Thermometers, liquid crystalline

In a 250 ml three-necked flask fitted with stirrer and internal thermometer 11.04 g (0.078 mol) of 2-chloro-l,4-phenylenediamine are dissolved in 150 ml dry N,N-dimethylacetamide (containing 2 wt% LiCl). 29.5 ml (0.233 mol) of highly pure trimethylchlorosilane (>99%) are dropped into the solution under stirring at 20°C. Then 15.71 g (0.078 mol) of terephthaloyl dichloride are added, whereupon the temperature and the solution viscosity increase immediately. After 2 h opaque, lytropic liquid crystalline solution is obtained. This solution is poured into a beaker and water is slowly added to the solution, whereupon the polyamide precipitates. It is washed with water to remove the salt-containing solvent. Finally, the product is purified by extraction with propane-2-ol. The polymer is dried in a vacuum oven at 100°C. The polyamide is characterized by determination of the solution viscosity at 20°C (1.25 g of polymer in 50 ml Af-methylpyrrolidone with 2 wt% of LiCl). 

Tetrahydrofurfuryl chloride. Place 204 g. (194 ml.) of freshly distilled tetrahydrofurfuryl alcohol (b.p. 177°) and 174 g. (178 ml.) of dry pyridine in a 1-litre three-necked flask, fitted with a dropping funnel, mechanical stirrer and thermometer. Cool in an ice bath, stir vigorously and add 250 g. (153 ml.) of freshly distilled thionyl chloride at the rate of 3-5 drops per second. A pasty crystalline mass begins to separate and the temperar ture commences to rise rapidly when one-third to one-half of the thionyl chloride has been added subsequently the mass largely redissolves and a dark brown liquid forms. Remove the ice bath when the addition is complete and stir the mixture for 3-4 hours. Pour the reaction product into a large separatory funnel and extract with seven 250 ml. portions of ether break up any lumps that may form with a glass rod. Remove the ether from the combined extracts by distillation, wash the residue with three 50 ml. portions of water, dry with anhydrous magnesium sulphate and distil under reduced pressure. The yield of tetrahydrofurfuryl chloride, b.p. 47-48°/15 mm., is 180 g. 

In a s-1. flask, fitted with stirrer, dropping funnel, exit tube, and thermometer, is placed 3500 g. (30 moles) of chlorosulfonic acid (Note 1), and to it is slowly added, with continuous stirring, 780 g. (10 moles) of benzene (Note 2), keeping the temperature between 20° and 250 by means of cold water. The hydrogen chloride which is evolved is led to a hood or absorbed in water. The addition requires two to three hours when this is complete, the mixture is stirred for an hour, and poured onto 6-7 kg. of crushed ice (Note 3). One liter of carbon tetrachloride is then added, the oil is separated as soon as possible (Note 4), and the watery layer is shaken with 500 cc. of carbon tetrachloride. The combined oil is washed with dilute sodium carbonate, and the bulk of the carbon tetrachloride is distilled under atmospheric pressure (Note 5) the pressure is then reduced (Note 6) and the benzenesulfochloride collected at ii3-ii5°/io mm. (118-120V15 mm.). The yield is 1320-1360 g. (75-77 per cent of the theoretical amount) of a colorless liquid which on cooling sets to a crystalline solid melting at M H°-... 

In a round-bottomed flask (capacity 1 1.) sodium hydroxide (80 g.) is dissolved by heating in water (80 c.c.), pure phenol (25 g.) is added to the hot solution, and the mixture is cooled to 60°-65° by dipping the flask in cold water, without shaking, however, so that separation of crystalline sodium phenoxide is avoided. By means of a two-holed cork the flask is then fitted with an efficient reflux condenser and a thermometer, the bulb of which dips into the liquid. Chloroform (20 g.) is next poured in through the condenser, and the contents of the flask are gently shaken a transient fuchsine-red colour is developed in the liquid. After a period of about ten minutes, during which the temperature of the mixture is maintained... 

In a 3-1., three-necked, round-bottomed flask fitted with a powerful slow-speed stirrer having a Teflon blade, a 500-ml. dropping funnel, and a thermometer arranged to dip into the liquid is placed 588 g. (366 ml., 6 moles) of concentrated sulfuric acid. The flask is surrounded by an ice-salt mixture, the stirrer started, and 1216 g. (1170 ml., 12 moles) of acetic anhydride (Note 1) is added at such a rate that the temperature does not rise above 20° (Note 2). The separatory funnel is removed and 912 g. (6 moles) of coarsely powdered D,L-camphor is added (Note 3). The flask is then closed with a stopper and stirring is continued until the camphor is dissolved. The stirrer is replaced by a stopper, the ice bath allowed to melt, and the mixture left to stand for 36 hours (Note 4). The camphorsulfonic acid is collected on a suction filter and washed with ether (Note 5). After being dried in a vacuum desiccator at room temperature, the nearly white crystalline product weighs 530-580 g. (38-42%). It melts at 202-203° with rapid decomposition and is relatively pure (Note 6). 

