Youngs taps

Peroxide-free tetrahydrofuran (THF) (predried first over KOH pellets followed by sodium wire) and 1,2-dimethoxyethane (dme) (predried over sodium wire) are distilled from sodium benzophenone ketyl and stored under purified nitrogen in Schlenk vessels equipped with Teflon Rotaflo or Young taps. 

Preparation. All glassware must be dried in the oven prior to use. 1,1-Diphenylethene is distilled under reduced pressure (b.p. 113 at 2 mmHg) from a small amount of potassium into a two-necked round-bottomed flask fitted with a septum and connected to the distillation apparatus via a Youngs tap such that the collecting flask can be filled with argon and removed from the distillation apparatus. Carbazole is purified by recrystallization from toluene, followed by methanol, and then sublimed in vacuum. 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8,8,8] hexacosane (Kryptofix 222) is dried by placing the required amount in a round-bottomed flask and heating at 60°C for 24 h. 

Into a dry tube fitted with a Youngs tap and a Quickfit joint (ofthe type used to polymerize butyl acrylate in Protocol 1) is placed a small piece of sodium (about the size of a match-head). The tube is connected to the manifold or a vacuum line, evacuated and a sodium mirror formed (as for potassium above.) The tube is then cooled ( 78°C, dry ice/acetone) and ethylene oxide (ca. 8 mL) is added from the cylinder. The tube is then held at -10°C for 24 h. After this time the liquid is once again connected to the gas-line, frozen (liquid nitrogen), and the tube evacuated. An identical tube containing a sodium mirror is also prepared on the same line and cooled to 78°C. The first tube is allowed to return to room temperature and ethylene oxide is then transferred by virtue of its low vapour pressure. The second tube is then isolated from the system and once again allowed to stand under vacuum for 24 h. 

A stock solution of diethylzinc is prepared in an 80-mL Schlenk tube equipped with a Young s tap by mixing toluene and 99% diethylzinc [(16.5 g, 134 mmol) in a lecture bottle, which is purchased from Aldrich Chemical Company, Inc.] to make a total volume of 30 mL. 

Of particular interest is the consumption of tap water by the young and the elderly, who are likely to be more susceptible to the potential health effects of contaminants (4). Table II shows that children consumed less water than adults did. However, when body weight is taken into account, the amount of water (and hence the quantity of contaminants) consumed is significantly higher in children than in adults. This finding is important not only because the dose of contaminants... 

Herbicidal soaps are most effective on young weeds with tender lenf tissue. They are not very effective against mature perennial weeds, especially those with tap roots. Spray on weeds according to label directions. 

Don t assume that bottled water is necessarily a better option than tap water. Most bottled water is a questionable alternative. Many brands are derived from municipal sources, and some actually contain tap water from major cities. Also, many brands are acidic. Biochemist Robert O. Young conducted a test of more than 60 brands ofbottled water, as well as tap water, to determine the pH of each. The chart below gives a sampling of his findings. As you can see, only the brands shaded in gray are alkaline. Several common brands are acidic. 

Place the benzyl acrylate (2 g, 0.012 mol) and AIBN (0.010 g, 6.1 X 10 mol) in a polymerization tube the add chlorobenzene (20 mL). A protective netting sleeve is then placed over the tube to minimize danger from glass, should the tube shatter. Attach the tube to the manifold and close the Young s tap at the top of the tube. 

Close the Young s tap on the polymerization tube and warm to room temperature. Place the tube in a thermostatted water-bath at 55°C for 18 h. 

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