Steam distillation

Evaporation and Distillation. Steam is used to supply heat to most evaporation (qv) and distillation (qv) processes, such as ia sugar-juice processiag and alcohol distillation. In evaporation, pure solvent is removed and a low volatiUty solute is concentrated. Distillation transfers lower boiling components from the Hquid to the vapor phase. The vapors are then condensed to recover the desired components. In steam distillation, the steam is admitted iato direct coatact with the solutioa to be evaporated and the flow of steam to the condenser is used to transport distillates of low volatiHty. In evaporation of concentrated solutions, there may be substantial boiling poiat elevation. For example, the boiling poiat of an 80% NaOH solution at atmospheric pressure is 226°C. 

The refining process most commonly used involves treatment with hot aqueous alkaH to convert free fatty acids to soaps, followed by bleaching, usually with hydrogen peroxide, although sodium chlorite, sodium hypochlorite, and ozone have also been used. Other techniques include distillation, steam stripping, neutralization by alkaH, Hquid thermal diffusion, and the use of active adsorbents, eg, charcoal and bentonite, and solvent fractionation... 

A solution of 10 g (0.023 mole) of cholesteryl acetate (mp 112-114°) in ether (50 ml) is mixed with a solution containing 8.4 g (0.046 mole) of monoperphthalic acid (Chapter 17, Section II) in 250 ml of ether. The solution is maintained at reflux for 6 hours, following which the solvent is removed by distillation (steam bath). The residue is dried under vacuum and digested with 250 ml of dry chloroform. Filtration of the mixture gives 6.7 g of phthalic acid (87% recovery). The solvent is evaporated from the filtrate under reduced pressure and the residue is crystallized from 30 ml of methanol, giving 6.0 g (58% yield) of -cholesteryl oxide acetate. Recrystallization affords the pure product, mp 111-112°. Concentration of the filtrate yields 1.55 g (15% yield) of a-cholesteryl oxide acetate which has a mp of 101-103° after crystallization from ethanol. 

For example, for steam (saturated vapor, no liquid) distillation with one organic compound (liquid), there are two phases, two components, and two degrees of freedom. These degrees of freedom that can be set for the system could be (1) temperature and (2) pressure or (1) temperature and/or (2) concentration of the s) stem components, or either (1) pressure and (2) concentration. In steam distillation steam may be developed from water present, so there would be both a liquid water and a vapor phase water (steam) present. For such a case, the degrees of freedom are F = 2 + 2- 3 = l. 

If an emulsion has formed, it may be broken by acidifying with hydrochloric acid, whereupon two clear layers are obtained. The benzene solution may be dried and then fractionated or preferably, it may be steam distilled. In the latter case it is transferred to a r-1. Claisen flask, the flask is set in an oil bath (Note 3) and the benzene distilled. Steam is then passed in, and after the last of the benzene is removed, the p-bromodi-phenyl distils with the steam. The temperature of the oil bath is held at 170° in order to hasten the distillation. The product solidifies in the condenser and receiving flask. There is obtained 23-24 g. of -bromodiphenyl which melts at 85-86.5°. 

In steam distillation, steam is introduced into the column to lower the partial pressure of the volatile components. It is used for the distillation of heat sensitive products and for compounds with a high boiling point. It is an alternative to vacuum distillation. The products must be immiscible with water. Some steam will normally be allowed to condense to provide the heat required for the distillation. Live steam can be injected... 

External Steam Distillation Internal Steam Distillation Steam Distillation Notes... 

Methods have been described for the determination of total fatty acids in raw sewage sludge. These methods [30-32] require a concentration steps such as simple distillation, steam distillation, evaporation, or extraction [33-35] which resulted in great losses of the volatile matter [36, 37],... 

To the reaction flask is added 200 ml. of ethanolamine, and it is heated to 140° with stirring. The slurry above is added in moderate portions over a 40- to 50-minute period (Note 7). When the heating bath is maintained at 230-240°, the addition of the slurry should provide an inner temperature at 120-140° as the water and oily product distill. After the addition is complete, the dropping funnel is rinsed with 100-150 ml. of water. As soon as the inner temperature has reached 160°, 50 ml. of ethanolamine is added and the temperature is maintained at 160-170° for 20 minutes. Water (50 ml.) is added through the dropping funnel to initiate a rapid steam distillation. Steam distillation is continued by the addition of 50-ml. portions of water at an inner temperature of 120-140° and a bath temperature of 230-240° until no more oil appears in the distillate (Note 8). 

