Toluene bath

For drying at temperatures up to 100°, the water bath or steam oven is generally used. For drying at higher temperatures the air oven is employed, but here a thermometer should be inserted and particular care taken that the substance is not over-heated. A very convenient form of drying apparatus is the toluene bath (p. 38). 

Toluene Bath (Fig. 35).—This bath consists of a double-walled enclosure, access to which is obtained by a hinged door carrying a stout rubber joint. The door is fastened by thumb-screws. Any suitable liquid can be placed in the outer jacket to which is attached a condenser the liquid, however, most generally used is toluene (B.P. 110°). The inner compartment... 

Dry Ice is added to a toluene bath as necessary to obtain the desired temperature. A wet ice-methanol bath may also be used but is somewhat more hazardous because of the violent reaction of triethylaluminum with water and methanol. 

Wet spinning also involves pumping a solution to the spinneret. Now, however, the polymer is precipitated in an immiscible liquid. Polyacrylonitrile in dimethyl formamide, for example, can be precipitated by passing a jet of the solution through a bath of water, which is miscible with the solvent but causes the polymer to coagulate. Cellulose triacetate can be wet-spun from a methylene chloride-alcohol mixture into a toluene bath, where it precipitates. In other fibers, the precipitation can involve a chemical reaction. Viscose rayon is made by regenerating cellulose from a solution of cellulose xanthate. 

Place 146 g. of adipic acid, 360 ml, (285 g.) of absolute ethyl alcohol 180 ml. of toluene and 1 - 5 g. of concentrated sulphuric acid in a 1-litre round-bottomed flask, attach a short fractionating column connected to a downward condenser, and heat in an oil bath at 115°, When the acid... 

Into a 500-ml. bolt head or three-necked fiask, provided with a mechanical stirrer and a reflux condenser, place 60 g. (69 ml.) of thiophene-free toluene (Section 11,47,16) and 60 g. (33 ml.) of concentrated sulphuric acid. Heat the mixture, with stirring, in an oil bath maintained at... 

Mix 1 0 g. of the phenol with 2 5 ml. of pyridine, add 2 g. of p-toluene-sulphonyl chloride, and heat on a water bath for 15 minutes. Pour into 25 ml. of cold water and stir until the oil solidifies. Filter, wash with cold dilute hydrochloric acid (to remove pyridine), with cold dilute sodium hydroxide solution (to remove any phenol present), and then with cold water. Recrystallise from methyl or ethyl alcohol. 

Equip a 1 litre three-necked flask wdth a reflux condenser, a mechanical stirrer, and a cork carrying a dropping funnel and a thermometer which reaches nearly to the bottom of the flask connect the upper end of the condenser to an absorption trap (Fig. II, 8, 1). Place 100 g. of p-bromo-toluene (Section IV.62) in the flask and immerse the latter in an oil bath (colourless oil in a large beaker). Heat the bath until the temperature of the stirred p-broniotoluene reaches 105°. Illuminate the liquid with... 

Y-Phenylbutyric acid. Prepare amalgamated zinc from 120 g. of zinc wool contained in a 1-litre rovmd-bottomed flask (Section 111,50, IS), decant the liquid as completely as possible, and add in the following order 75 ml. of water, 180 ml. of concentrated hydrochloric acid, 100 ml. of pure toluene (1) and 50 g. of p benzoylpropionic acid. Fit the flask with a reflux condenser connected to a gas absorption device (Fig. II, 8, l,c), and boil the reaction mixture vigorously for 30 hours add three or four 50 ml. portions of concentrated hydrochloric acid at approximately six hour intervals during the refluxing period in order to maintain the concentration of the acid. Allow to cool to room temperature and separate the two layers. Dilute the aqueous portion with about 200 ml. of water and extract with three 75 ml. portions of ether. Combine the toluene layer with the ether extracts, wash with water, and dry over anhydrous magnesium or calcium sulphate. Remove the solvents by distillation under diminished pressure on a water bath (compare Fig. II, 37, 1), transfer the residue to a Claisen flask, and distil imder reduced pressure (Fig. II, 19, 1). Collect the y-phenylbutyric acid at 178-181°/19 mm. this solidifies on coohng to a colourless sohd (40 g.) and melts at 47-48°. 

In a 500 ml. bolt-head flask provided with a thermometer (reaching almost to the bottom) and a calcium chloride (or cotton wool) guard tube, place 100 g. of a-bromo-wo-valerj l bromide and 50 g. of dry, finely-divided urea. Start the reaction by warming the flask on a water bath the temperature soon rises to about 80°. Maintain this temperature for about 3 horns the mass will liquefy and then resolidify. Transfer the sticky reaction product to a large beaker containing saturated sodium bicarbonate solution, stir mechanically and add more saturated sodium bicarbonate solution in small quantities until effervescence ceases. Filter at the pump, suck as dry as possible and dry the crude bromural upon filter paper in the air. RecrystaUise the dry product from toluene. Alternatively, recrystaUise the moist product from hot water (ca. 700 ml.). The yield of pure brommal, m.p. 154-155°, is 28 g. 

Aminopyridine. In a 1 litre three-neoked flask, equipped with a sealed mechanical stirrer, reflux condenser, thermometer and inlet tube for nitrogen, place 300 ml. of dry toluene (1) aud 75 g. of fine granular sodamide (2) bubble a steady stream of nitrogen thi ough the toluene. Stir the mixtiue vigorously and heat the flask in an oil bath until the internal temperatime is 110° (the bath temperatime required is approximately 130°). Add 100 g. of pure dry pyridine (compare Section 11,47,22)... 

Osmium s voice In the original patent a continuous, 27 hours extraction with hot toluene was used. This is very impractical. I recommend the following after extraction and removal of the ex traction solvent, dissolve the crude product in 400 - 450 ml hot toluene, put that solution in a beaker and cool it for at least 2 hours in an ice bath. Filter the precipitated product, wash with about 100 ml ice-cold toluene ahd dry at 70°C or in a desiccator to constant weight. Mp. 132.5-134.0°C.]... 

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