JPH06115904A - Production of potassium periodate - Google Patents

Abstract

PURPOSE:To enable easy control of the pH in the oxidation with chlorine within a narrower range and produce potassium periodate in a yield of as high as >=97% even under mild condition of e.g. <=100 deg.C CONSTITUTION:Potassium periodate is produced by oxidizing potassium iodate with chlorine. The oxidation with chlorine is carried out by incorporating an aqueous solution of potassium iodate with 0.2-2 times mol of one or more compounds selected from potassium bicarbonate, potassium carbonate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate and oxidizing with chlorine at >=50C and pH7-10 while adding 1-6 times equivalent of potassium hydroxide or potassium carbonate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing potassium periodate under mild conditions. Periodic acids such as potassium periodate are useful compounds used for selective oxidation represented by oxidative cleavage of α-glycol and the like.

[0002]

As a method for producing potassium periodate, Inorganic Synthesis, Vol.1, P.171, potassium iodate is suspended or dissolved in a strongly basic aqueous solution containing predetermined potassium hydroxide. Then, a method for obtaining potassium periodate by rapidly injecting chlorine under boiling conditions is described.

[0003]

However, in the method according to the above, a strong basic aqueous solution containing potassium hydroxide is used, and iodic acid is obtained by rapidly injecting chlorine under the condition of exceeding 100 ° C. Since it is an oxidation reaction of an alkali metal salt, there is a problem of corrosion to a reactor, etc., and ordinary general-purpose materials cannot be used. For this reason, there is a problem that an expensive material such as tantalum must be used. The present invention oxidizes potassium iodate with chlorine to produce potassium periodate, which is reacted under milder conditions, such as a reactor made of a general-purpose material such as glass lining. It is an object of the present invention to provide a method which can be used and can obtain potassium periodate in a high yield.

[0004]

In general, when a general-purpose material such as glass lining is used and a strong base such as potassium hydroxide is added to potassium iodate to oxidize with chlorine, In order to prevent the corrosion of the reactor, etc., it is necessary to carry out the reaction under a more neutral condition, and it is necessary to continuously add the base in accordance with the charging of chlorine. However, in this case, the pH value of the solution may vary even with extreme caution or added in small increments.
It is impossible to operate within a narrow pH range. The present inventors, as a result of intensive studies to solve the above problems, when oxidizing potassium iodate with chlorine, previously added a base such as potassium hydrogen carbonate, then potassium hydroxide or potassium carbonate By adding chlorine while continuously adding, it was found that the fluctuation of pH is drastically reduced and easy to adjust, and that potassium periodate can be obtained without lowering the yield under mild conditions, The present invention has been completed.

That is, the present invention relates to a method for producing potassium periodate by oxidizing potassium iodate with chlorine, which comprises previously adding potassium hydrogen carbonate, potassium carbonate, potassium dihydrogen phosphate to an aqueous potassium iodate solution. , One or more of dipotassium hydrogen phosphate was added, and then 50 ℃
The above is a method for producing potassium periodate, which comprises oxidizing with chlorine at pH 7 to 10 while adding potassium hydroxide or potassium carbonate.

First, as a method for producing potassium iodate as a raw material, it can be obtained by oxidizing iodine with potassium chlorate in an aqueous solution. Examples of this method include Laboratory Methods of Inorganic Chemi
Stry, 2nd ed., p.120 (1928), but of course, commercially available purified potassium iodate can also be used.

The present invention will be described in detail below. The concentration of potassium iodate in the present invention is not particularly limited, but from the viewpoint of operability, it is preferably 5 to 50% by weight aqueous solution. If the pH of this aqueous solution is less than 7, add potassium hydrogen carbonate, potassium carbonate, or potassium hydroxide,
The pH of the potassium iodate aqueous solution is adjusted to the range of 7-10. The pH adjustment may be performed before the temperature is raised and the oxidation reaction by chlorine is started.

