Flask stoppers

Dissolve 9-5 g. of hydrazobenzene (Section IV,87) in the minimum volume of ether (about 90 ml. are usually required), and add this solution in small portions from a separatory funnel to 100 ml. of ice-cold dilute hydrochloric acid (1 1) contained in a 350 ml. conical flask stopper the flask and shake after each addition. Benzidine hydrochloride separates out during the reaction. After all the hydrazobenzene has been introduced, add 50 ml. of concentrated hydrochloric acid and allow the mixture to stand for 30 minutes in ice water. Filter the benzidine hydrochloride at the pump, wash it first with 20 ml. of dilute hydrochloric acid (1 1) and then with two or three 20 ml. portions of ether (to dissolve any unchanged hydrazobenzene) (1). 

An alternative procedure, which does not require ice cooling, is to add all the 10 ml. of benzoyl chloride rapidly to a mixture of 50 ml. of concentrated ammonia solution and 60 ml. of water contained in a 200 ml. conical flask, stopper securely and shake vigorously for about 15 minutes. Heat is evolved So that the stopper should be held down tightly. After 30 minutes the benzamide is filtered off and worked up as above. 

Flaschen-hals, m. neck of a bottle or flask. -inhalt, m. contents of a bottle or flask or gas cylinder, -kappe, -kapsel, /. bottle cap. -kiirbis, m. bottle gourd calabash. -achild n. bottle (flask, etc.) label, -stdpsel, -ver-schluss, m. bottle (or flask) stopper or fastener, -zug, m. set of pulleys, block and tackle. 

In a one-liter separatory funnel, 94 g (0.215 mol) of scopolamine hydrobromide trihydrate was dissolved in 250 ml of water, made alkaline by shaking with 40 g (1 mol) of sodium hydroxide in 150 ml of water, and the free base immediately extracted with ether. As scopolamine is somewhat soluble in water, the aqueous layer was saturated with potassium carbonate and again extracted with ether. The combined ether extracts were dried over anhydrous magnesium sulfate and the ether removed by distillation, leaving 65 g (0.214 mol 100% yield) of nearly colorless oil. Then 100 g (1.05 mols) of cold methyl bromide was added to a chilled, 500-ml pressure flask containing the 65 g of scopolamine, the flask stoppered tightly with a clamp, and allowed to stand at room temperature for 96 hours. 

Given 62.371 g = Erlenmeyer flask + stopper 4.4 mL of volatile liquid 101.1°C boiling water bath = 374.1 K 63.088 g = flask, stopper, condensed vapor 261.9 mL = volume of stoppered flask 733 mm Hg = barometric pressure... 

Stuck but good And you can probably kiss your flask, stopper, product and grade goodbye ... 

Weigh 5.00 g of each soil sample to be tested into dry 50-mL Erlenmeyer flasks. Pipet 20 mL of extracting solution into each flask. Stopper and shake on a shaker for at least 20 min. 

Powdered 4 A molecular sieves (2.0 g) and PDC (2.5 g, 6.65 mmol) were placed in a 100 mL round-bottomed flask equipped with a magnetic stirrer bar and then stoppered with a rubber septum under nitrogen. A solution of 2, 3 -diisobutyl acetal (2) (1.0 g, 2.28 mmol) in dry CH2CI2 (60 mL) in a 100 mL round-bottomed flask stoppered with a rubber septum was transferred to the above-mentioned lOOmL round-bottomed flask via a glass syringe. The mixture was stirred at room temperature for 12 h. 

Ethyl isobutyrylisobutyrate. Add 24-6 g. (28-3 ml.) of ethyl iso-butyrate, b.p. 110-111°, to the solution of ca. 0 21 mol of sodium triphenyl-methide in approximately 1400 ml. of ether contained in the 2-litre conical flask. Stopper the flask, shake well to effect complete mixing, and keep at room temperature for 60 hours. Acidify the reaction mixture by adding, with shaking, 15 ml. of glacial acetic acid, and then extract with 100 ml. of water. Wash the ethereal solution with 50 ml. portions of 10 per cent, sodium carbonate solution until free from excess acid, dry over anhydrous magnesium sulphate, and distil off the ether on a steam bath. Distil the residue under reduced pressure from a Claisen flask with fractionating side arm (Figs. II, 24, 4—5). Collect the ethyl isobutyryl isobutyrate at 95-96°/18 mm. the yield is 15 g. The b.p. at atmospheric pressure is 201-202°. 

