Addition funnel glass joint

A. Preparation of a-bromoisobutyryl bromide. To a mixture of 250 g. (2.85 moles) of isobutyric acid and 35 g. (1.13 moles) of red phosphorus in a 1-1. three-necked flask, fitted by ground-glass joints to a dropping funnel, mechanical stirrer, and reflux condenser, is added, dropwise with stirring, 880 g. (5.5 moles) of bromine. After the addition is complete, the solution is warmed to 100° over a period of 6 hours. The unreacted bromine and hydrogen bromide are removed under reduced pressure (30 mm.). The a-bromoisobutyryl bromide is decanted from the phosphorous acid and fractionated through a short helices-packed column. After a considerable fore-cut, the main fraction, 493-540 g. (75-83%), is collected at 91-98° (100 mm.). 

The stem on a sep funnel can either be straight or have a ground glass joint on the end (Fig. 53). The ground glass joint fits the other jointware you may have and can be used that way as an addition funnel to add liquids or solutions... 

So a compromise was reached (Fig. 856). Since you ll probably do more extractions than additions, with or without reflux, the pressure-equalizing tube went out, but the ground glass joint stayed on. Extractions no problem. The nature of the stem is unimportant. But during additions, you ll have to take the responsibility to see that nasty vacuum buildup doesn t occur. You can remove the stopper every so often or put a drying tube and inlet adapter in place of the stopper. The latter keeps moisture out and prevents vacuum buildup inside the funnel. 

Modified Parfait Protocol. Teflon adsorbents were cleaned by 24-h extraction with acetone in a Soxhlet apparatus and stored in acetone. Cleaned Chromosorb T was used to fill a 150-mL silanized addition funnel equipped with a 24-40 male joint on the bottom. A plug of silanized glass wool supported the bed just above the stopcock. The Teflon bed was compressed slightly with a large stirring rod to keep the top of the bed in place while the bed was washed with at least 6 bed volumes (900 mL) of high-purity water. The washed Teflon was kept covered with water and used immediately. 

A 250-ml, three-necked, round-bottomed flask (to which is attached at the bottom a coarse-sintered-glass frit, a Teflon stopcock, and a standard-taper male joint) is equipped with a 100-ml pressure-equalizing addition funnel, a reflux condenser, and a Tru-bore glass mechanical stirrer with a Teflon blade. The system is flushed with dry nitrogen via a gas inlet in the addition funnel and a gas outlet in the condenser, leading to a mineral-oil bubbler. Magnesium turnings (3.5 g, 0.144 mole) and 100 ml of sodium-dried diethyl ether... 

Instead of stopping the reaction and opening the apparatus, you can put in the new chemicals using an addition or dropping funnel. Addition funnels are separatory funnels (see p. 119) with a ground-glass joint on the stem, and there are two types (Fig. 16.5) ... 

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