JPH06312974A - Method for stabilizing thiocarbohydrazide - Google Patents

Abstract

PURPOSE:To stabilize thiocarbohydrazide, excellent in preservation stability for a long period and useful as a photographic parent chemical, etc., without causing blackening by treating the thiocarbohydrazide with a chelating agent. CONSTITUTION:Thiocarbohydrazide is stabilized by carrying out the treatment such as recrystallization thereof in the presence of a chelating agent having a higher complex stability constant than that of the thiocarbohydrazide such as ethylenediaminetetraacetic acid or nitrilotriacetic acid, mixing thereof with the chelating agent, washing thereof with a solution containing the chelating agent or addition, etc., of the chelating agent to a production process for the thiocarbohydrazide.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for stabilizing thiocarbohydrazide.

[0002]

2. Description of the Related Art Thiocarbohydrazide is widely used as a raw material for photographic drug substances (magenta color formers) and agricultural chemicals. However, when the thiocarbohydrazide is stored for a long period of time, particularly when it is stored for about 6 months to 1 year, blackening occurs over time, and the quality of the photographic drug produced from the thiocarbohydrazide causing such blackening is remarkably deteriorated. However, there is a problem that it cannot withstand normal use.

As a result of repeated studies on the discoloration mechanism of thiocarbohydrazide, the present inventor has found that a chelate compound of thiocarbohydrazide and a metal ion is susceptible to oxidation and is oxidized by oxygen in the air to turn black. I got the knowledge.

On the other hand, thiocarbohydrazide is generally produced by reacting hydrazine with carbon disulfide. Of the above two kinds of raw material compounds, carbon disulfide is extremely flammable and highly toxic, so that it is usually stored in an iron drum. Therefore, it is fully expected that the thiocarbohydrazide produced and stored by the above method will contain iron ions. Further, it is well known that a trace amount of metal ions are mixed in industrial water.

[0005]

Means for Solving the Problems Based on the above findings, the present inventor has conducted a study for preventing the mixing of metal ions during the thiocarbohydrazide production process or for providing a purification process to remove the metal ions. As a result of repeated experiments, it was found that by treating thiocarbohydrazide with a chelating agent, a thiocarbohydrazide free from discoloration can be obtained even after long-term storage for 1 year or longer, and the present invention has been completed here.

That is, the present invention relates to a method for stabilizing thiocarbohydrazide, which comprises treating thiocarbohydrazide with a chelating agent.

No particular limitation is imposed on the thiocarbohydrazide to which the method of the present invention can be applied.
It includes all states such as those immediately after production, those which have passed the time after production but have not been discolored, and those which are partially or wholly discolored by storage.

The chelating agent used in the present invention is not particularly limited, and various known compounds capable of causing chelation with metal ions can be used, and among them, the complex stability constant for one or more metal ions is thio. Those higher than that of carbohydrazide are preferred. The complex stability constant of thiocarbohydrazide for cobalt ion, nickel ion, and zinc ion is about 2 to 11 [In
org.Chim.Acta, 3 (3), 459-62]. As a preferable chelating agent, for example, ethylenediaminetetraacetic acid (EDT
A), nitrilotriacetic acid (NTA), trans-1,2-
Diaminocyclohexane (CyDTA), diaminopropanol tetraacetic acid (DTPA-OH), diaminopropane tetraacetic acid (methyl EDTA), triethylenetetramine 6
Acetic acid (TTHA), iminodiacetic acid (IDA), hydroxyethyliminodiacetic acid (HIDA), nitrilotris (methylenesulfonic acid) trisodium salt (NTPO) and the like can be mentioned, and one of them can be used alone or two can be used. The above can be used in combination.

In the method of the present invention, the treatment of thiocarbohydrazide with a chelating agent is to bring the chelating agent and thiocarbohydrazide into contact with each other. The specific method is not particularly limited as long as it can bring them into contact with each other, for example, a method of recrystallizing thiocarbohydrazide in the presence of a chelating agent, a method of mixing thiocarbohydrazide and a chelating agent. Examples include a method of washing thiocarbohydrazide with a solution containing a chelating agent, a method of adding a chelating agent to a step during the production of thiocarbohydrazide, and the like.