To prepare a 0.1 M glucose solution, weigh 18.02 g of glucose and transfer to a 1-liter volumetric flask. Add about 700-800 mL of purified water and swirl to dissolve. Then add water so that the bottom of the meniscus is at the etched line on the flask. Stopper and mix well. The flask must be labeled with solution contents (0.1 M glucose), date prepared, and name of preparer. 

A 25-mL Erlenmeyer flask, a standard Pyrex watch glass and a 1000-W micro-wave are used to carry out the microwave synthesis. 0.43 mL of benzaldehyde 1 and 0.3 mL of pyrrole 2 are mixed in the flask. Once the reactants are thoroughly mixed 0.63 g of silica gel is added, the flask stoppered, and the reagents mixed well until the silica gel is evenly and completely covered with the reactant mixture. The flask containing the reaction mixture is then placed in the micro-wave oven, covered with the watch glass and heated for 10 min in five 2-min intervals. Once the reaction is complete, it is allowed to cool to room temperature and ca. 15 mL of ethyl acetate added. The solution is filtered to remove the silica gel and then the ethyl acetate is removed using a rotary evaporator. Prior to... 

Add 5 g (4.8 ml, 0.034 mol) of dimethyl succinate to 25 ml of concentrated ammonia solution (dO.88) in a 100-ml conical flask. Stopper the flask and shake the contents for a few minutes allow to stand for 24 hours with occasional shaking. Filter off the crystals of succinamide, and wash with a little cold water. Recrystallise from a little hot water and dry in an oven. The yield is 3.5 g (88%). Pure succinamide melts at 254 °C with decomposition. 

Cognate preparation. Acetone cyanohydrin. Dissolve 110 g of sodium metabisulphite in 200 ml of cold water contained in a 1-litre round-bottomed flask. Add slowly 58 g of acetone while swirling the liquid mixture slowly, followed by a solution of 60 g of potassium cyanide in 200 ml of cold water (CAUTION). During this latter slow addition the cyanohydrin separates as the upper layer. When separation is complete the contents of the flask are transferred to a separatory funnel and the lower layer removed. The upper layer is transferred to a flask, sodium sulphate added to effect drying and the flask stoppered and kept in the dark. The dried cyanohydrin (60 g, 70%) is slightly discoloured it may be distilled under reduced pressure when it distils at 80-82°C/15mmHg. 

Next the material from the filter flask is poured over the tin and the 1-1. flask stoppered with the one-hole stopper. The temperature in the water bath is maintained at 25 2° and the reduction continued for exactly 2 hours. During this time the reduction solution will go from blue to purple to reddish-brown or green. Shortly before the reduction is over, a stoppered, 500-ml. Erlenmeyer flask is packed in crushed ice in a Dewar jug. The air in the flask is displaced with hydrogen chloride gas to avoid air oxidation. When the reduction is finished, the solution is decanted into the 500-ml. flask, the remaining tin being drained. This tin can be washed and reused. The reduction solution is resaturated with hydrogen chloride gas. (This step requires... 

Two and four tenths grams of d-cts-dinitrobis (ethylene-diamine) cobalt (III) bromide (3.4 X 10-3 mol) is suspended in 35 ml. of water in a 100-ml. conical flask. Freshly precipitated silver chloride (6 g.) is added, the mixture heated to 50 to 60°, and the flask stoppered and shaken vigorously for 4 to 5 minutes. The mixture is kept at about 50 to 60° during this time by warming periodically. The mixture is filtered and the silver halide precipitate washed with 5 ml. of warm water. Four grams of potassium ethylenedia-... 

Carefully measure 5cm of magnesium ribbon and grip it below the flask stopper as shown. 

Decant the cell suspension into a 250-mL Erlenmeyer flask, leaving the sand behind. Cool the solution to room temperature. Add 5 mL of 6 M NaC104 solution and mix well. Transfer 40 mL of the chloroform-isopentyl alcohol mixture into the flask. Stopper the flask with a cork. Shake it for 10 min., sloshing the contents from side to side once every 15 sec. A frothy emulsion will form. After 10 min., let the emulsion settle. 

The Stopper Plug. There are two types of ground stoppers reagent bottle stoppers and flask stoppers. They have the same 1 10 taper as the joints previously mentioned, however, they are listed by only one number based on their width measurement (see Fig. 3.7). Both stopper types have a flattened disk above the ground section for easy holding. Because the term pennyhead stoppers can refer to either reagent or flask stoppers, a complete description of the stopper you want is important for complete identification. 

Flask stoppers come in widths (sizes) that are different from other joints and stoppers therefore, flask stoppers are not interchangeable with joints or stoppers (see Table 3.2). 

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