Absolute

In chemistry, absolutization means the absolute purification of a solvent to 100% content. In principle, organic solvents are usually not 100% pure because they contain tiny amounts of water. So has z. B. Monopoly fuel only has a content of 96%, because ethanol forms an azeotrope with water at this point . Absolute alcohol, which is necessary as a solvent in many chemical synthesis steps, is obtained e.g. B. by drying with calcium chloride and then with elemental sodium and diethyl phthalate . Glacial acetic acid, on the other hand, is made absolute by adding acetic anhydride . Absolute (anhydrous) diethyl ether is obtained from commercially available ether by pressing in sodium wire and distilling off. Methanol can be made absolute with elemental magnesium . In doing so, the formation of magnesium methoxide is used. Methods for the absoluteization of many solvents are described in the specialist chemical literature.

See also

Azeotrope rectification (process for the absoluteization of ethanol)

Individual evidence

1. ↑ Entry on desiccants. In: Römpp Online . Georg Thieme Verlag, accessed on March 24, 2016.
2. ↑ Heinz GO Becker, Werner Berger, Günter Domschke, Egon Fanghänel , Jürgen Faust, Mechthild Fischer, Fritjof Gentz, Karl Gewald , Reiner Gluch, Roland Mayer , Klaus Müller, Dietrich Pavel, Hermann Schmidt, Karl Schollberg, Klaus Schwetlick , Erika Seiler and Günter Zeppenfeld: Organikum , Johann Ambrosius Barth Verlag, 1993 , 19th edition, ISBN 3-335-00343-8 .