Schlenk tubes design

Figure 2. (a) The original design for a Schlenk tube, (b) A modern Schlenk tube with grease-free joint and valve and pear-shaped chamber to facilitate stirring and solvent removal under vacuum. 

The common principle on which these containers are based is that they can be evacuated and so opened that an inert gas flow protects the opening from air. Their design is based on the Schlenk tube, which was devised for such purposes. 

Due to the design of a Schlenk tube, this must generally be of a larger volume than the corresponding round-bottomed flask for a reaction of a given scale. 

This is a modification and extension of the preparation given by Manzer. Using the general procedures just described, a quantity of N,N-2-trimethylaniline (3.37 g, 25 mol) is placed in a Schlenk tube, and to this is added hexane (50 mL), diethyl ether (2mL), and 2.5M of butyllithium in hexane (24 mmol, 10 mL). The serum cap is replaced by a reflux condenser, which is connected to a nitrogen gas line and an oil bubbler that is suitably designed to prevent build up of internal pressure. The mixture is refluxed for 10 h. After cooling to room temperature, the precipitate is filtered off under inert atmosphere. Yield 2.8 g (79%). H NMR in THF-dg ( PPm) NMc2 2.50 (6H) CHjLi 1.48 (2H) aryl-H 5.65 (IH), 6.30 (2H) and 7.00 (IH). 

Fig. 4.3. Solvent storage tubes with Teflon valves, (a) The O-ring joint on the sidearm allows attachment to a vacuum line equipped with O-ring joints, (b) Same basic design as in (a) with a straight sidearm. This design is easily connected to a Schlenk line via Tygon or other flexible tubing that fits over the sidearm.

Fig. 5.3. Wayda-Dye greaseless vacuum line. This apparatus makes extensive use of metal bellows tubing and O-ring seals. Thus the reaction vessels, filters, and other items can be tilted and manipu lated like Schlenk ware, and high vacuum conditions can be achieved for the removal of atmospheric gases and for baking out residual moisture. Trap to-trap distillation of volatile solvents such as NH) or SO is readily accomplished with this apparatus. This version is not designed for the measurement of volatiles or trap-to-trap separation. (Reproduced from A.L. Way da and J. L. Dye, J. Chent. Educ. 62, 356 (1985) by permission of the copyright owner the Division of Chemical Education of the American Chemical Society.)...

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