Ultrasonic Acceleration for the Preparation of Dry Ether and Dry Tetrahydrofuran Dry ether and dry tetrahydrofuran (THF) are routinely used in chemical laboratories. Common practice is to prepare them just before actual use by distilling from nearly dry solvents over sodium metal and using henzophenone ketyl as indicator, Blue-violet coloration, which is an indication of solvent being dry, usually appears after prolonged refluxing on cut sodium pieces and benzophenone. We have found that under sonic vibration generated by a common ultrasonic cleaning bath (Dawe Sonicator operating at 50 kHz) appearence of blue-violet color takes less than 5 min and that a minimum amount of sodium pieces are required (less than 50 mgI100 mL ether once distilled over anhydrous CaCId. Dry solvent can now he distilled directly into the reaction flask after transferring the flask to a preheated oil bath. We hope that this application of ultrasoundl,2 to the preparation of dry solvents, viz., ether and THF, will find routine use.
' Lorimer. J. P.: Mason. T. J. Chem. Soc. Rev. 1987. 16.239. Lindley, J.: Mason, 1.J. Chem. Soc. Rev. 1987, 18, 275.
H. Sulya Prakash Rao Not%-Eastern Hill University Bljnl Complex. Laihlmukhrah Shlliong-793 003 Meghalaya, India
Volume 65
Number 10
October 1988
931
