Pyrex tube

Anthracene has also been crystd from EtOH, chromatographed through alumina in hot benzene (fume hood) and then vac sublimed in a pyrex tube that has been cleaned and baked at 100°. (For further details see Craig and Rajikan J Chem Soc, Faraday Trans 1 74 292 1978 and Williams and Zboinski J Chem Soc, Faraday Trans 1 74 611 1978.) It has been chromatographed on alumina, recrystd from n-hexane and sublimed under reduced pressure. [Saltiel J Am Chem Soc 108 2674 1986 Masnori et al. J Am Chem Soc 108 1126 1986.] Alternatively, it was recrystd from cyclohexane, chromatographed on alumina with n-hexane as eluent, and recrystd two more times [Saltiel et al. J Am Chem Soc 109 1209 1987]. 

Arsenic [7440-38-2] M 74.9, m 816°. Heated under vacuum at 350° to sublime oxides, then sealed in a Pyrex tube under vacuum and sublimed at 600°, the arsenic condensing in the cooler parts of the tube. Stored under vacuum [Shih and Peretti J Am Chem Soc 75 608 1953], POISONOUS. 

A heavy-walled Pyrex tube with a suitable lip can be sealed with a metal bottle cap and capper available at many hardware stores (Fig. A3.8). This vessel is suitable for reactions at moderate pressure only (for example, benzene heated to 100°). 

A reaction vessel as shown in Fig. 1 is made from Pyrex tubing (Note 1). The vessel is evacuated and the stopcock closed. A 500-ml. round-bottomed two-necked flask equipped with a gas inlet and a cold finger condenser containing dry ice is charged with 1 g. of finely powdered 4,4 -bis(dimethylamino)benzophenone... 

Apparatus. Mercury electrode. The electrode, together with the essential dimensions, is shown in Fig. 15.8 it is easily constructed from Pyrex tubing. 

Diazidonaphthalene. Pale yel crysts, mp 95—100° with decompn prepd by the bis-diazotation of 1,8-diajninonaphthalene followed by treatment with Na azide (Ref 5). It has been patented as a photosens ingredient in a photocopying process (Ref 6) 2,3-Diazidonaphthalene. Needles from petr eth (bp 40—60°), mp 63—4° prepd in five steps starting with 3-amino-2-naphthoic acid. Its pyrolysis in a Pyrex tube at 400° gave... 

PET powder was prepared from commercial PET bottles and had a number-average molecular weight of 30,000. PET powder (0.2 g) was placed in 30 mL of relatively dilute sulfuric acid (10 M) in a sealed Pyrex tube and heated to 150°C for 1-6 h in an oven. After the reaction mixture was allowed to cool, the precipitate of TPA and PET residue deposited was filtered through a 1G-5 glass filter. TPA was separated as the ammonium salt by dissolving it in 12 mL of 5 M NH3. The TPA was reprecipitated by sulfuric acid solution. The yield of TPA was 100% in 10 M sulfuric acid solution. 

Figure 10.6. Electrochemical cell (1) reference electrode, (2) molten catalyst, (3) porous Pyrex membrane, (4) counter electrode, (5) gas inlet Pyrex tube, (6) working electrode.12 Reproduced by permission of the Electrochemical Society.

The Pyrex tube was suspended, with capillary down, in a small-holed rubber stopper which, in turn, was fastened to a goniometer head by a length of stout copper wire. The solid material within the capillary was photographed in a cold room (4°C.) using copper x-radiation, a camera with radius 5 cm., and oscillation range 30°. The effective camera radius was established by superimposing a powder spectrum of NaCl during an exposure of the sample the lattice constant for NaCl at 4°C. was taken to be 5.634 A. 

The meltings occurred in Pyrex tubes under a vacuum of about 10-5 mm. Hg. The uniformity of the reguli with respect to composition was achieved by two measures first, the alloys were kept in the molten state about 100° C. above their melting-points for more than 2 hr. and secondly, effective agitation was provided by a magnetically driven stirring device. 

The four tellurium compounds are obtained as polycrystalline samples by annealing stoichiometric amounts of the elements in sealed silica or Pyrex tubes at temperatures between 280 (AuTel) and 350°C... 

It should be pointed out however that there is no proof for the intermediate formation of free radicals and other mechanisms may explain the product distribution equally well. Such an alternative may be an ionic mechanism, possibly catalyzed by impurities or the walls of the container. In the above experiments Pyrex tubes were used [64]. 

Diaphragm discharge is a liquid phase discharge at ambient temperature and atmospheric pressure [9], The reactor configuration, as shown in Fig. 1 [10], consists of Pyrex tube and a pair of electrodes set in the liquid fuel. The insulated teflon-membrane (diaphragm membrane), with its single pinhole, is placed in the gap of electrodes. 

