Acetone vapor-phase

Figure 4. Boundary of limiting superheats of acetone and water solutions in acetone 1 - acetone, 2 - acetone + 10 % water, 3 - acetone + 30 % water. Solid line - line of liquid-acetone vapor phase equilibrium, C - critical point, dashed line - calculation by homogeneous nucleation theory for J = 10 s m (acetone). ...

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). 

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 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... 

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). 

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. 

The oxidation of n-butane represents a good example illustrating the effect of a catalyst on the selectivity for a certain product. The noncatalytic oxidation of n-butane is nonselective and produces a mixture of oxygenated compounds including formaldehyde, acetic acid, acetone, and alcohols. Typical weight % yields when n-butane is oxidized in the vapor phase at a temperature range of 360-450°C and approximately 7 atmospheres are formaldehyde 33%, acetaldehyde 31%, methanol 20%, acetone 4%, and mixed solvents 12%. 

Figure 14.1 Vapor-liquid equilibrium data and calcidated values for the n-pentane-acetone system, x andy are the mole fractions in the liquid and vapor phase respectively [reproduced with permission from Canadian Journal of Chemical Engineering].

Polyethylene (PE) was a commercial LD type (without additives) with a density of 0.92 and polypropylene (PP) was also a commercial material with a density of 0.91. The polvolefin samples were melt pressed to 1 mm thick sheets (plates) which were wiped clean with acetone and used directly for the grafting experiments with the vapor-phase process. 

The vapor phases of liquids such as acetone and alcohol are more flammable than their liquid phases. For flammable liquids, what is the relationship between evaporation rate and the likelihood that the liquid will burn ... 

There are several other routes to acetone of minor importance air oxidation of IPA reaction between IPAand acrolein for the production of allyl alcohol, with acetone as the by-product vapor phase oxidation of butane coproduction when IPA is oxidized yielding acetone and H2O2, hydrogen peroxide, the principal ingredient of bleach and by-product production from the manufacture of methyl ethyl ketone. 

The photochemistry of biacetyl has been extensively studied, both in the vapor phase and in solution. In the vapor phase the products include carbon monoxide, ethane, methane, acetone, ketene, and 2,3-pentanedione. It has been shown that the primary process is cleavage of the carbon-carbon bond between the two carbonyl groups to yield acyl radicals, which on further reaction give the observed products.14,43... 

Polybrominated Diphenyl Ethers. Like PCBs, air samples containing PBDEs are usually collected by pumping air through a sampler containing a glass fiber filter and adsorbent trap to separate the particle bound and vapor phase fractions, respectively (Dobber et al 2000a Hillery et al 1997). The filters and adsorbants are then Soxhlet extracted with acetone/hexane, and the extracts are cleaned-up and analyzed by high resolution GC techniques. 

Fukuhara and Bigelow reported two significant vapor-phase fluorinations. Acetone afforded hexafluoroacetone. 1-fluoroacetone, trifluoroacctyl fluoride, oxalyl difluoride, fluorocar-... 

Treatment of acetone with uranium(VI) fluoride in the vapor phase at room temperature gives13 some acetyl fluoride, along with much polymeric material. Under the same conditions, cyclohexanone also produces an unidentified acid fluoride initially, but this is then consumed to give polymeric material. 

Acetone, Nitration. Krauz Stepanek(Ref 1) attempted to prepare terrani from ethane by nitration of acetone, but failed, instead, they obtained (after treating the resulting product with a silver salt) a very expl solid claimed to be Ag salt of acetylmethylnitrolic acid, also called a-nitro - a -isonitroso-acetone. Hass Hudgin(Ref 3) nitrated acet, using a vapor-phase nitration technique described in Ref 2. The high-boiling fractn from the nitration gave an odor of acetic acid, an acidic reaction in aq soln, a red color with ferric chloride and a yel salt with Ag nitrate soln,... 

It was claimed by Henry(Ref 2) that 0. de Battice prepd nitroacetone in 1895 in Belgium by oxidation of nitroisopropanol with chromic mixture. Henry described the compd as a coi, mobile liq with a sharp odor, a 1.070 at 14°, bp 152° at 767 mm and insol in w. Lucas c]aimed(Ref 3) that the compd described by Henry was not nitroacetone, but this statement was disputed by Henry(Ref 4). Harries also claimed(Ref 5) that the compd described by Henry is not nitroacetone More recently, Hass Hudgin(Ref 7) claimed that they had isolated some nitroacetone from the high-boiling fraction of the vapor-phase nitration of acetone but it is not clear from their paper whether the substance was liq or solid. Hurd NilsonfRef 8) prepd nitroacetone as pale-green crysts, mp 47°, by oxidizing 1—nitro—2—propanol with sodium dichromate and sulfuric acid. The yield was (5% of theoretical. The explosifcility of this compd was not mentioned... 

Alkylation. Friedel-Crafts alkylation (qv) of benzene with ethylene or propylene to produce ethylbenzene [100-41 -4], CgH10, or isopropylbenzene [98-82-8], C9H12 (cumene) is readily accomplished in the liquid or vapor phase with various catalysts such as BF3 (22), aluminum chloride, or supported polyphosphoric acid. The oldest method of alkylation employs the liquid-phase reaction of benzene with anhydrous aluminum chloride and ethylene (23). Ethylbenzene is produced commercially almost entirely for styrene manufacture. Cumene [98-82-8] is catalytically oxidized to cumene hydroperoxide, which is used to manufacture phenol and acetone. Benzene is also alkylated with C1Q—C20 linear alkenes to produce linear alkyl aromatics. Sulfonation of these compounds produces linear alkane sulfonates (LAS) which are used as biodegradable deteigents. 

Data on the influence of solvents as sensitizers in the vapor phase were collected for water, benzene, carbon tetrachloride, methanol, ethanol, formaldehyde, acetone, acetic add, acetic anhydride and methyl propionate (157). 

In the vapor phase, the emission from excited acetone has been shown to be a mixture of fluorescence and phosphorescence [254]. The estimated lifetime of the excited singlet state is 10 ns, a figure commonly accepted as a reasonable approximation to the excited singlet to triplet (St - TJ transition time in aliphatic ketones. The overlap of the fluorescence and phosphorescence spectra reflects the fact that the energetic separation between the lowest n, n single and triplet states is small, at least in comparison with the S2 — Tt splitting between lowest excited n, n singlet and triplet states. 

The fact that the rate of exothermic triplet energy transfer in solution approaches the diffusion-controlled limit does not establish that every collision of donor and acceptor is 100% efficient in transferring energy. Rebbert and Ausloos have measured the efficiencies with which several compounds quench acetone phosphorescence in the vapor phase.160,161 They find that with compounds such as oxygen,... 

The lifetime of triplet acetone at 25° in the vapor phase, as measured from the rate of decay of phosphorescence, is 0.0002 sec,318 so that the rate of decay is 5 x 103 sec-1. This figure represents the sum of the rates of all decay processes. Since the data at 40° 308 indicate that decomposition and internal conversion of triplet acetone occur approximately 40 times as fast as emission, the radiative lifetime must be on the order of 0.01 sec. Measurements of the rate of phosphorescence decay from solid acetone at 77°K, where all activated fragmentation and most radiationless decay normally disappear, have actually yielded values approximately one-tenth as large as that obtained in the gas phase at room temperature.319 The most recent measurements of the lifetime of triplet acetone at 77°K in frozen glasses does indeed yield an estimate of 0.01 sec for the radiative lifetime of triplet acetone.318... 

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