Purification and drying of solvents

The use of appropriately purified solvents is vital to the success of the procedures for which they are used. It is important to note that the degree of purity and dryness required depends on the intended application, so when choosing a method from this chapter remember to pick one which is appropriate for your purpose. Consult Appendix 1 for useful data about commonly used organic solvents. 

Remember that solvents are hazardous materials and beware particularly of the flammability of the hydrocarbons and ethers, the toxicity of benzene, chloroform, and carbon tetrachloride, and the possibility of peroxide contamination of ethereal solvents. 

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All reactions are performed in air. Solvents of analytical purity are used throughout, as further purification and drying are found to have no effect on... 

For solvent purposes various grades of xylenes (the mixture of isomers and ethylbenzene) are available purification and drying procedures are similar to those used for benzene and toluene. For chemical purposes the commercially available pure isomeric xylenes are usually available in at least 99 per cent purity. 

On the whole the choice of solvent is by no means a matter of routine, but requires instead a good deal of judicious thinking along the lines discussed above. One last point worth mentioning, although not related to the solvents chemistry or polarity, is the ease of purification of a given solvent. Considerable work has been carried out by the best schools in the field to establish optimal procedures for the purification and drying... 

The crude product is isolated and initially purified by removal of solvent by rotary evaporation followed by extraction with three small washes of THF (3 X 10 mL) to remove the extremely soluble by-product, K[Lu(CgHg)2]. Final purification and removal of KCl are achieved by transfer of the crude product (- 4.3g) to a Kontes Schlenk Soxhlet extraction apparatus. The apparatus is removed from the dry box and the residue is extracted with THF (60 mL) over a 24-h period on a Schlenk line under argon. During extraction, the pure white product precipitates in the Soxhlet receiver flask. It is isolated in 50% yield (1.73 g) by vacuum filtration in the dry box. Cooling of the light yellow filtrate to — 40 °C does not yield additional microcrystalline product. In practice, it is normally discarded (by removal from the dry box and careful quenching with 2-propanol) since it contains K[Lu(CgHg)2], which has not been removed by the previous purification step. 

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