Toluene, production volume

Important commercial isocyanates include the diisocyanate monomers toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and MDI-, TDI-, and HDI-based isocyanates (e.g., prepolymers and polyisocyanates). World-wide production volume is estimated at over 12 billion lb. Isocyanates (diisocyanates, polyisocyanates, and prepolymers) all cause similar health effects, most commonly asthma [32]. Isocyanates are reported to be the leading attributable cause of work-related asthma [16]. Isocyanates are potent sensitizers that can trigger a severe and potentially fatal asthma attack in sensitized persons at very low isocyanate exposure levels [16]. Toluene diisocyanate is reasonably anticipated to be a human carcinogen by National Toxicology Program. 

Since no data are available on humans except for skin penetration data in vitro, no direct comparison can be made. Because in humans most of the dose seems to be excreted as hippurate (lARC, 1986) and because the metabolism of the primary hydrolysis product of benzyl acetate, benzyl alcohol, is very similar in rodents and humans (see, e.g., the monograph on toluene (this volume)), it is to be expected that the fate of benzyl acetate in humans is very similar to that in rodents. 

In 1999, the total demand for the xylenes (12.3 billion lb) was roughly comparable to that for toluene. The volume of o-, m- and /7-xylene were approximately 1.1, 0.27, and 9.9 billion lb, respectively. The principal uses of the three xylene isomers are the production of terephthalic acid (or di-methyl terephtha-late), phthalic anhydride, and isophthalic acid, respectively. 

In an exactly analogous manner Sn(OCH2CH2)2NCH3 can be obtained from the reaction of tin (II) butoxide and 7V-methyldiethanolamine in dry toluene. However, since the product is slightly soluble in hot toluene, the volume of the final reaction solution must be reduced to about 100 ml to facilitate precipitation of the product. The material is then filtered and dried in vacuo to give 13.1 g (90%) of product. 

The industrial alkylation of aromatics with olefins is one of the major examples of development of environmentally friendly processes with solid acid catalysts [221, 222]. The principal products obtained are ethylbenzene (EB), cumene (CUM), p-diethylbenzene, p-diisopropylbenzene, Cio-Ci4linear alkylbenzenes (LAB) and cymene. Figure 2.28 summarizes several aromatic alkylations industrially applied for the preparation of important chemical intermediates [222]. These reactions include the most important aromatic substrates, benzene, toluene and xylene, and different olefins. They also include two different kinds of alkylation electrophilic alkylation on the aromatic ring catalyzed by acids and side-chain alkylation catalyzed by bases. In terms of production volume, add-catalyzed alkylations are by far the most... 

Disulfide Formation in Polystyrene Networks. Polymer-bound thiols were prepared by copolymerizations of bis -vinylbenzyl)disulfide with other divinyl monomers followed by diborane reduction (Scheme 5) (fiS). The initially formed thiols were juxtaposed for reoxidation to disulfides. Polymer-bound thiols were prepared also by copolymerization of p-vinylbentyl thiolacetate with divinyl monomers followed by hydrolysis (Scheme 6). llie latter thiols were distributed randomly throughout the polymer network. The copolymer reactivity ratios for p-vinylbenzyl thiolacetate and styrene are unknown, but should be similar to those of styrene (Mi) and p-vinyl-bentyl chloride (M2) ri = 0.6, r2 = 1.1 (fifi). Copolymeiizations with equal volumes of monomers and 1/1 acetonitrile/toluene product macroporous 40-48% DVB-cross-linked networks (651. 

The optimal combination from Donald s finding suggests that 60% of the reactor product volume must be retained and a reaction time of 0.5 h must be used. This gives a toluene concentration of 0.0690 mol/L, or approximately 11% over Sam s investigation. Happy with this result, Sam, Alex, and Donald report back to their boss with the updated operating procedure. 

XI/) The examples reported in [19] were clearly chosen so as to avoid to report the best experimental conditions with respect to all variables vide supra). With this limitation in mind, the best reported example involved the reaction of PhN02 (0.100 mol), PhNH2 (0.050 mol) and Ru3(CO)i2 (0.2 mmol) in MeOH (6.4 g, 0.200 mol) and toluene (total volume 75 ml) at 160 °C and under 68 atm CO. Complete conversion was reached in 8.5 h, with a 95 % selectivity in methyl phenylcarbamate and 4 % in additional aniline (the remaining 1 % being probably due to condensation products of aniline and formaldehyde, as evidenced by comparison with other examples). Note that, with respect to the conditions reported in [171], the addition of aniline allows the use of higher catalytic ratios without a drop in selectivity. The addition of an alkylammonium salt under these conditions should result in a further improvement of the rate. 

