Vapor acetone

Detection of a volatile compound in blood does not always indicate VSA or occupational/environ-mental exposure to solvent vapor. Acetone and some of its homologs may occur in high concentrations in ketotic patients. Large amounts of acetone and... 

After depositing the charged powder on the paper (see Fig. XII.S.c), the charges may leak off so that the powder adhesion will become weaker. Hence it is necessary to fix the deposited powder this can be done by heating, by applying pressure, or by using a solvent. When heating is used, the adherent powder particles are fused and thus fixed on the paper. A solvent vapor (acetone, carbon tetrachloride, diethyl ether, etc.) will partially dissolve and also fix the toner particles on the paper. 

Application of the algorithm for analysis of vapor-liquid equilibrium data can be illustrated with the isobaric data of 0th-mer (1928) for the system acetone(1)-methanol(2). For simplicity, the van Laar equations are used here to express the activity coefficients. 

Vapor-Liquid Equilibrium Data Reduction for Acetone(1)-Methanol(2) System (Othmer, 1928)... 

The composite curves for this flowsheet are shown in Fig. 14.86. The composite curves are dominated by the reboilers and condensers of the two distillation columns and the feed vaporizer for the acetone feed. It is immediately apparent that the two distillation columns are both inappropriately placed across the pinch. Linnhoflf and Parker ... 

Chloroacetyl chloride [79-04-9] (CICH2COCI) is the corresponding acid chloride of chloroacetic acid (see Acetyl chloride). Physical properties include mol wt 112.94, C2H2CI2O, mp —21.8 C, bp 106°C, vapor pressure 3.3 kPa (25 mm Hg) at 25°C, 12 kPa (90 mm Hg) at 50°C, and density 1.4202 g/mL and refractive index 1.4530, both at 20°C. Chloroacetyl chloride has a sharp, pungent, irritating odor. It is miscible with acetone and bensene and is initially insoluble in water. A slow reaction at the water—chloroactyl chloride interface, however, produces chloroacetic acid. When sufficient acid is formed to solubilize the two phases, a violent reaction forming chloroacetic acid and HCl occurs. 

Dehydrogenation of isopropyl alcohol accounts for most of the acetone production not obtained from cumene. The vapor is passed over a brass, copper, or other catalyst at 400—500°C, and a yield of about 95% is achieved (1.09 unit weight of alcohol per unit of acetone) (13). 

Although the selectivity of isopropyl alcohol to acetone via vapor-phase dehydrogenation is high, there are a number of by-products that must be removed from the acetone. The hot reactor effluent contains acetone, unconverted isopropyl alcohol, and hydrogen, and may also contain propylene, polypropylene, mesityl oxide, diisopropyl ether, acetaldehyde, propionaldehyde, and many other hydrocarbons and carbon oxides (25,28). 

Acetone can be handled safely if common sense precautions are taken. It should be used in a weU-ventilated area, and because of its low flash point, ignition sources should be absent. Flame will travel from an ignition source along vapor flows on floors or bench tops to the point of use. Sinks should be rinsed with water while acetone is being used to clean glassware, to prevent the accumulation of vapors. If prolonged or repeated skin contact with acetone could occur, impermeable protective equipment such as gloves and aprons should be worn. 

C using a wide variety of catalysts (28) and even with no catalyst (29). Vapor-phase catalysts capable of converting acetic acid to acetone directiy convert the steam—acetylene mixture to acetone (28,30,31). 

The physical properties of some common ketones are Hsted in Table 1. Ketones are commonly separated by fractional distillation, and vapor—Hquid equihbria and vapor pressure data are readily available for common ketones. A number of other temperature dependent physical properties for acetone, methyl ethyl ketone, methyl isobutyl ketone, and diethyl ketone have been pubHshed (3). 

The one-step route from 2-propanol coproduces diisobutyl ketone and acetone, and is practiced in the United States by Union Carbide (61). The details of a vapor-phase 2-propanol dehydrogenation and condensation process for the production of acetone, MIBK, and higher ketones have been described in recent patents (62,63). The process converts an a2eotropic 2-propanol—water feed over a copper-based catalyst at 220°C and produces a product mixture containing 2-propanol (11.4%), acetone (52.4%), MIBK (21.6%), diisobutyl ketone (6.5%), and 4-methyl-2-pentanol (2.2%). 

Mesityl oxide can also be produced by the direct condensation of acetone at higher temperatures. This reaction can be operated ia the vapor phase over 2iac oxide (182), or 2iac oxide—2irconium oxide (183), or ia the Hquid phase over cation-exchange resia (184) or 2irconium phosphate (185). Other catalysts are known (186). 

