JP2552513B2 - Method for oxidizing (poly) oxyethylene alkyl ether compound - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to the following general formula R—O— (CH ₂ CH ₂ O) _n-1 —CH ₂ COOH (wherein R is an alkyl group having 1 to 30 carbon atoms). Group, an alkenyl group, a cycloalkyl group, an aryl group, and an araryl group, wherein n is an integer of 2 to 100) and is a (poly) oxyethylene alkyl ether acetic acid compound industry. Manufacturing method.

(Poly) oxyethylene alkyl ether acetic acid is used for a surfactant, a modifier for a functional polymer material, a biopolymer material, and the like.

BACKGROUND ART It is already known that (poly) oxyethylene alkyl ether acetic acid can be generally produced by the following method.

A method of chemically oxidizing a (poly) oxyethylene alkyl ether compound with an oxidizing agent such as potassium permanganate, ammonium vanadate, and sodium hypochlorite. A.Fradat
and E. Marechal, Polymer Bulletin, 4 , 205-210,
(1981)) A method of reacting a (poly) oxyethylene alkyl ether compound with a salt or ester of a halogenated acetic acid.
(Id.) A method of oxidizing a (poly) oxyethylene alkyl ether compound with an oxygen-containing gas in an aqueous solution in the presence of a platinum catalyst. (Japanese Patent Application Laid-Open No. 54-79229) Among these methods, the methods and are inevitably mixed with by-products and reaction raw materials, and since the target product is a water-soluble polymer, purification is difficult, In terms of yield and manufacturing cost, industrial implementation is virtually impossible. In the method of, a relatively high-purity target product is obtained in a free acid form,
Although it is a good method, it has a drawback that it is difficult to react due to vigorous bubbling due to the surface activity of the substrate and product. Also,
Since it is a batch-type reaction, it has some drawbacks when considering industrial production. In other words, the time required to complete the reaction is as long as 8 to 12 hours, and when reacting a low molecular weight substrate, the oxygen partial pressure must be higher than the air composition in order to increase the reaction rate, and the reaction concentration Is around 20%, which requires a large reactor because it is thin, and the solubility of oxygen is small, which requires a considerably large amount of power for agitation in order to improve gas-liquid solid contact, and the contact is a fine powder. Therefore, the operation is considerably troublesome when the catalyst is repeatedly used.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present inventors have overcome such drawbacks of conventional methods,
As a result of intensive studies on the oxidation method of (poly) oxyethylene alkyl ether compounds suitable for industrial production, the fixed bed reactor has significantly improved operability and can be continuously operated in a short time in a small reactor. (Poly) oxyethylene alkyl ether acetic acid compound can be produced,
Moreover, they have found that the purity of the product is improved, and have completed the present invention.

Means for Solving the Problems That is, according to the present invention, a fixed bed reactor packed with a granular platinum-palladium carbon catalyst has the following general formula (I) R—O— (CH ₂ CH ₂ O) _n —H ( I) (In the formula, R is one group 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 araryl group, and n is 2 to
The method for oxidizing a (poly) oxyethylene alkyl ether compound is characterized in that a non-alkaline aqueous solution of the (poly) oxyethylene alkyl ether compound represented by the formula (3) is reacted with an oxygen-containing gas.

As a continuous reactor generally used for catalytic reaction,
There are fixed bed type and fluidized bed type. However, as a characteristic of the oxidation reaction of the (poly) oxyethylene alkyl ether compound,
Since unreacted (poly) oxyethylene alkyl ether compound and (poly) oxyethylene alkyl ether acetic acid compound have similar properties, separation and purification are almost impossible. Therefore, unreacted substances and by-products in the reaction solution It is necessary to keep things very small. It is difficult to satisfy this condition by the fluidized bed method, and since the reaction heat is not so much generated in this reaction, the fixed bed method can be said to be suitable as a method for producing a (poly) oxyethylene alkyl ether acetic acid compound. .

