Benzene volatility

Additional emission reductions of benzene, volatile organic compounds, and particulate matter... 

Several patents discuss the use of Raman spectroscopy to determine the properties of finished products.93 94 For reformulated gasoline, some of these properties include sulfur, olefin, benzene, volatile organic carbon (VOC), nitrogen oxides (NOx), aromatic contents, total air pollutants (TAPs), Reid Vapor Pressure (RVP), distillation properties, motor and research octane numbers, and drivability. For the octane numbers, the accuracy of the Raman method was limited by errors in the reference method. 

Miscible with water, alcohols, acetone, ether, trichloromethane, benzene Volatile, hygroscopic... 

The importance of this synthetic route has been shown in the preparation of anhydrous tris-j6-diketonates of lauthanides, the hydrated forms of which obtained from aqueous solutions tend to decompose into hydroxy-derivatives. By nsing isopropoxides or ethox-ides as starting materials and removing the liberated alcohol by fractionation as a lower boiling azeotrope with a solvent such as benzene, volatile stable intermediate products may be obtained. The alkoxide groups in these mixed derivatives are much more reactive than the j6-diketonate ligands, as illustrated by Eqs (2.220)-(2.223) ... 

The reactor effluent is thus likely to contain hydrogen, methane, benzene, toluene, and diphenyl. Because of the large differences in volatility of these components, it seems likely that partial condensation will allow the effluent to be split into a vapor stream containing predominantly hydrogen and methane and a liquid stream containing predominantly benzene, toluene, and diphenyl. 

It frequently happens that more than one volatile product is evolved, a fact which may be of considerable value. For example, benzamide, CeHjCONHt, will give off first ammonia, and then benzonitrile and benzene on stronger heating salicylamide, HOC H CONHj, will give off ammonia and then phenol. Sulphanilamide, NH,C,H,SO,NH (p. 181), gives off ammonia and aniline. 

Nitrobenzene is an extremely versatile solvent, and may frequently be employed for the crystallisation of compounds which do not dissolve appreciably in the common organic solvents. The vapour is somewhat poisonous, so that recrystaUisations must be carried out in the fume cupboard. After the crystals have been collected, they should be washed with a volatile solvent, such as benzene, alcohol or ether, to remove the excess of nitrobenzene (compare Section 11,32). The only disadvantage of nitrobenzene as a solvent is that it has a pronounced oxidising action at the boihng point. 

The principle of headspace sampling is introduced in this experiment using a mixture of methanol, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene, and p-xylene. Directions are given for evaluating the distribution coefficient for the partitioning of a volatile species between the liquid and vapor phase and for its quantitative analysis in the liquid phase. Both packed (OV-101) and capillary (5% phenyl silicone) columns were used. The GG is equipped with a flame ionization detector. 

Alkylated aromatics have excellent low temperature fluidity and low pour points. The viscosity indexes are lower than most mineral oils. These materials are less volatile than comparably viscous mineral oils, and more stable to high temperatures, hydrolysis, and nuclear radiation. Oxidation stabihty depends strongly on the stmcture of the alkyl groups (10). However it is difficult to incorporate inhibitors and the lubrication properties of specific stmctures maybe poor. The alkylated aromatics also are compatible with mineral oils and systems designed for mineral oils (see Benzene Toulene Xylenes and ethylbenzene). ... 

Borane—dimethyl sulfide complex (BMS) (2) is free of these inconveniences. The complex is a pure 1 1 adduct, ca 10 Af in BH, stable indefinitely at room temperature and soluble in ethers, dichioromethane, benzene, and other solvents (56,57). Its disadvantage is the unpleasant smell of dimethyl sulfide, which is volatile and water insoluble. Borane—1,4-thioxane complex (3), which is also a pure 1 1 adduct, ca 8 Af in BH, shows solubiUty characteristics similar to BMS (58). 1,4-Thioxane [15980-15-1] is slightly soluble in water and can be separated from the hydroboration products by extraction into water. 

