Xylenes


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Xylenes

 

(dimethylbenzenes). Three isomers (ortho-xylene, meta-xylene, and para-xylene) are known. All are colorless liquids that are readily soluble in organic solvents and poorly soluble in water. (See Table 1 for some physical properties of xylenes.) Their structural formulas are

Xylenes form highly explosive vapor-air mixtures. They cause acute and chronic damage to the blood-forming organs, as well as dermatitis upon contact with skin. Oxidation of xylenes yields toluic and phthalic acids. Xylenes are obtained from the products formed as a result of the coking of coal or during petroleum aromatization. The isomers are separated by fractional

Table 1. Some properties of xylenes
Propertieso-xylenem-xylenep-xylene
*1 cp (centipoise) = 10−3 newtons • sec/m2
Melting point, °C ...........−25.18B47.8713.26
Boiling point, °C............144.41139.10138.35
Density at 20°C, g/cm3.........0.88020.86420.8611
Refractive index np20 .....1.50541.49721.4958
Viscosity at 20°C, cp* ........0.8090.6170.644

crystallization and rectification. Xylenes are used as solvents, high-octane additives to aviation gasoline, and the initial material in the preparation of xylidines. Of greatest importance is ρ-xylene, which is used in the manufacture of terephthalic acid.

References in periodicals archive ?
Detailed information of all active plants and planned Xylenes projects in Russia with capacity forecasts to 2019 and additional details such as process, technology, operator and equity
Detailed information of all active plants and planned Xylenes projects in Korea with capacity forecasts to 2019 and additional details such as process, technology, operator and equity
Paraxylene is the most important product on the market for xylenes.
Tables 2 and 3 show the toluene conversion and xylenes selectivity's obtained for the unmodified and modified catalysts, respectively.
Xylenes industry supply scenario in the region from 2000 to 2016 consisting of capacity growth, installed plant capacity by production process and technology
Xylenes industry supply scenario in Brazil from 2005 to 2019, comprising plant capacity growth and installed plant capacity by production process and technology
Xylenes industry supply scenario in Argentina from 2005 to 2019, comprising plant capacity growth and installed plant capacity by production process and technology
Regarding the fate of hydrocarbons in the environment, we know that if contaminants such as polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylenes (BTEXs) are not degraded aerobically, they are likely to be transported into anaerobic regions.
The Kuwaiti petrochemicals industry lacks a sufficiently broad product portfolio - notable by its failure to diversify into the purified terephthalic acid-polyethylene terephthalate chain despite sizeable xylenes feedstock availability - and this will mean the country will register a lacklustre performance compared to regional peers in 2012.
Xylenes industry supply scenario in the United States from 2005 to 2019, comprising plant capacity growth and installed plant capacity by production process and technology
Xylenes industry supply scenario in Canada from 2005 to 2019, comprising plant capacity growth and installed plant capacity by production process and technology
Honeywell s UOP Tatoray process converts toluene and C9 aromatics to mixed xylenes and high-purity benzene without the need for sulfolane extraction.