# US 5,344,971 A · Process for deodorizing a mercapto acid by extracting malodorous compound therefrom with a supercritical fluid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,971 A - Document ID: US5344971A - Status: Granted - Kind: A - Application number: 08/045,095 - Filed: 1993-04-12 - Granted: 1994-09-06 - Earliest claimed: 1992-10-15 - Assignees: L'oreal - Inventors: Michel Dedieu; Herve Burgaud; Eric Lapoirie; Veronique Gurfein; Gerard Malle - Web page: https://patentgrep.com/patent/US5344971A ## CPC - C07C 319/28: Separation; Purification - A61K 8/46: containing sulfur (A61K8/44 takes precedence) - A61Q 5/04: Preparations for permanent waving or straightening the hair - A61Q 9/04: Depilatories - A61Q 15/00: Anti-perspirants or body deodorants (deodorisation of air A61L9/00) - Y02P 20/54: using solvents, e.g. supercritical solvents or ionic liquids - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - 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 - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A process for deodorizing a mercapto acid includes extracting malodorous compounds present therein by treating the mercapto acid in the presence of a polar solvent with a supercritical extraction fluid having a critical temperature ranging from 0.degree. to 135.degree. C. and a critical pressure ranging from 10.sup.6 to 10.sup.7 Pascals. The mercapto acid has the formula HS--A--COOH wherein A represents ##STR1## wherein n is an integer ranging from 1 to 4 and R is a linear or branched C.sub.1 -C.sub.3 alkyl. ## Claims ### Claim 1 A process for deodorizing a mercapto acid by extraction of a greater part of malodorous decomposition products contained therein, said process comprising (a) treating said mercapto acid in the presence of at least one polar solvent for said mercapto acid with a supercritical extraction fluid having a critical temperature ranging from 0.degree. to 135.degree. C. and a critical pressure ranging from 10.sup.6 to 10.sup.7 Pascals, said mercapto acid having the formula HS--A--COOH (I) wherein A represents (i) --(CH.sub.2).sub.n -- wherein n is an integer ranging from 1 to 4, (ii) ##STR4## wherein R represents linear or branched C.sub.1 -C.sub.3 alkyl, or (iii) ##STR5## and (b) lowering the extraction pressure whereby said malodorous decomposition products are removed with said extraction fluid. ### Claim 2 (depends on 1) The process of claim 1 wherein said supercritical extraction fluid is carbon dioxide. ### Claim 3 (depends on 1) The process of claim 1 wherein said mercapto acid is thioglycolic acid or thiolactic acid. ### Claim 4 (depends on 1) The process of claim 1 wherein said polar solvent is selected from the group consisting of water, a linear or branched C.sub.1 -C.sub.5 monohydric alcohol, a C.sub.2 -C.sub.4 diol, a C.sub.3 -C.sub.6 polyol and a mixture thereof. ### Claim 5 (depends on 4) The process of claim 4 wherein said monohydric alcohol is selected form the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methylpropanol and 1-pentanol. ### Claim 6 (depends on 4) The process of claim 4 wherein said diol is selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, and 1,6-hexanediol. ### Claim 7 (depends on 4) The process of claim 4 wherein said polyol is glyercol. ### Claim 8 (depends on 1) The process of claim 1 wherein said polar solvent is present in an amount ranging from 1 to 99 percent by weight relative to the weight of said mercapto acid. ### Claim 9 (depends on 1) The process of claim 1 wherein said mercapto acid is present in the form of an aqueous solution having a mercapto acid concentration ranging from 0.1 mol/liter to 14 mols/liter. ### Claim 10 (depends on 1) The process of claim 1 wherein said extraction is performed in the presence of an inert gaseous compound. ### Claim 11 (depends on 10) The process of claim 10 wherein said inert gaseous compound is selected from the group consisting of helium, nitrogen and argon. ### Claim 12 (depends on 1) The process of claim 1, effected in a discontinuous fashion, said process comprising (a) introducing into a reactor said mercapto acid, said polar solvent, said extraction fluid and optionally an inert gaseous compound and closing said reactor, (b) establishing in said closed reactor said critical temperature and pressure conditions defined in claim 1, (c) permitting said mercapto acid, said polar solvent, said extraction fluid and optionally said inert gaseous compound to remain in contact for a period of time ranging from 5 to 30 minutes, (d) removing said extraction fluid by decompression, (e) optionally repeating steps (a) to (d) under the said critical temperature and pressure conditions defined in claim 1, and (f) collecting a solution of deodorized mercapto acid. ### Claim 13 (depends on 1) The process of claim 1, effected in a semi-continuous fashion, said process comprising (a) introducing into a reactor said mercapto acid and said polar solvent, (b) filling said reactor with said extraction fluid and closing said reactor, (c) establishing in said reactor temperature and pressure conditions exceeding the critical temperature and pressure condition defined in claim 1, (d) establishing a washing flow of said supercritical extraction fluid and thereafter discontinuing said flow, (e) effecting decompression of said reactor and (f) collecting deodorized mercapto acid. ### Claim 14 (depends on 13) The process of claim 13 wherein said extraction fluid is carbon dioxide and said washing flow ranges from 0.5 to 3 kg/hour. ### Claim 15 (depends on 14) The process of claim 14 wherein said mercapto acid is thioglycolic acid, said washing flow of carbon dioxide ranges from 1 to 30 kg/hour per kg of thioglycolic acid/polar solvent mixture. ### Claim 16 (depends on 1) The process of claim 1 wherein said extraction is carried out in a continuous fashion in a separating column. ### Claim 17 (depends on 12) The process of claim 12 which includes recycling said extraction fluid subsequent to removal of said malodorous decomposition products.