Xylene, ortho

In 1975, Weber and Vogtle showed that open-chained polyethers, 2,6-pyridine-dimethanol, and ortho-xylene derivatives terminated in an 8-quinolinyl group could form stable, 1 1, crystalline complexes with a variety of metal salts. The podands were prepared from 8-hydroxyquinoline and the corresponding dihalides. A typical example is shown in Eq. (7.10). 

System Para/ortho Xylene at 16 mm Hg abs and total reflux... 

Para/Ortho Xylene 740mm Hg Metal Intalox No. 25 0.8-1.3... 

Broekhoven, E. V, and Wijngaards, H., Investigation of the Acid Site Distribution of FCC Catalysts with Ortho-xylene as a Model Compound, 1988 Akzo Chemicals FCC Symposium, Amsterdam, The Netherlands. 

Ortho-Xylene Ozonide. C8H10O6 (probable structural formulae are shown in Ref 2), colorl crysts. 

Levine A A, AG Cole (1932) The ozonides of ortho-xylene and the structure of the benzene ring. J Am Chem Soc 54 338-341. 

Ortho-xylene (A) is oxidised to phthalic anhydride (B) in an ideal, continuous flow tubular reactor. The reaction proceeds via the complex consecutive parallel reaction sequence, shown below. The aim of the reaction is to produce the maximum yield of phthalic anhydride and the minimum production of waste gaseous products (C), which are CO2 and CO. 

Figure 1.11 Plot of the logarltha of the adjusted retention tine against the reciprocal of coluan tesperature for two honologous series of n-alkane and n-alkylbensenes (and ortho-xylene) on a 2 seter 20% (H/H) colunn of tetrahutylaanoniua 4-toluenesulfonate coated onto Chronosorb (W-AH). Solute identification, 1 decane, 2 - undecane, 3 - dodecane, 4 trideceme, 5 tetradecane, 6 -pentadecane, 7 > benzene, 8 - toluene, 9 - ethylbenzene, 10 -propylbenzene, 11 - ortho-xylene, and 12 - butylbenzene.

Either naphthalene or ortho-xylene is an acceptable starting material for partial oxidation to phthalic anhydride, but current raw materials costs favor the former as a starting material. Both fixed and fluidized bed processes have been used on a commercial scale, but you are to focus your attention on the former. Figure 13.5 is a schematic flow diagram of the proposed process. Most research groups that have studied the catalytic oxidation of naphthalene over vanadium pentoxide agree that the principal reactions are... 

Figure 9. Model for STDP. Bz benzene, T toluene, P,M,o para-, meta-, and ortho-xylene.

The zeolites and catalysts used in this study were prepared as described previously (1,16,18,20). The ortho-xylene sorption rate data, obtained on a computer-controlled Du Pont 951 TGA, were measured at 120°C and P(o-xylene) 3.8 torr. The isomerization and disproportionation data were obtained using a... 

Interesting conformational effects may be encountered in alkyl substituted benzenes such as the three rotamers of ortho xylene shown below ... 

A = -,54)191) and ethylene (A = -2.8)2S Hence, pi nonbonded attractive interactions are enhanced in ortho xylene relative to cis 2-butene. 

We conclude from the above considerations that pi nonbonded attractive interactions may dominate sigma nonbonded attractive interactions and, consequently, conformational stability in ortho xylene could vary in the following way SS > EE > SE. 

The preferred conformation of ortho xylene has been determined by C13 NMR and the most stable rotamer was found to be the SS conformation192. ... 

The isomers, called ortho-xylene, meta-xylene, and para-xylene, each have unique properties. Two such properties are the freeze points, at which xylenes turn from liquid to crystals, and the boiling points, at which xylenes turn from liquid to vapor. These two properties figure importantly in the apparatus used to separate xylene isomers from each other. Mixed xylenes, a commonly traded commodity, is a combination of the three isomers. 