Aromatic Hydrocarbons. These are the most toxic of the hydrocarbons and inhalation of the vapor can cause acute intoxication. Benzene is particularly toxic and long-term exposure can cause anemia and leukopenia, even with concentrations too low for detection by odor or simple instmments. The currendy acceptable average vapor concentration for benzene is no more than 1 ppm. PolycycHc aromatics are not sufftcientiy volatile to present a threat by inhalation (except from pyrolysis of tobacco), but it is known that certain industrial products, such as coal tar, are rich in polycycHc aromatics and continued exposure of human skin to these products results in cancer. 

The price of aniline is also dependent on the cost of benzene, the raw material for nitrobenzene. During the decade of the 1980s, benzene prices ranged from a low of 0.185/L to a high of 0.595/L. A 0.01/L change in price of benzene is roughly equivalent to a 0.01/kg change in the cost of aniline. At times aniline prices are stated on an "ex-benzene" basis to eliminate the effect of volatility in benzene prices on the price of the aniline sold. 

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

Higher alkoxides, such as tetra(2-ethylhexyl) titanate, TYZOR TOT [1070-10-6], can be prepared by alcohol interchange (transestenfication) in a solvent, such as benzene or cyclohexane, to form a volatile a2eotrope with the displaced alcohol, or by a solvent-free process involving vacuum removal of the more volatile displaced alcohol. The affinity of an alcohol for titanium decreases in the order primary > secondary > tertiary, and... 

Removal of Volatile Organics. Volatile organics, eg, benzene and toluene, should usually be removed prior to biological treatment. 

Recent air pollution regulations limit the amount of volatile organic carbon (VOC) that can be discharged from wastewater treatment plants. Benzene is a particular case in which air emission controls are required if the concentration of benzene in the influent wastewater exceeds 10 mg/L. 

Benzene [71-43-2] 6 6 volatile, colorless, and flammable liquid aromatic hydrocarbon possessing a distinct, characteristic odor. Benzene is used as a... 

Esters of low volatility are accesible via several types of esterification. In the case of esters of butyl and amyl alcohols, water is removed as a binary azeotropic mixture with the alcohol. To produce esters of the lower alcohols (methyl, ethyl, propyl), it may be necessary to add a hydrocarbon such as benzene or toluene to increase the amount of distilled water. With high boiling alcohols, ie, benzyl, furfuryl, and P-phenylethyl, an accessory azeotroping Hquid is useful to eliminate the water by distillation. 

For apphcation to distiUation (a nearly isobaric process), as shown in Figs. 13-8 to 13-13, binary-mixture data are frequently plotted, for a fixed pressure, as y versus x, with a line of 45° slope included for reference, and as T versus y and x. In most binary systems, one of the components is more volatile than the other over the entire composition range. This is the case in Figs. 13-8 and 13-9 for the benzene-toluene system at pressures of both 101.3 and 202.6 kPa (1 and 2 atm), where benzene is more volatile than toluene. 

The impurities present in aromatic nitro compounds depend on the aromatic portion of the molecule. Thus, benzene, phenols or anilines are probable impurities in nitrobenzene, nitrophenols and nitroanilines, respectively. Purification should be carried out accordingly. Isomeric compounds are likely to remain as impurities after the preliminary purifications to remove basic and acidic contaminants. For example, o-nitrophenol may be found in samples ofp-nitrophenol. Usually, the ri-nitro compounds are more steam volatile than the p-nitro isomers, and can be separated in this way. Polynitro impurities in mononitro compounds can be readily removed because of their relatively lower solubilities in solvents. With acidic or basic nitro compounds which cannot be separated in the above manner, advantage may be taken of their differences in pK values (see Chapter 1). The compounds can thus be purified by preliminary extractions with several sets of aqueous buffers... 

Coal tar pitch volatiles, see Particulate polycyclic aromatic hydrocarbons (PPAH), as benzene solubles Cobalt metal, dust and fume (as Co)... 

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). 

The principal PIC for penta and penta-treated wood would include volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), dioxins and furans, as well as SOj, COj, NO, and HCl. Penta would be expected to have undergone a very high destruction efficiency (DRE) during the fire (> 99.99%). Among the VOC emissions, the following chemicals likely contributed to air pollution problems benzene, bromobenzene, chloromethane, 1,3-butadiene, iodomethane, acetone, chloroform, and 1,2-dichloroethane. 

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