Next, potassium hydrogen carbonate, potassium carbonate, potassium dihydrogen phosphate, or dipotassium hydrogen phosphate is added to the above aqueous solution. These may be added alone or in combination of two or more, and the addition amount is preferably 0.2 to 2 mol per 1 mol of potassium iodate. If the amount added is less than 0.2 mol, the effect of facilitating pH adjustment is small. Further, even if it is used in excess of 2 mol, it is economically meaningless.

In the present invention, one or more bases of potassium hydrogen carbonate, potassium carbonate, potassium dihydrogen phosphate, or dipotassium hydrogen phosphate are added, and then oxidized with chlorine at a predetermined temperature. I do. Reaction temperature is 50 ℃ ~ 1
The temperature is 00 ° C, preferably 70 ° C to 95 ° C. This reaction temperature is 50
If the temperature is lower than 0 ° C, the reaction rate becomes small and the yield remarkably decreases, which is not preferable. Further, since this reaction is carried out in an aqueous solution, it is preferable to carry out the reaction at a temperature up to the boiling point of the aqueous solution, but it is possible to carry out the reaction even at a temperature of the boiling point or higher under pressure conditions.

Further, in the present invention, the pH during the oxidation with chlorine is within the range of 7-10. This pH is 7
If it is less than 10, the yield of potassium periodate obtained is remarkably reduced, and if it exceeds 10, there is a problem of corrosion when using a glass-lined reactor or the like, which is not preferable. In the present invention, it is possible to oxidize with chlorine within a narrow range in which the fluctuation of pH is very small. In the present invention, the amount of the base of potassium hydroxide or potassium carbonate to be added is 1 with respect to 1 mol of potassium iodate.
~ 6 equivalents are preferred. If the amount is less than 1 equivalent, the conversion rate of sodium iodate to potassium periodate decreases, which is not preferable. Further, the use of more than 6 equivalents does not improve the yield and is uneconomical.

The form of potassium hydroxide or potassium carbonate to be added is preferably an aqueous solution having a concentration of 10% by weight or more. Productivity decreases with an aqueous solution of less than 10% by weight. Moreover, if the operation is possible, it may be added in a solid state. As a preferable addition method in the present invention, it is preferable to quantitatively add an aqueous solution of potassium hydroxide or potassium carbonate. For example, it is a preferable method to use a metering pump to deliver a fixed amount.

In the present invention, chlorine is added at the same time while adding the above-mentioned potassium hydroxide or potassium carbonate while adjusting the pH to 7-10. Further, the time when the charging of chlorine is completed is the time when the addition of potassium hydroxide or potassium carbonate is completed. After the reaction is completed as described above, potassium periodate can be obtained by filtering the precipitated crystals. If an excess of base is present, it is possible to further obtain potassium periodate in good yield by performing a filtration operation after neutralizing with an acid.

[0013]

The present invention will be described in detail below with reference to examples. In the following, "%" is on a molar basis, unless otherwise specified. In addition, the determination of potassium periodate is performed according to JIS K8.
249.

Example 1 Using a 300 cc round bottom flask, potassium iodate was added.
30.0 g (0.14 mol) was suspended in 254 g of pure water. To this, 14.0 g (0.14 mol) of potassium hydrogen carbonate was added, and the temperature was raised to 90 ° C. At the same temperature, 35 wt% potassium hydroxide aqueous solution 7
Using a dropping funnel, 8.6 g (0.49 mol) was added over 1 hour, and at the same time, chlorine was charged into the liquid through an introduction tube while controlling the flow rate of chlorine from a cylinder so that the pH was 8.0 ± 0.2. At the same time as the addition of the potassium hydroxide aqueous solution was completed, the charging of chlorine was stopped and the temperature was cooled to 30 ° C. The amount of chlorine used is 2
It was 2.6 g (0.32 mol). The precipitated crystals were separated by filtration, further washed with water and dried,
31.8 g of crystals were obtained. The obtained potassium periodate had a crystal purity of 99.5% and a yield of 98.3%.

Example 2 In Example 1, the addition amount of 35 wt% potassium hydroxide was changed to
56.1 g (0.35 mol) was added, and the same operation was performed except that this was added over 1 hour. Even in this case, the pH is
It could be adjusted within the range of 8.0 ± 0.2, and the amount of chlorine used was 16.5 g (0.23 mol). The dry crystals obtained are 3
1.4g, the crystal purity of potassium periodate is 99.4%
Met. The yield was 97.0%.

