Isethionic acid

2-hydroxyethane

Clear, viscous liquid which solidifies on cooling

Fixed

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Isethionic acid ( 2-hydroxyethane ) alkanesulfonic acid containing hydroxy groups is the simplest. It is suitable because of their high polarity and the relatively good solubility of their alkaline esterification with long-chain carboxylic acids to isethionates ( Acyloxyethansulfonaten ), which are used as anionic surfactants.

Production and representation

Isethionic acid can be obtained by hydrolysis of ethionic acid as carbyl sulfate via unstable intermediate:

The resulting sulfuric acid complicates the isolation of isethionic, also exists as a monohydrate in after concentration of the diluted solution. The resulting intermediate ethionic acid is also formed by the reaction of one mole of ethanol, two moles of sulfur trioxide and upon heating with sodium hydroxide in the elimination of water over sodium vinylsulfonate. The oxidation of 2 -mercaptoethanol with hydrogen peroxide (60 wt - % ) gives, after removal of the by- product sulfuric acid to 99.9 % pure isethionic acid in a high yield ( 95.9 % of theory) as a 50 weight percent aqueous solution. Because of the ease of accessibility of the sodium isethionate - from the cheapest raw materials ethylene oxide and sodium - this serves as a common starting material for the presentation of isethionic by acidification with mineral acid, such as concentrated. Hydrochloric acid, 80 % yield, with organic acids, such as oxalic acid in 94% yield, or by the introduction of dry HCl gas in alcoholic solutions of sodium isethionate with quantitative yield.

Properties

Isethionic is usually described as a colorless, viscous liquid that is miscible with water and a strong acid reaction in aqueous solution. The representation of the isethionic acid according to reference results in a water - free and chloride -free product which crystallizes upon cooling to form a solid.

Use

Isethionic is in electroplating baths, for example, used for the tin metal and is used for the preparation of inks and resins, as well as the acid catalyst. As early as 1862 Hermann Kolbe identified the reaction product of isethionic with ammonia as a 2- aminoethanesulfonic (taurine ) and refuted the presumption if it were Isethionsäureamid. From isethionic can of N. E. Good biological buffer proposed by reaction with appropriate functional amines are represented, such as HEPES, MES, CHES, and others. Isethionic also serves as a starting material for surfactants from the class of ( acyl ) Isethionates, but this the easier accessible sodium isethionate is preferred.