F o-Xylene

In addition, since this coal crude was distilled from a coal hydrogenation mixture leaving pitch, coke, and other residue behind, it is unnaturally deficient in residue compared with petroleum-based crude oil. The distillation yields show that the coal crude is especially rich in the medium naphtha-kerosene fraction boiling up to 250°C (480°F) and can be attributed to the presence of benzene (bp 80°C [176°F]), toluene (bp 111°C [232°F]), o-xylene (bp 144°C [291 ]), m-xylene (bp 139°C [282°F]), p-xylene (bp 138°C [280°F]), naphthalene (bp 218 C [424 F]), and tetralin (bp 207°C [405°F]), as well as various alkyl (methyl) derivatives of the aforanentioned compounds, hydroaromatic analogs, and alkanes. 

In that case. Units E, F, and G would be eliminated. To recover -xylene only, the xylene spHtter is reduced in size and is used to spHt between o-xylene and the Cg aromatics. The o-xylene temn stiH is then eliminated. 

Subsequently, rate coefficients were determined for the zinc chloride-catalysed bromination of benzene, toluene, i-propyl-benzene, r-butylbenzene, xylenes, p-di-f-butylbenzene, mesitylene, 1,2,4-trimethyl-, sym-triethyl-, sym-tri-f-butyl-, 1,2,3,5-and 1,2,4,5-tetramethyl- and pentamethylbenzenes, all at 25.4 °C and in acetic acid, and it was shown that the reaction was inhibited by HBr.ZnCl2 which accumulates during the bromination and was considered to cause the first step of the reaction (formation of ArHBr2) to reverse320. The second-order coefficients for bromination of o-xylene at 25.0 °C were shown to be inversely dependent upon the hydrogen bromide concentration and the reversal of equilibrium (155)... 

Harms G, K Zengle, R Rabus, F Aeckersberg, D Minz, R Rossell6-Mora, F Widdel (1999) Anaerobic oxidation of o-xylene, m-xylene, and homologous alkylbenzenes by new types of sulfate-reducing bacteria. Appl Environ Microbiol 65 999-1004. 

The process. A typical process for phthalic anhydride starts with mixing hor q-xylene vapor with excess preheated air in a ratio of 20 1 air to o-xylene by weight. The gaseous mixture is then fed to a reactor consisting of tubes packed with vanadium pentoxide catalyst on a silica gel. The reaction takes place at 800—1000°F. Like most oxidation reactions, this one is exothermic, and the heat of reaction must be removed from the tubes to maintain the reaction temperature. 

Figure 4. FT-IR spectra of the adsorbed species arising from contact of the catalyst with o-xylene/oxygen at r.t. (a), 373 K (b), 423 K (c), 473 K (d), and 523 K (e). (f) phtalic anhydride adsorbed at r.t., producing also phtalate ions.

A. a,a,ot, a -Tetrabromo-o-xylene. In a 2-1. three-necked flask equipped with an oil-lubricated Trubore stirrer, a dropping funnel, a thermometer extending nearly to the bottom of the flask, and a reflux condenser (Note 1) attached to a gas absorption trap 2 is placed 117 g. (1.1 moles) of dry o-xylene (Note 2). An ultraviolet lamp such as a General Electric R.S. Reflector Type 275-watt sun lamp is placed about 1 cm. from the flask so as to admit the maximum amount of light. The stirrer is started, and the o-xylene is heated to 120° with an electric heating mantle. A total of 700 g. (4.4 moles) of bromine (n.f. grade) is added in portions from the dropping funnel to the reaction flask at such a rate that the bromine color is removed as fast as it is added. 

The ultimate in xylene separation is claimed, however, by Hetzner (10), who first distills the mixture to remove o-xylene by taking m-p-xylene and ethylbenzene overhead in a column having about 35 to 60 theoretical plates. It is reported that concentrates containing up to 97% o-xylene have been produced by this process. The m-xylene, p-xylene, and ethylbenzene mixture is selectively sulfonated to remove m-xylene. In this operation, 2 moles of Sulfuric acid (96 to 98%) are added per mole of m-xylene in the mixture to be treated. After separation, the aqueous layer is hydrolyzed at 250° to 300° F. to recover a concentrate containing 90% or more m-xylene. The hydrocarbon layer is cooled to produce p-xylene crystals, which are separated by filtration or centrifugation. The 85 to 90% p-xylene concentrate is reprocessed to recover a final product containing 96% p-xylene. The mother liquor from the p-xylene crystallization contains impure ethylbenzene and is rejected from the system. 

