Method for preparing stannous fluoride from stannic oxide

Abstract

The invention provides a method for preparing stannous fluoride from stannic oxide. The method comprises steps as follows: stannic oxide, a fluorinating agent and a reducing agent are taken as raw materials, toluene is taken as a water-carrying agent, after toluene which is 1-4 times the weight of stannic oxide is added, stannic oxide is added at a certain stirring speed, the materials are heatedto 80-85 DEG C, then the fluorinating agent and the reducing agent are slowly added, the reaction system is kept at the temperature of 80-85 DEG C after addition, backflow is controlled, toluene-waterazeotrope is removed out of the reaction system by an oil-water separator, the temperature is preserved for 5-7.5 h, the materials are filtered, cyclohexane is added for washing a filter cake, the washed filter cake is filtered, transferred into a drying device and dried under the conditions of temperature being 50-80 DEG C and pressure being 5-20 kPa, and stannous fluoride is obtained. The process of the preparation method is simple, by means of formation of the toluene-water azeotropic system, water is removed out of the reaction system, generated stannous fluoride and water are prevented from reacting and generating stannous oxyfluoride, and stannous fluoride with content higher than 99% and residual impurity quantity lower than 0.005% is obtained and is particularly suitable for beingused for fine chemical engineering.

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.