Evaporation of Acetone

Problem Students often describe evaporation of a liquid as the disappearance of the substance rain puddles disappear . In order to show that a liquid is transformed to a gas, one should use a glass syringe and an analytical scales to show the vapor of acetone which results from the evaporation process. One can also smell the mixture of acetone vapor and air. 

Material Analytical balance, watch glass, Erlenmeyer flask with glass beads and stopper, glass syringe acetone. 

Procedure Place a few drops of acetone on a watch glass and weigh, after some time weigh it again. In the Erlenmeyer flask connected to a syringe, add a few drops of acetone, warm with hands and shake the glass beads. Open the flask and smell. 

Observation The analytical balance shows a decreasing weight reading until finally all liquid acetone evaporates. In the second step the syringe fills up with a colorless vapor, until the liquid is completely evaporated and the gas weight remains constant. Opening the flask the gas can be smelled acetone respectively the mixture of air and acetone. 

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Ascher and Nemny 495) found that residues of triphenyltin acetate on glass, resulting from the evaporation of acetone solutions thereof, were, on contact to houseflies, less toxic with rising concentration. As triphenyltin acetate is likely to be a self-associated polymer in the solid state [similar to trimethyltin acetate (355)] and in concentrated solutions, it was suggested 495) that the monomer, which exists in dilute solutions, is toxic to insects, and the polymer, nontoxic. Interestingly, in this connection, a triphenyltin methacrylate copolymer has 470) a very low mammalian toxicity (acute, oral LDso for mice >2000 mg/kg). 

Ensure that empty cylinders have the valve closed to prevent evaporation of acetone. Close cylinder valve before shutting off regulator, to permit gas to bleed from regulator. When used e.g. for welding, avoid the careless use of flame which could fuse the metal safety plug in the cylinder. 

Ensure that empty cylinders have the valve closed to prevent evaporation of acetone. 

The high purity carbon nanotubes (CNTs) used in this study were obtained by decomposition of acetylene over a powdered CoxMgi xO solid solution catalyst [19]. Different proportions of CNTs from 15 to 70% and polyacrylonitrile (PAN, Aldrich) have been mixed in an excess of acetone to obtain a slurry. After evaporation of acetone, precursor electrodes were formed by pressing the CNTs/PAN mixture at 1-2 tons/cm2. The C/C composites were formed by carbonisation of the pellets at 700-900°C for 30-420 min under nitrogen flow [20], The optimal capacitance properties of the composite were obtained for a mixture CNTs/PAN (30/70 wt%) treated at 700°C. Such C/C composite remains still quite rich in nitrogen (9 at% of N) demonstrating that PAN is an efficient nitrogen carrier. On the other hand,... 

Excessive evaporation of acetone during extraction will alter the acetone/water ratio, causing incomplete pigment extraction. The tubes should be capped during extraction and handling to minimize evaporation. 

Solvent evaporation Precipitation reactions can be controlled by use of mixed solvents. Slow evaporation of acetone from a buffered water-acetone solution produces results similar to PFHS in the precipitation of aluminum 8-hydroxy-quinolate. 

SOLUTION The composition profiles in the Stefan tube are given by Eq. 8.6.2. Before we can compute the profiles we must determine the rates of evaporation of acetone and methanol. Since the evaporating species are present in low concentrations at the top of the tube (although not at the bottom) we shall use the dilute solution limit for the effective diffusivities... 

As the catalyst, concentrated (98%) sulfuric acid is almost exclusively used in the industrial practice. The cleavage is run in the presence of 0.2-1% of acid, under reduced pressure, at the boiling temperature of the cumyl hydroperoxide-acetone mixture, which depends on the acetone content. Again, the reaction is strongly exothermic ( 250 kj mol ) and the heat is removed by evaporation of acetone from the reaction mixture. At 70-80 °C, cumyl hydroperoxide conversion is virtually quantitative, with a selectivity to phenol up to 94-95%. 