Give the number of lines in the ESR spectrum of the anion radical of each of the following molecules. (Assume all lines are resolved.) (a) Naphthalene (b) anthracene (c) pentacene (d) azulene (e) o-xylene (f) w-xylene (g) p-xylene (h) nitrobenzene (i) />-fluoronitrobenzene. 

It is a logical extension that the reduction of the diffusional resistance, such as by decreasing the crystallite size, should result in apparent kinetics that approach that of a simple series reaction scheme. If we compare the apparent kinetics for large and small crystallite catalysts, we find the o-xylene p-xylene path at 400° F is essentially eliminated with small crystallites. 

Temperature Dependence of the Activity and Selectivity of Xylene Isomerization over AP Catalyst. Based upon our analysis of the intracrystalline diffusional resistance in AP catalyst, we would expect that when the reaction temperature is increased, the selectivity would shift toward p-xylene since the diffusional effects are increased as the activity increases. A shift in selectivity toward p-xylene as the reaction temperature was increased was observed and is shown in Figure 6. The role of diffusion in changing the selectivity can be seen in the Arrhenius plot of Figure 7. The reaction rate constant for the o-xylene - p-xylene path, fc+3i, goes from an almost negligible value at 300°F to a substantial value at 600°F. Furthermore, the diffusional effects are also demonstrated by the changing... 

Hydroxyphthalazin-1 (2/f )-one is obtained in a smooth reaction between phthalic anhydride and hydrazine hydrate and this is again the starting compound for many 1-substituted and/or 1,4-disubstituted phthalazines. The transformations of 1,4-dichloro-phthalazine, which is prepared in the usual manner, follow a similar pattern as shown for pyridazines in Scheme 110. On the other hand, phthalonitrile is the preferential starting compound for amino- and hydrazino-phthalazines. The most satisfactory synthesis of phthalazine is the reaction between a,a,a, a -tetrachloro-o-xylene and hydrazine sulfate in sulfuric acid (67FRP1438827), although catalytic dehalogenation of 1-chloro- or 1,4-dichloro-phthalazine or oxidation of 1-hydrazinophthalazine also provides the parent compound in moderate yield. 

Notably, this reaction shows a high tolerance towards a wide variety of functional groups, such as CHO, C02R, I, Br, Cl, F, OH and OMe, and also thiophene and furan derivatives, which is a rare feature in Friedel-Crafts-type chemistry. In the reaction with o-xylene, various alcohols were successfully used as benzylation agents, forming the corresponding products in high yield and selectivity (Table 6.1). 

Calibration Inject about 2 pL of the upper layer of the Standard Preparation into the chromatograph, and record the chromatogram. The retention times for methyl iodide, isopropyl iodide, toluene, and o-xylene are approximately 3, 5, 7, and 13 min, respectively. Calculate the relative response factor, F, of equal weights of toluene and methyl iodide by the formula... 

Problem 12.12 Which of the following vibrational modes show no ir absorption bands (a) Symmetrical C02 stretch, (b) antisymmetrical C02 stretch, (c) symmetrical 0=C=S stretch, (d) C=C stretch in o-xylene, (< ) C=C stretch in p-xylene and (f) C=C stretch in p-bromotoluene. M... 

In oil processing, separation of aromatic isomers Cg (ethylbenzene 7b= 136°C,p-xylene 7b= 138.3°C, m-xylene Ty, = 139.1°C, >-xylene T], = 144.4°C) is required. According to the literary data, the following isomers of hydrocarbons are separated p-xylene/m-xylene, p-xylene/o-xylene, -hexane/2,2-dimethylbutane, -hexane/3-methylpentane, and n-butane/f-butane [8,83,130-137]. Pervaporation method is the most effective for this purpose. To separate the isomers, membranes based on various polymers were used. Good separation for aU isomer mixtures was attained by the polyimide Kapton film (fip = 1.43-2.18) but parylene films and cellulose acetate also exhibited a relatively high separation factor (fip = 1.22-1.56 and /3p = 1.23-1.56, respectively). Temperatures >200°C were required to obtain a reasonable flux through the polyimide film and a pressure of about 20 atm was necessary to keep the feed stream liquid [8]. 

C.R. Dias, M.F. Portela, M. Galan Fereres et al.. Selective Oxidation of o-Xylene to Phthalic Anhydride, Catal. Lett. 43(1-2), 117-121 (1997). 

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