Teflon taps

Isobutylene (Philips Research Grade) was purified as described [17] by distillation on a vacuum line through a trap containing sodium at 350 °C. It was stored as liquid on a sodium mirror. Solutions in methyl bromide were made up by distilling the required quantities of solvent and isobutylene from hanging burettes along a vacuum line into a reservoir with Teflon tap, which was subsequently cut from the vacuum line and fused to a burette with Teflon tap which was then fused to the main vacuum manifold as shown in Figure 1. 

Figure 1 Apparatus for polymerisations. For details see Grattan [9]. The polymerisations and other experiments are done in the conductivity cell E fitted with electrodes, stirrer, thermocouple, phial retainer, and phial breaker. TF1 to TF10 are Rotaflo Teflon taps TF5 goes to the vacuum line, TF6 to the solvent supply line. Bl, B2, B3 are burettes of 1 cm3, 2 cm3 and 20 cm3 capacity, respectively. A is a 50 cm3 flask containing tritiated water, C contains monomer solution, and D contains toluene...

Fig. 12.22. Cell for partial H30+ discharge current (/H) measurements. A, Anodic compartment B, cathodic compartment C, capillary (diameter 0.3 mm) W, water jacket Fe, iron test electrodes E, reference electrode X, T, Z, Teflon taps G, taps for connection with Nichrome furnaces. (Reprinted from J. O M. Bockris, A. Despic, and D. M. Drazic, Electrochim Acta 32 p. 329, copyright 1961, Fig. 1 with permission from Elsevier Science).

A simple piece of equipment which is applicable to a variety of tasks is a 3-way Teflon tap connected to a Quickfit cone joint (Fig. 4.9). 

Add some dry petroleum ether to the apparams and qitickly coimect a Quickfit 3-way Teflon tap to the top. 

Separatory funnels will have glass or Teflon taps with a rubber ring and clip or screw cap on the end to prevent the tap slipping from the barrel, or a... 

For Teflon taps disassemble the tap, wipe the tap and barrel with clean tissue, reassemble without grease, check for free movement of the tap and for leakage as described above. When you have finished using the funnel, loosen the clip/cap on the tap since Teflon will flow under pressure and the tap may seize in the barrel. 

A total of 0.11 g (0.4 mmol) of Ni(cod), is dissolved in 5 ml, of toluene in a lube with a Teflon tap. Then 0.4 mmol of aminophosphinite ligand (D)-FphosNH is dissolved in 5 mL of toluene and 2.0 g of internal standard (heptane or decane) are added. This solution is introduced under N, into the reaction tube and the diene (piperylene) is then added under N2. The tube is then closed and put into a LhermoslalLed bath (40 C) where the solution is stirred with a magnetic stirrer. At the end of the reaction (3 h), the mixture is filtered over silica gel to eliminate the nickel catalyst, and the mixture is analyzed by GC and separated via preparative chromatography and distillation. With 95% conversion of the diene the product contains 16% ( ,Z)-4,5-dimethyI-l,3,6-octatriene (90% ee, NMR) and 12% ( , )-4,5-dimcthyl-l,3,6-octatriene (35 % ee, NMR) besides other (achiral) products. At lower conversions (75% after 0.75 h) the contents of the two chiral isomers are 21 % and 70%, respectively. 

All ground glass joints must be fitted with Teflon sleeves so as to afford a perfect seal, and also to avoid frequent jamming. Likewise, Teflon taps should always be preferred in place of glass taps in the collecting head specifically. 

Figure 5 Marsh s static vapour-pressure apparatus for two volatile components. A, vapour pressure cell B, mercury cut-off manometer C, mercury reservoir T4, Teflon tap in thermostat to control mercury height in manometer Tl, T2, Teflon taps D, ampoule loaders...

Two-necked round-bottomed flask (25 cm ) with a rubber septum in one neck and Teflon tap in the second neck, plus magnetic stirrer bar Two-necked round-bottomed flask (25 cm ) with a rubber septum in one neck and water condenser with rubber septum in the second neck, plus magnetic... 

Amounts of Mo(CO)e (5 g, 0.02 mol) and 200 mL of acetonitrile are placed into a 250-mL round-bottomed Schlenk flask containing a magnetic stirring bar. A silicone oil bath is put in place, and the flask is attached to the nitrogen line. A reflux condenser is put in place and also connected to the nitrogen line via a Teflon tap, making sure that both outlets to the nitrogen line are closed. The... 

Plastic syringe (2 mL) fitted with polypropylene filter frit and Teflon tap. 

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