JPH05331096A - Production of bismuth acetate - Google Patents

Abstract

PURPOSE:To provide a simple process for producing high-purity bismuth acetate of low bismuth oxide content. CONSTITUTION:Bismuth oxide is dissolved in a glacial acetic acid and acetic anhydride mixture under boiling and the crystallized bismuth acetate is collected. As the bismuth oxide, is preferred alpha-type bismuth oxide and the glacial acetic acid is needed 10 to 20 times the reaction molar equivalent, while the acetic anhydride is required 4.5 to 10.5 moles per mole of the bismuth oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple method for producing bismuth acetate having a low bismuth oxide content.

[0002]

2. Description of the Related Art As a conventional example of a method for producing bismuth acetate, a method in which (subsequent) bismuth carbonate is boiled while refluxing with glacial acetic acid to obtain a solution, and a method in which metal bismuth is heated to a boiling point with 98% acetic acid are used. A method of obtaining by cooling has been reported (Inorganic Chemistry Encyclopedia (Maruzen)).

[0003]

However, the bismuth acetate produced by the above-mentioned conventional method sometimes contains an oxide of bismuth, which makes it difficult to obtain high-purity bismuth acetate.

[0004]

The method for producing bismuth acetate according to the present invention is characterized in that bismuth oxide is boiled and dissolved with glacial acetic acid and acetic anhydride, and bismuth acetate is crystallized from the obtained solution.

In addition, in the method for producing bismuth acetate according to the present invention, the bismuth oxide is α-type bismuth oxide, and the amount of glacial acetic acid added is 10 to 20 times the reaction equivalent of bismuth oxide and acetic acid. It is characterized in that the number of moles of acetic anhydride added is 4.5 to 10.5 times the number of moles of bismuth oxide.

[0006]

In the present invention, the fact that bismuth acetate having a low bismuth oxide content can be produced by dissolving bismuth oxide in glacial acetic acid and acetic anhydride is partly due to the reaction of bismuth oxide and glacial acetic acid. It is considered that the generated bismuth acetate is likely to be hydrolyzed so that the hydrolysis is difficult to occur by adding acetic anhydride.

As the bismuth oxide of the present invention, α-type bismuth oxide is easily dissolved in acetic acid, so that α-type bismuth oxide is preferably used.

If the amount of glacial acetic acid added is less than 10 times the reaction equivalent amount of bismuth oxide and acetic acid, bismuth oxide cannot be completely dissolved, and bismuth acetate undissolved substances are mixed, resulting in more than 20 times. Because the added amount is not economical,
The amount of glacial acetic acid added is 1 equivalent to the reaction amount of bismuth oxide and acetic acid.
It must be 0 to 20 times.

Focusing on the water generated by the reaction which greatly affects the hydrolysis of bismuth acetate, the Bi quality (wt%) of the bismuth acetate produced and the number of moles of acetic anhydride added versus the water generated by the reaction of bismuth oxide and acetic acid. The relationship with the molar value is shown in FIG. In FIG. 1, the theoretical value of Bi quality of bismuth acetate is 54.
1%, and the higher the Bi grade of bismuth acetate, the more the bismuth oxide is mixed.

In FIG. 1, when the amount of acetic anhydride added / amount of generated water (number of moles) is 1.5 to 3.5, Bi quality of bismuth acetate is low, and bismuth acetate with a small oxide amount of bismuth mixed therein can be produced. Is shown.

That is, when the amount of acetic anhydride added / amount of generated water (molar ratio) is less than 1.5 (corresponding to the amount of acetic anhydride added / α-type bismuth oxide (molar ratio) = 4.5), the bismuth acetate produced is partly produced. Is easily hydrolyzed to form bismuth oxide, and the amount of acetic anhydride added / amount of generated water (molar ratio) is 3.5 (acetic anhydride added / alpha-type bismuth oxide (molar ratio)
(Corresponding to 10.5), the amount of acetic anhydride, which is originally difficult to react with bismuth oxide, increases, so that bismuth acetate becomes difficult to dissolve in a mixed solution of glacial acetic acid and acetic anhydride, and oxidation is difficult. Since bismuth tends to remain, the number of moles of acetic anhydride added needs to be 4.5 to 10.5 times the number of moles of bismuth oxide.

