Reflux origin

The enrichment of the vapor stream as it passes through the column in contact with reflux is called rectification. It is immaterial where the reflux originates, provided its concentration in low boiler is sufficiently great to give the desired product. The usual source of reflux is the condensate leaving condenser... 

Hydrolysis of the original compound will confirm its identity. Boil 0-5-1 0 g. of the original substance with 10-20 ml. of concentrated hydrochloric acid under reflux for 2 hours ... 

Method 2. Place 90 g. of sodium benzenesulphonate (Section IV,29) (previously dried at 130-140° for 3 hours) and 50 g. of powdered phosphorus pentachloride (1) in a 500 ml. round-bottomed flask furnished with a reflux condenser heat the mixture in an oil bath at 170-180° for 12-15 hours. Every 3 hours remove the flask from the oil bath, allow to cool for 15-20 minutes, stopper and shake thoroughly until the mass becomes pasty. At the end of the heating period, allow the reaction mixture to cool. Pour on to 1 kilo of crushed ice. Extract the crude benzenesulphonyl chloride with 150 ml. of carbon tetrachloride and the aqueous layer with 75 ml. of the same solvent. Remove the solvent under atmospheric pressure and proceed as in Method 1. The yield is about 170 g., but depends upon the purity of the original sodium benzenesulphonate. 

Method 2. Place a mixture of 126-5 g. of benzyl chloride, 76 g. of thiourea and loO ml. of rectified spirit in a 500 ml. round-bottomed flask fitted with a reflux condenser. Warm on a water bath. A sudden exothermic reaction soon occurs and aU the thiourea passes into solution. Reflux the resulting yellow solution for 30 minutes and then cool in ice. Filter off the white crystals and dry in the air upon filter paper. Concentrate the filtrate to half its original volume and thus obtain a further small crop of crystals. The yield of crude hydrochloric acid as in Method 1 the m.p. is raised to 150°, although on some occasions the form, m.p. 175°, separates. 

Fission of ethers with hydriodic acid. Reflux 1 ml. of the compound with 5 ml. of freshly distilled constant b.p. hydriodic acid (b.p. 126-128°) for 2-3 hours in a small flask fitted with a double surface condenser. Add 10 ml. of water, distil and collect about 7 ml. of liquid. Decolourise the distillate by the addition of a little sodium bisulphite and separate the two layers by means of a dropper pipette. If the original compound is suspected to be an aliphatic ether, determine the b.p. of the iodide by the Siwoloboff method (Section 11,12) if the amount of product is insufficient, repeat the original experiment. 

The catalyst commonly used in this method is 5 wt % palladium supported on barium sulfate inhibited with quinoline—sulfur, thiourea, or thiophene to prevent reduction of the product aldehyde. A procedure is found in the Hterature (57). Suitable solvents are toluene, benzene, and xylene used under reflux conditions. Interestingly, it is now thought that Rosenmund s method (59) originally was successful because of the presence of sulfur compounds in the xylene used, since the need for an inhibitor to reduce catalyst activity was not described until three years later (60). 

The design of a plate tower for gas-absorption or gas-stripping operations involves many of the same principles employed in distillation calculations, such as the determination of the number of theoretical plates needed to achieve a specified composition change (see Sec. 13). Distillation differs from gas absorption in that it involves the separation of components based on the distribution of the various substances between a gas phase and a hquid phase when all the components are present in Doth phases. In distillation, the new phase is generated From the original feed mixture by vaporization or condensation of the volatile components, and the separation is achieved by introducing reflux to the top of the tower. 

The original flask used for the enamine formation can be used after the attachment of a Y-shape tube fitted with a dropping funnel and a reflux condenser protected with a tube packed with a drying agent such as anhydrous calcium chloride. 

To extract die EPBC liquids, die plant employs a cryogenic temperature process in combination with a refluxed demedianizer process in two trains. The two turboexpander trains are die heart of die process and bodi have operated at efficiencies higher dian originally expected at die design stage. 

It was then stirred and refluxed for 8 hours. About 400 ml of methanol was distilled out and the remaining solution was evaporated to about one-third its original volume in vacuo and poured into ice water. This mixture was extracted twice with ether, acidified with 6N HCI, and again extracted with ether. The ether extracts were combined, washed with saturated NaCI solution, dried over anhydrous sodium sulfate, and evaporated in vacuo. The residual oil was distilled through a 15 cm Vigreux column, yielding 666 grams of a-methyl-3-phenoxybenzyl alcohol, BP 132° to 134°C (0.35 mm), no = 1.5809. 

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