Dropping funnel

Preparation of Tetryl. Twenty grams of dimethylaniline is dissolved in 240 grams of concentrated sulfuric acid (d. 1.84), the temperature being kept below 25°, and the solution is allowed to run from a separatory funnel drop by drop into 160 grams of 80 per cent nitric acid (d. 1.46), previously warmed to 55° or 60°, while this is stirred continuously and kept at a temperature between 65° and 70°. The addition requires about an hour. After all has been added, the stirring is continued while the temperature of the mixture is maintained at 65° to 70°. The material is allowed to cool the solid matter is collected on an asbestos filter, washed with water, and boiled for an hour with 240 cc. of water while further water is added from time to time to replace that which boils away. The crude tetryl is filtered off, ground under water to pass a 150-mesh sieve, and boiled twice for 4 hours each time with 12 times its weight of water. The solid is dried and treated with benzene sufficient to dissolve all readily soluble material. The solution is filtered and allowed to evaporate spontaneously, and the residue is recrystal-... 

Synthesis of p-chlorophenyldimethylethoxysilane. A 2-liter three-necked round-bottomed flask equipped with a pressure-equalized dropping funnel and a thermometer was flushed with argon and charged with 287 g (1.5 moles) of p-bromochlorobenzene dissolved in 600 ml anhydrous diethylether. The flask was chilled to — 10°C and the solution was stirred with a magnetic stir bar. 400 ml of chilled 2.5 M butyllithium in ether (1 mole) was transferred into the dropping funnel. Drops of butyllithium were added over a period of 3 h, allowing a... 

The heavy colourless dibromide (30 gms.) is now mixed with mete-xylene (30 gms,), and added through a funnel drop by drop to a mixture of sodium (15 gms.) in small pieces, and 70 c.c. of m-xylene. The reaction is vigorous, and if a condenser be fitted to the side-tube of the reaction-flask, the resulting hexamethylene distils over between 70° and 100° this may be refractionated over sodium and that part... 

Sulphuric acid is used in making many other acids. As an example, nitric acid— tremendously important in manufacturing explosives and cellulose films—may be made in your home laboratory, but use a glass retort as nitric acid reacts on cork and rubber. Through a paper funnel, drop 25 grams of sodium nitrate into the retort. Carefully pour 20 cc. of concentrated sul-... 

Bromine in acetic acid (3.1 mL, 0.06 mmol, in 25 mL) is then added from the dropping funnel drop-wise over a period of about 1 h in order to ensure the temperature remains at about 10-15°C. 

Care must be taken to ensure that the liquid from the funnel drops directly into the reaction and not onto the walls of the flask where it will solidify. 

Sometimes the crude substance may contain an insoluble impurity, and on cooling the solution it may be difficult to judge how much of the solid matter is merely undissolved impurity and how much is solute which has subsequently crystallised from solution. To avoid this difficulty, the hot solution should be filtered, and should thus always be absolutely clear before cooling is attempted. Therefore filter the hot solution into a clean tube through a very small fluted filter-paper contained in a correspondingly small glass funnel, which should have had its stem cut off as that shown in Fig. 6, p. 12 (and for the same reason). Unless the upper part of the filter is cut awav to reduce its size to a minimum, a large proportion of the solution will remain held mechanically in the pores of the paper itself and only a few drops of clear filtrate will be obtained. 

Fig. 23(B) shows a modification of the reflux assembly to allow a gas to be passed through the boiling liquid cf. Fischer-Speier esterification, p. 104). The inlet-tube A fits into a three-necked adaptor shown in Fig. 22(J). The stopper B can be replaced by a dropping-funnel, etc.

Fig. 23(E) shows a distillation assembly particularly useful for distilling ether from an ethereal extract. When all the ether has distilled over, the drop-ping-funnel may be replaced by a thermometer for distillation of the residual liquid the adaptor A and the receiver B can then be replaced by the simple adaptor shown in Fig. 23(D) and a flask or bottle of suitable size.

