JPH04202003A - Production of sodium metaperiodate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] Sodium metaperiodate is a useful compound used in the production of aldehyde starch and the like.

The present invention relates to a method for producing sodium metaperiodate.

[Conventional technology]

InorganicSynthesi is a method for producing sodium metaperiodate, in which sodium paraperiodate is placed in water, treated with nitric acid, and then concentrated to precipitate crystals of sodium metaperiodate.
s Co11ectiveνo1.1. p, 168~
171.

(19).

Moreover, a method for obtaining sodium metaperiodate by neutralizing periodic acid obtained by electrolytic oxidation of an aqueous iodic acid solution with an alkali such as sodium hydroxide or sodium carbonate is described in East German Patent No. 79005.

[Problem that the invention seeks to solve]

In the production of sodium and lithium metaperiodate by the two methods described above, it is necessary to precipitate sodium metaperiodate as crystals from an aqueous solution of sodium metaperiodate.

In this case, if the cooling temperature is too low, the crystalline form of sodium metaperiodate will transform from the anhydrous salt to the trihydrate salt.

Therefore, in order to obtain the anhydride, the cooling temperature cannot be lowered too much, and sodium metaperiodate is lost by the amount of water solubility at that temperature.

In order to recover sodium metaperiodate in this mother liquor, a method can be considered in which the mother liquor is reused as a reaction solution for neutralization or the like. In this case, inorganic salts such as sodium nitrate accumulate in the aqueous solution, which is undesirable because it causes a decrease in the purity of the sodium metaperiodate crystals.

The present invention allows
The purpose of the present invention is to provide a process for producing high-yield, high-purity sodium metaperiodate.

[Means for solving problems]

As a result of extensive studies, the present inventors discovered that by adding an alkali to an aqueous solution of sodium metaperiodate, the periodic acid content could be recovered as sodium periodate in high yield, and the present invention was completed. I ended up doing it.

That is, in a method for producing sodium metaperiodate by treating sodium paraperiodate with an acid in an aqueous solution, periodate is extracted from the mother liquor as bulk sodium periodate after separating the crystals of sodium metaperiodate. This is a method for producing sodium metaperiodate, which is characterized by recovering the acid content.

The present invention will be explained in detail below.

First, sodium para-periodate as a raw material is suspended in water and treated with an acid to obtain an aqueous solution or suspension of sodium meta-periodate.

In order to easily obtain high purity sodium metaperiodate, the operating conditions for this step were
hesis Colective Vol, I,
p, 168-171°.The conditions described in (19) were improved as described below.

The raw material, sodium paraperiodate, is prepared under alkaline conditions.
It can be produced by the method described in the above-mentioned document, in which sodium iodate is oxidized with chlorine.

Sodium paraperiodate obtained in this way is the trisodium salt.

In the present invention, sodium paraperiodate used as a raw material may be a trisodium salt, a disodium salt, or a mixture thereof.

As disodium para-periodate, one recovered from the mother liquor treatment step described later can be used.

The concentration of sodium para-periodate is as follows: the concentration of sodium meta-periodate aqueous solution or suspension after adding water and acid is 10
Adjust the amount to 50% by weight.

Sodium metaperiodate aqueous solution or suspension concentration is 10
If it is less than 50% by weight, the production efficiency will be poor, and if it exceeds 50% by weight, the purity of the sodium metaperiodate crystals will decrease.

The acid added to convert sodium paraperiodate into sodium metaperiodate is preferably an inorganic acid such as sulfuric acid, phosphoric acid, or nitric acid.

The amount of this acid differs depending on whether the raw material sodium paraperiodate is disodium salt or trisodium salt.

1.00 to 1.20 for 1 mole of disodium salt
P equivalents of acid are added, preferably 1.02 to 1.1 or equivalents.

If the amount of acid is less than x, oor equivalents, the bulk sodium periodate will not be completely converted to sodium metaperiodate. Therefore, sodium para-periodate is mixed into the precipitated crystals of sodium meta-periodate, and the purity of the sodium meta-periodate crystals is reduced.

When the amount of acid exceeds 1.2 or equivalent, sodium metaperiodate further becomes periodic acid and its solubility increases. Therefore, the yield of sodium metaperiodate crystals decreases.

When the raw material sodium periodate is trisodium salt, twice the amount of acid is required as when it is disodium salt.

Next, the resulting aqueous solution or suspension of sodium metaperiodate is heated and cooled to precipitate crystals of sodium metaperiodate.

The heating temperature is preferably from 50°C to reflux temperature, and 50°C to reflux temperature is preferable.
Below °C, crystals of sodium metaperiodate do not grow sufficiently.

Also, if the concentration of sodium metaperiodate is low,
After raising the temperature, water can be concentrated to precipitate crystals.

If the cooling temperature is too low, the crystals of sodium metaperiodate will transition from anhydrous salt to trihydrate and precipitate.
A temperature of 0°C or higher is desirable.

Furthermore, the precipitated sodium metaperiodate crystals are separated and dried to obtain highly pure sodium metaperiodate crystals as the target product.

