Aromatics Toluene Xylene

Olah and co-workers219 have applied Nafion-H in the benzylation of benzene with benzyl alcohols [Eq. (5.83)] and also reported the reaction of benzyl alcohol with substituted aromatics (toluene, xylenes, mesitylene) to yield diphenylmethanes. The reaction is performed under mild conditions and produces the corresponding dibenzyl ethers as byproducts (2-22%). The substrate and positional selectivity in competitive benzylation of benzene and toluene (1 1 molar ratio) was found to be almost the same as observed in solution-phase Friedel-Crafts benzylation with benzyl chloride (AICI3-CH3NO2). Cyclic products 56 and 57 resulting from cyclialkylation were isolated when Nafion-H-catalyzed benzylation was applied to 2-(hydroxymethyl) diphenylmethane and 3,4-dimethoxybenzyl alcohol, respectively. 

Aromatic Toluene, xylene, benzene Nausea ventricular Headache, anorexia. 

In fact, the El mass spectra in Figure 5.12 show that at 340°C xmsubstituted aromatic compounds (benzene, naphtiralene, anthracene) are present together with HCl, whereas at 450°C are mainly foimd alkyl aromatics (toluene, xylene, methylnaphthalene, and the like). ... 

Concentrated sulphuric acid. The paraffin hydrocarbons, cych-paraffins, the less readily sulphonated aromatic hydrocarbons (benzene, toluene, xylenes, etc.) and their halogen derivatives, and the diaryl ethers are generally insoluble in cold concentrated sulphuric acid. Unsaturated hydrocarbons, certain polyalkylated aromatic hydrocarbons (such as mesitylene) and most oxygen-containing compounds are soluble in the cold acid. 

Similarly, A[-carboxy-a-amino acid anhydrides react with aromatics such as toluene, xylenes, and mesitylene to give a-amino acylated products ia moderate yields with almost complete retention of configuration of the a-amino acid. 

Proof of the existence of benzene in the light oil derived from coal tar (8) first estabHshed coal tar and coal as chemical raw materials (see Eeedstocks, COAL chemicals). Soon thereafter the separation of coal-tar light oil into substantially pure fractions produced a number of the aromatic components now known to be present in significant quantities in petroleum-derived Hquid fuels. Indeed, these separation procedures were for the recovery of benzene—toluene—xylene (BTX) and related substances, ie, benzol or motor benzol, from coke-oven operations (8) (see BTX processing). 

PMMA is not affected by most inorganic solutions, mineral oils, animal oils, low concentrations of alcohols paraffins, olefins, amines, alkyl monohahdes and ahphatic hydrocarbons and higher esters, ie, >10 carbon atoms. However, PMMA is attacked by lower esters, eg, ethyl acetate, isopropyl acetate aromatic hydrocarbons, eg, benzene, toluene, xylene phenols, eg, cresol, carboHc acid aryl hahdes, eg, chlorobenzene, bromobenzene ahphatic acids, eg, butyric acid, acetic acid alkyl polyhaHdes, eg, ethylene dichloride, methylene chloride high concentrations of alcohols, eg, methanol, ethanol 2-propanol and high concentrations of alkahes and oxidizing agents. 

Petrochemicals are those chemicals produced from petroleum or natural gas and can be generally divided into three groups (/) aliphatics, such as butane and butene (2) cycloaliphatics, such as cyclohexane, cyclohexane derivatives, and aromatics (eg, ben2ene, toluene, xylene, and naphthalene) and (J) inorganics, such as sulfur, ammonia, ammonium sulfate, ammonium nitrate, and nitric acid. 

Polymethylbenzenes (PMBs) are aromatic compounds that contain a benzene ring and three to sis methyl group substituents (for the lower homologues see Benzene Toluene Xylenes and ethylbenzene). Included are the trimethylbenzenes, (mesit iene (1), pseudocumene (2), and hernimeUitene (3)),... 

In order to obtain pure aromatics, cmde reformate is extracted to separate the aromatics from unreacted paraffins and cyclop araftins. The aromatics are, in turn, separated by simple fractional distillation to yield high purity benzene, toluene, xylenes, and aromatics. 

Unbumed Hydrocarbons Various unburned hydrocarbon species may be emitted from hydrocarbon flames. In general, there are two classes of unburned hydrocarbons (1) small molecules that are the intermediate products of combustion (for example, formaldehyde) and (2) larger molecules that are formed by pyro-synthesis in hot, fuel-rich zones within flames, e.g., benzene, toluene, xylene, and various polycyclic aromatic hydrocarbons (PAHs). Many of these species are listed as Hazardous Air Pollutants (HAPs) in Title III of the Clean Air Act Amendment of 1990 and are therefore of particular concern. In a well-adjusted combustion system, emission or HAPs is extremely low (typically, parts per trillion to parts per billion). However, emission of certain HAPs may be of concern in poorly designed or maladjusted systems. 

Aromatic compounds such as toluene, xylene, and phenol can photosensitize cis-trans interconversion of simple alkenes. This is a case in which the sensitization process must be somewhat endothermic because of the energy relationships between the excited states of the alkene and the sensitizers. The photostationary state obtained under these conditions favors the less strained of the alkene isomers. The explanation for this effect can be summarized with reference to Fig. 13.12. Isomerization takes place through a twisted triplet state. This state is achieved by a combination of energy transfer Irom the sensitizer and thermal activation. Because the Z isomer is somewhat higher in energy, its requirement for activation to the excited state is somewhat less than for the E isomer. If it is also assumed that the excited state forms the Z- and -isomers with equal ease, the rate of... 