For carrying out the method of the present invention, for example, the method of performing recrystallization, known recrystallization methods can be widely adopted except that a chelating agent is used. That is, thiocarbohydrazide is usually heated to about 50 to 100 ° C., preferably about 90 to 95 ° C. in the presence of a chelating agent in water or a mixed solvent of water and a suitable organic solvent, and then usually 0 to It may be cooled to about 40 ° C, preferably about 20 to 30 ° C. During heating, in order to remove impurities other than metal ions and the like, hot filtration may be performed. It is not limited, and it may be added at any time until the thiocarbohydrazide is recrystallized, but it is usually added to the solvent together with thiocarbohydrazide and heated and cooled. The amount of the chelating agent added is not particularly limited, and may be appropriately selected according to the amount of metal ions contained in the starting thiocarbohydrazide, but it is usually about several ppm to 10 ppm. The effect does not change even if added in excess of 10 ppm, but considering economic efficiency, about 10 ppm is a standard.
The thiocarbohydrazide precipitated by the recrystallization operation can be easily separated by a usual means such as filtration. When an unreacted chelating agent remains in the remaining filtrate obtained by separating thiocarbohydrazide, it can be repeatedly used.

When the thiocarbohydrazide and the chelating agent are mixed, for example, a small amount of the chelating agent powder is usually added to the thiocarbohydrazide and mixed. In the case of washing, for example, thiocarbohydrazide may be mixed with an aqueous solution of a chelating agent and then thiocarbohydrazide may be separated. When the chelating agent is added during the production, for example, the chelating agent or an aqueous solution thereof may be added to the reaction system in which hydrazine is reacted with carbon disulfide to produce thiocarbohydrazide. The amount of the chelating agent added in these methods may be appropriately selected according to the amount of metal ions contained in thiocarbohydrazide as in the case of recrystallization.

The thiocarbohydrazide stabilized by the method of the present invention may have a very small amount of chelating agent remaining, but the stability is not affected at all, and this is not affected by photographic agents or agricultural chemicals. It can be used as a raw material.

[0013]

According to the method of the present invention, the metal ions remaining in the thiocarbohydrazide produced by a conventional method are chelated with a chelating agent to remove the metal ions, and thus the discoloration is particularly caused even after long-term storage for one year or more. It is possible to obtain thiocarbohydrazide which does not cause blackening and has excellent quality as a photographic drug substance.

[0014]

EXAMPLES The present invention will be made clearer with reference to the following Reference Examples and Examples.

Reference Example 1 18 kg (2.88 kmole) of 80% hydrazine hydrate and 175 kg of ion-exchanged water were charged into a 500 liter glass lining container and the liquid temperature was 30 to 40 ° C.
95kg (1.25kmole) of carbon disulfide while maintaining
Was added dropwise, and after the addition was completed, the temperature was maintained and the mixture was stirred for 2 hours. Then, after heating to 70 ° C. and reacting for 12 hours, 2
It was cooled to 0 ° C. and the precipitate was collected by filtration. The solid obtained was washed with cold ion-exchanged water and dehydrated to give 125 kg of thiocarbohydrazide crude crystals (thiocarbohydrazide content 95%).
Got The iron ion content in the crude crystals was 5 ppm (4.5
mM).

Example 1 Reference Example 1 in a 500 liter glass lining container
52.6 kg of crude thiocarbohydrazide crystals and 450 liters of ion-exchanged water were charged, and 0.2 kg (538 mM) of EDTA.2 sodium salt was further added. The aqueous solution was heated to 90 ° C., filtered while hot, cooled to 25 ° C., and the precipitate was collected by filtration. The obtained solid was dried under reduced pressure at 60 ° C. for about 3 hours to obtain 47.5 kg of white thiocarbohydrazide crystals with a content of 99%.

