Enhancer of benzene

Duffy and Nelson (1997) report during commutes in Sydney, Australia, that the benzene concentrations inside vehicles were 10-25 times those in ambient air and that the concentrations of 1,3-butadiene were more than 55-115 times greater. The source appeared to be primarily from the exhausts of surrounding vehicles. Similar enhancements of benzene and other VOCs such as toluene, ethylbenzene, and the xylenes in automobiles and buses have been reported in many countries, including Korea (Jo and Choi, 1996), Taiwan (Chan et al., 1993), and the United States (e.g., Chan et al., 1991a,b Lawryk and Weisel, 1996). 

The predicted enhancement of benzene mobility in NaX zeolite was explained by using a simple model, which accounts for both the enhancement effect and its order of magnitude. The addition of a new sorption site (the Sill site) in NaX zeolite that is of approximately the same strength... 

Addition of dimethylformamide makes it possible to achieve essential increase in monoohlorobenzene yield. In this case the total current efficiency of the benzene chlorination products is 9056, 3B-33% substance yield, while the chlorobenzene current efficiency 15%. This effect mi t have been concerned with the enhancement of benzene solubility in the water phase. Furthermore dimethylformamide depresses side processes, concerned v/ith both electrochemical conversion of chlorine, formed on the electrodes and formation of dichlorobenzene. As fair as chlorination of benzene derivatives to the side oliain is concerned, the factors that influence the chemical chlorination (UV and more hard radiation, the presence of different initiators of free radicals formation) favorably affect the isolation of benzyl chloride, o-, m-, p-xylylchloric -. The current efficiency is more than 85%. 

The value of the second-order rate constant for nitration of benzene-sulphonic acid in anhydrous sulphuric acid varies with the concentration of the aromatic substrate and with that of additives such as nitromethane and sulphuryl chloride. The effect seems to depend on the total concentration of non-electrolyte, moderate values of which (up to about 0-5 mol 1 ) depress the rate constant. More substantial concentrations of non-electrolytes can cause marked rate enhancements in this medium. Added hydrogen sulphate salts or bases such as pyridine... 

Propiophenone. Propiophenone [93-55-0] (ethyl phenyl ketone) is a colorless Hquid with a flowery odor. It can be prepared by the Friedel-Crafts reaction of benzene and propionyl chloride in the presence of aluminum chloride (346), or by the catalytic reaction of benzoic acid and propionic acid in the presence of water (347). Propiophenone is commercially available (348), and is sold in Japan at 2700 Y/kg (349). It is used in the production of ephedrine, as a fragrance enhancer, and as a polymerization sensitizer. 

In the absence of die polyether, potassium fluoride is insoluble in benzene and unreactive toward alkyl halides. Similar enhancement of solubility and reactivity of other salts is observed in the presence of crown ethers The solubility and reactivity enhancement result because the ionic compound is dissociated to a tightly complexed cation and a naked anion. Figure 4.13 shows the tight coordination that can be achieved with a typical crown ether. The complexed cation, because it is surrounded by the nonpolar crown ether, has high solubility in the nonpolar media. To maintain electroneutrality, the anion is also transported into the solvent. The cation is shielded from interaction with the anion as a... 

The amount of diketone 9 formed during the reaction could be enhanced by using no solvent or ethanol solvent in place of benzene solvent. The use of... 

Radiocontrast media (RCM) are highly concentrated solutions of triiodinated benzene derivatives used for performing diagnosis and treatment of vascular disease and enhancement of radiographic contrast [1,2]. However, adverse reactions after RCM administration are common [3]. The frequency and mechanisms of hypersensitivity reactions differ between monomeric and dimeric as well as between ionic and non-ionic types of RCM. Mild immediate reactions have been reported to occur in 3.8-12.7% of patients receiving ionic monomeric RCM and in 0.7-3.1% of patients receiving non-ionic RCM [4-6]. Severe immediate adverse reactions to ionic RCM have been reported in 0.1-0.4% of intravenous procedures, while reactions to nonionic iodinated RCM are less frequent (0.02-0.04%) [4-7]. Fatal hypersensitivity... 

The preparation of iron impregnated activated carbon as catalysts and the catalytic performance of these catalysts were studied in benzene hydroxylation with hydrogen peroxide as oxidant. 5.0Fe/AC catalyst containing 5.0 wt% iron on activated carbon yielded about 16% phenol. The addition of Sn on 5.0Fe/AC catalyst led to the enhancement of selectivity towards phenol. 

The reason for enhancement of adsorption performance of PA/AC was considered to be due to combination effect of increase of BET surface area and chemical modification by the treatment with PA. Consequently, lwt%-PA/AC was determined to be a best candidate as an adsorbent for removing benzene, toluene, p-xylene, methanol, ethanol, and iso-propanol. Therefore, lwt%-PA/AC was used as the adsorbent to investigate the adsorption isotherm, adsorption and desorption performance. 

Figure 7. Time-of-flight mass spectra showing results of platinun cluster reactions with benzene. The lower trace is clean metal without reactant. The upper trace is with the pulsed addition of. 21 % benzene in heliun. The notation indicates the nmber of adducts on each metal cluster. The metal cluster are all two photon ionized, while the observed products are single photon ionized, hence the enhancement of the product over metal signals. Reproduced from Ref. 17.

The enhanced stabilizations of benzene are apparently due to the unique cyclic conjugative topology in which all sites are of closed-CT type. Each site thereby participates in complementary bi-directional donor-acceptor interactions,... 

This example involves a continuous adiabatic nitration process for the manufacture of mono-nitrobenzene (MNB) [215] by the reaction of benzene with nitric acid in a CSTR system. The process is designed to be inherently safe. No external cooling is used, but the reaction mass is heated by the reaction itself to a temperature level controlled by the amount of sulfuric add-water mixture circulating through the system. This acid actually acts as both a heat sink and as a nitration enhancer. If the sulfuric add pumps fail, the nitric add and benzene pumps are automatically shut off. 

Resonance Raman scattering, 21 326-327 Resonance stabilization of benzene, 3 599 Resonance theory, 20 774 Resonant cavity, 14 851 Resonant-cavity enhanced structures,... 

As mentioned earlier, at higher temperature the selective conversion of ethylbenzene is further enhanced by opening an additional pathway, i.e., dealkylation, that yields increased amounts of benzene of high purity ... 

Ultrasonic agitation during leaching has recently been reported to increase the catalytic activity of skeletal nickel for the hydrogenation of benzene to cyclohexane, with the enhanced activity related to changes in the catalyst structure and surface species [47],... 

GfSOj) for Hq/Bp (50) PSF is intermediate between G(S02> for the homopolymers. Thus, there is no additional protective effect analogous to the non-linear response of G(H.) as the mole fraction of benzene in cyclohexane is increased (3.47. This indicates that the spatial range of enhanced radiation protection afforded by the biphenyl group is limited. 

Addition of benzene to a solution of / -CD8 causes a two-fold enhancement of Eu3+ luminescence intensity. The stability constant of the complex between / -CD8 and benzene ( 200) is comparable to that of the complex with the native /i-CD. In contrast, benzoic and naphthoic acids show much stronger associations with / -CD8 than with native / -CD because association is assisted by the interaction between the carboxylic groups and the metal ion. Moreover, the enhancement factor of the luminescence is larger. 

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