Stirrer Hershberg

A useful stirrer—sometimes termed a Hershberg stirrer— Fig. 11,7,5. for efficient agitation in round-bottomed vessels, even of... 

The mercury-sealed stirrer is of the Hershberg type made of tantalum wire. 

In a 500 ml. three-necked flask, equipped with a thermometer, a sealed Hershberg stirrer and a reflux condenser, place 32-5 g. of phosphoric oxide and add 115-5 g. (67-5 ml.) of 85 per cent, orthophosphoric acid (1). When the stirred mixture has cooled to room temperature, introduce 166 g. of potassium iodide and 22-5 g. of redistilled 1 4-butanediol (b.p. 228-230° or 133-135°/18 mm.). Heat the mixture with stirring at 100-120° for 4 hours. Cool the stirred mixture to room temperature and add 75 ml. of water and 125 ml. of ether. Separate the ethereal layer, decolourise it by shaking with 25 ml. of 10 per cent, sodium thiosulphate solution, wash with 100 ml. of cold, saturated sodium chloride solution, and dry with anhydrous magnesium sulphate. Remove the ether by flash distillation (Section 11,13 compare Fig. II, 13, 4) on a steam bath and distil the residue from a Claisen flask with fractionating side arm under diminished pressure. Collect the 1 4-diiodobutane at 110°/6 mm. the yield is 65 g. 

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked flask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of diinethylform-amide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts as described above the 3ueld of product, m.p. 124-125°, is 11 - 5 g. 

Into a 1-litre three-necked flask, equipped with a reflux (double surface) condenser, a mechanical stirrer (preferably of the Hershberg type. Fig. II, 7, 8) and a gas lead-in tube extending to near the bottom of the flask, place 200 g. (227 ml.) of dry benzene, 20 g. of paraformaldehyde (1) and 20 g. of finely-pulverised, anhydrous zinc chloride. Support the flask on a water bath so arranged that the level of the water in it is about... 

Equip a 500 ml. three-necked flask with an efficient stirrer (e.g., a Hershberg stirrer. Fig. II, 7, 8) and a reflux condenser stopper the third neck. Place a solution of 30 g. of sodium hydroxide in 100 ml. of water, and also 20-5 g. (17-1 ml.) of pure nitrobenzene in the flask, immerse it in a water bath maintained at 55-60°, and add 21 g. of anhydrous dextrose in small portions, with continuous stirring, during 1 hour. Then heat on a boiUng water bath for 2 hours. Pour the hot mixture into a 1 litre round-bottomed flask and steam distil (Fig. II, 40, 1) to remove aniline and nitrobenzene. When the distillate is clear (i.e., after about 1 htre has been collected), pour the residue into a beaker cooled in an ice bath. The azoxybenzene soon sohdifies. Filter with suction, grind the lumps of azoxybenzene in a mortar, wash with water, and dry upon filter paper or upon a porous plate. The yield of material, m.p. 35-35-5°, is 13 g. Recrystallise from 7 ml. of rectified spirit or of methyl alcohol the m.p. is raised to 36°. ... 

Place a mixture of 125 ml. of A.R. benzene and 32 -5 g. of di-re-butyl d-tartrate (1) in a 500 ml. three-uccked flask, equipped with a Hershberg stirrer (Section 11,7) and a thermometer. Stir the mixture rapidly and add 58 g. of lead tetra-acetate (Section 11,50,15) in small portions over a period of 20 minutes whilst maintaining the temperature below 30° by occasional cooling with cold water. Continue the stirring for a further 60 minutes. Separate the salts by suction filtration and wash with two... 

I. The Hershberg stirrer, shown in part in Fig. 2, provides very efficient agitation of this or other pasty mixture. Two glass rings are sealed to the end of a stirrer shaft at right angles to one another, and each is threaded with B. and S. No. 18... 

The checkers employed a Mixmaster -type motor and a Hershberg stirrer made from tantalum wire. 