Steam heat. It is very easy to produce and can be used safely for so many things steam distillations, steam cleaning, creating a vacuum, etc. No lab should be without it. Make sure that steam does not get into anhydrous or dry reactions. 

Provide the points as necessary (distillator, steam generator, tanks DIW, etc.). 

Batch Distillation Evaporation and Condensation Continuous Distillation Fractionation Rectification Reflux Distillation Vacuum Distillation Steam Distillation Azeotropic Extractive Distillation Destructive Distillation Molecular Distillation Distillation by Compression and Sublimation)... 

Disodium 1,2 ethanedithiol, 39, 23 Disodium monohydrogen phosphate dodecahydrate, 34, 83, 37, 74 Distillation, steam, of p dithiane,... 

A 500 kg batch had been prepared in glacial acetic acid using 35% aqueous hydrogen peroxide with 2% sulfuric acid as catalyst. When the reaction was complete, solvents were removed by vacuum distillation, steam was turned off and the reaction vessel... 

After the removal of the benzene by distillation, steam is passed into the residue (flask in oil bath at 150-175°). The 4-methylbiphenyl which comes over solidifies readily. After distillation at atmospheric pressure (b.p. 267-268°), it weighs 38 g. (22%) and melts at 47°. Vacuum distillation is recommended forworking up larger quantities. The product from three runs (321 g. of p-toluidine) is distilled at 20 mm. pressure. The fraction boiling at 145-153° is nearly pure 4-methylbiphenyl yield, 109 g. (21%). 

If the solution so obtained is distilled, steam and hydrochloric acid pass off at first, later a mixture of hydrochloric acid and antimony trichloride, and finally pure antimony trichloride. 

In steam distillation, steam - which is water vapour - is passed through the plant material at high pressure. Constituents that are insoluble in the water... 

Step C Preparation of -2-ThiopheruMehyde). To the reaction mixture described under Step A is added enough 10% sodium hydroxide to r e the of the mixture to 5-6.5, preferably 6.0-6.5 (as determined by Hydrion Paper). The mixture is then steam distilled any material (unreacted thiophene) coming over below 100° is discarded. The 2-thiophenealdehyde is collected in the distillate. Steam distillation is continued until all odor (oil of bitter almonds) of 2-thiophenealdehyde disappears. If the distillate is basic, it is acidified with hydrochloric acid to a pH of. 2-4. The product is taken up in ether and the aqueous layer extracted twice more with ether. The ether solution is dried over calcium sulfate, the ether is removed by distillation, and the product is distilled from a Claisen flask, b.p. 72.5° at 7 mm., np 1.5920. 

Replace the thermometer with the steam-inlet tube. To start the steam distillation, heat the flask containing the mixture with a Thermowell to prevent water from condensing in the flask to the point where water and product splash over into the receiver. Then turn on the steam valve, making sure the screw clamp on the bottom of the trap is open. Slowly close the clamp, and allow steam to pass into the flask. Try to adjust the rate of steam addition and the rate of heating so the water level in the flask remains constant. Unlike ordinary distillations, steam distillations are usually run as fast as possible, with proper care to avoid having material splash into the receiver and to avoid having steam escape uncondensed. 

B) Preparation of Quinoline (M.). The results are generally better by the macro method. Use five times the amount of reagents, and a 500-ml reaction flask. The condenser should be very efficient. Use same precautions given for the micro method in starting the reaction, and allow it to proceed without external application of heat for 15-20 minutes. Boil for four hours. Transfer the mixture to a two-liter Florence flask for steam distillation. Steam-distill until about 1500-1700 ml of distillate has been collected. Use three 60-ml portions of ether with a separatory funnel to extract the distillate, and for the remainder of the experiment proportionate amounts of reagents. After the final extraction and recovery of ether use a small flask for the final distillation. If a vacuum pump is available, use a small Claisen flask and distill under diminished pressure. Collect the fraction which boils at 116-122 at 20 mm pressure. 

The smoke generation from wood can be done by dry distillation, steam distillation, or burning as is shown in Table 3.31. 

One participant repeated its analysis with a higher combustion time and additional water steam and iron phosphate and found higher results than those previously submitted. Fluoride could not be found in the residue (verified by fusion) and was assumed to be lower than the detection limit, i.e. 20 mg kg. The three methods used were in good agreement (ISE after combustion, fusion/steam distillation, steam distillation). 

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