In a 500 ml beaker, 100 g of the purified thiocarbohydrazide crystals obtained above and deionized water 1
Add 50 g, stir for 30 minutes, filter, and add 1
Concentrated to 5 ml. 0.1 mol acetic acid-0.
After adjusting the pH to 4.5 by adding a 1 molar aqueous sodium acetate solution, Fe [2,4,6-tris (2-pyridyl)]
-1,3,5-Triazine] ₂ ²⁺ 5 × 10 ^-4 mol aqueous solution (2 ml) was added, and deionized water was further added to bring the total volume to 25 ml.
And As a result of measuring the absorbance at 593 μm of this aqueous solution with a spectrophotometer, the amount of EDTA in the aqueous solution was 1.2 ppm or less. Converted from this value, residual EDTA in 100 g of purified thiocarbohydrazide crystals
The amount was 0.3 ppm or less.

The thiocarbohydrazide crystals obtained were subjected to a storage stability test. That is, the crystals were heated to 54 ° C.
When the colored state was observed after storage for a day, no coloring was observed at all, and the crystals were white crystals as they were. The content was also 99%, which was unchanged. Furthermore, even if this crystal was stored for 1 year, it was not colored.

Comparative Example 1 47.5 kg of white thiocarbohydrazide crystals having a content of 99% were obtained by the same procedure as in Example 1 except that EDTA.2 sodium salt was not used.

When the obtained thiocarbohydrazide crystals were subjected to the same storage stability test as in Example 1, coloration (blackening) was observed and the content was reduced to 85%.

From the above Example 1 and Comparative Example 1, EDTA
-By adding the disodium salt, it is clear that a thiocarbohydrazide crystal having excellent storage stability can be obtained.

Example 2 52.6 kg of crude thiocarbohydrazide crystals of Reference Example 1 and Example 1 were placed in a 500 ml glass lining container.
After the thiocarbohydrazide in Example 2 was filtered off, ion-exchanged water was added to the filtrate to make a total amount of 450 liters, and thiocarbohydrate was added in the same manner as in Example 1 without newly adding EDTA.2 sodium salt. A hydrazide crystal was obtained.

The reuse of this filtrate was repeated 5 times, and the storage stability of the obtained thiocarbohydrazide crystals was examined in the same manner as in Example 1. As a result, no thiocarbohydrazide crystals were observed and the content was There was no change.

Example 3 0.0045 kg of EDTA.2 sodium salt was added.
The procedure is the same as in Example 1 except that the amount of the white thiocarbohydrazide crystal is 47%.
5 kg was obtained. When this crystal was subjected to the same storage stability test as in Example 1, no coloring was observed and it was a white crystal as it was, and the content was 99%, which was not changed.

Examples 4 to 6 47.5 kg of white thiocarbohydrazide crystals having a content of 99% were obtained in the same manner as in Example 1 except that the chelating agents shown in Table 1 below were used. The crystals were subjected to the same storage stability test as in Example 1. The results are also shown in Table 1.

[0026]

[Table 1]

It can be seen from Table 1 that thiocarbohydrazide crystals having excellent storage stability can be obtained even with a chelating agent other than EDTA.

Claims (4)

[Claims] 1. A method for stabilizing thiocarbohydrazide, which comprises treating thiocarbohydrazide with a chelating agent. 2. The treatment comprises recrystallization of thiocarbohydrazide in the presence of a chelating agent, mixing of thiocarbohydrazide and the chelating agent, washing of thiocarbohydrazide with a solution containing the chelating agent, or thiocarbohydrazide production step. The method according to claim 1, which is the addition of a chelating agent. 3. The method according to claim 1, wherein the chelating agent is a chelating agent having a higher complex stability constant than thiocarbohydrazide. 4. The chelating agent is ethylenediaminetetraacetic acid,
From nitrilotriacetic acid, trans-1,2-diaminocyclohexane, diaminopropanol tetraacetic acid, diaminopropane tetraacetic acid, triethylenetetramine hexaacetic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid and nitrilotris (methylenesulfonic acid) trisodium salt The method according to claim 3, wherein the method is at least one selected from the group consisting of