Methylamine Hydrochloride. 125 g of ammonium chloride and 250 g 40% aqueous formaldehyde solution are placed in a distilling apparatus, with the thermometer well below the surface of the liquid. The mixture is slowly heated to 104° and held at this temp until no more liquid distills. The product in the flask is cooled and filtered from ammonium chloride. The liquid is then evaporated on a water bath to half its original volume and a second crop of ammonium chloride is filtered off. The filtrate is concentrated at 10(T until a crystalline scum forms on the surface. On cooling methylamine hydrochloride separates and is removed by filtration. Further evaporation and cooling produces another crop of methylamine hydrochloride, which is also filtered. The combined yield is treated with boiling chloroform, filtering hot, washed with room temp chloroform, and dried in a vacuum desiccator. Yield 40 g. 

Twenty grains of coarse lumps of tin are used and 54g of dry bromine are added from a long-stemmed dropping funnel whose delivery tip reaches to the end of the neck of the reaction flask. The bromine is introduced at such a rate that no brown vapors pass out of the flask the reaction is very vigorous and the metal may burn in the halogen. At the end of the addition a thermometer is inserted and the liquid in the flask is heated just to reflux, in order to drive off any excess bromine. The almost colorless residual product is then distilled the portion boiling at 200-205°C comprises the pure material, which sets eventually to a white crystalline mass (m.p. S3°C) in the receiver. If the tetra-bromide is still colored it may be redistilled and preserved in a sealed container away from moisture. 

The residue from Experiment Mo. 9 may be used, or the compound may be prepared independently as follows Twenty grains of arsenic trioxide are treated dropwise with 2ttml of concentrated nitric add under the hood and the mixture is heated on the steam bath until the evolution of nitrogen oxides is complete. The liquid is decanted from any undissolved made and evaporated just to dryness over a very small flame. The residue is dissolved in 75ml of hot water and filtered by suction if necessary. A thermometer is placed in the filtrate and the latter is evaporated until the viscous liquid has reached a temperature of 130° C. The vessel and contents are transferred to a vacuum desiccator which is placed in the refrigerator an almost solid mass of white crystalline product is obtained. 

Thirty grams of sodium. pentacyanonitrosylferrate (II) 2-hydrate (No. 74) are covered with 120ml of ice-cold water in a 250ml suction flask with a gas-inlet tube and a thermometer. The flask is cooled in an ice-salt bath while a steady stream of ammonia (3 bubbles/sec) is led in under the hood. Csre must be taken that the temperature does not rise above 20°C during this time because decomposition would occur the optimum range is 8-12°C. When no more gas is absorbed at this temperature, (indicated when the level of the liquid fails to rise in the inlet tube as the current of gas is interrupted), the dark yellow-brown solution is allowed to stand at 0°C for about 2 days. The amber-colored crystalline product separates with attendant evolution of gas,... 

Dissolve 30 g (31.5 ml, 0.25 mol) of Af,/V-dimethylaniline in 105 ml of concentrated hydrochloric acid contained in a 600-ml beaker, and add finely crushed ice until the temperature falls below 5°C. Stir the contents of the beaker mechanically (or, less satisfactorily, with a thermometer) and slowly add (c. 10 minutes) a solution of 18 g (0.26 mol) of sodium nitrite in 30 ml of water from a separatory funnel, the stem of which dips beneath the surface of the liquid. Maintain the temperature below 8°C by the addition of ice, if necessary. When all the nitrite solution has been added, allow the mixture to stand for 1 hour, filter the yellow crystalline p-nitrosodimethylaniline hydrochloride at the pump, wash it with 40 ml of dilute hydrochloric acid (1 1), drain well and finally wash with a little alcohol. The yield is good and depends upon the purity of the original dimethylaniline. If the pure hydrochloride is required, it may be recrystallised from hot water in the presence of a little dilute hydrochloric acid yellow needles, m.p. 177 °C. Recrystallisation is, however, unnecessary if the free base is to be prepared. 

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