Flask heating

Assemble the apparatus shown in Fig. 1 V, 67, 1 this is self-explanatory. The distilling flask has a capacity of 250 ml. and the beaker contains 150 ml. of 10 per cent, sodium hydroxide solution. All corks must fit well and should be coated with paraflSn wax (by dipping into molten wax, and allowing to drain). Place half of the yield of the dry phenyldiazonium fluoborate in the distilling flask. Heat the solid gently with a small luminous flame at one point near its surface until decomposition begins withdraw the flame and allow the reaction to continue... 

While the diazotisation is in progress, cautiously add 165 ml. of concentrated sulphuric acid to 150 ml. of water in a 1-litre round-bottomed flask. Heat the mixture just to boiling. Add the supernatant Uquid (diazonium solution) from a separatory funnel supported over the flask at such a rate that the mixture boils very vigorously (about 30 minutes). Then add the residual damp soUd (or suspension) in small portions avoid excessive frothing. When aU the diazonium salt has been introduced, boil for a further 5 minutes and pour the mixture into a 1-Utre beaker... 

Liberate the free base by adding to the phenylhydrazine hydrochloride 125 ml. of 25 per cent, sodium hydroxide solution. Extract the phenyl-hydrazine with two 40 ml. portions of benzene, dry the extracts with 25 g. of sodium hydroxide pellets or with anhydrous potassium carbonate thorough drying is essential if foaming in the subsequent distillation is to be avoided. Most of the benzene may now be distilled under atmospheric pressure, and the residual phenylhydrazine under reduced pressure. For this purpose, fit a small dropping funnel to the main neck of a 100 ml. Claisen flask (which contains a few fragments of porous porcelain) and assemble the rest of the apparatus as in Fig. II, 20, 1, but do not connect the Perkin triangle to the pump. Run in about 40 ml. of the benzene, solution into the flask, heat the latter in an air bath (Fig. II, 5, 3) so that... 

Method 1. Place 20 g. of crude benzoin (preceding Section) and 100 ml. of concentrated nitric acid in a 250 ml. round-bottomed flask. Heat on a boiling water bath (in the fume cupboard) with occasional shaking until the evolution of oxides of nitrogen has ceased (about 1 -5 hours). Pour the reaction mixture into 300-400 ml. of cold water contained in a beaker, stir well until the oil crystallises completely as a yellow solid. Filter the crude benzil at the pump, and wash it thoroughly with water to remove the nitric acid. RecrystaUise from alcohol or methylated spirit (about 2-5 ml. per gram). The yield of pure benzil, m.p. 94-96°, is 19 g. 

Method 2. Intimately mix 99 g. of pure phthahc anhydride and 20 g. of urea, and place the mixture in a 1 litre long-necked, round-bottomed flask. Heat the flask in an oil bath at 130-135°, When the contents have melted, eflfervescence commences and graduaUy increases in vigour after 10-20 minutes, the mixture suddenly froths up to about three times the original volume (this is accompanied by a rise in temperature to 150-160°) and becomes almost sohd. Remove the flame from beneath the bath and allow to cool. Add about 80 ml. of water to disintegrate the sohd in the flask. Alter at the pump, wash with a httle water, and then dry at 100°. The yield of phthahmide, m.p. 233° (i.e., it is practically pure) is 86 g. If desired, the phthahmide may be recrystalhsed from 1200 ml. of methj lated spirit the first crop consists of 34 g. of m.p. 234°, but further quantities may be recovered from the mother hquor. 

Homophthalic acid. Place a mixture of 25 g. of o-carboxyphenylacetonitrile and 25 g. of 50 per cent, sulphuric acid in a 100 ml. flask, heat... 

Ethyl phenylethylmalonate. In a dry 500 ml. round-bottomed flask, fitted with a reflux condenser and guard tube, prepare a solution of sodium ethoxide from 7 0 g. of clean sodium and 150 ml. of super dry ethyl alcohol in the usual manner add 1 5 ml. of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60° and maintain this temperature for 30 minutes. Meanwhile equip a 1 litre threenecked flask with a dropping funnel, a mercury-sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g. of ethyl phenylmalonate and 60 g. of ethyl iodide in the flask. Heat the apparatus in a bath at 80° and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indieator is never more than faintly pink. The addition occupies 2-2 -5 hoius continue the stirring for a fiuther 1 hour at 80°. Allow the flask to cool, equip it for distillation under reduced pressure (water pump) and distil off the alcohol. Add 100 ml. of water to the residue in the flask and extract the ester with three 100 ml. portions of benzene. Dry the combined extracts with anhydrous magnesium sulphate, distil off the benzene at atmospheric pressure and the residue under diminished pressure. C ollect the ethyl phenylethylmalonate at 159-160°/8 mm. The yield is 72 g. 