The apparatus consists of a 3-1. three-necked round-bottomed creased flask, with standard ball joints and an indented cone-shaped bottom (Note 1), which is heated by means of an electric mantle and is equipped with a high-speecT stirrer of stainless steel driven by a 10,000 r.p.m. motor (Note 2). One side neck is fitted with a bulb-type air-cooled condenser (Note 3), on top of which fits a 1-1. pressure-equalizing Hershberg dropping funnel (Note 4). The top of the dropping funnel is to be connected in turn to a U-tube containing a 1-cm. head of mercury. The entire apparatus is securely fastened to a sturdy support. 

Any sealed mechanical stirrer may be used. Those of the Hershberg type were found particularly efficient during the formation of the sodium amide. 

Dana2ol was prepared from 4.32 grams of 17a-ethynyl-2-hydroxymethylene-4-androsten-17(3-ol-3-one, 1.00 gram of hydroxylamine hydrochloride, 1.12 grams of fused sodium acetate and 135 ml of acetic acid. To a 500 ml, 3-necked flask, equipped with a sealed Hershberg-type stirrer, a reflux condenser and a stopper, was added the above androstenone derivative in 300 ml of 95% ethanol. Stirring was commenced and a slurry of fused sodium acetate and hydroxylamine hydrochloride in glacial acetic acid was added. 

In a 3-1. three-necked flask, equipped with a mercury-sealed Hershberg stirrer, a dropping funnel, and a reflux condenser protected with a calcium chloride tube, is placed 67 g. (0.5 mole) of powdered anhydrous aluminum chloride. The flask is cooled in an ice bath, 500 ml. of dry ether is slowly added from the... 

Since the mixture tends to foam toward the end of the reaction, it is advisable to use an effective stirrer. A Hershberg stirrer (Org. Syn. 17, 3i) of tantalum wire gave good service in the hands of the checkers, and the metal was not appreciably attacked after repeated use. 

It is necessary to provide an efficient stirrer driven by a powerful motor. The yields reported were obtained using a Hershberg Chromel wire stirrer (Org. Syn. 17, 31) with other stirrers the yields were lower by about 10 per cent. 

A. 2-BromoaUylhexamimum bromide. A 2-1. three-necked flask fitted with a Hershberg stirrer,2 a dropping funnel, and a condenser is charged with a solution of 154 g. (1.10 moles) of hexamethylenetetramine (Note 11 in 1250 ml. of chloroform. The solution is stirred and heated under reflux while 200 g. (1.00 mole) of 2,3-dibromopropene (Note 2) is added dropwise over a period of 1 hour. Precipitation of the product is noted soon after the first addition of 2,3-dibromopropene. After the addition is complete, the reaction mixture is stirred under reflux for 3 hours and allowed to stand overnight. The mixture is cooled in an ice bath, and the salt is collected by suction filtration. After air-... 

A 2-1. three-necked round-bottomed flask in an electric heating mantle is fitted with a mercury-sealed Hershberg stirrer, a dropping funnel, and an efficient reflux condenser topped with a tube containing soda lime and calcium chloride. In this flask are placed 21.3 g. (0.56 mole) of pulverized lithium aluminum hydride (Note 1) and 300 ml. of dry ether. The mixture is heated under reflux until most of the hydride has dissolved. A solution... 

In a 1-1. three-necked round-bottomed flask equipped with a Hershberg stirrer, a thermometer, and a 250-ml. dropping funnel are placed 80 g. (0.666 mole) of acetophenone, 60 ml. of ether, and 100 ml. of water. The apparatus is assembled in a well-ventilated hood, the flask is surrounded by an ice-salt bath, and 82 g. (1.67 moles) of granulated sodium cyanide is added all at once with vigorous stirring. When most of the sodium cyanide has dissolved and the temperature of the mixture has fallen to 5°, 140 ml. (1.7 moles) of concentrated hydrochloric acid is... 

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