Mix 100 g. of active alumina with dry benzene until a suspension or slurry of suitable consistency is obtained, and pour this carefully into the tube. Clamp a dropping-funnel just above the top of the tube and Fig 2 benzene to run slowly down as the alumina... 

Fit a 500 ml. bolt-head flask F with a well-fitting cork which is free from flaws, and which carries a dropping-funnel D and a delivery tube (or knee-tube ) T, the latter being connected to a water-condenser C (Fig. 52). Attach an adaptor A to the lower end of the condenser. (Alternatively, use a ground-glass flask (Fig. 22(a), p. 43) with a distillation-head (Fig. 22(F)) the dropping-funnel can be fitted into the distillation-head, the side-arm of which is connected to a condenser as in Fig. 23(0), p. 45.)... 

Fit a 50 ml. bolt-head flask F (Fig. 53) with a reflux water-condenser C, to the top of which a dropping-funnel D is fixed by means of a cork having a vertical V-shaped groove G cut or filed in the side to... 

To prepare pure acetylene, assemble the apparatus shown in Fig. 57. F is a wide-necked 300 ml. bolt-head flask, to which is fitted a double-surface reflux water-condenser C and the dropping-funnel D. From the top of C, a delivery-tube leads down to the pneumatic trough T, where the gas can be collected in jars in the usual way. (Alternatively, use the apparatus shown in Fig. 23(A),... 

Ethyl bromide soon distils over, and collects as heavy oily drops under the water in the receiving flask, evaporation of the very volatile distillate being thus prevented. If the mixture in the flask A froths badly, moderate the heating of the sand-bath. When no more oily drops of ethyl bromide come over, pour the contents of the receiving flask into a separating-funnel, and carefully run oflF the heavy lower layer of ethyl bromide. Discard the upper aqueous layer, and return the ethyl bromide to the funnel. Add an equal volume of 10% sodium carbonate solution, cork the funnel securely and shake cautiously. Owing to the presence of hydrobromic and sulphurous acids in the crude ethyl bromide, a brisk evolution of carbon dioxide occurs therefore release the... 

Fit a 500 ml. round-bottomed flask with a dropping-funnel, and with an efficient reflux water-condenser having a calcium chloride guard-tube at the top. 

Place 8 0 g. of magnesium turnings or ribbon and 80 ml. of the dry benzene in the flask. Prepare a solution of 9-0 g. of mercuric chloride in 50 ml. of the dry acetone, transfer it to the dropping-funnel, and then allow it to enter the flask slowly at first, and then more rapidly, so that the addition takes about 3-5 minutes. The reaction usually starts shortly after the initial addition of the mercuric chloride solution if it is delayed, it may then start vigorously, and the flask may have to be cooled in water to prevent escape of acetone through the condenser. 

As the reaction beings to subside, run in from the dropping-funnel without delay a mixture of 25 ml. of acetone and 20 ml. of benzene, in order to maintain a brisk and continuous reaction. When the reaction finally subsides, heat the mixture on a boiling water-bath for 45 minutes with occasional shaking. If the shaking does not break up the spongy mass of magnesium pinacolate,... 

Assemble in a fume-cupboard a 3-necked flask fitted with a stirrer, a reflux condenser, and a dropping-funnel, the apparatus... 

Distil the filtered ethereal solution, using a 100 ml. flask fitted with a dropping-funnel and a side-arm for the condenser observe all the normal precautions for ether distillation (p. 162) and run the ethereal solution into the flask as fast as the ether distils over. When all the ether has distilled off, detach and cool the flask, when the oily colourless residue of saligenin will rapidly crystallise. Weight of product, 5-0 g. m.p. 75-82°. Recrystallise either from a mixture of benzene and petroleum (b.p. 60-80°), or from a minimum of water, allowing the stirred aqueous solution to cool to 65-70° before chilling. The dry crystalline saligenin has m.p. 85-86°. 

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