Diethylene glycol method. Place 0-5 g. of potassium hydroxide pellets, 3 ml. of diethylene glycol and 0 5 ml. of water in a 10 or 25 ml. distilling flask heat the mixture gently until the alkali has dissolved and cool. Add 1-2 g. of the ester and mix well. Fit the flask with a thermometer and a small water-cooled condenser in the usual way. Heat the flask over a small flame whilst shaking gently to mix the contents. When only one liquid phase, or one hquid phase and one solid phase, remains in the flask, heat the mixture more strongly so that the alcohol distils. Identify the alcohol in the distillate by the preparation of the 3 5 dinitrobenzoate (Section 111,27,2). 

Steam distillation.—For small quantities of compounds, which are readily volatile in steam, water may be added to the contents of the reaction flask (e.g. Figs. XII, 2,4 and XII, 2, 11) and the flask heated in an air bath or with a small flame. Alternatively, if preferred, steam may be passed into the reaction flask from a separate generator this may consist of a small conical flask provided with the usual safety tube (compare Fig. II, 40, 1). 

The apparatus illustrated in Fig. 3 is assembled, in a large hood if possible (Note 3). A is a 5- . round-bottom flask heated by a large ring burner and provided with a specially treated four-hole cork stopper covered with tin foil (Note 4). To these holes are fitted the column Z), the tube B reaching to the bottom of A, the specially bent tube C reaching up the inside of D, and the tube K connected with the tubes leading to the 2-I. separatory funnel H, so that the distance between the stopper of A and the stopcock of H is at least 100 cm. The bottom of the column D is of 20 mm. bore while the main portion is 30 mm. The side arm should be at least 85 cm. above the stopper of 4. The tube C... 

This is conveniently done by adding the toluene to the residue in the flask, heating to reflux in an oil bath and then filtering the hot mixture. 

Preparation and Standardisation of Alumina. The activity of alumina depends inversely on its water content, and a sample of poorly active material can be rendered more active by leaving for some time in a round bottomed flask heated up to about 200° in an oil bath or a heating mantle while a slow stream of a dry inert gas is passed through it. Alternatively, it is heated to red heat (380-400°) in an open vessel for 4-6h with... 

A flask heated in an oil bath is fillad with 600 ml water and 60 g (1 mol) glacial acatic acid (or an equivalent quantity of diluted acetic acid). While stirring 235 g (1.1 mols) anhydrous p-aminobenzenesulfonamidoguanidine (or an equivalent quantity of a nonanhydrous product) and 122 g (1 mol) sodium acetylacetonate 100% purity (or an equivalent quantity of product of a lower purity) are introduced into the flask while stirring. 

Add 2.0 g of salicylic acid, 5.0 mL of acetic anhydride, and 5 drops of 85% H3P04 to a 50-mL Erlenmeyer flask. Heat in a water bath at 75°C for 15 minutes. Add cautiously 20 mL of water and transfer to an ice bath at 0°C. Scratch the inside of the flask with a stirring rod to initiate crystallization. Separate aspirin from the solid-liquid mixture by filtering through a Buchner funnel 10 cm in diameter. 

The reaction mixture is then stirred very vigorously and boiled at such a rate that the nitrobenzene condenses in the upper third of the air-cooled reflux condenser and flows back in an almost steady stream. The water formed in the reaction passes over, together with a small amount of nitrobenzene and iodobenzene, and is condensed by the water-cooled condenser. This distillate is freed of water by shaking with a small quantity of sodium sulfate and returned at intervals through the separatory funnel to the reaction flask. Heating is continued for about twenty-four hours or until the reaction is complete, as is evidenced by the non-evolution of water (Note 5). 

The deep red solution is cooled in an ice bath and neutralized by the addition, with shaking, of an ice-cold solution of 15 cc. of concentrated sulfuric acid in 200 cc. of water. The ether layer is separated, washed with water, and dried over sodium sulfate. The ether is removed by dropping the solution from a separatory funnel the stem of which extends to the bottom of an evacuated Claisen flask heated on the steam bath. The residue is a pale yellow oil consisting of a mixture of ethyl a-ethoxalyl-y-phenyl-butyrate and unchanged ethyl oxalate (Note 5). 

To obtain a crystalline product, a solution of the residue in 30 ml. of benzene containing a few drops of triethylamine (Note 4) is placed in a 250-ml. Erlenmeyer flask, heated gently on a steam bath, and diluted with 150 ml. of hexane. Heating is continued for about 5 minutes (Note 5), after which the solution is allowed to cool to room temperature, seeded, and put in a freezer at —15° for at least 5 hours. The resulting solid is collected by suction filtration and washed with cold hexane. After vacuum drying, 5.8 g. (94%) of light cream-colored crystals, m.p. 75-77°, is obtained. 

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