Epoxidation of allylic phosphonates is achieved wilh success at room temperature witli MeCOjH in Et O, CF3CO3H in CHCI3, MCPBA in ( HT I- or MOO5/HMPA complex in CH2CI2 to give the corresponding 2,3-epoxyalkylphosphonates as a mixture of diastereomers. s- Allylic phosphonates may also be converted into 2,3-epoxyphosphonates via the 1,1,1-trifluorodimethyl-dioxirane-mediated oxidation. Dimethyldioxirane (DMD) in acetone at room temperature or methyl(trifluoromethyl)dioxirane (TED) in CHjClj at low temperature can be used instead of MCPBA. Because the reaction is quantitative, evaporation of acetone and excess of DMD allow the direct isolation of the pure product. 2,i55... 

Film Casting Technique. After the membrane is cast on the glass plate, the acetone is allowed to evaporate from the films for a short time before immersion in water. If evaporation of the acetone were allowed to proceed to completion before the film was immersed in water, the desalinization capacity of the film would be seriously impaired. The proper time interval between casting and immersion depends on the rate of evaporation of acetone from the membrane and hence is a function of the temperature at which the membrane is cast and allowed to remain, prior to immersion. At room temperature, this time interval is relatively short, which made it difficult under these conditions to fabricate membranes which would give satisfactory, reproducible data. For this reason the membranes are cast in a freezer, with all components at about 0° C. It is also... 

Utilized for a standard operation. The operating cx)nditions of spray-evaporation of acetone solvent are shown in Table I. 

Tabic I. Operating Conditions for Spray-Evaporation of Acetone ... 

Figure 2.51. Comparison of IR spectra of oxidized surface compounds on galena (PbS) powder 50-70 M-m size (1) transmission of powder layer deposited from acetone on KBr plate after evaporation of acetone (2) DTIFTS of powder layer deposited from acetone on ZnSe wedge (Section 4.2.2) (3) DRIFTS (4) DRIFTS of 1 3 mixture with KBr (5) transmission of 1 3 mixture of galena and KBr squeezed between two KBr windows.

Typical Procedure forEq. 46.A concentrated aqueous solution of KHFj (3.3 equivs) is added to a methanol solution of ArB(OH)2 at room temperature. After stirring for 10 min, the solvent is evaporated in vacuo. The resulting solid is extracted with several portions of acetone. Evaporation of acetone gives crude ArBFjK which is recrystallized or reprecipitated from acetone/ether. Yields are more than 95%. 

DPD was extracted from each specimen using a Soxhlet s extractor with acetone for 7 hours. After evaporation of acetone, extracted DPD was dissolved in chloroform. Concentrations of DPD in chloroform were analysed by HPLC using the ultraviolet rays of X=254nm, with the columns of polystylene gel Shodex A801 and Shodex A802 from Showadenko Co., Ltd., under a flow rate of 1.0 cm /minute. 

Guijt et al. [7] suggested an on-chip heating and cooling technique by using endothermic or exothermic processes in a microchannel to cool or heat solutions within an adjacent sample channel. Chemical or physical processes of solutions in a channel such as evaporation of acetone and exothermic dissolution of H2O4 in water are used to cool and heat an adjacent channel (Fig. 3). 

As an alternative to the PES membranes, cellulose acetate (CA with 39.8% acetyl content) membranes (with a thickness of 25 [im) were also prepared by solvent casting method. The composition of the casting solution was 2% CA (w/v) in acetone. Film formation was achieved by evaporation of acetone at room temperature (20 C) in 80% relative humidity environment. 

To about 2 5 g in a beaker add 0 5 g of kaolin and mix. Add 5 ml of 70 per cent ethanol, stir thoroughly, then add a further 45 ml of ethanol and stir again. Filter through a pleated open-texture filter paper, transferring the precipitate to the filter with further portions of the ethanol. Place the filter paper and precipitate in an extraction thimble, transfer to a continuous extraction apparatus and exhaust with ether, continuing the extraction for about two hours. Transfer the ethereal extract to a separator, and wash with two 15-ml portions of water. Transfer the solution to a weighed flask, remove the solvent, add 5 ml of acetone and evaporate. Repeat the addition and evaporation of acetone until the residue is free from water. Dry at 100° for fifteen minutes and weigh the oil. 

Dried and pulverized leaves were exh cted with ten times volume (w/v) of acetone-water (8 2). After evaporation of acetone fi om the extract, ethyl acetate was added to the aqueous residue, then partitioned to give the ethyl acetate-soluble fraction and the water-soluble fraction. 

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