Solvent Purification

UV-transparent solvents are essential for spectroscopy below 300 nm. Classical methods of purifying solvents for UV spectroscopy are very timeconsuming and complex. This is not the case when using adsorption filtration. UV-transparent solvents can be quickly and easily prepared from solvents of ordinary analytical purity. Moreover, they are less sensitive to air and thus more stable.

A sample of 300 ml analytical grade n-hexane or pre-purified (by shaking with sulfuric acid to remove alkenes or olefines) technical grade cyclohexane is simply filtered without suction through a column (25 mm I.D. and 250 mm height) filled with 150 g Alumina Basic, Act. I (Cat.# 15640). The filtrate is anhydrous and can immediately be used.

Technical grade cyclohexane, which is not pre-purified, can easily be purified by filtering through a combined Silica Gel, Active, 60 Å, 63-200 μm/Alumina Basic, Act. I column. A column (25 mm I.D. and 400 mm height) is first filled with 100 g Alumina Basic, Act. I (Cat.# 15640) and on top of this,100 g of Silica Gel, Active, 60 Å, 63-200 μm (Cat.# 10840) is added. Then the crude cyclohexane is dripped through. Purified cyclohexane is anhydrous.

Depending on the kind of impurities, which depends on the origin and the nature of the solvent, the solvent can be filtered through a column filled with Silica Gel, Active, 60 Å, 63-200 μm, Alumina (Acid, Neutral or Basic), Act. I, or a combination of the two with the alumina section of the column above the silica gel section of the column. The following table gives recommendations on the amount and type of adsorbent to be used as well as the solvent yield and obtained purity.