JPS6041656B2 - Method for oxidizing (poly)oxyethylene ether compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for oxidizing the terminal hydroxyl group of a (poly)oxyethylene ether compound using molecular oxygen in the presence of an improved platinum carbon catalyst in a non-alkaline aqueous solution.

Compounds in which the terminal hydroxyl group of a (poly)oxyethylene ether compound is substituted with a carboxylic acid, such as polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl phenyl ether acetic acid, and their salts are used as surfactants, antistatic agents, and dyes. It is used in many fields as an auxiliary agent.

(Poly) From oxyethylene ether compound (Poly)
Oxyethylene alkyl ether acetic acid can be obtained by reacting the terminal hydroxyl group of (poly)oxyethylene alkyl ether with monochloroacetic acid in the presence of an alkali;
and a method in which a (poly)oxyethylene ether compound is oxidized with oxygen using a platinum catalyst, and the resulting acid is constantly reacted at pH 7 or higher while neutralizing it with an alkali (U.S. Patent No. 3)
, 342, 858), etc. are known.

In all of these methods, the product obtained is a salt type, and obtaining the product directly as a free acid requires a purification process such as desalting, which is complicated. The present inventors (poly)
The present invention was completed through extensive research into a method for economically oxidizing (poly)oxyethylene ether compounds with molecular oxygen without cutting the ether bonds of the oxyethylene ether compounds.

That is, the present invention provides the method for treating a (poly)oxyethylene ether compound in a non-alkaline aqueous solution using molecular oxygen in the presence of an improved platinum carbon catalyst that is highly active even under acidic to neutral reaction conditions. This article relates to a method for oxidizing poly)oxyethylene ether compounds.

Prior to filing the present invention, the present inventors filed a patent application for a method for oxidizing a non-alkaline aqueous solution of a (poly)oxyethylene ether compound using a platinum carbon catalyst (Japanese Patent Application No. 52-11).
However, the present invention relates to a method of using a catalyst which has been improved to have enhanced activity and durability of the activity.

In one embodiment of the present invention, an aqueous solution of (poly)oxyethylene alkyl ether and platinum carbon as described below are placed in a reaction vessel equipped with a pressure accumulator, a pressure regulator, a reaction gas inlet, a thermometer, a pressure gauge, and a stirrer. A catalyst is added and oxygen or an oxygen-containing gas is blown into the solution through the reaction gas inlet, and the oxidation reaction is carried out with stirring while maintaining the solution at a temperature of 60 to 150'C under normal or increased pressure. As the reaction progresses, oxygen consumption is observed, and the progress of the reaction is confirmed from the amount of oxygen consumed.
Catalyst after reaction? Otherwise, an aqueous solution of (poly)oxyethylene alkyl ether acetic acid is obtained directly as the free acid. For many industrial applications, the catalyst must be used in its distilled form or concentrated. I can do it. The (poly)oxyethylene ether compound which is the starting material for the method of the present invention has the general formula (wherein R is alkyl having 1 to 30 carbon atoms or .
is an alknyl group, a cycloalkyl group, an aryl group or an alkylaryl group, where n is an integer of 1 to 30).

These include those widely used as ordinary solvents such as ethylene glycol monomethyl ether, ethylene glycol monophenyl ether, diethylene glycol monobutyl ether, and surfactants such as polyethylene glycol lauryl ether and polyethylene glycol nonylphenol ether. There are substances that are widely used as agents. When supporting a platinum compound on activated carbon, the catalyst used in the present invention contains at least one selected from the group consisting of alkali metal hydroxides, carbonates, bicarbonates, and alkaline earth metal hydroxides. Adjust the pH of the suspension in water to 8 or higher, drop an aqueous solution of platinum salt such as chloroplatinic acid into the water, and if the PH drops to 8 or lower during the process, add alkali as needed and mix the platinum with activated carbon. completely absorb. Next, the platinum compound adsorbed on the activated carbon is reduced by adding a reducing agent such as formalin, formic acid, or sodium borohydride, and then thoroughly washed with water and subjected to an oxidation reaction as it is or after drying. The amount of platinum supported in the platinum-carbon catalyst used in the present invention is 1 to 1 weight percent, preferably 2 to 6 weight percent, as platinum metal based on the activated carbon.

