be converted into mono- or polyethylene glycol dimethyl ether, which is the object of the present invention, without separating it from the crude product. The present invention has been achieved by discovering the following.That is, the present invention is based on the following general formula [I] (with ether compounds represented by r"H,
0(-CH,CH,0)-, CHa-CI] (where n represents 0 or a natural number from 1 to 10) The crude product obtained by reacting ethylene oxide is brought into contact with water to remove coexisting impurities. This is a method for purifying ethers, which is characterized by hydrolysis and then reaction with a methylating agent.

The crude product used for purification, which is the object of the present invention, is a reaction product of the compounds represented by the above-mentioned general formula CD and ethylene oxide, and although there is no particular limitation on the manufacturing method, it is understood that the above-mentioned acetals is 0.1 to 10% by weight
The purification method of the present invention should be applied to crude products containing a certain degree. Such crude products are described in the above-mentioned publications and are often obtained after reaction in the presence of L catalyst.

The crude product is brought into contact with water (the amount of water used should be at least 3 times the mole of the acetal C to be decomposed, preferably 3 times the mole or more. However, there are operational problems,
Considering separation after contact, etc., it is preferable that the amount is less than or equal to multiplied molar.

There is no particular restriction on the contact temperature with water, but if it is too high, the decomposition of the target product glycol dimethyl ethers may be accelerated, which is undesirable.
Temperatures below 100°C are preferred. The method of contacting with water may be any conventionally known method, and may be a continuous method or a batch method. In either method, it is preferable to remove aldehyde generated from the reaction between acetals and water from the system. This is to prevent the ethers present in large amounts in the system from reacting again with the aldehyde to generate acetal, or to prevent the aldehyde from reacting by itself. In order to accelerate the hydrolysis reaction of acetals upon contact with water, there is no problem in using known catalysts, such as +i, 1M acid, sulfuric acid, 9-acid, 1-toluenesulfonic acid, etc. Examples include acidic compounds.

If the above-mentioned conditions are used, the hydrolysis reaction will proceed quickly (usually within 1 hour) and will be almost completed, and most of the by-products in the crude product will be converted into mono(or) polyethylene glycol monomethyl ether. and a small amount of mono(or) polyethylene glycol.

Next, the method for converting the above by-product into mono(or) polyethylene glycol dimethyl ether is not particularly limited, and a methylating agent capable of converting the terminal hydroxyl group of the above-mentioned by-product into a methoxy group may be used. Examples of the curing agent include halogenated methane such as monochloromethane and monobromomethane, dimethyl sulfate, diazomethane, methyl orthoformate, methyl nitrite, dimethyl sulfite, dimethyl carbonate, trimethyl orthophosphate, and dimethyl orthosilicate. Considering the removal of excess water coexisting with the crude product at the end of the hydrolysis reaction mentioned above, the handling of the methylating agent, etc., it is possible to remove the alkaline compound and monochrome without necessarily removing the excess water coexisting with the crude product. Preference is given to methylating with lomethane or monobromomethane I, N. The target compound of the process of the invention, mono(or) polyethylene glycol di, methyl ethyl, which accounts for the majority of the crude product, is methylated with this preferred methylating agent. Another feature of the method of the present invention is that it exhibits an extremely favorable solvent effect in the methylation reaction.

Examples of the above-mentioned alkaline compounds include alkali metals such as sodium, potassium, and lithium, and their hydrides, hydroxides, and oxides. These are 1w or a mixture of two or more types, and the amount is required to be at least equivalent to the number of terminal hydroxyl groups of the by-products present in the crude product after water decomposition, preferably at least 2 times equivalent, and 10 times equivalent. Below is now.

