Schlenk vacuum line

The complexes described below are extremely air and moisture sensitive. Therefore, the syntheses are conducted under nitrogen with rigorous exclusion of air and water by using Schlenk, vacuum line, and glove box techniques. Caution. Tetrahydrofuran and toluene are harmful if inhaled or absorbed through the skin. They should be handled in a well-ventilated fume hood, and gloves should be worn. THF forms explosive peroxides only fresh, peroxide-free material should be distilled. Potassium hydride removed from oil suspension and KC Mej are pyrophoric they should be manipulated in an inert atmosphere only. The compound l,2-C2H l2 is heat and light sensitive, as well as sublimable. 

All manipulations of compounds were carried out using standard Schlenk, vacuum line, and glovebox techniques. Pentane, diethyl ether, tetrahydrofuran, and toluene... 

The complexes described below are extremely air and moisture sensitive. Therefore, the syntheses are conducted under nitrogen with rigorous exclusion of air and water by using Schlenk, vacuum-line, and glove-box techniques. ... 

The procedures described are conducted under an inert atmosphere using either Schlenk-vacuum-line or dry-box techniques. An argon atmosphere is recommended for the reduction reactions because of the facile formation of low valent tungsten dinitrogen complexes. Solvents must be free of oxygen and water. Toluene and tetrahydroliiran (THF) are distilled from CaH2 or sodium benzophenone. Pentane is distilled from n-butyl lithium or CaHj. Dichloromethane is distilled from CaHj or P4O10. 

Today, the glassware required consists of either a round-bottom flask or a Schlenk tube serving as the reaction chamber. This chamber is equipped with a magnetic stirbar and a Teflon high-vacuum valve (or glass stopcock) which provides for easy vacuum control after attachment to a vacuum line (Fig. 8.7). 

Not only the preparation of so far unknown compounds, but also the development of new synthesis techniques such as the Schlenk technique and vacuum-line technique which allow the handling and manipulation of air- and moisture-sensitive, pyrophoric compounds, are the most striking breakthroughs of their fascinating work. 

Some of the procedures described in the following chapters had to be carried out under an inert atmosphere, nitrogen or argon, to minimize contact with oxygen and moisture. It is then necessary to use Schlenk techniques including the utilization of a vacuum line connected to a high vacuum pump and an inert gas inlet. The use of such equipment requires experience in working under anhydrous conditions. 

Specifically, the glass connection between the Schlenk tube receiver (C) and stopcock (D) should extend about 130 mm below the top of the 24/40 standard taper inner joint and approximately 50 mm into Dewar flask (E) to prevent loss of the especially volatile V(CO)e to the vacuum line during the reaction and sublimation. The Schlenk tube receiver is cooled to about —70°C with dry ice/acetone or dry ice/isopropyl alcohol. The level of coolant should be near the top of the Dewar so that the glass connection between the stopcock (D) and the Schlenk tube is entirely covered. The apparatus is evacuated very slowly and cautiously... 

Vacuum-lines, Schlenk and Glovebox Techniques. Manipulations involving materials sensitive to air or water vapour can be carried out by these procedures. Vacuum-line methods make use of quantitative transfers, and P(pressure)-V(volume)-T(temperature) measurements, of gases, and trap-to-trap separations of volatile substances. 

The syntheses of the precursors were carried out following procedures reported in the literature. All methods used distilled solvents, an argon filled glove box or Schlenk type glassware connected to a vacuum line. Thermoanalytical studies were carried out on a Setaram TG-DTA 92 analyzer in line with a Leybold Heraeus QX 2000 quadrupolar mass spectrometer. 

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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