[0012]

【Example】

Example 1 50 g of α-type bismuth oxide was placed in a flat-bottomed flask having a volume of 500 ml, and then 12.9 times the equivalent amount of glacial acetic acid (reagent 1
Grade) and acetic anhydride (reagent grade 1) 46 g were added, and a condenser tube containing a ball was set in a flat-bottomed flask, followed by boiling and stirring for 1 hour using a hot stirrer.
At this time, the inside of the flask became completely transparent. After that, the heating was stopped, and the mixture was left standing to cool to room temperature for crystallization. After sufficiently cooling and crystallization, solid-liquid separation is performed by suction filtration and drying to give 75.2 g of bismuth acetate crystals.
Got When this crystal was measured by X-ray diffraction, no peak other than the peak of bismuth acetate was observed. The Bi quality of this crystal was analyzed and found to be 5 against 54.1% of the theoretical amount.
It was 5.6%.

The relationship between the Bi quality (% by weight) of the obtained bismuth acetate and the calculated amount of acetic anhydride added / amount of generated water (molar ratio) is shown in FIG.

The α-type bismuth oxide used in this example is
Bismuth nitrate (first-grade reagent) and sodium bicarbonate (first reagent)
Bismuth subcarbonate is produced by reacting bismuth carbonate) and then the bismuth subcarbonate is roasted at 400 ° C.

Example 2 The same procedure as in Example 1 was carried out except that the added acetic anhydride was changed to 32.8 g to obtain 75.4 g of bismuth acetate crystals. When this crystal was measured by X-ray diffraction, no peak other than the peak of bismuth acetate was observed. B of this crystal
When the i grade was analyzed, it was 54.1% against 54.1% of the theoretical amount.
8%, and this value is also shown in FIG. 1 as in Example 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the amount of acetic anhydride added was changed to 82 g. When boiling and stirring was performed for 1 hour using a hot stirrer, the inside of the flask was slightly clouded. After that, the heating was continued for 1 hour, but since the turbidity did not disappear, the heating was stopped and the mixture was allowed to cool to room temperature for crystallization. After sufficient cooling and crystallization, solid-liquid separation was performed by suction filtration and drying to obtain 75.0 g of bismuth acetate crystals. When this crystal was measured by X-ray diffraction, a slight peak of bismuth oxide was observed. When the Bi quality of this crystal was analyzed, it was 57.2% against 54.1% of the theoretical amount. This value is also shown in FIG. 1 as in Example 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that acetic anhydride was not added and the boiling and stirring time was 1.5 hours. At this time, the solution in the flask did not become transparent during boiling and stirring. The amount of the obtained bismuth acetate crystal was 64.8 g. When this crystal was measured by X-ray diffraction, a bismuth oxide-like peak was found in addition to the bismuth acetate peak, but it could not be identified.
When the quality of Bi in the crystal was analyzed, it was 73.3%, which was a very high value compared to 54.1% of the theoretical amount. This value is also shown in FIG. 1 as in Example 1.

[0018]

According to the present invention, pure bismuth acetate can be produced by a simple production method.

[0019]

[Brief description of drawings]

FIG. 1 Bi quality (wt%) of bismuth acetate produced
FIG. 5 is a diagram showing the relationship between the number of moles of acetic anhydride added and the number of moles of water generated by the reaction of bismuth oxide and acetic acid.

Claims (2)

[Claims] 1. A method for producing bismuth acetate, characterized in that bismuth oxide is boiled and dissolved with glacial acetic acid and acetic anhydride, and bismuth acetate is crystallized from the resulting solution. 2. The bismuth oxide is α-type bismuth oxide, the amount of glacial acetic acid added is 10 to 20 times the reaction equivalent of bismuth oxide and acetic acid, and the number of moles of acetic anhydride added is the number of moles of bismuth oxide. It is 4.5 to 10.5 times of the above.
A method for producing bismuth acetate as described.