Decant aqueous layers

By far, the most common prejudice (sometimes completely overlooking the other alternative) is to propose the most volatile composition (low-boiling node) as distillate (Fig. 28). In this region containing the decant aqueous layer, the lightest composition is the ternary azeotrope. With enough stages, all of the azeotropic composition in the decant aqueous layer may be recovered, and the underflow will contain only a binary ethanol-water mixture. If the distillate of... 

Fig. 27. Ethanol dehydration Reachable distillative compositions from decant aqueous layer.

Place 35 ml. of water in the separatory funnel and run it into the vigoroiisly stirred reaction mixture at such a rate that rapid refluxing occurs. Follow this by a cold solution of 15-5 ml. of concentrated sulphuric acid in 135 ml. of water. Two practically clear layers will now be present in the flask. Decant as much as possible of the ethereal layer A) into a 500 ml. round-bottomed flask. Transfer the remainder, including the aqueous layer, into a separatory funnel wash the residual solid with two 10 ml. portions of ether and combine these washings with the liquid in the separatory funnel. Separate the ethereal portion and combine it with (A). Distil off the ether through an efficient fraction-... 

I) The steam distillation may be omitted, if desired, by utilising the following method of purihcation. Allow the reaction mixture to cool, decant the aqueous layer and dissolve the residue in about 150 ml. of benzene. Wash the benzene solution with water, I per cent, sodium hydroxide solution, and finally with water dry with anhydrous magnesium sulphate, distil oft the benzene on a water bath, and distil the residue under diminished pressure. 

Decant the liquid layer into a 2 5 litre flask, and dissolve the sodium derivative of acetylacetone in 1600 ml. of ice water transfer the solution to the flask. Separate the impiue ethyl acetate layer as rapidly as possible extract the aqueous layer with two 200 ml. portions of ether and discard the ethereal extracts. Treat the aqueous layer with ice-cold dilute sulphimic acid (100 g. of concentrated sulphiu-ic acid and 270 g. of crushed ice) until it is just acid to htmus. Extract the diketone from the solution with four 200 ml. portions of ether. Leave the combined ether extracts standing over 40 g. of anhydrous sodium sulphate (or the equivalent quantity of anhydrous magnesium sulphate) for 24 hours in the ice chest. Decant the ether solution into a 1500 ml. round-bottomed flask, shake the desiccant with 100 ml. of sodium-dried ether and add the extract to the ether solution. Distil off the ether on a water bath. Transfer the residue from a Claisen flask with fractionating side arm (Figs. II, 24, 4r-5) collect the fraction boiling between 130° and 139°. Dry this over 5 g. of anhydrous potassium carbonate, remove the desiccant, and redistil from the same flask. Collect the pure acetji-acetone at 134r-136°. The yield is 85 g. 

Note 2. The separation of the layers may give some difficulties, owing to the presence of aluminium hydroxide. Too vigorous shaking during the extraction procedure should be avoided. The best way to separate the layers is to run off as much of the aqueous layer as possible and subsequently decant the ethereal layer. 

After leaving the reactor, the reaction mixture consisting of aniline, water, and excess hydrogen is cooled and condensed prior to the purification steps. First, the excess hydrogen is removed and recycled back to the reactor. The rest of the mixture is sent to the decanter where the water and aniline are separated. The cmde aniline, which contains less than 0.5% of unreacted nitrobenzene and about 5% water, is distilled in the cmde aniline column. The aniline is further dehydrated in the finishing column to yield the purified aniline. Meanwhile, the aqueous layer from the decanter, which contains about 3.5% aniline, is extracted to recover the aniline and clean up the water before it is sent to the waste-water treatment plant. 