In the present invention, the mother liquor from which the crystals of sodium metaperiodate have been separated is treated with an alkali, and the periodic acid content is recovered into the system as sodium paraperiodate.

Usually, sodium metaperiodate is lost and inorganic salts are present as impurities in the mother liquor.

Among the sodium periodate salts, one with low water solubility is rose sodium periodate.

Therefore, sodium metaperiodate is converted to sodium paraperiodate in the mother liquor by alkali treatment. Sodium paraperiodate is separated as crystals from this aqueous solution.

The inorganic salt remains in the residual liquid, and some of it is mixed into the crystals of sodium paraperiodate. The inorganic salts in the crystals can be removed from the yarn by washing the crystals with water.

The alkali added to convert sodium metaperiodate to sodium paraperiodate includes sodium hydroxide,
Examples include, but are not limited to, sodium carbonate. Further, its shape may be either solid or aqueous solution.

The reaction temperature at this time may be room temperature, but preferably 4
The temperature is 0°C or higher. There is no restriction on the timing of adding the alkali, and it may be added at any time before the start of the reaction.

- The amount of this alkali is 1.00 to 3.0% per mole of periodic acid in the generated mother liquor. oor equivalent.

This amount is 1. If the amount is less than the oop equivalent, the yield of bulk sodium periodate decreases, and 3. When the amount exceeds oor equivalent, there is no difference in the effect of alkali addition.

It is desirable to leave the obtained aqueous solution at the same temperature or after raising the temperature for about 1 hour while stirring. Since the standing time varies depending on the reaction temperature, it cannot be absolutely limited.

After standing, crystals of sodium paraperiodate precipitated from the aqueous solution are separated.

The temperature at this time is preferably 50°C or less, and 50'C
If the concentration is exceeded, loss of sodium paraperiodate may be observed.

Sodium paraperiodate recovered as above is
It is a disodium salt and has better separation and operability compared to the trisodium salt.

The recovered bulk disodium periodate can be used as a raw material to produce the target product, sodium metaperiodate.

Therefore, according to the present invention, sodium metaperiodate can be produced with almost no loss.

〔Example〕

The present invention will be explained in detail below using Examples.

In the following, "%" is on a molar basis unless otherwise specified.

Note that the purity of sodium meta-periodate and sodium para-periodate was determined by iodometric titration.

Example 1 271.9 g (1.0 mol) of rose disodium periodate is suspended in 160.1 g of water, and 102.9 g (0,525 mol) of a 50% sulfuric acid aqueous solution is added. This suspension was heated to 100°C and left at 100°C for 30 minutes.

After standing, it was cooled to 20°C, and the precipitated crystals were filtered.
After drying, 195.1 g of sodium metaperiodate was obtained.

The purity of the sodium metaperiodate crystals was 99.5%, and the yield was 90.9%.

- Disodium paraperiodate was recovered from 329.9 g of the filtrate containing sodium metaperiodate obtained here.

The filtrate contained 19.5 g (0.0 g) of sodium metaperiodate.
,091 mol).

To this filtrate, add 40% by weight sodium hydroxide l) rum aqueous solution9.
1 g (0,091 mol) was added.

Thereafter, the temperature was raised to 80°C and left at 80°C for 30 minutes.

This was cooled to 30°C, and the precipitated crystals were filtered, washed with water, and dried.
．． 7g was obtained.

The purity of the obtained crystals was 99.0%, and the recovery rate of disodium paraperiodate was 97.0%.

This crystal could be used in the production of sodium metaperiodate without any problem.

Example 2 Crystals of disodium paraperiodate were obtained in exactly the same manner as in Example 1, except that the temperature was raised to 50° C. after addition of the 40% by weight aqueous sodium hydroxide solution.

96. from the filtrate as disodium paraperiodate.
5% recovered.

This crystal could be used in the production of sodium metaperiodate without any problem.

Example 3 Crystals of disodium para-periodate were obtained in exactly the same manner as in Example 1, except that the amount of 40% sodium hydroxide added was changed to 10.0 g (0.10 mol). Ta.

97. from the filtrate as disodium paraperiodate.
2% was recovered.

This crystal could be used in the production of sodium metaperiodate without any problem.

Comparative Example 1 Crystals of disodium para-periodate were obtained in exactly the same manner as in Example 1, except that the amount of 40% by weight sodium hydroxide was changed to 7.3 g (0,073 mol). .

The recovery rate of rose disodium periodate was 65%.

Comparative Example 2 Crystals of disodium paraperiodate were obtained in exactly the same manner as in Example 1, except that the temperature was raised to 20°C after addition of the 40% by weight aqueous sodium hydroxide solution.

The recovery rate of disodium paraperiodate was 87%.

〔Effect of the invention〕

According to the present invention, the produced sodium para-periodate can be effectively used for producing sodium meta-periodate with almost no loss.

Claims (1)

[Claims] (1) In a method for producing sodium metaperiodate by treating sodium paraperiodate with an acid in an aqueous solution, sodium paraperiodate is extracted from the mother liquor after separating crystals of sodium metaperiodate. A method for producing sodium metaperiodate, which comprises recovering a periodic acid component.