Isethionic acid
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| General | |||||||||||||||||||
| Surname | Isethionic acid | ||||||||||||||||||
| other names |
2-hydroxyethanesulfonic acid |
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| Molecular formula | C 2 H 6 O 4 S | ||||||||||||||||||
| Brief description |
clear, highly viscous liquid that solidifies on cooling |
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| Molar mass | 126.13 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Isethionic acid (2-hydroxyethanesulfonic acid) is the simplest alkanesulfonic acid containing hydroxyl groups . Because of its high polarity and the relatively good solubility of its alkaline earth metal salts, it is suitable for esterification with long-chain carboxylic acids to form isethionates (acyloxyethanesulfonates), which are used as anionic surfactants .
Extraction and presentation
Isethionic acid can be obtained as an unstable intermediate product by hydrolysis of carbyl sulfate via ethionic acid.
The sulfuric acid formed makes it difficult to isolate the isethionic acid, which is also present as a monohydrate after the dilute solution has been concentrated. The ethionic acid obtained as an intermediate is also produced by the reaction of one mole of ethanol with two moles of sulfur trioxide and, when heated with sodium hydroxide solution, changes to sodium vinyl sulfonate with elimination of water .
The oxidation of 2-mercaptoethanol with hydrogen peroxide (60% by weight) gives up to 99.9% pure isethionic acid in high yield (95.9% of theory) as a 50% by weight aqueous solution after the sulfuric acid formed as a by-product has been separated off.
Because of the easier accessibility of the sodium isethionate - from the inexpensive raw materials ethylene oxide and sodium hydrogen sulfite - this serves as a common starting material for the preparation of isethionic acid by acidification with mineral acid, such as. B. conc. Hydrochloric acid with 80% yield, with organic acids, such as. B. oxalic acid with 94% yield or by introducing dry HCl gas into alcoholic sodium isethionate solutions with quantitative yield.
properties
Isethionic acid is usually described as a colorless, viscous liquid that is miscible with water and reacts strongly acidic in aqueous solution. The representation of isethionic acid according to Ref. Leads to an anhydrous and chloride-free product which crystallizes to a solid on cooling.
use
Isethionic acid is used in electroplating baths, e.g. B. used for tinning metals and is used for the production of inks and resins, and as an acid catalyst. As early as 1862, Hermann Kolbe identified the reaction product of isethionic acid with ammonia as 2-aminoethanesulfonic acid ( taurine ) and refuted the assumption that it was isethionic acid amide. The biological buffers proposed by NE Good can be prepared from isethionic acid by reacting with appropriate functional amines, such as B. HEPES , MES , CHES and others. Isethionic acid is also used as the starting material for surfactants from the (acyl) isethionate class , although the more easily accessible sodium isethionate is preferred for this purpose .
Individual evidence
- ↑ a b Patent US5053530 : Preparation of isethionic acid with organic acid. Filed April 10, 1990 , published October 1, 1991 , applicant: Phillips Petroleum Corp., inventor: JS Roberts, HW Mark.
- ↑ a b c d e f Patent US4696773 : Process for the preparation of isethionic acid. Applied July 7, 1986 , published September 29, 1987 , Applicant: Johnson & Johnson Baby Products Co., Inventors: ER Lukenbach, P. Naik-Satam, AM Schwartz.
- ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
- ↑ Kurt Kosswig: Sulfonic Acids, Aliphatic . In: Wiley-VCH (Ed.): Ullmann's Encyclopedia of Industrial Chemistry . 2000. doi : 10.1002 / 14356007.a25_503 .
- ^ DL Wooton, WG Lloyd: Hydrolytic reactions of carbyl sulfate . In: J. Org. Chem. Band 39 , no. 14 , 1974, p. 2112-2114 , doi : 10.1021 / jo00928a031 .
- ^ DS Breslow, RR Hough, JT Fairclough: Synthesis of sodium ethylenesulfonate from ethanol . In: J. Am. Chem. Soc. tape 76 , no. 21 , 1954, pp. 5361-5363 , doi : 10.1021 / ja01650a033 .
- ↑ Patent EP0854136A1 : Process for the production of alkanesulfonic acids. Applied on January 20, 1998 , published on July 22, 1998 , Applicant: Tokai Denka Kogyo KK, Inventors: K. Kushibe, H. Kobayashi, H. Nitoh, H. Kitamura.
- ↑ Patent US4499028 : Preparation of isethionic acid. Applied September 7, 1982 , published February 12, 1985 , Applicant: Witco Chemical Corp., Inventor: KD Longley.
- ↑ Patent WO2008100648A1 : High speed tin plating process. Filed January 4, 2008 , published August 21, 2008 , applicant: Arkema Inc., inventors: NM Martyak, GE Stringer, GS Smith.
- ↑ H. Kolbe: XIX.-On the chemical constitution and artificial formation of taurine . In: J. Chem. Soc. tape 15 , 1862, p. 94-104 , doi : 10.1039 / JS8621500094 .
- ^ NE Good, GD Winget, W. Winter, TN Connolly, S. Izawa, RMM Singh: Hydrogen ion buffers for biological research . In: Biochemistry . tape 5 , no. 2 , 1966, p. 467-477 , doi : 10.1021 / bi00866a011 .
- ↑ Data sheet "Good" buffers from Sigma-Aldrich , accessed on June 17, 2013 ( PDF ).