Stirring, magnetic

Mention must also be made of magnetic stirring. A rotating field of magnetic force is employed to induce variable speed stirring action within either closed or open vessels. The stirring is accomplished with... 

Many forms and sizes of magnetic stirring apparatus are available commercially. These include those fitted with an electric hot plate attached to the flat top the hot plate is controlled by an energy regulator or variable transformer (Variac). 

Synthesis of Alkviamines. General Procedures. Method (A). The synthesis of p-phenethylamine is representative. A flame dried, nitrogen-flushed, 100 ml flask, equipped with a septum inlet, magnetic stirring bar and reflux condenser ivas cooled to 0°C. Sodium borohydride (9.5 mmol, 0.36 g) was placed in the flask followed by sequential addition of THF (13-15 ml) and BF3-Et20 (12 mmol, 1.5 ml) at 0°C. After the addition, the ice bath was removed and the contents were stirred at room temperature for 15 min. The solution... 

A suspension of 7.5 grams LAH in 500ml anhydrous Et20 was magnetically stirred, and heated in an inert atmosphere to a gentle reflux. The condensing Et20 leached out a total of 9.8 g 2-nitro-... 

Apparatus 200-ml round-bottomed, three-necked flask provided with a gas inlet, a thermometer and a gas outlet magnetic stirring. 

In hydrodynamic voltammetry the solution is stirred either by using a magnetic stir bar or by rotating the electrode. Because the solution is stirred, a dropping mercury electrode cannot be used and is replaced with a solid electrode. Both linear potential scans or potential pulses can be applied. 

In bofh CW and pulsed lasers fhe dye solution musf be kepf moving to prevenf overheating and decomposition. In a pulsed laser fhe dye is continuously flowed fhrough fhe confaining cell. Alternatively, magnetic stirring may be adequate for low repetition rates and relatively low power. In a CW laser fhe dye solution is usually in fhe form of a jef flowing rapidly across fhe laser cavify. 

A. p-Methoxyphenyllead triaaetate. A 1-L Erlenmeyer flask, equipped with a magnetic stirring bar, is charged with 50 g (0.11 moll of lead tetraacetate (Note 1), chloroform (200 mL), and 140 g (1.09 moll of dichloroacetic acid (Note 21. To this solution is added 16 g (0.15 mol) of anisole (Note 3), and the mixture is stirred at 25°C until lead tetraacetate can no longer be detected (Note 41. The reaction mixture is washed with water (2 x 250 mil and the chloroform solution is treated with 1.5 L of hexane (Note 51. The yellow... 

B. Ethyl l-( p-methoxyphenyl I-2-oxoayotohexaneaar hoxylate. A 250 mL, one-necked, round-bottomed flask, equipped with a magnetic stirring bar, is charged with 22.2 g (45 mmol) of p-methoxyphenyl 1 ead triacetate, 10.8 g (135 mmol) of pyridine (Note 8), and 70 mL of chloroform (Note 9). To this solution 1s added 7.0 g (41 mmol) of ethyl 2-oxocyclohexanecarboxylate (Note 10), a calcium chloride drying tube Is put 1n place, and the mixture is stirred at 40°C (Note 11). 

A. E)-(2-Methyl-l,3-butadienyl)dimethylalane. An oven-dried, 1-L, twonecked, round-bottomed flask equipped with a magnetic stirring bar, a rubber septum, and an outlet connected to a mercury bubbler is charged with 7.01 g (24 mmol) of dichlorob1s(n -cyclopentadienyl)z1rconium (Note 2) and flushed with nitrogen. To this are added sequentially at 0 C 100 mL of 1,2-d1chloro-ethane (Note 3), 12.48 g (120 mtiol) of a 5016 solution of l-buten-3-yne in... 

A. (zi- -Bromostyrene. In a 1-L, round-bottomed flask equipped with a magnetic stirring bar are placed 30.8 g (0.100 mol) of er tlir<3-a,g-dibrorao-g-phenylpropionic acid (Note 1), 13.0 g (0.200 mol) of sodiun azide (Note 2),... 

A dry 1-L, three-necked, round-bottomed flask equipped with a large Teflon-covered magnetic stirring bar, a thermometer, and a dry ice condenser (Note 1) is flushed with argon (Note 2), then capped with a serun stopper and subsequently maintained under a positive pressure of argon (Note 3). A 30 dispersion of lithium metal (in mineral oil) containing 1% sodium (13.9 g, 2.00 g-atom of lithium) (Note 4) is rapidly weighed and transferred to the flask. 

A. 2,2-Dimethyl-4-pentenal. In a SOO-mL, one-necked, round-bottomed flask which contains a magnetic stirring bar are placed 108 g (1.5 mol) of 1 sobutyraldehyde (Note 1), 58 g (1.0 mol) of ally alcohol (Note 1), 230 ml of p-cymene (Note 1), and 0.4 g (2 mnol) of p-toluenesulfonic acid nonohydrate... 

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