The major aromatics (organics having at least one ring structure with six carbon atoms) manufactured include benzene, toluene, xylene, and naphthalene. Other aromatics manufactured include phenol, chlorobenzene, styrene, phthalic and maleic anhydride, nitrobenzene, and aniline. Benzene is generally recovered from cracker streams at petrochemical plants and is used for the manufacture of phenol, styrene, aniline, nitrobenzene, sulfonated detergents, pesticides such as hexachlorobenzene, cyclohexane (an important intermediate in synthetic fiber manufacture), and caprolactam, used in the manufacture of nylon. Benzene is also used as a general purpose solvent. 

Of the top ten most frequently reported toxic chemicals on the TRI list, the prevalence of volatile chemicals explains the air intensive toxic chemical loading of the refining industry. Nine of the ten most commonly reported toxic chemicals are highly volatile. Seven of the ten are aromatic hydrocarbons (benzene, toluene, xylene, cyclohexane, 1,2,4-trimethylbenzene, and ethylbenzene). 

Aromatic — organic molecular structure having the benzene ring (C H ) as the basic unit (e.g., toluene, xylene). 

Attenlion should be drawn to ihe use of tin oxide systems as heterogeneous catalysts. The oldest and mosi extensively patented systems are the mixed lin-vanadium oxide catalysis for the oxidation of aromatic compounds such as benzene, toluene, xylenes and naphthalene in the. synthesis of organic acids and acid anhydride.s. More recenily mixed lin-aniimony oxides have been applied lo the selective oxidaiion and ammoxidaiion of propylene to acrolein, acrylic acid and acrylonilrile. 

Benzene, toluene, xylenes (BTX), and ethylbenzene are the aromatic hydrocarbons with a widespread use as petrochemicals. They are important precursors for many commercial chemicals and polymers such as... 

Simple aromatic hydrocarbons come from two main sources coal and petroleum. Coal is an enormously complex mixture made up primarily of large arrays of benzene-like rings joined together. Thermal breakdown of coal occurs when it is heated to 1000 °C in the absence of air, and a mixture of volatile products called coal for boils off. Fractional distillation of coal tar yields benzene, toluene, xylene (dimethylbenzene), naphthalene, and a host of other aromatic compounds (Figure 15.1). 

A PVC-poor light fraction separated from mixed plastic household waste was pyrolysed to yield aromatic oils and heat-providing gas. Target products were benzene, toluene, xylenes, and styrene. Problematic pollutants were... 

Aromatic hydrocarbons G L Benzene Toluene Xylene Coal tar distillation Vehicle exhauks Petrochemicals Pesticides Herbicides... 

Catalytic upgrading of bio-oil was carried out over Ga modified ZSM-5 for the pyrolysis of sawdust in a bubbling fluidized bed reactor. Effect of gas velocity (Uo/U ,f) on the yield of pyrolysis products was investigated. The maximum yield of oil products was found to be about 60% at the Uo/Umf of 4.0. The yield of gas was increased as catalyst added. HZSM-5 shows the larger gas yield than Ga/HZSM-5. When bio-oil was upgraded with HZSM-5 or Ga/HZSM-5, the amount of aromatics in product increased. Product yields over Ga/HZSM-5 shows higher amount of aromatic components such as benzene, toluene, xylene (BTX) than HZSM-5. 

Aromatization of cyclic products to benzene, toluene, xylenes, etc. 

Aromatic solvent Benzene, toluene, xylene, residues of BTX distillation 10 to 60... 

Branched polyesters contain oxalkylated primary fatty amines or oxalkyl-ated polyamines together with at least trivalent oxalkylated alkanol that is responsible for branching. The condensation is achieved with a dicarboxylic acid or a dicarboxylic acid anhydride [216]. In this way, branched polyoxyalkylene mixed polyesters are formed. Suitable solvents are water or organic solvents, such as methanol, isopropanol, butanol, or aromatic hydrocarbons (e.g., toluene, xylene). 

About 100 gal of process wastewater is typically generated from 1 t of coke produced.15 These wastewaters from byproduct coke making contain high levels of oil and grease, ammonia nitrogen, sulfides, cyanides, thiocyanates, phenols, benzenes, toluene, xylene, other aromatic volatile components, and polynuclear aromatic compounds. They may also contain toxic metals such as antimony, arsenic, selenium, and zinc. Water-to-air transfer of pollutants may take place due to the escape of volatile pollutants from open equalization and storage tanks and other wastewater treatment systems in the plant. 

The most common hydrophobes used as the basis for surfactants are those containing eight to eighteen carbon atoms, such as those listed as carboxylates in Table 9.1. Some hydrophobes are aromatic (benzene or naphthalene) moieties, often containing lower alkyl substituents dodecylbenzene (9.1) is a common example. Alkyl-substituted toluenes, xylenes and phenols, and mono- and di-alkylated naphthalenes (9.2 and 9.3), are also used. 

As shown in Table 8, the spray paint solvent is predominately a mixture of several linear aliphatic, branched aliphatic, and cycloaliphatic hydrocarbons, and toluene, xylenes, and ethyl benzene. 2-Butanone (also known as methyl ethyl ketone) was also detected. The breakdown of the solvent mixture by class of compound (aromatic, //-alkane, iso-alkane, cyclic alkane, and others) is shown in Table 9. The solvent appears to be consistent with a mixture of a VM P naphtha... 

When ethylene is reacted at 573 K in the presence of water in static conditions, oligomerization and conjunct polymerization give rise to paraffinic, olefinic and aromatic products (8). Nevertheless, the distribution of the aliphatics and aromatics is quite different from that of the steam-cracking products. In the former a great variety of products is formed they include propane, n-butane, isobutane and isopentane as aliphatics, and toluene, xylenes and ethylbenzene as aromatics (Figure 6B). 

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