The catalyst carrier used in the method of the present invention is preferably activated carbon, and carriers such as alumina, silica, and silica-alumina are unsuitable for the method of the present invention because they promote the cleavage of ether bonds or have a slow reaction rate.

When preparing the catalyst used in the method of the present invention, the alkali used in the alkaline suspension of activated carbon with a pH of 8 or higher is an alkali such as an alkali metal hydroxide such as sodium, potassium, or lithium, carbonate, bicarbonate, or barium hydroxide. Ammonia is an unsuitable hydroxide of earth metals.

The amount of alkali used is such that the pH of the suspension is 8 or higher even after chloroplatinic acid is completely adsorbed on activated carbon. The starting material is preferably subjected to the reaction as an aqueous solution, and the concentration in the aqueous solution may be any concentration as long as it is below the saturation solubility at the reaction temperature, but is usually preferably 10 to 5 percent by weight.

Note that a starting material having a long alkyl group and a small number of moles of ethylene oxide added and hardly soluble in water can be dissolved in a mixed solvent of acetone, dioxane, etc. and water and subjected to the reaction, if necessary. The amount of the platinum-carbon catalyst used in the present invention can be determined in consideration of the desired reaction rate, economic efficiency, etc., but it is generally appropriate to range from 5 to 1 percent by volume based on the raw materials.

The oxidizing agent used in the method of the present invention is oxygen or an oxygen-containing gas, and its pressure is normal pressure to increased pressure.When oxygen alone is used, the reaction is sufficient at normal pressure, but when air is used, there is no particular upper limit. However, it is preferable to carry out the reaction under a pressure of 5 to 20k91d. In the method of the present invention, the reaction temperature affects the reaction rate and is 50 to 200°C, preferably 60 to 150°C. In the method of the present invention, a non-alkaline aqueous solution is one in which an acid or alkali is not added at the beginning of the reaction, and the reaction proceeds without adding an alkali during the reaction.

Therefore, the reaction system of this reaction, which was neutral before the start of the reaction, becomes a fermenting atmosphere due to the generated acid. The present inventors (1) catalyst used in the method of the present invention (2) activated carbon was suspended in water, and an aqueous solution of chloroplatinic acid was added thereto to adsorb the chloroplatinic acid onto the activated carbon under neutral or acidic conditions. After that, a catalyst for alcohol oxidation is reduced with formalin and sodium carbonate (explained in Comparative Example 1). After adsorbing chloroplatinic acid onto activated carbon, a catalyst (
Platinum (1
11) Determine the average particle diameter determined from the half width of the surface, and the reaction time and conversion rate when polyoxyalkyl ether is oxidized using these catalysts according to Example 1 described later, and calculate the reaction rate with the catalyst. We considered the differences.

The results will be explained in detail in Examples and Comparative Examples, but all of the catalysts used in the present invention have an average platinum particle size of amorphous or less than 50A, and show a conversion rate of 90% or more at a reaction time of about 4 to 5 hours. On the other hand, the catalysts (2) and (3) had slow reaction rates depending on the average platinum particles, reaction time, and conversion rate, and the reaction virtually stopped at a conversion rate of about 60 to 70%.

Furthermore, the catalyst obtained by the method of the present invention has a particularly remarkable effect when it contains a large number of ethylene glycol units.

For example, commercially available polyoxyethylene dodecyl ether with an average of 5 ethylene glycol units has about 1 to 8
When polyoxyethylene alkyl ether is oxidized using the catalyst according to the method of the present invention, ethylene glycol units are distributed up to
Furthermore, it is surprisingly possible to oxidize the terminal hydroxyl group to obtain polyoxyethylene alkyl ether acetic acid in high yield regardless of the number of ethylene glycol units. However, when polyoxyethylene alkyl ether is oxidized using the catalysts (2) and (3), ethylene glycol, diethylene glycol, and
Triethylene glycol and the like are produced as by-products, and as the number of ethylene glycol units increases from 4 to 8, the terminal hydroxyl group tends to be either not oxidized at all or becomes extremely difficult to oxidize. Furthermore, even if polyoxyethylene alkyl ether is oxidized at a reaction temperature of 130°C or higher to increase the conversion rate using such a low-activity catalyst, the reaction will stop midway and the conversion rate will increase to 70% or higher. This was difficult, and the result was that the cleavage of the ether bond was promoted. Therefore, in order to obtain a highly active catalyst with a high conversion rate and excellent selectivity without breaking the ether bond during the oxidation of polyoxyethylene ether compounds, it is necessary to use activated carbon at a pH of 8.
It is necessary to adsorb the chloroplatinic acid onto activated carbon after suspending it in the above aqueous alkaline solution.

