Liquid air traps

Di-tert-butyl peroxide (tert-butyl peroxide) [110-05-4] M 146.2, d 0.794, n 1.389. Washed with aqueous AgN03 to remove olefinic impurities, water and dried (MgS04). Freed from /cr/-butyl hydroperoxide by passage through an alumina column [Jackson et al. J Am Chem Soc 107 208 1985], and if necessary two high vacuum distns from room temp to a liquid-air trap [Offenbach and Tobolsky J Am Chem Soc 79 278 1957]. The necessary protection from EXPLOSION should be used. 

The prepared flask is supported so that the tube B can be sealed to a vacuum system. If a suitable furnace is available the flask is surrounded by this, with the constriction A still within reach of the hand torch flame otherwise the heating must be done by flame. A liquid air trap is included between the flask and diffusion pump. With a vacuuih of below 10 mm of mercury the temperature of the flask is raised to near the softening point—the heating may be rapid... 

The Dewar seal is important and useful, although a ring seal can sometimes be substituted in simple apparatus—as, for example, in the cold finger liquid air trap shown in Figure 52, III. In the making... 

The catalyst was used in the form of a wire sealed down the axis of a cylindrical reaction vessel and care was taken to prevent its contamination, by baking it out and using a liquid air trap. Instead of the usual... 

This main bulb was connected to a second bulb containing a modern ion gauge which measures or records gas pressures in a fraction of a second. It can measure pressures from about 10" ° to 10" mm. The system was connected to a liquid air trap and mercury diffusion pump through a movable glass plate with a small hole. The effective area of this hole was 0.010 cm. , and the pump speed was 0.12 liter/sec. This pump speed could be increased more than tenfold by removing the glass plate. 

The checker found that carrying out the reaction in a copper tube made the location of the hot zone impossible after the reaction had been running for a few minutes. Consequently, the gaseous reactant was admitted until the exit end of the reaction tube again approached room temperature. It was assumed that most of the excess carbon monoxide was swept through the liquid air trap by the flow of the inert gas. 

Calculation of the pressure from the weight gain can be readily made. The interpretation of this pressure should be made clear. It is the approximate pressure in a system consisting of a source (the walls of the ceramic tube) and three sinks (namely, the mercury pumps, the liquid air trap, and the specimen of zirconium). No intention is made to relate this pressure to the pressure in the system without the zirconium specimen. 

Conventional methods of analysis were used to determine (a) the amount of metal deposited, (b) the undissociated halide sublimed onto the reaction tube, and (c) the halogen or hydrogen halide collected in the liquid air trap which followed the reaction tube in the flow system. 

Neon gas at 0.1-mm. mercury pressure was circulated over a tungsten wire 18 cm. X 0.0066 cm. sealed in tube A. Charcoal traps B cooled in liquid air protected the wire from oxygen, and a liquid air trap was inserted between the wire and the McLeod gauge. A standard current could be passed through the wire, raising its temperature about 20° above that of a bath surrounding A. The resistance of the wire, and hence its temperature Tt, was determined by a Wheatstone bridge. An additional circuit allowed the wire to be flashed for a short time at 2500° K. to remove adsorbed Aims. 

The tube is connected via a liquid air trap to a vacuum apparatus. The best results are obtained when a film of sodium is distilled over the inside of the tube, to act as a trap for oxygen. The whole reaction tube is normally immersed in liquid air. The filaments may be heated electrically by separate circuits, and an additional circuit allows a potential to be applied between the two wires and the associated thermionic current to be measured. 

The oxidation of humulone is performed either in the solid state or on Celite in aqueous suspension. The highest yield of volatile oxidation products is obtained by stirring humulone (10 g) in a closed vessel (1 I) under oxygen at 100°C during 10 h. At 30-minutes time intervals the volatile components are collected in a liquid air trap and the humulone-containing vessel is afterwards filled with oxygen again (60). 

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