Kutscher-Steudel apparatus
The Kutscher-Steudel apparatus is a glass device that is used in chemical laboratories for liquid-liquid extraction in cases where repeated shaking in the separating funnel would be too tedious.
history
At the beginning of the 20th century, Friedrich Kutscher and Hermann Steudel in the physiological institute of the University of Marburg “felt compelled to completely remove the ether-soluble components from the meat extract” in order to assess meat extracts , which have been a popular nutrient since Liebig's invention in the 19th century . Since the glass apparatuses that were previously assembled with cork stoppers showed deficiencies, these analysts designed an extraction apparatus that has since been used in many laboratories of organic and physiological (biological) chemistry and named after the inventor.
Working method
Diethyl ether is heated in a boiling vessel . The steam enters the apparatus through an upwardly sloping "knee tube" and finally reaches a reflux condenser , where it is condensed. The drops are caught in a funnel-shaped glass insert with an opening at the bottom. The insert is in a cylindrical vessel in which the previously filled aqueous solution to be extracted is located. At the end of the use, the ether comes into contact with the aqueous solution. The drops move upwards individually because they are specifically lighter than water. On their way they are loaded with the extractable substances and collect over the water phase. As soon as the level of the ether has reached the "knee tube", the organic phase flows back into the boiling vessel, where it is evaporated again. In this way, the substances slowly accumulate in the boiling flask. After cooling, the ether extract can be analyzed analytically.
The Kutscher-Steudel apparatus was developed for the extraction of aqueous solutions with solvents that have a lower density than water, originally diethyl ether, but also, for example, pentane , hexane or ethyl acetate .
The use of the original apparatus (1903) carried a bell-shaped vessel at the bottom that acted as a contact zone for the two liquids. The ether droplets were directed upwards through a glass spiral. In the course of time the apparatus was changed and optimized, but the principle of extraction was retained. After porous sintered glass frits were successfully produced, these were melted at the end of the insert (see illustration). As a result, particularly small droplets of the solvent (with a large surface area) are formed, which migrate upwards and improve the efficiency of the extraction.
Kutscher Steudel apparatus are manufactured in various sizes and offered by several companies. For repeated extraction with specifically heavier solvents such as chloroform , dichloromethane and the like. a. the Wehrli extraction apparatus is usually used.
See also
Individual evidence
- ^ Fr. Kutscher and H. Steudel: Description of an ether extraction apparatus. In: Hoppe-Seyler's Journal for Physiological Chemistry . Volume 39, 1903, pp. 473-476, especially p. 474, doi : 10.1515 / bchm2.1903.39.6.473 .
- ↑ S. Wehrli: An apparatus for the extraction of solutions with heavier solvents. In: Helvetica Chimica Acta . Volume 20, 1937, p. 927.