Furthermore, when polyoxyethylene ether is oxidized by the method of the present invention, the life of the catalyst is very long, as is clear from the examples described later, and even though an expensive platinum catalyst is used, the cost of the catalyst in the product is reduced. can be reduced.

Follow. Therefore, the method of the present invention is easy to implement industrially and is highly economical. Examples will be described in detail below.

Example 1 Chloroplatinic acid obtained by dissolving 5.0 y of platinum in aqua regia and evaporating the remaining acid to dryness was dissolved in 100 ml of a 5% aqueous hydrochloric acid solution.

Commercially available activated carbon (manufactured by Takeda Pharmaceutical Co., Ltd.) 95y was suspended in 1' of a 114 N sodium carbonate aqueous solution (the P of this suspension was
H is about 11), into which the entire amount of chloroplatinic acid was added dropwise over 10 minutes with stirring, and then at room temperature for 1 hour,
The mixture was heated to ±5°C and stirred for 2 hours to completely adsorb chloroplatinic acid onto the activated carbon. (The pH of the suspension at this time is approximately 1
0) Next, 10 mt of Aoi% formalin aqueous solution was added and kept at 80±5°C for 1 hour to reduce, and after washing with water, it was dried to 5%
A platinum carbon catalyst was obtained. The (111) plane of platinum determined from X-ray diffraction of this catalyst was amorphous. This catalyst 1
Equipped with a pressure accumulator, a gas inlet and outlet, a thermometer, and a pressure gauge. The mixture was added to a 1.5e autoclave with electromagnetic induction stirring.

Nitrogen gas was added into this autoclave through a pressure accumulator and a pressure regulator to give a pressure of 2 kg/C7lf, and then oxygen was added to bring the total pressure to a constant pressure of 7.0 k91 cIL while stirring.
The reaction was maintained at 00±5°C. As the reaction progresses, oxygen absorption is observed, and 3. Approximately 9 minutes after Chima
The rate of oxygen uptake slowed down, consuming 8% of the theoretical amount of oxygen. After a reaction time of 4 hours, the reaction was completed, and after cooling the autoclave, the reaction product was taken out and the catalyst was removed to obtain a milky white aqueous solution. The entire amount was concentrated and dried to obtain a slightly yellow liquid 98y. As a result of collecting and analyzing a portion of this material, an acid value and a hydroxyl value of 10.0 were obtained. In addition, as a result of gas chromatography analysis of a part of this product, a methyl ester derivative obtained with diazomethane and a trimethylsilyl derivative obtained with a trimethylsilylation agent, glycolic acid and diglycolic acid, which are decomposition products, were not detected, but ethylene glycol, Diethylene glycol was present in trace amounts, and polyoxyethylene dodecyl ether acetic acid having the same composition as the corresponding raw material and having ethylene glycol units distributed from 1 to 8 was observed. The conversion rate of the raw material (hydroxyl value 131) to polyoxyethylene dodecyl ether acetic acid was approximately 92%, indicating that the terminal hydroxyl group was converted to carboxylic acid without breaking the ether bond of polyoxyethylene dodecyl ether. Admitted. Example 2 An aqueous solution 407711 containing 10.0f of the 5% platinum carbon catalyst obtained in Example 1 and 100y of commercially available polyoxyethylene (24 mol) dodecyl (trade name Emalex 724, manufactured by Nippon Emulsion Co., Ltd.) was added to Example 1. When an oxidation reaction was carried out in the same manner, about 90% of the theoretical amount of oxygen was absorbed in a reaction time of 4 hours, and the oxygen absorption rate became slow.

