Conversion with naphthalene

Conversions to pyridine-solubles for non-THF-extracted Linby coal were much greater with naphthalene than with phenanthrene and pyrene (Table m, pre-soaking at 250% has little effect on conversions) and, even after THF extraction, naphthalene conversions are comparable to those of pyrene. 

Although Neavel obtained high yields of pyridine-solubles with naphthalene at short contact times for some US bituminous coals (201. conversions were much lower after longer extraction times. This trend is not evident for Linby coal... 

Figure 1. Conversion of THF-extracted Linby coal with naphthalene at 400 C. Pyridine-solubles and THF-solubles.

Conversion calculated with naphthalene as an internal standard unless otherwise stated. 

Phthalic anhydride is the most important product in the oxidation of o-xylene, which has become competitive with naphthalene as a feedstock for the industrial production of this component. This process is carried out at 350— 400°C and the industrial catalysts consist of doped V2Os or V2Os—Ti02 mixtures, pure or supported. Maximum yields of 70—75 mol. % (95—105 wt. %) are reported. Carbon oxides are the main by-products, besides minor amounts of tolualdehyde and maleic anhydride. Tolualde-hyde is the main product at low conversion and an essential intermediate in the phthalic anhydride formation, while maleic anhydride is mainly formed as a side-product directly from o-xlyene. 

When the enone chromophore of the diketone (148) is excited selectively using 2537 A-light, a smooth conversion to the two stereoisomeric cyclopropyl diketones (149) and (150) takes place exclusively.27,28,44 Experiments with the 4a-deuteriomethyl analog of (148) establish a stepwise reaction sequence with the diradicals (151) [- (149)] and (152) [-> (150)] as the most likely intermediates formed in the primary photoprocess. Total quenching with naphthalene indicates the triplet nature of the reaction. 

That the observed effect of benzoannelation is consistent with the aromatic character of the benzenonium ion is confirmed by comparison with corresponding effects on the stabilities of tropylium49,167 and pyrylium ions168,169 shown in Scheme 24. In both cases the stabilities of the ions are severely reduced by the additional benzene rings. Indeed, the effect may be compared with the effect of benzoannelation on the aromatic stabilization of benzene itself, which is characteristically decreased by conversion to naphthalene and phenanthrene or anthracene. The fact that, in contrast to pAR, the pAa of the benzenonium ion is increased by benzoannelation implies that benzoannelation does not have as large an effect on the aromaticity of the benzenonium ion as on benzene itself. 

Aromatic mononitro compounds may sometimes be characterised by conversion into the corresponding dinitro or trinitro derivatives. It may be noted that many poly-nitro compounds form characteristic addition compounds with naphthalene. 

If the released electrophile HSOs+ is not intercepted during the protodesulfonylation as in Figure 5.7, it reacts with the defunctionalized aromatic compound again. In this way an isomer of the original sulfonic acid may be obtained. The best-known example of such an isomerization is the conversion of naphthalene-1-sulfonic acid into naphthalene-2-sulfonic acid (Figure 5.8). Naphthalene-1-sulfonic acid is destabilized by the so-called peri-interaction, that is, the steric interaction between the Cs—H bond of the naphthalene and the substituent on Cl. The peri-interaction is thus a cis-alkene strain. Because naphthalene-2-sulfonic acid does not... 

Activity. We concentrate on the conversion of the "actual" feed reactant, cumene, as the measure of activity. We note how the conversion changes when different amounts of different coking additives (decane, naphthalene) are mixed with the feed, and pulsed over a catalyst of different coke levels. We also report data on the conversions of the additives decane or naphthalene under the same conditions. As mentioned earlier, cumene conversion is obtained by carrying out a benzene-ring balance on the contents of the sample collector after each pulse procedure, while conversions of naphthalene or decane are obtained by comparing peak areas with and without catalyst. 

Bromine, iodine monobromide, and N-bromosuccinimide have been employed as brorainating agents in the treatment of certain polycyclic hydrocarbons. The conversion of naphthalene to its a-bromo derivative with one equivalent of bromine occurs rapidly at room temper-... 

Walborsky el at. examined a number of reducing systems and obtained highest conversions with lithium-ammonia (-78°) and with naphthalene-sodium (1, 711-712 2, 289 this volume) in glyme (1,2-dimethoxyethane) at 25°. Electrolysis in acetonitrile (25°) was also very effective. 

Assuming that pyrolysis selectivity Is not affected by SC water, rate constants of pyrolysis at various SC water densities were calculated with naphthalenes as pilot compounds and the "dry experiment as the reference pyrolysis rate. The rate constant of hydrolysis ki, 2 subsequently followed as the difference of total ether conversion rate constant and pyrolysis rate constants. 

Fig. 6 shows the naphthalene conversion as a function of the reaction temperature and gas velocity with a 1 wt % nickel-modified filter disc. The blank disc was also used as a reference. As shown in Fig. 6, almost complete naphthalene cracking was achieved above 800 °C with any gas velocity lower than 4 cm/s. Even with a gas velocity of 6 cm/s, the conversion still remains about 97 %. However, below 800 °C the conversion of naphthalene significantly decreased as the reaction temperature decreased and the gas velocity increased. In addition, benzene was identified as one reaction product of naphthalene cracking at 750 and 800 °C. Table 1 lists the amount of benzene in the outlet gas after reaction over the nickel-modified filter disc. It is evident that for all gas velocities at 750 °C, benzene is present in the outlet gas with a significant amount. Above 800 °C,... 

