Benzene 445 table

The feedstock is usually extracted toluene, but some reformers are operated under sufftciendy severe conditions or with selected feedstocks to provide toluene pure enough to be fed directiy to the dealkylation unit without extraction. In addition to toluene, xylenes can also be fed to a dealkylation unit to produce benzene. Table 20 Hsts the producers and their capacities for manufacture of benzene by hydrodealkylation of toluene. Additional information on hydrodealkylation is available in References 50 and 52. 

Table 3 shows the number of stmctural isomers possible when one, two, three, or four substituents, X, Y, and Z, replace the hydrogens of benzene. Table 3. Number of Structural Isomers of the Substitution Products of Benzene...

As in hydrocracking, this reaction increases the gas yield and changes the relative equilihrium distrihution of the aromatics in favor of benzene. Table 3-7 shows the properties of feed and products from Chevron Rheiniforming process. 

In helium, all hexanes give benzene (Table IV) (97, 97a). Methylcyclo-pentzne and methylpentanes give similar benzene yields. No saturated isomers are detected, and the ring opening of methylcyclopentane is negligible. 

The adduct of silyl radicals to 4-substituted pyridines and pyrazine monitored by EPR results from the attack at the nitrogen atom to give radicals 52 and 53, respectively [68,69]. The rate constant for the addition of Et3Si radical to pyridine is about three times faster than for benzene (Table 5.3) [24]. 

The regioselectivity of these ring opening reactions is sensitive to additional annelation on benzene (Table 7). In the tetralin derivative (59), little selectivity between type I and type II products is observed with either set of electrophilic reagents. A reversal of regioselectivity is observed in cyclobutabenzene and indan... 

However, in contrast to benzene (Table IX), hexazine is thermodynamically unstable with respect to decomposition into molecular nitrogen... 

Microbial biosensors associated with respiration have been described for the following aromatics phenol, benzoate, naphthalene, dibenzofuran, biphenyl, and benzene. Table 10 gives a survey of the characteristic parameters of these microbial sensors along with interfering substances. 

When 5 moles of benzene and 1 mole of II competed in concentrated sulfuric acid for the nitronium ion, the nitration of the first ring proceeded about 300 times faster than the nitration of benzene (Table II). Similarly the nitration of II proceeded about 150 times faster than that of toluene and comparable to that of p-chlorophenol. 

The quantity of aromatic contaminants that adsorb onto TiO2 surfaces is also relatively low. d Hennezel and Ollis [47] measured the dark adsorption of the BTEX compounds at a gas-phase concentration of 50 mg/m . Benzene displays the lowest dark adsorption, followed by ethylbenzene. Higher dark adsorption was observed for toluene and xylenes. At 50 mg/m, the dark adsorption of m-xylene was nearly 10 times that of benzene (Table 1). 

From the heat of combustion of benzenamine we know that it has a 3 kcal mole-1 larger stabilization energy than benzene (Table 21-1). This difference in stabilization energies can be ascribed in either valence-bond or molecular-orbital theory to delocalization of the unshared pair of electrons on nitrogen over the benzene ring. The valence-bond structures are... 

Further details of the phase separation of polymer mixtures were obtained by analyzing the high styrene phase sedimented at a weight concentration gB of benzene (Table II). 

The dependence of the parajmeta ratio for substitution in toluene on the relative rates of reaction of toluene and benzene (Table 1) prompted... 

The shortening of B-H is twice as much, while that of N-H bond is a half as much as the shortening of the C-H bonds in benzene (Table 12). Changes in valence angles (p (BNB) and (p (NBN) do not exceed 2°. 

In another paper Fendler et al.59) investigated again the CMC dependence of alkylammonium propionates on the number of carbon atoms in the alkyl group of the quaternary ammonium cation (Fig. 12). The same feature as mentioned with octylammonium carboxylates is observed, i.e., the constancy of the CMC values for these alkylammonium propionates in carbon tetrachloride, while in benzene a linear plot is obtained. The latter is taken to indicate the decreased solubility of the monomers with increasing alkyl chain length in benzene. Table 471 exhibits in addition... 

The sulfoxidation of benzene (Table 4, entry 38) yields benzenesulfonic acids and the respective derivatives. The electrophilic aromatic substitution reaction gives high yields and aqueous sulfuric acid or oleum is used for the sulfonation reaction, which is performed in cascades of reactor vessels. 

The vast majority of reactivities and regioselectivities observed in the reaction with electrophiles on monosubstituted benzenes (Table 5.2) are in agreement with the preceding generalizations (columns 2 and 4). The very few substituents that are not in agreement (column 3) deactivate the aromatic compound as do electron acceptors, but they are para- > ortho-directing as are electron donors. 

C o solubility increases in the similar sequence, from iodobenzene to chlorobenzene. The exception is fluorobenzene in which C6o solubility is lower than in iodobenzene. Apparently, in the case of interaction between fluorobenzene and C6o fullerene the factor of high fluorine electronegativity prevails. Moreover, as Table 3 indicates the fluorobenzene nitration gives rise to mainly para-isomer and very little ort/zo-isomers. Consequently, the entire negative charge is localized in the /jara-position in a fluorobenzene molecule. Therefore, as with Cgo solubility in alkyl derivatives of benzene (Table 2), one can anticipate that for the C6o molecule that is an electrophilic reagent, the ortho-position will be the more preferential location for electrophilic attack than the /w/ra-position. 

Sulphonylation as well as sulphonation of toluene and benzene (Table 19) also indicate that the reactivity-selectivity principle is obeyed (Olah, 1971). 

Asphaltenes could not be applied on silica gel in the same manner as the resins because of their insolubility in nC5. Therefore, the sample of asphaltenes was dissolved in benzene, and this solution was stirred with sufficient amount of silica gel at 50°C in a rotary evaporator. Evaporation of benzene in vacuo furnished asphaltene-coated silica gel, which was added to the top of the silica gel column. The weight ratio of asphaltene to total silica gel was 1 100. The column was first eluted with nC5, then with benzene/nC5 mixtures of increasing proportions of benzene up to 100% benzene. Table I shows that already nC5 and 30% Bz/nC5 eluted 7.5% of the asphaltenes, 45% Bz/nC5 another 3.5%, and 60% Bz/nC5 an additional 6.6% altogether 17.6% asphaltenes were eluted with this series of solvents. Under very similar conditions, the elution of resins amounted to 60% of total resins. 

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