The end of the Pyrex tube that is to carry the wires is heated and shaped with tongs as shown in Figure 40,1 or II. The desired number... 

After scratching, 26 s.w.g. (or thicker) Nichrome wire is wrapped once round the scratch, which is wetted. The wire is heated to redness electrically, and kept taut round the glass—for this purpose it is convenient to have insulated handles on the wire. The tubing may then crack smoothly if not, it may be induced to crack by touching the scratch with wetted asbestos when the wire has been hot for about half a minute. An internally scratched Pyrex tube may not crack until it is put in a flame. 

When making a seal the tungsten rod is first beaded as with Pyrex. The bead of the special glass may either be fused directly into Pyrex (Figure 38,1) or first fused into a tube of the same glass and this tube cut near to the seal and fused to a Pyrex tube (Figure 38, It). 

The recoveries from air were evaluated by spiking known quantities into Pyrex tubes and then passing air through the tube and collection on two Chromosorb tubes in series. Recoveries in the first Chromosorb mbe were typically >97%. The recoveries obtained from fortified Chromosorb tubes ranged from 89 to 101%. The LOD was 0.5ngL when air was sampled at 1.5Lmin for 2h. 

Thermal-programmed solid insertion probe mass spectrometry (TP-SIP-MS) has been proposed [247,248], in which the solid insertion probe consisting of a water-cooled microfumace enters the mass spectrometer via an airlock. The sample is contained in a small Pyrex tube (i.d. 1 mm, length 20 mm). The TIC trace gives a characteristic evolved gas profile for each compound in a mixture of materials, and the mass spectra associated with each TIC peak give a positive identification of that component as it is vaporised. TP-SIP-MS is appropriate for analysis of small solid particles which are volatile, or produce volatile decomposition products. The technique is a form of evolved gas analysis. 

The eutectics examined and their melting points are given in Table 3.1. The compounds were melted in 10 mm inner diameter pyrex tubes, and polished sections were prepared from the solidified eutectic samples. 

The condenser, attached to the flask by a ground-glass joint, is a Pyrex tube 50 cm. long and 20 mm. in internal diameter, wound with No. 26 Nichrome wire covered with asbestos paper. It is connected to a variable transformer and adjusted so as to maintain a temperature of 100-110°. A copper Liebig condenser heated by steam is also suitable provided that the inner tube has a diameter of about 20 mm. 

Levenspiel and Smith Chem. Eng. Sci., 6 (227), 1957] have reported the data below for a residence time experiment involving a length of 2.85 cm diameter pyrex tubing. A volume of KMn04 solution that would fill 2.54 cm of the tube was rapidly injected into a water stream with a linear velocity of 35.7 cm/sec. A photoelectric cell 2.74 m downstream from the injection point is used to monitor the local KMn04 concentration. Use slope, variance, and maximum concentration approaches to determine the dispersion parameter. What is the mean residence time of the fluid ... 

In the preparation of 2-(tricarbonylferra)hexaborane(10) by co-pyrolysis of the reactants in a hot-cold Pyrex tube reactor, the latter was severely etched and weakened, sometimes splintering. At 230° a maximum cumulative service life of 4 months was observed, and at 260°C the reactor was replaced at the first signs of etching, usually after 6 runs. 

Figure 3s UV autoclave (after Gascard and Saus /A/) a magnetic stirrer, b autoclave lid, c connection to thermostat, d = pressure-stable quartz tube, e autoclave housing, f = quartz or Pyrex tube, g - lamp, h gas entrance and sampling valve, i = gas outlet.

Into a size 6A porcelain boat (88 X 13 X 10 mm.) is placed 10.0 g. (0.0113 mol) of Ag2ReBr6 (as much as 15 g. may be processed readily), and the boat is positioned near the sealed end of a 25 X 300 mm. Pyrex tube fitted with an inner 29/44 S.T. sleeve joint. The tube is connected to a mechanical vacuum pump (capable of reducing the pressure to ca. 50 p) via either a trap cooled by liquid nitrogen or a trap cooled by a Dry Ice-isopropyl alcohol slush, which is in turn connected to an 11-mm. Vycor combustion tube packed with copper gauze and maintained at 600° by means of a furnace. (Either protective system between the tube and the pump will serve to remove bromine, one of the reaction products.)... 

The reactions were carried out in sealed Pyrex tubes employing a prototype single-mode microwave cavity. The reagents were added to the resin-bound aryl halide under a nitrogen atmosphere and irradiated for the time periods indicated (Scheme 7.14). Rather short reaction times provided almost quantitative conversions, with minimal degradation of the solid support. 

Using conventional heating each step involved heating at 170 °C for 10 min, giving an overall radiochemical yield of 40-60%. In contrast, MW heating in a closed Pyrex tube gave a radioactivity gain of 91 % in a total reaction time of 1 min. 

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