Naphthalene yields

Benzo-l,2,3-triazin-4-ones with the general structure 6.54 (X = O, S, or H2) are obtained by diazotization of the appropriate aniline derivatives 6.53 (Scheme 6-38). In polar aprotic solvents (e. g., nitrobenzene) the reverse reaction takes place to give the diazonium ion (for an example see Kullick, 1966). Diazotization of 1,8-diamino-naphthalene yields l-i/-naphthol[l,8-cfe]triazine (6.55 Tavs et al., 1967). In concentrated HC1 the triazine ring is opened again. 

Under highly protic conditions, the major products of cathodic reductions of cyclic conjugated hydrocarbons are usually dihydro derivatives [56, 57, 187]. In 2-methoxyethanol, for example, naphthalene yields 1,4-dihydronaphthalene [187] and COT mainly provides 1,3,6,-cyclooctatriene [56, 57]. 

The difference in the reactivity of benzylic versus aromatic halogens makes it possible to reduce the former ones preferentially. Lithium aluminum hydride replaced only the benzylic bromine by hydrogen in 2-bromomethyl-3-chloro-naphthalene (yield 75%) [540]. Sodium borohydride in diglyme reduces, as a rule, benzylic halides but not aromatic halides (except for some iodo derivatives) [505, 541]. Lithium aluminum hydride hydrogenolyzes benzyl halides and aryl bromides and iodides. Aryl chlorides and especially fluorides are quite resistant [540,542], However, in polyfluorinated aromatics, because of the very low electron density of the ring, even fluorine was replaced by hydrogen using lithium aluminum hydride [543]. 

B2C14 can add to dienes (1,3-butadiene, 1,3- and 1,4-cyclohexadienes) to yield either mono- or diadducts depending on the reagent reactant ratio.474-477 1,3-Cyclohexadiene, for example, forms the unstable l,2,3,4-tetrakis(dichloroboryl)cy-clohexane with high selectivity when it reacts with a threefold excess of B2C14.476 Naphthalene yields a similar diadduct.476 477... 

Hydroxyacetophenone reacts with DMF under Vilsmeier conditions to yield chromone-3-carbaldehyde (72LA(765)8). The reaction appears to be generally applicable, various substituents being acceptable in the aromatic ring (74T3553). Furthermore, acetylhydroxy-naphthalenes yield the corresponding benzochromones, and the pyranochromone (452) is formed from the appropriately substituted coumarin. 

The direct oxidation of naphthalenes yields naphthoquinones in poor yields ... 

All of these reactions presumably arise through free radical mechanisms. The abstraction of hydrogen from tetralin by coal to produce naphthalene is of course expected. What sets this reaction apart from the rest is the linear dependence of naphthalene yield on coal concentration. From the slope of the yield curve, we calculate that hydrogen was removed from tetralin in the amount of 2.5 wt. percent of the added coal. This is a reasonable amount of hydrogen to be transferred to coal under liquefaction conditions. However, we note a recent report on the decomposition of 1,2-diphenylethane in tetralin in which Benjamin states that over twice the amount of naphthalene required in the formation of toluene was produced (11). Presumably, the excess appears as molecular hydrogen. In the present case, we cannot rule out the possibility that some fraction of the naphthalene was produced by a similiar mechanism. 

Figure 2. Naphthalene yield as a function of time in the presence of various additives. The dotted line is the sum of the thermal yield curve and the calculated amount of naphthalene obtained by the full reduction of 50 mg of pyrite...

The results described above illustrate the problem of separating effects due to catalysis provided by pyrrhotite from those due to the chemistry of the reduction of pyrite. It must also be borne in mind that reduction of pyrite produces a nearly equivalent amount of l S, which remains available to enter subsequent reactions by mechanisms now only poorly understood. In order to remove these complications, pyrrhotite was prepared by the reduction of pyrite with tetralin, isolated from the reaction residue, and then heated with fresh tetralin. Figures 4 and 5 contain the yields of naphthalene and 1-methylindan, and the ratios of trans- to cis-decalin as a function of concentration. In this case, the pyrite was a hand-picked sample of micro-crystals taken from a coal nodule. As may be seen, the yields of naphthalene and 1-methylindan, and the ratio of trans- to cis-decalin all increase with pyrite concentration. The slope of the line for naphthalene yield is 0.91. A slope of 0.53 is calculated for stoichiometric reduction of FeS to FeS by tetralin to yield naphthalene. Thus, roughly half of the naphthalene produced can be accounted for by the demand for hydrogen in the reduction of pyrite. 

Cyclic vicinal diazides undergo a thermal ring fission with formation of dinitriles. In this manner 1,2-diazidobenzenes yielded (in ca. 80% yield) cis, cw-l,4-dicyano-1,3-butadienes (78), and 1,2-diazido-naphthalene yielded as-2-cyanocinnamonitrile (79)... 

Attack by nitronium ion at the a-position of naphthalene yields an intermediate carbonium ion that is a hybrid of structures I and II in which the positive charge is accommodated by the ring under attack, and several structures like III in which the charge is accommodated by the other ring. 

Refined naphthalene, with a crystallization point above 79.6 °C, is usually obtained by crystallization or hydrogenation. The choice of process is made on economic grounds, especially the price of hydrogen, and on the required level of sulfur in the refined naphthalene. Crystallization is characterized by high naphthalene yields and favorable energy costs high yields are also favored by a high concentration of naphthalene in the feedstock. However, the sulfur content of coal-derived naphthalene cannot be reduced below 300-400 ppm by crystallization... 