It is convenient to divide the petrochemical industry into two general sectors (/) olefins and (2) aromatics and their respective derivatives. Olefins ate straight- or branched-chain unsaturated hydrocarbons, the most important being ethylene (qv), [74-85-1] propjiene (qv) [115-07-17, and butadiene (qv) [106-99-0J. Aromatics are cycHc unsaturated hydrocarbons, the most important being benzene (qv) [71-43-2] toluene (qv) [108-88-3] p- s.y en.e [106-42-3] and (9-xylene [95-47-5] (see Xylenes and ethylbenzene) There are two other large-volume petrochemicals that do not fall easily into either of these two categories ammonia (qv) [7664-41-7] and methanol (qv) [67-56-1]. These two products ate derived primarily from methane [74-82-8] (natural gas) (see Hydrocarbons, c -c ). 

Cyclic Hydrocarbons. The cyclic hydrocarbon intermediates are derived principally from petroleum and natural gas, though small amounts are derived from coal. Most cycHc intermediates are used in the manufacture of more advanced synthetic organic chemicals and finished products such as dyes, medicinal chemicals, elastomers, pesticides, and plastics and resins. Table 6 details the production and sales of cycHc intermediates in 1991. Benzene (qv) is the largest volume aromatic compound used in the chemical industry. It is extracted from catalytic reformates in refineries, and is produced by the dealkylation of toluene (qv) (see also BTX Processing). 

Yield for the process at low catalyst loading is 95%. AJ-Methyl-toluenediamiae, one of the reaction by-products, represents not only a reduction ia yield, but also a highly objectionable impurity ia the manufacture of toluene diisocyanate. Low concentrations of CO (0.3—6% volume) control this side reaction. 

A solution of 23.7 grams of 2-bromoacetamido-2 -fluorobenzophenone in tetrahydrofuran (100 cc) was added to liquid ammonia (approximately 500 cc) and allowed to evaporate overnight. The residue was treated with water (1 liter) and the crystals filtered off and refluxed in toluene (100 cc) for 30 minutes. The mixture was treated with decolorizing carbon (Norite) and filtered over Hyflo. The solution was concentrated to a small volume (25 cc) cooled, diluted with 20 cc of ether and allowed to stand. The product was re-crystallized from acetone/hexane to give 5-(2-fluorophenyl)3H-1,4-benzodiazepin-2(1 H)-one as white needles melting at 180° to 181°C. 

The kinetic effect of increased pressure is also in agreement with the proposed mechanism. A pressure of 2000 atm increased the first-order rates of nitration of toluene in acetic acid at 20 °C and in nitromethane at 0 °C by a factor of about 2, and increased the rates of the zeroth-order nitrations of p-dichlorobenzene in nitromethane at 0 °C and of chlorobenzene and benzene in acetic acid at 0 °C by a factor of about 559. The products of the equilibrium (21a) have a smaller volume than the reactants and hence an increase in pressure speeds up the rate by increasing the formation of H2NO. Likewise, the heterolysis of the nitric acidium ion in equilibrium (22) and the reaction of the nitronium ion with the aromatic are processes both of which have a volume decrease, consequently the first-order reactions are also speeded up and to a greater extent than the zeroth-order reactions. 

Klotz B et al. (1998) Atmospheric oxidation of toluene in a large-volume outdoor photoreactor in situ determination of ring-retaining product yields. J Phys Chem A 102 10289-10299. 

General procedure for C-S bond formation. A 50 mL of reactor was charged with 232.5 mg (0.25 mm) of POPdl, 1.36 g (12.0 mmol) of 3-chloropyridine, 1.18 g (10.0 mmol) of 1-hexanethiol and 1.92 g (20.0 mmol) of NaO-tBu in 15.0 mL of toluene. The resulting mixture was refluxed for 16 h before the mixture was cooled to room temperature and quenched with 100 mL of H20. The mixture was transferred to a separatory funnel, and extracted with EtOAc (2 X 200 mL). The layers were separated, and organic layer was washed with H20 (100 mL), brine (150 mL), and dried over MgS04, filtered, and the solvents removed from the filtrate by rotary evaporation. The final product was chromatographed on silica gel using ethyl acetate/hexane (5% volume ratio) as eluant. The eluate was concentrated by rotary evaporation to yield 1.90 g (97% yield) of 3-hexylthiopyridine. 

It may be assumed that the volume of the liquid phase does not change appreciably as the reaction proceeds, although, in practice there will be some departure from this assumption. If the reaction is considered complete at the stage when 1 kmol C2H2 (molecular mass = 26 kg/kmol) has been added to 1 kmol C7H8 (molecular mass = 92 kg/kmol), then per 1 kmol of toluene, the total mass in the reactor will have increased from 92 kg initially to 118 kg of product having a mass density similar to that of the original toluene. 

The production of toluene from benzene and xylenes was studied by Johanson Watson (National Petroleum News, 7 Aug 1946) in a standard 1-inch pipe reactor with a silica-alumina catalyst. At the reaction temperature of 932 F (773 K) the reaction mixture was vapor phase, but the feeds were measured as liquids. The feed consisted of an equimolal mixture of reactants. The stated LHSV is (ml feed at 60 F/h)/(ml reactor). The reactor contained 85 g catalyst packed in a volume of 135 ml. The densities of benzene and xylenes at 60 F are 0.879 and 0.870, respectively. 

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