Ortho-xylene can be separated by distillation ethylbenzene is only 3.9°F from para-xylene, but by using very tall, multitrayed distillation columns (200 feet high with 300 trays), it too can be separated fairly... 

Licensors offer a variety of catalysts to promote the isomerization— silica alumina by itself or enhanced with a noble metal like platinum or a non-noble metal like chromium. Another uses hydrofluoric acid with boron trifluoride In the case of the noble metal catalytic process, the feed enters a vessel with a fixed catalyst bed at 850°F and 14.5 psi. As is often the case, a small amount of hydrogen is present to reduce the amount of coke laying down on the catalyst. The effluent is processed in a standard fashion to separate the hydrogen, the para- and ortho-xylene, and any unreacted or miscellaneous compounds. Yields of para-xylene are in the 70% range. 

Mixed xylenes are used as an octane improver in gasoline and for commercial solvents, particularly in industrial cleaning operations. By far, most of the commercial activity is with the individual isomers. Para-xylene, the most important, is principally used in the manufacture of terephthalic acid and dimethyl terephthalate en route to polyester plastics and fibers (Dacron, films such as Mylar, and fabricated products such as PET plastic bottles). Ortho-xylene is used to make phthalic anhydride, which in turn is used to make polyester, alkyd resins, and PVC plasticizers. Meta-xylene is used to a limited extent to make isophthahc acid, a monomer used in making thermally stable polyimide, polyester, and alkyd resins. 

All the BTXs are high-octane gasoline blending components. In the petrochemicals business, toluene is used as a building block for polyurethane. Para-xylene and ortho-xylene are used to make polyester fibers and plastics, allcyd resins, and plasticizers. 

Until 1959, all the phthalic anhydride was made from coal tar naphthalene, the double-benzene ring compound also shown in Figure 18—3 was easily oxidized directly to phthalic acid. But with phthalic anhydride being only a small share of coal oil, and with the demand for phthalic anhydride escalating rapidly, coal tar became an inadequate source. The frantic search for an alternative route led to the development of the recovery process for ortho-xylene from refinery aromatics streams discussed in Chapter 3 and the... 

The bulk of the effluent is run through a cooler (heat exchanger) and a condenser to remove the light ends that include traces of carbon monoxide and carbon dioxide and by-product water. The bottom stream is maleic acid, which is easily dehydrated, as in Figure 20—4, by vacuum distillation or azeotropic distillation with ortho-xylene. See Chapter 3 if youVe forgotten totally everything about azeotropic distillation.) The dehydrated maleic acid is maleic anhydride. Further purification is done by distillation.,... 

Ortho-xylene Phthalic acid COOH 1 COOH Phthalic anhydride... 

Acetic anhydride (acetic acid), phthalic anhydride (ortho-xylene), and maleic anhydride (butane or benzene). Phthalic anhydride has a benzene ring as its unique feature, with its three double bonds maleic anhydride has its single, but reactive, double bond. Acetic anhydride has only the... 

Cobalt acetate is used to make acetic acid out of butane palladium chlo-ride/cupric chloride is used to make MEK out of butylene and lo and behold, to make phthalic anhydride out of ortho-xylene or naphthalene, you use vanadium pentoxide. 

Benzene and para-xylene are the most sought after components from reformate and pygas, followed by ortho-xylene and meta-xylene. While there is petrochemical demand for toluene and ethylbenzene, the consumption of these carmot be discussed in the same way as the other four. Toluene is used in such a large quantity in gasoline blending that its demand as a petrochemical pales in comparison. Fthylbenzene from reformate and pygas is typically dealkylated to make benzene or isomerized to make xylenes. On-purpose production of petrochemical ethylbenzene (via ethylene alkylation of benzene) is primarily for use as an intermediate in the production of another petrochemical, styrene monomer. Ethylbenzene plants are typically built close coupled with styrene plants. 

In the case of toluene alkylation with methanol an opportunity exists for para selectivity. Para-xylene ortho-xylene ratio was 3.1 over MFl and 0.6 over BEA framework types. 

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