# US 11,110,042 B2 · Methods for synthesizing stannous pyrophosphate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,110,042 B2 - Document ID: US11110042B2 - Status: Granted - Kind: B2 - Application number: 16/820,909 - Filed: 2020-03-17 - Published: 2020-10-22 - Granted: 2021-09-07 - Earliest claimed: 2019-04-18 - Assignees: Colgate-Palmolive Company - Applicants: Colgate-Palmolive Company - Inventors: Zhigang Hao; Paul Thomson; Long Pan; Tatiana Brinzari; Guofeng Xu; Sergio Leite; Yu Wang - Web page: https://patentgrep.com/patent/US11110042B2 ## CPC - A61K 8/24: Phosphorous; Compounds thereof - A61K 8/21: Fluorides; Derivatives thereof - A61Q 11/00: Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses - A61K 2800/84: Products or compounds obtained by lyophilisation, freeze-drying - A61K 2800/92: Oral administration - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) - A61Q: SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS ## Abstract Disclosed herein are improved methods for the synthesis of stannous pyrophosphate, as well as improved methods for the manufacture of oral care compositions comprising stannous pyrophosphate. ## Claims ### Claim 1 A method of making an oral care composition comprising stannous pyrophosphate, comprising the steps of (1) reacting stannous chloride with a tetrasodium pyrophosphate (TSPP) in a water or water/alcohol solvent mixture in a reactor tank, (2) precipitating the stannous pyrophosphate product, optionally (3) recovering the stannous pyrophosphate product by filtration, optionally (4) freeze-drying the stannous pyrophosphate product, and (5) transferring the stannous pyrophosphate product into a mixing tank containing at least one oral care ingredient and at least one orally acceptable solvent. ### Claim 2 (depends on 1) The method according to claim 1, wherein the stannous chloride is stannous chloride dihydrate (SnCl2-2H2O). ### Claim 3 (depends on 1) The method according to claim 1, wherein the stannous chloride and the tetrasodium pyrophosphate are combined in a molar ratio of 1:1 to 1:3. ### Claim 4 (depends on 1) The method according to claim 1, wherein solvent for step (1) is water. ### Claim 5 (depends on 1) The method according to claim 1, wherein the solvent for step (1) is a water/alcohol mixture. ### Claim 6 (depends on 5) The method according to claim 5, wherein the alcohol is selected from methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, neopentyl glycol, glycerol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, pentaerythritol, and sorbitol. ### Claim 7 (depends on 1) The method according to claim 1, wherein the step (3) and step (4) are omitted, and step (2) yields a liquid slurry of the stannous pyrophosphate product precipitate in the water or water/alcohol solvent mixture and this slurry is transferred into the mixing tank of step (5). ### Claim 8 (depends on 1) The method according to claim 1, wherein step (4) is omitted, and the filtered solid from step (3) is transferred into the mixing tank of step (5). ### Claim 9 (depends on 1) The method according to claim 1, wherein the reaction step (1) is substantially complete. ### Claim 10 (depends on 1) The method according to claim 1, wherein the method further comprises the step of incorporating stannous fluoride into the oral care composition. ### Claim 11 A method of making stannous pyrophosphate, comprising the steps of (1) reacting stannous chloride with tetrasodium pyrophosphate in a water or water/alcohol solvent mixture, (2) precipitating the stannous pyrophosphate product, (3) recovering the stannous pyrophosphate product by filtration, and (4) freeze-drying the stannous pyrophosphate product. ### Claim 12 (depends on 11) The method of claim 11, wherein the stannous chloride is stannous chloride dihydrate (SnCl2-2H2O). ### Claim 13 (depends on 11) The method according to claim 11, wherein the stannous chloride and the tetrasodium pyrophosphate are combined in a molar ratio of 1:1 to 1:3. ### Claim 14 (depends on 11) The method according to claim 11, wherein solvent for step (1) is water. ### Claim 15 (depends on 11) The method according to claim 11, wherein the solvent for step (1) is a water/alcohol mixture. ### Claim 16 (depends on 15) The method according to claim 15, wherein the alcohol is selected from methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, neopentyl glycol, glycerol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, pentaerythritol, and sorbitol. ### Claim 17 (depends on 11) An oral care composition comprising stannous pyrophosphate made according to the method of claim 11. ### Claim 18 An oral care composition comprising stannous pyrophosphate and sodium chloride in a molar ratio of about 4 parts sodium chloride to one-part stannous pyrophosphate. ### Claim 19 (depends on 18) An oral care composition according to claim 18, wherein the composition comprises from 0.1 to 3% by weight of stannous pyrophosphate. ### Claim 20 (depends on 18) An oral care composition according to claim 18, wherein the composition comprises 0.05 to 2% by weight of sodium chloride.