If the amount used exceeds 10 equivalents, unreacted methylating agent will be separated and recovered on the side, which is not preferable. There is no particular restriction on the reaction temperature, and since the reaction proceeds sufficiently quickly even at a relatively low temperature such as room temperature, a temperature of less than 100°C is sufficient. This terminal methylation reaction may be carried out in a continuous manner or in a batch manner, or any combination of these methods may be used. An example of the terminal methylation reaction when using methyl 10genide as a methylating agent is as follows: The above-mentioned crude product after hydrolysis and the above-mentioned alkali compound are placed in a reactor, and the halogenation reaction is carried out under stirring. The methylation reaction is carried out by adding methyl once (two times or in small amounts) continuously or intermittently.The reaction time varies depending on the amount of by-products with a terminal C dihydroxyl group mixed therein, but usually the crude oil shown in the present invention is In the case of products, the process is completed in about 2 hours.

As described above, according to the method of the present invention, most of the by-products present in the original crude product become mono- or polyethylene glycol dimethyl ether, which is the target compound, and other by-products that are difficult to remove are substantially do not.

As mentioned above, in the case where an alkali compound is added, the unreacted compound and the salts generated from the methylation reaction may be separated by a known method such as filtration or liquid separation. Thereafter, the crude product is distilled (thereby, each target compound may be produced individually or in the form of a mixture).

By using the method of the present invention, impurities that could not be separated into two by physical means such as distillation, extraction, or adsorption can be converted into the target compounds with an extremely simple operation. Therefore, the two objectives of increasing the purity and yield of target compounds can be achieved at once, which is extremely advantageous industrially.

In addition, the following (= parts) indicate parts by weight unless otherwise specified.

Example 1 The reaction described in Example 1 of JP-A-56-164131 was carried out using a boron trifluoride/water-suspended catalyst at a dimethyl ether/ethylene oxide molar ratio of 17'1, and the following reaction was obtained. The impurities mainly consisting of acetals contained in the crude product were 35% by weight. 200 parts of the crude product and 15 parts of water were charged into a reactor equipped with a stirrer and a cooling tube, and refluxed for 3 hours under reduced pressure of 700 mHg. The generated acetaldehyde was removed from the system through a cooling pipe.

Next, 212 parts of the hydrolyzed solution (=1 part of diisopropyl ether) was added and dehydrated by a known azeotropic method. Diisopropyl ether was distilled off. 6 parts of sodium hydroxide was added to the reaction solution and the mixture was heated at 50 to 90°C. 7.6 parts of methyl chloride was added and reacted with stirring in a temperature range of Monomethyl ethers were substantially absent, and the purity of dimethyl ethers was 99.5% or higher.This was rectified by a known method to obtain 99.0% of each of mono-, di-, and triethylene glycol dimethyl ethers. % or more recovery rate and purity of 99.8% or more.

The remaining tetraethylene glycol dimethyl ether had a purity of 99% or more.

Example 2 Using the method described in JP-A-56-166137 Example 1 (2), dodecatungstosilicic acid was used as a catalyst, and the molar ratio of dimethyl ether/ethylene oxide was 1.
When the reaction was carried out at 1/1, impurities mainly consisting of acetals were contained in the crude product (24.8% by weight).

200 parts of this crude product, 11 parts of water, and 5 parts of concentrated hydrochloric acid as a catalyst were placed in two similar reactors C in the same manner as shown in Example 1, and refluxed for 1 hour under a pressure of 700 μHg. went. The generated acetaldehyde was collected outside the system through a cooler.

Next, 8.2 parts of sodium dihydroxide and 13 parts of dimethyl sulfuric acid were added to the reaction solution 6, which was dehydrated in the same manner as in Example 1 and further removed by distillation of C diisopropyl ether, and reacted by heating. When this reaction solution was separated by gas chromatography after passing t1, it was found that most of the impurities and mono- or polyethylene glycol monomethyl ethers had been converted to dimethyl ethers. When we conducted a distillation test on a portion of this, we were able to obtain mono-, di-, and triethylene glycol dimethyl ethers with a purity of over 99.8%, and the purity of the remaining tetra or higher ethylene glycol dimethyl ethers was also 99.8%. It was .0% or more.

. Example 3 The Minato method described in Example 1 of JP-A-56-166136 was carried out using trifluoromethanesulfonic acid as a catalyst and a dimethyl ether/ethylene oxide molar ratio of 1.
When the reaction was carried out at 1/1, 4.0 weight of impurities mainly consisting of acetals were present in the crude product.