Inspection of the data reveals a clear inverse correlation (with the exception of a few scattered data points) between the ionic radii of the various tripositive lanthanide ions and the extent of nitration whereby the the heavier congeners are the most effective. Thus lanthanum(IH) (Z = 57) triflate gave a 64% conversion of naphthalene to mononitronaphthalenes over lh, whereas the ytterbium(HI) (Z =70) triflate catalysed reaction gave a >95% conversion over the same time period. 

The two phase nature of the reaction mixture (aqueous nitric acid/lanthanide salt and solvent/substrate) poses a number of questions. Foremost amongst these is the following in which phase does the actual nitration occur Comparison of the nitration rates using 1,2-dichloroethane (b.p. 83 °C) versus cyclohexane (b.p. 80 °C) as the solvents (both reactions performed at reflux) allows speculation on this matter. For the nitration of naphthalene with 10 mol% ytterbium(III) triflate a 78% conversion of naphthalene to mononitronaphthalenes occurred over 0.5h in 1,2-dichloroethane whereas for cyclohexane only a 24% conversion was observed. Based on this result it seems reasonable to conclude that the electrophilic substitution process transpires in the organic phase. 

Experiments have used cells with a metabolic capability that may plausibly be predicted as relevant to that of the xenobiotic. For example, elective enrichment failed to yield organisms able to grow at the expense of dibenzo-[l,4]-dioxin, but its metabolism could be studied in a strain of Pseudomonas sp. capable of growth with naphthalene (Klecka and Gibson 1979). Cells were grown with salicylate (1 g/1) in the presence of dibenzo-[l,4]-dioxin (0.5 g/1), and two metabolites of the latter were isolated a s-l,2-dihydro-l,2-diol and 2-hydroxydibenzo-l,4-dioxin. The former is consistent with the established dioxygenation of naphthalene and the role of salicylate as coordinate inducer of the relevant enzymes for conversion of naphthalene into salicylate. 

Autoclave charged with naphthalene (10 mmol), isopropyl alcohol 20 mmol, 0.5 g zeolite H-Beta (Si/Al = 12.5), cyclohexane (100 ml), undecane (10 mmol) as internal standard, 200 °C, 2 MPa N 2. After 1 h the selectivities to 2-isopropylnaphthalene and to the cyclic compound I are 50 and 46 %, respectively, at 19 % naphthalene conversion. 

The conversion of naphthalene to 2-naphthoic acids by irradiation with carbon dioxide and electron donors (e.g. amines or dimethoxybenzene) has been further investigated and the quantum yields of the reaction measured for different solvents and donors. Electron transfer also occurs in the photochemical phosphonation of naphthalene and phenanthrene achieved by irradiation with trialkyl-phosphites and electron acceptors such as 1,3-dicyanobenzene. The photonitration of phenol in aqueous solutions of nitrate ion has been reported and phenols have been prepared by irradiation of substituted benzenes with the aromatic N-oxide (132). ... 

Another use of vanadium is as a catalyst in a variety of reactions. Vanadium pentoxide, ivhen placed on an inert support material, is the principal catalyst used in the oxidation of SO2 to SO3 in the production of sulfuric acid, and for the conversion of naphthalene into phthalic anhydride during the formation of plastics. In addition, vanadium oxychloride, tetrachloride and triacetylacetonate are used as polymerization catalysts in the production of soluble copolymers of ethylene and propylene. In the reaction vessels, these polymers are viscous liquids, which can trap the vanadium catalysts and result in a vanadium content of up to 500 mgkg in products used for the packaging of food and pharmaceuticals. The disposal of spent catalysts could also be a point source for a contamination of the biosphere and of food with vanadium (Byerrum 1991). Furthermore, vanadium is used for the production of yellow pigments and ceramics. 

The amounts of naphthalene formed were small and were independent of the time of residence on the charcoal. The amount of decalin which could strongly adsorbed appeared to be between one and two molecular layers. Material adsorbed in excess of this amount could be pumped off easily and was unchanged in composition. For the strongly adsorbed material, the average conversion to naphthalene was 1.8% at 90° and 4.6% at 190°. The naphthalene formed could be removed from the surface by extraction with benzene, but not with ether or carbon tetrachloride. It is also of interest to note that, as part of the standard pretreatment of the charcoal, it had been refluxed with benzene. If that was not done, no reaction of the decalin to form naphthalene was observed. Blank experiments showed that no naphthalene was produced by the interaction of benzene alone with the catalyst. 

Like other chemical reactions, a rise of 10 C in temperature about doubles the rate of sulfonation. This has been demonstrated, for example, with 4-nitrotoluene using oleum or sulfuric acid, for the conversion of naphthalene-1,5-disodiumsulfonate to the 1,3,5-trisulfonyl chloride using chlorosulfonic acid over the range 10-100°C, and for the svilfonation of 4-aminoazobenzene discussed in a previous section. 

Touring studies at NIH, it was discovered that enzymatic hydroxyla-tion of (deuterated or tritiated) substrates leads to a novel and mechanistically important shift of the deuterium or tritium from the point of substitution by oxygen to an adjacent position in the aromatic ring (12). [It has been found recently that arene oxides are likely intermediates in the metabolism of aromatic compounds. They rearrange to phenols with concomitant NIH Shift, and they are enzymatically converted to dihydrodiols and premercapturic acids. In addition, naphthalene oxide has now been demonstrated as an intermediate in the conversion of naphthalene to a-naphthol, frari5-l,2-dihydro-I,2-dihydroxynaphthalene, and... 

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