Extraction stopcock, Teflon

After the Teflon stopcock is closed, the reaction vessel is transferred to a water bath maintained at 60°. The lower end of the vessel should be immersed to within about 1 in. below the fritted-glass retainer. As refluxing of the bromine proceeds, a liquid layer should accumulate above the fritted-glass retainer. If this does not happen, some bromine should be poured through the bypass arm so that a liquid layer ca. 1 in. thick is maintained on the frit. It is essential that liquid bromine contact the tribromide in order to attain efficient conversion to tetrabromide. As the reaction proceeds, the product, dissolved in liquid bromine, extracts into the lower vessel and deposits there as fine black crystals. 

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. 

Stock solutions of 5% APCD (Fisher Scientific) are made daily in distilled deionized water and extracted at least three times with MIBK. Seawater samples are stored in acid-soaked, deionized, water-rinsed polypropylene bottles. All reagents used were reagent grade or the highest grade readily available. Polypropylene graduated cylinders and separatory funnel stoppers and Teflon stopcocks were used in all cases. 

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