The reaction was completed after a reaction time of 5 hours, and the reaction product was taken out.
The milky white aqueous solution obtained by separating the catalyst was concentrated and dried to obtain a 100y white solid. The chemical analysis value of this substance is acid value 48. The hehydroxyl number was 10.0. The conversion rate of the raw material (hydroxyl number 57.1) to polyoxyethylene dodecyl ether acetic acid was about 82%. Example 3 10.0y of the 5% platinum carbon catalyst obtained in Example 1 and polyoxyethylene (7.5 mol) alkyl phenyl ether (
400 ml of an aqueous solution containing 100y (trade name: NIKKOLNP-7.5, manufactured by Nikko Chemicals Co., Ltd.) was subjected to an oxidation reaction according to Example 1, and the reaction was completed in 4 hours.

The reaction product was taken out and the catalyst was removed, and the resulting milky white aqueous solution was concentrated to obtain 100q of pale yellow liquid. The chemical analysis value of this product is acid value 103.0 and hydroxyl value 8.
0, and the conversion rate of the raw material (hydroxyl number 108.1) to polyoxyalkylphenyl ether acetic acid was about 93%. Example 4 Example 1 except that the 114N aqueous sodium hydroxide solution 114N barium hydroxide aqueous solution and 10ml of 38% formalin used in obtaining the 5% platinum carbon catalyst in Example 1 were replaced with 10ml of a 30% sodium borohydride aqueous solution. A platinum carbon catalyst was obtained according to .

The average particle diameter of platinum determined by X-ray diffraction of this catalyst was 40
It was A. Using 10.0 y of this catalyst, 40 y of an aqueous solution containing 100 y of diethylene glycol monoethyl ether was prepared.
When 0ml was oxidized according to Example 1, the reaction was completed in 6 hours.

After the reaction was completed, the catalyst was filtered off, and the resulting colorless and transparent reaction liquid was concentrated to obtain 108q of colorless and transparent liquid. The chemical analysis value of this substance is acid value 348. The hydroxyl value was 37.6. As a result of gas chromatography analysis of a methyl ester derivative obtained from a portion of this product using diazomethane and a trimethylsilyl derivative obtained using a trimethylsilylation agent, trace amounts of glycolic acid were detected, as well as acetic acid and acetic acid, which are thought to be decomposition products. Ethoxy acetic acid, ethylene glycol, diethylene glycol, etc. were not detected, and since it was only a small amount of raw material and oxyethylene ethyl ether acetic acid, almost no decomposition reaction was observed. The conversion rate of the raw material (hydroxyl number 418) to oxyethylene ethyl ether acetic acid was 91.0%, and the yield of oxyethylene ethyl ether acetic acid was 89.8%. Example 5 The catalyst obtained by separating the reaction product from the reaction product after the completion of the reaction in Example 1 was used as it was in the second reaction according to Example 1.

Further, from the third time onwards, the reaction was repeated 50 times and the durability test of the catalyst was conducted, and the results shown in Table 1 were obtained. These results show that the method of the present invention allows the catalyst to be used repeatedly 50 times or more, the reaction time does not increase even after the 50th use, the catalyst has excellent durability, and polyoxyethylene alkyl ether can be oxidized without breaking the ether bond. It was recognized that this method is possible and highly economical. Comparative example 1 NewerMeth0ds0fPreparative
0rganicChemistryV0I, ■ No. 327
Catalyst preparation method according to page.

95q of activated carbon was suspended in 600 ml of an aqueous solution of chloroplatinic acid containing 5y of platinum metal.

This suspension was neutralized with a 114N aqueous sodium carbonate solution while stirring, then heated and kept at 80±5°C. 55mL of a 38% formalin aqueous solution was occasionally added with a 114N aqueous sodium carbonate solution to keep the pH at 7 to 8. While doing so, it was dripped over 4 times. Further, this suspension was kept at 80±5° C. for 2 hours, then cooled and the catalyst was separated. The catalyst was thoroughly washed with water and dried to obtain a 5% platinum carbon catalyst. The average particle diameter of platinum in this catalyst was determined by X-ray diffraction to be 84A. Using 10.0 Da of this catalyst, polyoxyethylene (5 mol) dodecyl ether was oxidized according to Example 1.

