Wasserfreier

Wasserfreier is a German term used to describe a substance that contains no water or only negligible amounts of it. In scientific and industrial contexts it corresponds to the English term anhydrous and is applied to solvents, reagents, and other materials that have been dried and kept moisture-free. The word contrasts with terms such as wasserhaltig or feucht, which indicate water presence above a defined threshold.

In chemistry, pharmaceuticals, and related fields, wasserfreier materials are important to prevent hydrolysis, unwanted reactions, or degradation that water could trigger. Solvents and reagents are often described as wasserfrei when their water content has been reduced to very low levels and maintained under dry conditions. Labels may specify a target moisture content, sometimes measured by Karl Fischer titration, with typical values given in parts per million or percent.

Producing wasserfreier substances involves drying techniques such as azeotropic distillation, use of desiccants (for example molecular sieves, calcium oxide, or phosphorus pentoxide), vacuum drying, or freeze-drying for certain solids. Quality control may include moisture determinations and loss on drying to verify adherence to the required dryness.

Applications span chemical synthesis, catalysis, electronics manufacturing (where dry environments are crucial), pharmaceuticals, and food processing areas where moisture control enhances stability and performance. Etymologically, wasserfrei derives from Wasser (water) and frei (free), and in German technical usage functions as an adjective describing materials that are prepared, stored, or used without appreciable water content.