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Xylene
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
MW 106.18; CAS [1330-20-7]; [95-47-6] for o-xylene, [108-38-3] for m-xylene and [106-42-3] for p-xylene; used as a solvent and in the manufacture of dyes and drugs; occurs in gasoline and petroleum solvents; colorless liquid with characteristic odor; boiling point for o-, m-, and p-isomers 144.4°C, 139.1°C, and 138.4°C, respectively; their vapor pressures at 20°C are 6.7, 8.4, and 8.8 Torr, respectively; density 0.880, 0.864, and 0.861 g/mL, respectively; practically insoluble in water; readily miscible with organic solvents.
Study of Pyrolyzates from a Variety of Indian Coals and Their Dependency on Coal Type and Intrinsic Properties – An Analytical Fast Pyrolysis Study
Published in Combustion Science and Technology, 2022
Devi Prasad Mishra, Kanak Kumar, Jaya Narayan Sahu
The alkyl benzenes, alkyl indenes, alkyl phenols, alkyl phenanthrenes and alkyl anthracenes, and alkyl naphthalenes found in pyrolyzates of Indian coals are presented in Table 4. The results show the abundances of alkyl benzenes in coal pyrolyzates. BCCL contains the highest and MCL contains the lowest amounts of C0 to C3-alkylbenzenes. The major constituents of light aromatic alkylbenzene are identified as toluene, o-xylenes, and benzene. Toluene covers almost one-third area composition of the total percentage of alkylbenzenes and it is highly abundant in CCL, BCCL, NCL, and SAIL. O-xylene is the major alkylbenzene product found in BCCL, as it covers 35.6% of the total area composition followed by SAIL and CCL. Though the presence of benzene in coal samples is moderate, it is mostly found in BCCL, CCL, and SAIL. In chemical industry, o-xylene is a key precursor to phthalic anhydride, which is a vital industrial chemical especially used for large-scale production of plasticizers for plastic manufacturing.
Hydrodeoxygenation of bio-oil and model compounds for production of chemical materials at atmospheric pressure over nickel-based zeolite catalysts
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zhiyu Li, Weiming Yi, Zhihe Li, Xueyuan Bai, Peng Fu, Chunyan Tian, Yuchun Zhang
As shown in a product distribution analysis in Figure 6, the reaction pathway of the HDO of GUA is as follows: most GUA produced phenol and CH4 by HDO (GUA+H2→Ph+CH3O−). o-Xylene was primarily produced from the transalkylation, HDO and hydrogenation (or dehydrogenation) of phenol (Ph+CH3O−+H2→methylphenol+H2O; methylphenol+H2→Tol+H2O; Tol+H2+ CH3O−→O-xy+H2O). Anisole was primarily produced from the HDO of GUA (GUA+H2→An+H2O). Benzene was primarily produced by the demethoxylation of anisole (An+H2→Ben+CH3O–). Styrene was formed by combining transalkylation and HDO (Ben+H2+ CH3O–→Sty+H2). Benzene in phenol HDO can be ignored because this rarely occurs under environmental pressure (Saidi et al. 2013). Additionally, benzene derivatives were prepared by transferring methyl or methoxy groups of GUA and anisole into benzene rings. Methoxyl or methyl groups were also transferred to phenol rings to produce phenol derivatives and other oxygen compounds. Methylphenol was formed by the HDO of GUA (Nimmanwudipong et al. 2011). (An: anisole, Ph: phenol, Tol: toluene, O-xy: o-xylene, Ben: benzene, Sty: styrene)
Biomonitoring of firefighting forces: a review on biomarkers of exposure to health-relevant pollutants released from fires
Published in Journal of Toxicology and Environmental Health, Part B, 2023
Bela Barros, Marta Oliveira, Simone Morais
Benzene, toluene, ethylbenzene, and xylene (BTEX) are among the most characterized VOCs in firefighting scenarios. Firefighters may be exposed to BTEX during the burning of VOCs-containing materials, principally during structure fires such as residential, industrial or oil wells facilities training exercises and prescribed forest fires, which frequently use diesel fuel, heating oil, plywood, pallet, straw, firewood, and particle chipboard as fuels (Fent et al. 2019; Kirk and Logan 2015; Stec et al. 2018). Benzene (1) occurs naturally in petroleum derivatives such as crude oil and gasoline, (2) is used as a solvent for chemical and drug industries including rubber, lubricants, detergents or pesticides and (3) as an additive to unleaded gasoline. Exposure to benzene induces oxidative stress, alters DNA repair, induces genomic instability and promotes oxidative DNA damage (Figure 5) (2010a; IARC 2010b). Thus, benzene exhibits genotoxic, immunosuppressive, and carcinogenic properties (group 1; IARC 2022a). Exposure to benzene and ethylbenzene used in the manufacture of styrene and as a solvent in inks, dyes, and petrol; IARC group 2B) is associated with increased risk of leukemia and multiple myeloma (2022a; IARC 2010b). Toluene is frequently used as a high-octane blending stock in gasoline and as a solvent/intermediate in several industrial processes such as production of coatings, paints, resins, and detergents. Xylene, mixture of dimethyl benzene isomers (m-, p-, and o-xylene), is refined from crude oil and widely utilized in production of plastic bottles and polyester clothing as well as a solvent in paints and varnishes. Despite being classified as IARC group 3 carcinogen (inadequate evidence), chronic exposures to toluene and xylene may induce adverse reproductive effects (McKenzie et al. 2012).