After a reaction time of 6 hours, the amount of oxygen absorbed was approximately 70% of the theoretical amount and the reaction was completely stopped. The milky platinum reaction solution obtained by removing the catalyst from the reaction solution was concentrated to obtain a pale yellow liquid 99y. The chemical analysis values of this substance are acid value 90.1 and hydroxyl value 4.
1.9, the conversion rate of the raw material to polyoxyethylene dodecyl acetic acid was about tin%. As a result of gas chromatography analysis of a methyl ester derivative obtained from a portion of this product using diazomethane and a trimethylsilyl derivative obtained using a trimethylsilylation agent, it was found that as the ethylene glycol unit of polyoxyethylene dodecyl ether increases, polyoxyethylene dodecyl ether acetic acid is formed. The ratio was low, and conversely, the remaining ratio of unreacted raw materials was high. In addition, decomposition products such as ethylene glycol and diethylene glycol were also produced as by-products. Therefore, it was found that this catalyst easily cleaves ether bonds and is difficult to oxidize the terminal hydroxyl group of polyoxyethylene alkyl ether having a relatively large ethylene glycol unit. Comparative Example 2 A catalyst was prepared according to Catalyst Handbook, page 557, Jijinshokan (published in 1967).

Activated carbon 95y was suspended in a 10% nitric acid aqueous solution 1' and boiled for 2 hours, then the activated carbon was separated and thoroughly washed with water until no nitrate radicals were detected. This nitric acid-treated activated carbon was suspended in 1e of water, and 25ml of a chloroplatinic acid aqueous solution containing 5f1 as platinum metal was added and stirred at 50±5°C for 4 hours to completely adsorb chloroplatinic acid onto the activated carbon. . Then, the suspension was left to cool, and 100 mt of 114N sodium carbonate solution was added to make it alkaline. After adding 30 ml of 50% hydrazine hydrate, the suspension was heated to 80±5°C to complete the reduction.
The catalyst was separated, thoroughly washed with hot water, and dried to obtain a 5% platinum carbon catalyst. The average particle diameter of platinum in this catalyst was determined to be 75A by X-ray diffraction. Polyoxy (5 mol) dodecyl ether (Emarex 705) was oxidized in the same manner as in Example 1 using 10.0 q of this catalyst.

When the amount of oxygen absorbed reached about 64% of the theoretical amount after a reaction time of 7 hours, the absorption of oxygen completely stopped. The catalyst was filtered out from the reaction solution to obtain a milky white reaction solution, and the entire amount was concentrated to obtain pale yellow liquid 99y. The chemical analysis values of this product were that the acid value was 81.3 and the hydroxyl value was 48.2, and the conversion rate to the raw material polyoxyethylene alkyl ether acetic acid was about 1%. Comparative Example 3 Polyoxyethylene (5 mol) dodecyl ether was prepared in the same manner as in Example 1 except that 10.0 q of the catalyst obtained in Comparative Example 1 was used and the reaction temperature in Example 1 was changed from 100±5°C to 130±5°C. was oxidized.

Claims (1)

[Claims] 1. In the presence of a platinum carbon catalyst, molecular oxygen is used to convert the general formula R-O-(CH_2CH_2O) into a non-alkaline aqueous solution.
) nH in the formula, R is selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, and an alkylaryl group, and n is an integer of 1 to 30) (poly) When oxidizing the terminal hydroxyethyl group of an oxyethylene ether compound to form the corresponding carboxylic acid, alkali metal hydroxides, carbonates,
Using a platinum carbon catalyst obtained by adsorbing a platinum salt on activated carbon suspended in an aqueous solution with a pH of 8 or more containing at least one selected from the group consisting of bicarbonates and hydroxides of alkaline earth metals, and then reducing the resultant mixture. A method for oxidizing a (poly)oxyethylene ether compound, the method comprising: reacting a (poly)oxyethylene ether compound. 2. The method according to claim 1, wherein the alkali metal used in preparing the platinum-carbon catalyst is at least one selected from the group consisting of sodium, potassium, and lithium. 3. The method according to claim 1, wherein the alkaline earth metal in preparing the platinum carbon catalyst is barium. 4. Claim 1, wherein the reducing agent is at least one selected from the group consisting of formalin, formic acid, and sodium borohydride in the preparation of the platinum carbon catalyst.
The method described in section.