200 parts of this crude product and 13 parts of water were hydrolyzed in the same manner as in Example 1. Next, 8.3 parts of methyl chloride and 7 parts of sodium hydroxide were added to the reaction solution, which was dehydrated using diisopropyl ether and the ether was removed by distillation.
When treated using Method C described in Example 1, most of the impurities and mono- or polyethylene glycol monomethyl ethers were converted to dimethyl ethers, and the purity of the glycol dimethyl ethers was 99.5% or more.

Example 4 Using the method described in Example 1 of JP-A No. 53-34709, dimethyl ether/ethylene oxide molar ratio 5/1,
When the reaction was carried out using dimethyl ether boron fluoride as a catalyst, 3 impurities mainly consisting of acetals were
．． A crude product containing 3 weight ducks was obtained.

Hydrolysis using 200 parts of this crude product and 10 parts of water,
Next, methylation was carried out as described in Example 1 using 9.5 parts of Mizuaya-lium and 9.0 parts of methyl bromide. The purity of glycol dimethyl ethers was 99.6% or more.

Example 5 A reaction was carried out using dimethyl ether boron fluoride as a catalyst at a molar ratio of ethylene glycol dimethyl ether/ethylene tei oxide of 4/11 using the method described in Example 2 of JP-A No. 53-34709. Impurities are 3. It was contained in the OIff Okigamo crude product. Using 200 parts of this crude product, Example 1
When hydrolysis and methylation were carried out using the method described above, glycol dimethyl ethers containing almost no acetals and mono-, bolier-, and terene glycol methyl ethers were obtained, and the purity thereof was 99.2% or more. there were.

Example 6. 7゜The same reaction solution of dimethyl ether and ethylene oxide as in Example 1 was subjected to hydrolysis, dehydration, and isopropyl ether separation in the same manner as in Example 1. 200 parts of the reaction solution was prepared as shown in the table below (2). When the reaction was carried out using the appropriate methylating agent and conditions and analyzed by a conventional method, the results shown in the table below were obtained.

Procedures Amendment 1, Indication of the case Patent Application No. 43917 of 1982 2, Name of the invention Method for purifying ethers 3, Person making the amendment Relationship with the case Jukiho applicant 4-chome, Nihonbashi Honmachi, Chuo-ku, Tokyo No. 1 Nisso Yuka Kogyo Co., Ltd. Representative: Takashi Inatsugu, 24, Agent: No. 1, 2-2 Otemachi, Chiyoda-ku, Tokyo, Nippon Shotatsu Co., Ltd. (7125)・'(15 Scope of Claims of the Specification Subject to Amendment and Detailed Explanation of the Invention 6 Contents of Amendment (1) Percentage of Claims As attached.

(2) Insert "su" between "gu" and "call" on the bottom line of the second page of Ming #l.

(6) Page 4, line 8 [Insert "dimethyl" between call j and "ether."

(4) On page 8, line 16, “hereinafter” was revised to “hereinafter”)
do.

(5) Claim 1 characterized by the phrase "obtained" on page 12, line 4 of the same, ether compounds represented by the following general formula [1] and OH,O((!H2CH2O←cl(3- CI] (where Kn is 0 or a natural number from 1 to 10) The crude product obtained by reacting ethylene oxide is brought into contact with water to hydrolyze coexisting impurities, and then reacted with a methylating agent. A method for purifying ethers.

Claims (1)

[Claims] 1 Ether compounds represented by the following general formula [I] and CH,O-(CH,CH,0+nC1(3-[: I
] (Here, C2n represents 0 or a natural number from 1 to 10.) The crude product obtained by reacting ethylene oxide is fused with water to hydrolyze coexisting impurities, and then reacted with a methylating agent. A method for purifying ethers. 2. Claims in which the methylating agent is one type or 2N or more compound selected from the group consisting of methyl monohalide, σ alkali metal, alkali metal hydroxide, alkali metal oxide, or alkali metal hydride. The purification method according to item 1.