Needle, double-ended technique

An alternative to the syringe technique for the transfer of liquids uses the double-ended needle and is suitable when it is not necessary to know precisely the volume of liquid being transferred, or when the volume is being measured in some other way, e.g. by transfer from a septum-capped measuring cylinder. This... 

Fig. 18.7 Transfer of air-sensitive reagents using the double-ended needle technique.

Ethereal methyllithium from methyl chloride added slowly under N2 with Dry Ice-acetone cooling via the double-ended needle technique (s. H. C. Brown et al., Organic syntheses via boranes, Wiley, 1975, p. 210) to a mixture of B-ethyl-9-borabicyclo[3.3.1]nonane and dry pentane, stirred 10 min. at -78°, allowed to come to room temp., stirred 1.5 hrs., water-cooled, acetyl chloride added drop-wise from a syringe, and stirred ca. 2 hrs. -> c/>y-bicyclo[3.3.0]oct-l-ylethylmethyl-borane (Y 97%) treated with alkaline HgOg in tetrahydrofuran cw-bicyclo-[3.3.0]octan-l-ol (Y 95%). - The above rearrangement by a variety of reducible compds. (in the above case acetyl chloride, which is converted into ethyl acetate) furnishes many compds. containing the d5 -bicyclo[3.3.0]oct-l-yl moiety whidi have previously been difficult to prepare. F. e. s. G. W. Kramer and H. C. Brown, Am. Soc. 98, 1964 (1976) one-pot procedure s. J. Org. Chem. 42, 2832 (1977). 

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