When the addition of the nitric acid solution is complete, the reaction mixture is removed from the ice bath and allowed to stand at room temperature for two hours. The flask is then warmed, with shaking, to 50 on a water bath (Note 3) and maintained at that temperature for ten minutes. The cooled reactants are then poured slowly into 800 cc. of ice water and well stirred. About 40 g. of sodium chloride is added, and the aqueous layer is decanted and extracted with 200-250 cc. of a commercial grade of ether. The ethereal extract is added to the residual nitromesitylene, and this ethereal solution is washed... 

To the acid chloride, mechanically stirred and heated on the steam bath, is added 2.5 kg. (805 ml. 15.6 moles) of dry bromine as rapidly as it will react (Note 5). The addition requires about 12 hours. The contents of the flask are stirred and heated an additional 2 hours, transferred to a dropping funnel (Note 6), and added in a thin stream to 5 1. of absolute ethyl alcohol, which has previously been placed in a 12-1. flask provided with a stopper carrying an effleient reflux condenser, a separatory funnel, and a mechanical stirrer. The resulting vigorous reaction is controlled by external cooling. After the dibromoacid chloride has been added, the reaction mixture is allowed to stand at room temperature overnight and is then poured into 5 1. of cold water. The top alcoholic aqueous layer is decanted and extracted once with 8 1. of ether. The oily bottom layer is dissolved in the ether extract, washed first with 1 1. of a 2% sodium bisulfite solution, then with two 1-1. portions of 3% sodium carbonate solution, and finally with several portions of water. The ether solution is dried over 175 g. of potassium carbonate the solvent is distilled on the steam bath. The yield of residual ester (Note 7) amounts to 2260-2400 g. (91-97% of the theoretical amount). 

The wastewater stream of the plant is composed of the off-gas condensate, aqueous layer of the decanter, bottom product of the distillation column and the... 

Pure Commercial Benzene, obtained from coal-tai naphtha, should distil w lthin one degiee (80—Si ), and solidify completely when cooled to 0°. Other tests are as follow s shaken with concentrated sulphuric acid for a few minutes, the acid should not darken, and a drop of bromine water should not be immediately decolourised. A single distillation over a few small pieces of sodium, which absorb any traces of water, is usually a sufficient purification. If the benzene impart a brown or black colour to the sulphuric acid, it must be repeatedly shaken with about 20 per cent, of the acid until the lattev becomes only slightly yellow on standing. This is done in a stoppered separating funnel, and after shaking fora few minutes the mixture is allow ed to settle, and the low er layer of acid diawn off. The benzene is then shaken tw o 01 three times with water to free it from acid, carefully separated from the aqueous layer, and left in contact with fused calcium chloride until the liquid becomes clear. It is then decanted, frozen in ice, and any liquid (carbon bisulphide, paraffins) carefully drained off, and die benzene finally distilled over sodium. 

The distillate is neutralized by means of concentrated HCI, decanted, and the aqueous layer extracted by means of ether. The oily layer and the ethereal extract are mixed, washed with diluted HCI, then with water, and finally dried over sodium sulfate. The solvent Is removed and the residue rectified under reduced pressure. In this way, 130 grams of 2-propyl coumarone are obtained, boiling at 112°C under 17 mm of mercury. 

Chloro-lO-13-(di-N-2-chloroethvl)aminopropvl)lphenthiazine hydrochloride (1.8 g) is heated in a sealed tube for 4 hours at 140°C with a 290 g/l aqueous solution (9 cc) of monomethylpiperazine. The contents of the tube are treated with chloroform (40 cc). The aqueous layer is decanted and the chloroform layer is shaken with N hydrochloric acid (15 cc followed by 2 cc). The aqueous solution is treated with sodium hydroxide (d = 1.33, 10 cc) and chloroform (20 cc). After evaporation of the solvent, the base (1.5 g) is obtained. A solution of maleic acid (1 g) in ethanol (5 cc) is added and after recrystallization from water, 3-chloro-10-13-(4 -methyl-1 -piperazinvDpropyll phenothiazine dimaleate is obtained, melting point 228°C (inst.). 

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