Ma.nufa.cture. Isophorone is produced by aldol condensation of acetone under alkaline conditions. Severe reaction conditions are requited to effect the condensation and partial dehydration of three molecules of acetone, and consequendy raw material iaefftciency to by-products is limited by employing low conversions. Both Hquid- and vapor-phase continuous technologies are practiced (186,193,194). 

In the vapor phase, acetone vapor is passed over a catalyst bed of magnesium aluminate (206), 2iac oxide—bismuth oxide (207), calcium oxide (208), lithium or 2iac-doped mixed magnesia—alumina (209), calcium on alumina (210), or basic mixed-metal oxide catalysts (211—214). Temperatures ranging... 

The acetone-selective, siUcone mbber membrane is best used to treat dilute acetone feed streams and concentrate most of the acetone in a small volume of permeate. The water-selective, poly(vinyl alcohol) membrane is best used to treat concentrated acetone feed streams containing only a few percent water. Most of the water is then removed and concentrated in the permeate. Both membranes are more selective than distillation, which rehes on the vapor—hquid equiUbrium to achieve a separation. 

Selected physical properties of various methacrylate esters, amides, and derivatives are given in Tables 1—4. Tables 3 and 4 describe more commercially available methacrylic acid derivatives. A2eotrope data for MMA are shown in Table 5 (8). The solubiUty of MMA in water at 25°C is 1.5%. Water solubiUty of longer alkyl methacrylates ranges from slight to insoluble. Some functionalized esters such as 2-dimethylaniinoethyl methacrylate are miscible and/or hydrolyze. The solubiUty of 2-hydroxypropyl methacrylate in water at 25°C is 13%. Vapor—Hquid equiUbrium (VLE) data have been pubHshed on methanol, methyl methacrylate, and methacrylic acid pairs (9), as have solubiUty data for this ternary system (10). VLE data are also available for methyl methacrylate, methacrylic acid, methyl a-hydroxyisobutyrate, methanol, and water, which are the critical components obtained in the commercially important acetone cyanohydrin route to methyl methacrylate (11). 

In petroleum and oxygenate finish removers, the major ingredient is normally acetone, methyl ethyl ketone [78-93-3], or toluene. Cosolvents include methanol, / -butanol [71-36-3], j -butyl alcohol [78-92-2], or xylene [1330-20-7]. Sodium hydroxide or amines are used to activate the remover. Paraffin wax is used as an evaporation retarder though its effectiveness is limited because it is highly soluble in the petroleum solvents. CeUulose thickeners are sometimes added to liquid formulas to assist in pulling the paraffin wax from the liquid to form a vapor barrier or to make a thick formula. Corrosion inhibitors are added to stabili2e tbe formula for packaging (qv). 

Dehydrogenation. Before the large-scale availabiUty of acetone as a co-product of phenol (qv) in some processes, dehydrogenation of isopropyl alcohol to acetone (qv) was the most widely practiced production method. A wide variety of catalysts can be used in this endothermic (66.5 kj/mol (15.9 kcal/mol) at 327°C), vapor-phase process to achieve high (75—95 mol %) conversions. Operation at 300—500°C and moderate pressures (207 kPa (2.04 atm)) provides acetone in yields up to 90 mol %. The most useful catalysts contain Cu, Cr, Zn, and Ni, either alone, as oxides, or in combinations on inert supports (see Catalysts, supported) (13-16). 

Various types of detector tubes have been devised. The NIOSH standard number S-311 employs a tube filled with 420—840 p.m (20/40 mesh) activated charcoal. A known volume of air is passed through the tube by either a handheld or vacuum pump. Carbon disulfide is used as the desorbing solvent and the solution is then analyzed by gc using a flame-ionization detector (88). Other adsorbents such as siUca gel and desorbents such as acetone have been employed. Passive (diffuse samplers) have also been developed. Passive samplers are useful for determining the time-weighted average (TWA) concentration of benzene vapor (89). Passive dosimeters allow permeation or diffusion-controlled mass transport across a membrane or adsorbent bed, ie, activated charcoal. The activated charcoal is removed, extracted with solvent, and analyzed by gc. Passive dosimeters with instant readout capabiUty have also been devised (85). 

Other Derivatives and Reactions. The vapor-phase condensation of ethanol to give acetone has been well documented in the Hterature (376—385) however, acetone is usually obtained as a by-product from the cumene (qv) process, by the direct oxidation of propylene, or from 2-propanol. 

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