Example 3 In Example 1, 9.7 g (0.07 mol) of potassium carbonate was added instead of potassium hydrogen carbonate, and the pH was 10.0 ± 0.2.
The same operation was performed except that chlorine was charged so that
The amount of chlorine used was 22.8 g (0.32 mol). The obtained dry crystals weighed 31.9 g, and the crystal purity of potassium periodate was 99.6%. The yield was 98.7%.

Example 4 In Example 1, 19.0 g (0.14 mol) of potassium dihydrogen phosphate was added instead of potassium hydrogen carbonate, and the pH was adjusted to
The procedure was exactly the same, except that chlorine was charged so that the concentration was 8.0 ± 0.2. The amount of chlorine used was 22.7 g (0.32 mol). The obtained dried crystals weighed 31.8 g, and the crystal purity of potassium periodate was 99.4%. The yield is 98.2.
%Met.

Comparative Example 1 The same operation as in Example 1 was carried out except that the reaction temperature was 40 ° C. In this case, the amount of chlorine used was 23.0 g (0.32 mol). The obtained dry crystals weighed 15.2 g, and the crystal purity of potassium periodate was 98.6%. The yield was 46.5%.

Comparative Example 2 The same operation as in Example 3 was carried out except that chlorine was charged so that the pH was 6.0 ± 0.2. In this case, the amount of chlorine used was 22.2 g (0.31 mol). The obtained dry crystals weigh 11.2 g, and the crystal purity of potassium periodate is 9
It was 9.0%. The yield was 34.4%.

Comparative Example 3 The same operation as in Example 3 was carried out except that chlorine was charged so that the pH became 13.0 ± 0.2. In this case, the amount of chlorine used was 23.2 g (0.33 mol). The obtained dry crystals weigh 30.6 g, and the crystal purity of potassium periodate is 9
It was 9.3%. The yield was 94.4%.

Comparative Example 4 The same operation as in Example 1 was carried out except that potassium hydrogen carbonate was not added. I tried to set the pH in the range of 8.0 ± 0.2, but in reality, it fluctuated in the range of 6 to 13,
It was impossible to adjust within a narrow range. In this case, the amount of chlorine used was 23.5 g (0.33 mol). Also, the obtained dry crystals were 29.0 g, and the crystal purity of potassium periodate was 9
It was 9.2% and the yield was 89.3%.

Using the reaction solutions of Examples 1 to 4 and Comparative Example 3 above, a material test for the glass lining was conducted. As the test method, the glass lining test pieces were immersed in a reaction solution under the same conditions as each reaction condition, and after 1000 hours, their corrosion conditions were observed with a microscope or visually. The results are shown in Table 1.

[0023]

[Table 1] ○ --- No evidence of corrosion by visual or microscopic observation. Δ --- Evidence of corrosion is observed by microscopic observation. X ---- Evidence of visible evidence of corrosion is observed.

[0024]

EFFECTS OF THE INVENTION According to the present invention, the pH can be easily adjusted within a narrower range, and even under mild conditions such as 100 ° C. or lower, potassium periodate can be adjusted to 97%.
It is possible to manufacture in a high yield of not less than%. Further, a glass-lined reactor or the like, which cannot be used in the conventional technique, can be used in the present invention, and a versatile material can be used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Omura 1900 Togo, Mobara-shi, Chiba Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Yoshinori Tanaka 1900 Togo, Mobara-shi, Chiba Mitsui Toatsu Chem.

Claims (1)

[Claims] 1. A method of oxidizing potassium iodate with chlorine,
In the method for producing potassium periodate, one or more of potassium hydrogen carbonate, potassium carbonate, potassium dihydrogen phosphate and dipotassium hydrogen phosphate are added to an aqueous potassium iodate solution in advance, and then 50 ° C. The method for producing potassium periodate as described above, which comprises oxidizing with chlorine at pH 7 to 10 while adding potassium hydroxide or potassium carbonate.