A kind of method preparing stannous fluoride by tin dioxide

Abstract

The invention provides a method for preparing stannous fluoride from tin dioxide. The method is to use tin dioxide, a fluorinating agent and a reducing agent as raw materials, use toluene as a water-carrying agent, and first add tin dioxide by weight 1- After 4 times of toluene, add tin dioxide at a certain stirring speed, heat the material to 80-85°C and then slowly add fluorinating agent and reducing agent. After the addition, keep the reaction system at 80-85°C, control reflux and separate oil and water The toluene-water azeotrope is removed from the reaction system, kept warm for 5-7.5 hours, filtered the material, added cyclohexane to wash the filter cake, filtered the washed filter cake and transferred to the drying equipment, at 50-80 ° C, 5 Dry under the condition of ‑20kPa to obtain stannous fluoride. The preparation method of the present invention has a simple process. By forming a toluene-water azeotropic system, water is removed from the reaction system to avoid the reaction of the generated stannous fluoride and water to form stannous oxyfluoride, and the obtained content is greater than 99%, and the amount of residual impurities is The stannous fluoride less than 0.005% is especially suitable for use in fine chemicals.

Description

technical field [0001] The invention relates to a preparation method of an inorganic compound, in particular to a preparation method of stannous fluoride, and more particularly to a method for preparing stannous fluoride from tin dioxide. Background technique [0002] Stannous fluoride is a fluoride with great application potential. It can be used as a welding aid in the electronics industry. In addition, stannous fluoride has an excellent bactericidal effect on skin bacteria and fungi, and is effective against Pseudomonas aeruginosa, abalone The biofilm of Acinetobacter mannequin and Streptococcus mutans has a certain inhibitory effect, which can effectively inhibit the growth of pathogenic bacteria such as Acinetobacter baumannii and the production of biofilm. Therefore, in the field of stomatology, stannous fluoride is an excellent It is an excellent dental anti-cavity agent, and has good curative effect on dental diseases such as plaque, gingivitis, allergy, enamel decal...

AI Technical Summary

Problems solved by technology

[0003] At present, the disclosed methods for preparing stannous fluoride mainly include: (1) using tin elemental substance to react with hydrofluoric acid to prepare stannous fluoride. 20-30% hydrofluoric acid is used as raw material, and stannous fluoride is produced by reaction at 63-80°C. Although this method can obtain stannous fluoride products, the method has low yield and many by-products , the relatively difficult problem of separation; (2) adopting stannous chloride and sodium fluoride to prepare stannous fluoride through metathesis reaction, as the Czech patent of publication number 231928, discloses the use of stannous chloride and sodium fluoride to directly Perform ion exchange to obtain stannous fluoride. Although this method is simple to operate, there are problems that stannous fluoride and sodium chloride cannot be effectively separated, the impurity content is high, and the purity of stannous fluoride is low; (3) copper fluoride is used Prepare stannous fluoride with metallic tin powder by displacement reaction, as the Chinese patent application that publication number is CN1141884A, disclose adopting elemental tin powder and copper fluoride to prepare stannous fluoride by displacement reaction, although this method is easy to operate and obtains The product has high purity, but requires a high mesh number of tin powder, and the price of high mesh tin powder and copper fluoride is quite expensive, which makes the cost of this method too high and has little economic significance; Tin and hydrofluoric acid are raw material preparation stannous fluoride, as the Chinese patent that publication number is CN103332731B, it is disclosed to take 20-50% hydrofluoric acid, stannous oxide as raw material, and by adding tin particle bag and adding oxidation From the beginning of the stannous to the end of the reaction, two measures are used to pass nitrogen into the hydrofluoric acid to prevent the product from being oxidized during the synthesis process. The product obtained by this scheme has high purity, but because the by-product water is evaporated from the Under this condition, the by-product water and the generated stannous fluoride are easy to react to form stannous oxyfluoride, resulting in the deterioration of stannous fluoride; (5) the reaction of tin dioxide and calcium fluoride to prepare Stannous chloride, such as the Chinese patent with publication number CN105800675A, discloses that materials containing tin dioxide, materials containing calcium fluoride and sodium carboxymethyl cellulose are ground and mixed, and placed in CO and CO 2 In a mixed atmosphere, roast at a temperature of 500°C to 1000°C to recover stannous fluoride from the roasting flue gas. Although this scheme has the advantage of high product purity, it consumes a lot of energy and the carbon monoxide used is poisonous. And it is flammable and explosive. In addition, the roasting temperature of this scheme exceeds 300 ° C. During the roasting process, stannous fluoride is easy to polymerize and form polymers, which affects product performance.