Acetone separation

Dissolve I ml. of benzaldehyde and 0-4 ml. of pure acetone in 10 ml. of methylated spirit contained in a conical flask or widemouthed bottle of about 50 ml. capacity. Dilute 2 ml. of 10% aqueous sodium hydroxide solution with 8 ml. of water, and add this dilute alkali solution to the former solution. Shake the mixture vigorously in the securely corked flask for about 10 minutes (releasing the pressure from time to time if necessary) and then allow to stand for 30 minutes, with occasional shaking finally cool in ice-water for a few minutes. During the shaking, the dibenzal -acetone separates at first as a fine emulsion which then rapidly forms pale yellow crystals. Filter at the pump, wash well with water to eliminate traces of alkali, and then drain thoroughly. Recrystallise from hot methylated or rectified spirit. The dibenzal-acetone is obtained as pale yellow crystals, m.p. 112 yield, o 6 g. 

The crude sulphonyl chloride, even if dry, cannot bo kept without considerable decomposition. It may be purified by dissolving it in a mixture of equal volumes of benzene and acetone, separating the water, and allowing the solvent to evaporate until crystallisation occurs the recrystallised substance may be preserved for long periods. 

Solvent selection ana screening approaches can be divided into two levels of analysis. The first level focuses on identification of functional groups or chemical famihes that are hkely to give favorable solvent-key component molecular interactions. The second level of analysis identifies and compares individual-candidate solvents. The various methods of analysis are described briefly and illustrated with an example of choosing a solvent for the methanol-acetone separation. 

Even with the best technique, however, some interference will still be encountered from fats and waxes. With the acetone separation method described this interference is reduced to a point where it seldom lowers the transmittance by as much as 1% and never by more than 3%. It has been found that the off-colors introduced by any one type of biological material are remarkably constant and it is therefore thoroughly practical to apply a correction for this interference. 

For some time the acetone separation step was performed before dehydrohalogena-tion. However, great difficulty was experienced in preventing rather sizable losses, because some methoxychlor would dissolve in the precipitated fat. With milk in particular these losses became prohibitive. After dehydrohalogenation most of the fat is saponified and removed, so that only a small nonsaponifiable portion remains to be separated. If any methoxychlor does dissolve in this remaining fraction it is too small to be measured. 

Method I.—6 gms. (1 mol.) of fresh dry sodium ethylate (see p. 509) are added to 20 gms. (excess) of dry ethyl acetate under cooling by water. After 15 minutes, 10 gms. (1 mol.) of acetophenone are added the separation of the sodium salt of benzoyl acetone immediately begins. A little dry ether is added, and in 4 hours the sodium compound is filtered off, washed with ether, air-dried, dissolved in cold water, and the solution acidified with acetic acid. Benzoyl acetone separates. 

Calcium hydroxide is an excellent adsorbent for resolving carotenoid cis-trans isomers compared with alumina, it is less retentive and less sensitive to temperature and moisture content of the mobile phase. However, calcium hydroxide columns are not commercially available, and separations using them can be difficult to reproduce, owing to extreme sensitivities to mobile-phase composition and temperature. Nine cis-/3-carotenes were characterized from a chromatogram of 18 peaks after isocratic elution of a mixture obtained by thermal isomerization and photoisomerization of /3-carotene (162). Chandler and Schwartz (10), using a calcium hydroxide column and a mobile phase of hexane containing 0.3% acetone, separated six carotene isomers from canned carrots. These were, in order of elution, two cw-a-carotenes, all-tram-a-carotcnc, 13-m-/3-carotcnc, all- ram-/3-carotene, and 9-cw-/3-carotene. A mobile phase of hexane modified with 2% p-methylanisole separated all-rram-/3-carotcnc and its 9-, 13-, and 15-cis isomers in an iodine isomerized mixture (163). 

Fig. 2. Treatment of cell cultures with deoxymannojirimycin (DMM) inhibited processing of the complex carbohydrate moiety of the epsi-APase but did not affect excretion into the medium. Three-day-old cells grown —Pi as previously described (Goldstein etal., 1988a) were treated with 0.1 mM DMM for 24 h which resulted in inhibition of processing of the complex carbohydrate moiety of the epsi-APase. Culture-medium proteins from +DMM or -DMM treatments were precipitated with 50% acetone, separated via SDS-PAGE and activity stained (also as previously described, Goldstein etal., 1988b). As shown here, inhibition of carbohydrate processing caused a visible increase in apparent molecular mass but did not inhibit the excretion of epsi-APase into the medium.

Chemically enhanced distillation is similar to extractive distillation, but this time the solvent is an ionic salt or a complex organic molecule. As an example, acetone separates easier from a solution with methanol in the presence of a concentrated solution of calcium chloride. More modern solvents are based on ionic liquids. 

The colored acid chloride was developed by Butenandt s group for use in ah investigation of the sex attractant principle secreted by the female silkworm moth, bombykol, which indeed was isolated as the 4 -nitroazobenzene-4-carboxylic ester (2). Twelve milligrams of pure ester, m.p. 95-96°, was isolated from 500,000 pairs of scent glands. Oxidation of 1 mg. of this ester with permanganate in acetone, separation of the colored fragment, and esterification with diazomethane gave an... 

Put the ground sample stack into acetone until it detaches from the specimen holder. The stack is very brittle so it is impossible to pick it up with tweezers. Use a small piece of tissue paper soaked in acetone. The stack will stick to the soaked tissue paper and can thus be removed. The acetone on the tissue paper evaporates quickly and the stack then falls off by its own weight. Clean the sample carefully with a lens tissue wrapped around the tip of a pair of tweezers using acetone. Separate all strips of the cross-section carefully with a sharp knife. The glue is not so strong any more since the cross-section is less than... 

The reverse effect can easily be shown using our first example When table salt is added to a 1 1 mixture of acetone and water, the acetone separates into a second layer on top of the solution ( salting-out effect, compare Experiment 13.5). 

A five-equilibrium-stage, tray absorber is used for the acetone separation described in Section... 

Scheme 12.8 Flow process to make hydrazine, illustrating minimal use of the auxiliary, acetone (separation and recyele), which is used to achieve...

As a Viton/acetone solution at the same solvent level was too viscous to be transported, adaptation of that process to MTV was achieved by feeding all solids and acetone separately. It was found that a solvent level of 16.5-19wt% acetone is satisfactory both to solvate Viton and disperse the composite. The viscosity r] of an MTV with 19wt% acetone feeding stream at 27°C was found to relate with shear rate, y, (s ) in the following manner ... 

Y.K. Ong, N. Widjojo, T.S. Chung, Fundamentals of semi-crystalline poly(vinylidene fluoride) membrane formation and its prospects for biofuel (ethanol and acetone) separation via pervaporation. Journal of Membrane Science, 378 (2011) 149-162. 

---