A Convenient Technique for Transfer ot Air-Sensitive Intermediates
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Douhle-tipped needles offer a convenient method for transfer- ,m, ring air-sensitive liquids. Different techniques utilizing this device have been previously d e ~ i b e dWe . ~ have used a modification of Shriver's double-tipped needle technique3b in our laboratory that allows us to transfer an air-sensitive reaction intermediate, prepared under nitrogen, from one flask into another flask at any desired rate, thus eliminating the need for an addition funnel.' Our apparatus is illustrated partially in the figure. To transfer the solution of the intermediate, first the end of the double-tipped needle in flask 1 is dipped below the liquid level, and then the Haffmann tubing clamp on the nitrogen inlet tubing connecting the flrr I i k kz two flasks is gently tightened. Once the needle is filled with liquid and a small amount of liquid is transferred as the result of the pressure differential, the rate of transfer can be adjusted by the degree t o which the clamp is carefully tightened and by the rate of nitrogen flow as indicated by the ail bubbler. By dipping the end of the needle in flask 1so that it touches the bottom of the flask, the last few drops ofthe solution can be transferred.
Author to whom correspondence should be addressed. Present addreas: Renaslaer Polytechnic Institute, Troy, NY 12180. (a) Kramer, G. W.; Levy, A. B.; Midland, M. M. I n Brown, H. C. Organic Syntheses via Boranes; Wiley: New York, 1915; (b) Shriver, D. F. The Manipulation of Air-Sensitiue Compounds; McGraw-Hill: New York, 1969; (c) Aldricb Technical Information Bulletin Number AL-135, Equipment for Handling Air-Sensitiue Reagents. In our experience, the addition of air-sensitive liquids by means of the conventional funnels with a pressure equalizing connection and glass or Teflon stopcocks, is not conveniently controllable and requires constant manipulation of the stopcock in order to keep the flow a t a constant rate, especially for slow additions. Hamld S. Kamal' and Rlchard E. Taylor2
East Tennessee State University Johnson City, TN 37614
Volume 66
Number 9
September 1989
773
