Funnel glass

Cylinders, graduated mixing with ground-glass joints and stoppers, 50-, 250-mL Flasks, round-bottom with 24/40 ground-glass joint, 500-mL Flasks, volumeAic, Class A, various sizes Funnels, glass... 

A suspension of 10.0 g (0.026 mole) of [[2-methyl-l-(l-oxopropoxy)propoxy] (4-phenylbutyl)phosphinyl]acetic acid in 50 ml of isopropyl ether was stirred vigorously for 15 min, then kept at 5°C for 20 hours. The colorless product was filtered, washed with a small amount of cold isopropyl ether to give 5.0 g of [[2-methyl-l-(l-oxopropoxy)propoxy](4-phenylbutyl)phosphinyl]acetic acid (A/B isomer, racemic mixture), m.p. 87-89°C. The filtrate was evaporated in vacuo and retained for isolation of isomer C/D. A solution of the above material in 110 ml of hot isopropyl ether was filtered through a hot glass funnel (glass wool). The cooled solution gave 4.6 g (92%) of desired product, m.p. 90-92°C. 

Funnels. Glass appropriate size to accommodate filter paper (12.5 cm). 

Six large test tubes with stand, hard white cardboard, long-stem funnels (glass or polyethylene, filter paper, two glass bottles, safety glasses, protective gloves. 

X-ray absorption. Assembled tubes must have sufficiently high x-ray absorption to meet federal standards. Lead is generally used in neck and funnel glass for good electrical properties as well as radiation absorption (see Sec. 6.2.3.5, Radiation-absorbing glasses ) it is not used as much in the panel glass (screen) because it browns under irradiation. 

We note here that CTV neck and funnel glasses often contain between 20 and 30 wt% PbO. Because of the tendeney for electron browning mentioned in Sec. 6.1.2.2, current panel glasses contain less than 5 percent PbO, and sometimes none. Barium oxide (BaO), strontium oxide (SrO), and zirconium oxide (ZrOj) provide the required magnitude of x-ray absorption. Tables 6.7 and 6.8 show compositions and properties for several commercial TV panel glasses. 

For the filtration of small quantities of dilute solution, it is often possible to dispense with the outer heater, and use the ordinary glass funnel which has been heated above a flame immediately before use. 

Sometimes the crude substance may contain an insoluble impurity, and on cooling the solution it may be difficult to judge how much of the solid matter is merely undissolved impurity and how much is solute which has subsequently crystallised from solution. To avoid this difficulty, the hot solution should be filtered, and should thus always be absolutely clear before cooling is attempted. Therefore filter the hot solution into a clean tube through a very small fluted filter-paper contained in a correspondingly small glass funnel, which should have had its stem cut off as that shown in Fig. 6, p. 12 (and for the same reason). Unless the upper part of the filter is cut awav to reduce its size to a minimum, a large proportion of the solution will remain held mechanically in the pores of the paper itself and only a few drops of clear filtrate will be obtained. 

For the filtration of very small quantities of crystals, the simple apparatus shown in Fig. 46 is often used. It consists of a fine glass rod (sometimes termed a filtration nail ) which is flattened at one end, the flattened surface being preferably roughened. It fits as shown into a small funnel which replaces F (Fig. 45). A circular piece of filter-paper is cut e-g.y with a clean sharp cork-borer) so as to fit completely and snugly over the flat end. After draining, the nail is raised and the filter-paper and crystals are removed with forceps and dried. 

Fit a 500 ml. bolt-head flask F with a well-fitting cork which is free from flaws, and which carries a dropping-funnel D and a delivery tube (or knee-tube ) T, the latter being connected to a water-condenser C (Fig. 52). Attach an adaptor A to the lower end of the condenser. (Alternatively, use a ground-glass flask (Fig. 22(a), p. 43) with a distillation-head (Fig. 22(F)) the dropping-funnel can be fitted into the distillation-head, the side-arm of which is connected to a condenser as in Fig. 23(0), p. 45.)... 

Place 0 5 ml. of the pyridine in a 200 ml. round- or flat-bottomed flask and add 34 ml. (30 g.) of benzene. Fit the flask with a reflux water-condenser, and then place it in a cold water-bath. If the experiment is conducted in a fume-cupboard, the top of the condenser can be closed with a calcium chloride tube bent downwards (as in Fig. 61, p. 105 or in Fig. 23(A), p. 45, where the outlet-tube A will carry the calcium chloride tube) and the hydrogen bromide subsequently allowed to escape if, however, the experiment is performed in the open laboratory, fit to the top of the condenser (or to the outlet-tube A) a glass delivery-tube which leads through a piece of rubber tubing to an inverted glass funnel, the rim of which dips just below the surface of some water... 

Filter the product at the pump, using an alkali-resisting filter-paper, or a sintered glass filter-funnel. Wash the crystals on the filter with a small quantity of ethanol to remove the purple colour, and then drain thoroughly. 

Add dil. H2SO4 until the solution is acid to litmus. Cool, and scratch the sides of the vessel with a glass rod a white precipitate indicates an aromatic carboxylic acid or uric acid, or a solid phenol insoluble in water (e.g., i- or 2-naphthol). If a precipitate is obtained, filter off through a Buchner funnel, wash with water, recrystallise if necessary and identify. 

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