The catalyst used in the present invention is a catalyst supported on granular activated carbon containing platinum and palladium as essential components. However, among them, the catalyst prepared by the method described in Japanese Examined Patent Publication No. 60-40453 is highly active and excellent. That is, 5 to 50
A granular activated carbon of about mesh size is immersed in water, an alkali is added thereto to adjust the pH to 8 or more, and then a mixed aqueous solution of a water-soluble salt of platinum and palladium is added dropwise with stirring to adsorb platinum and palladium on the activated carbon. Then, a reducing agent such as formalin, formic acid, and sodium borohydride is added to reduce the platinum and palladium salts to their respective metals, which are then thoroughly washed with water, and then used as they are or after dried to be subjected to this reaction.

Examples of the (poly) oxyethylene alkyl ether compound used in the present invention include ethylene glycol monomethyl ether, diethylene glycol phenyl ether, diethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, polyethylene glycol lauryl ether, and polyethylene glycol nonyl phenyl ether. To be Such a (poly) oxyethylene alkyl ether compound is used for the reaction as an aqueous solution. The concentration varies depending on the molecular weight, but is preferably 10 to 50% by weight. If the concentration is too low, the production efficiency will be poor, and if the concentration is too high, it will be difficult to remove the reaction heat and control the reaction temperature will be difficult.

In the present invention, the term “non-alkaline” literally means a substance that reacts in a pH range other than alkaline. At the beginning of the reaction of the present invention, since the raw material is alcohol, the liquid property is neutral, and the reaction liquid becomes acidic as the reaction proceeds. As described above, the pH of the reaction solution is in the neutral to acidic region unless otherwise specified, and therefore it is not necessary to control the pH by adding acid or alkali at the beginning of the reaction or during the reaction.

The fixed bed reactor used in the present invention is a so-called irrigation packed column reactor which is widely adopted in the petrochemical industry. In other words, both gas-liquid phases flow between the fixed beds filled with relatively small porous particles, and the gas-liquid solid reaction proceeds, and the fluid flow in the device is close to the extrusion flow, and the reaction rate is high. Can be taken. The flow directions of both gas and liquid phases are
Upward cocurrent, downward cocurrent or countercurrent can be taken, but downward cocurrent is most preferred from the problems of flooding and pressure loss. The reactor is basically equipped with a raw material liquid inlet, an oxygen-containing gas inlet, a reaction liquid outlet, and a jacket for heating or cooling. The reaction is carried out under normal pressure or increased pressure. The higher the reaction pressure, the faster the reaction because the amount of dissolved oxygen increases, but it is 4 to 10 as an industrial production method.
It is preferable to carry out at Kg / cm ² . Therefore, the reactor must have a structure that can withstand the pressure. As additional equipment, a liquid metering pump, a gas pressure adjusting valve, a check valve, a pressure gauge, a thermometer, a gas flow meter, etc. are required.

To describe the reaction method of the present invention, an aqueous solution of a (poly) oxyethylene alkyl ether compound having a concentration of 10 to 50% by weight is circulated in a reactor filled with a catalyst by a wet method to cause a reaction. ) When the molecular weight of the oxyethylene alkyl ether compound is 750 or less, W / F is 2 × 10 ³ hr.g ^- cat, where F is the flow rate (molar amount per unit time) and W is the catalyst amount (g). / mol or more, molecular weight 75
When it is 0 or more, it is advisable to supply the raw material aqueous solution at a rate such that the W / F becomes 4 × 10 ³ hr.g ^- cat / mol or more. At the same time, air is supplied while purging at a flow rate of 6 ml / min (normal pressure conversion) or more per 1 g of the catalyst while raising the temperature, and the pressure is maintained at 4 to 10 kg / cm ² . The gas composition at this time is more advantageous for the reaction as the oxygen partial pressure is higher, but in the method of the present invention, the reaction proceeds sufficiently with the air composition. The liquid and gas supply rates are controlled so that the gas-liquid flow maintains the irrigation flow state. The reaction temperature should be maintained at 30 to 90 ° C, preferably 40 to 80 ° C. Usually, 0.5 to 3 hours after reaching the reaction temperature, unreacted substances are no longer detected and a steady state is reached, and the (poly) oxyethylene alkyl ether acetic acid compound can be continuously taken out without filtering the catalyst.

 Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 5.0 g of platinum and 1.5 g of palladium were dissolved in 20 ml of aqua regia,
The remaining acid was evaporated to dryness to obtain chloroplatinic acid and palladium chloride, which were dissolved in 100 ml of a 5% hydrochloric acid aqueous solution. 95 g of commercially available crushed activated carbon (particle size: 20 to 48 mesh) was suspended in 1 liter of a 0.25N sodium carbonate aqueous solution, and the whole amount of the chloroplatinic acid and the palladium chloride aqueous solution was added dropwise to this while stirring for 10 minutes. Thereafter, the mixture was further heated at room temperature for 1 hour at 80 ± 5 ° C. and stirred for 2 hours to completely adsorb chloroplatinic acid and palladium chloride on the crushed carbon. Then, 10 ml of 38% formalin aqueous solution was added and reduced by keeping at 80 ± 5 ° C. for 1 hour, then filtered, washed with water and dried to obtain a platinum-palladium carbon catalyst.

20 of commercial polyethylene glycol monomethyl ether (Aldrich, average molecular weight 750, hydroxyl value 80.1)
Suspend 40g of the above catalyst in 200ml of wt% aqueous solution,
The catalyst was packed in a cylindrical reaction tube having a size of mm and a height of 215 mm.
A pressure gauge, a thermometer, a gas flow meter, a check valve and a pressure adjusting valve are attached, and the above 20% polyethylene glycol monomethyl ether aqueous solution is continuously operated at 5.0 x 10 using a metering pump.
^It was fed at a rate of ^-3 mol / hr. The W / F at this time is 8.0 × 10 ³ h
It was rg ^- cat / mol. Next, supply air from an air cylinder to raise the pressure to 6 kg / cm ^{2 and} then 600 ml / min (converted to normal pressure)
The temperature was raised to 70 ° C. in 1 hour while purging the above air. The samples were sequentially sampled and analyzed by high performance liquid chromatography. One hour after reaching 70 ° C., unreacted substances were no longer detected, and a steady state was reached. After reaching the steady state, 500 g of the reaction solution was collected and concentrated and dried to obtain 100 g of a colorless transparent liquid. This product had a neutralization value of 79.0 and a hydroxyl value of 0, and was found by analysis by high performance liquid chromatography to be polyethylene glycol monomethyl ether acetic acid having a purity of 100%.

Example 2 40 g of the catalyst obtained in Example 1 was mixed with commercially available polyethylene glycol monomethyl ether (produced by Aldrich Co., average molecular weight).
2000, a hydroxyl value of 29.1) was suspended in a 20% by weight aqueous solution and the reaction tube was filled in the same manner as in Example 1. The same aqueous solution was continuously supplied at a rate of 8.0 × 10 ⁻⁴ mol / hr using a metering pump. The W / F at this time was 5.0 × 10 ⁴ hr.g ^- cat / mol. When the reaction was carried out in the same manner as in Example 1, unreacted substances were not detected within 2 hours after reaching 55 ° C., and a steady state was reached. Thereafter, 500 g of the reaction solution was collected and concentrated and dried to obtain 100 g of a white solid. This product has a neutralization value of 29.9 and a hydroxyl value of 0, and has a purity of 10 by analysis by high performance liquid chromatography.
It was found to be 0% polyethylene glycol monomethyl ether acetic acid.

EFFECTS OF THE INVENTION According to the present invention, a foamable (poly) oxyethylene alkyl ether acetic acid compound can be produced more easily, less degradation occurs, and a high quality and low cost (poly) oxyethylene alkyl ether acetic acid compound can be obtained. .

Claims (2)

(57) [Claims] 1. A fixed-bed reactor filled with a granular platinum-palladium carbon catalyst is represented by the following general formula (I) R—O— (CH ₂ CH ₂ O) _n —H (I) (wherein R is It is a group 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 araryl group, and n is 2 to
A non-alkaline aqueous solution of a (poly) oxyethylene alkyl ether compound represented by the formula 100) and an oxygen-containing gas are circulated, and the reaction is carried out at a reaction temperature of 30 to 90 ° C. and a reaction pressure of 4 to 10 kg / cm ^2. And a method for oxidizing a (poly) oxyethylene alkyl ether compound. 2. A platinum-palladium-carbon catalyst is prepared by adsorbing a water-soluble salt of platinum and palladium on granular activated carbon in an aqueous solution having a pH of 8 or more and then reducing it with a reducing agent selected from formalin, formic acid or sodium borohydride. The method according to claim 1, which is a platinum-palladium carbon catalyst obtained by the above.