Transition metal-incorporated zeolites have been shown to be effident catalysts for direct conversion of methane to benzene and toluene under nonoxidative conditions [45,46]. Bao and co-workers revealed that Mo/ H-MCM-22 catalysts are desirable bifiinctional catalysts for methane dehydroaromatization reaction [47]. In terms of catalytic performances of Mo/H-MCM-22 with varied metal loading, catalyst with a Mo loading of ca. 6 wt% was found to exhibit the optimal benzene selectivity, suppressed naphthalene yield, and prolonged catalyst hfe under a moderate methane conversion. Although both Bronsted and Lewis acid sites are capable of catalysing methane conversion reaction, active sites with higher acidic strengths are anticipated to play the dominant role. 

Polymerization with sodium naphthalene yields a chain with two simultaneously growing ends (276,277). 

Cyclic Sulfides. The three-membered cyclic thiiranes can be polymerized cationically, anionically, or by a coordination mechanism. The four-membered cyclic thietanes can be polymerized by cationic and anionic mechanisms, but five-membered rings cannot be polymerized. Polymerization of propylenesulfide initiated with sodium naphthalene yields telechelics with naphthalene groups on both ends, if the living chain is terminated 1-chloromethylnaphthalene (321). 

Et4N F ... SHF is a more convenient depolarizer for general use. In the presence of this complex at an anode potential of +1.6 to +1.8 V, naphthalene yields 1-fluoro- (27%) and 1,4-difluoro-naphthalene (3%), 1-fluoro-naphthalene gives 1,4-difluoronaphthalene (40%), and 1,4-difluoronaphthalene gives the addition compound (8) (22%) with traces of 1,2,3-trifluoro-and 1,2,3,4-tetrafluoro-naphthalene. Two one-electron transfer steps arc suggested for each fluorination stage of the reaction e.g. Scheme 3) and the... 

A variety of non-volatile tertiary amine bases, which would either completely favor the ammonium phosphate salt and/or form an ammonium phosphate salt that could be removed prior to distillation by precipitation and filtration, were evaluated. Only l,8-his(dimethylamino) naphthalene, known for its bidentate nature [255], which most probably favors the formation of the ammonium phosphate salt, furnished benzyl isocyanate in good yield and with high purity [256). About 75% of the ammonium phosphate salt was removed by precipitation and filtration prior to distillation. Consequently, a simple method for the synthesis of high purity isocyanates from carboxylic acids was developed using DPPA and 1,8-his(dimethylamino) naphthalene. Yields evaluated for the monoisocyanates ranged from 60% to 81.5% (Table 4.17) [256]. 

Orthopalladation of (l-/-butylsulfanylethyl)benzene, (l-methylulfanylethyl)benzene, and 2-(l-t-butylsulfanyl-ethyl)naphthalene yields the respective racemic sulfur chloro-bridged palladacycles. Single isomers as well as a mixture of two diastereomers have been isolated. Variable-temperature NMR shows that the S-/-Bu pallada-... 

Compounds with somewhat more complex side-chains may behave somewhat abnormally, for example, acetophenone yields CeHiCOCO- H and naphthalene yields some CcHrCOiH-COCOiH. In such special cases, the MnOj is not filtered from the reaction mixture but the latter is acidified directly. In acid solution. MnO- will oxidize quickly the above oxalyl derivatives to benzoic and phthalic acid, respectively. Any excess MnOj is then removed by the addition of a little sodium bisulfite. 

Dinaphthoazulene 55, having pleiadiene fused with acenaphthalene, was first synthesized by Bestmann and Rupper, as shown in Scheme 4.12 [50]. In this synthesis, reaction of bisylide 56 with l,8-bis(bromomethyl)naphthalene yielded bisphosphonium salt 57, which on alkaUne hydrolysis gave 58 as well as triphenylphosphine oxide. Compound 55 is characterized by the formally fixed double bonds. No alternative Kekule structures that involve these bonds can be drawn without radicals or ions. The fixed double bonds suggest 55 has the nature of a diene more than aromatic azulene although its reactions were not reported. 

The decarboxylation of PBT and PEN occurs in the same way as for PET in the presence of Ca(OH)2 in a fixed bed reactor [48], Best results are obtained at 700°C with a Ca(OH)2/polyester repeating unit ratio of 5 1 with a benzene yield of 67% from PBT and a naphthalene yield of 80% from PEN, as well. 1,4-Butanediol undergoes secondary reactions and the subsequent dehydration leads to the formation of tetrahydrofuran and butadiene (Figure 13). 

Electron donating group like —OMe present on aromatic system facilitate o-and p-substitution. The photochemical substitution of cyanide ion in 2-methoxy naphthalene and 1-methoxy naphthalene, yields o-products. 

The sulfonation of naphthalene yields a number of isomers, and the product may be controlled to some extent by the choice of agent. With any one agent, temperature and time of reaction determine the result. It rarely is possible to obtain a single isomer, but effort is directed toward forming a preponderant... 

Photocatalysis by semiconductor powders, most usually titanium dioxide, has been applied to the oxidation of several aromatics. In many such photocatalytic reactions, the key intermediates are hydroxyl radicals formed by oxidation of water. With rather good donors such as aromatic compounds, hole transfer on the excited semiconductor surface is a viable alternative in this case, the reaction of the radical cation of the substrate or further intermediates arising from it with oxygen or superoxide anion may have a role. Photocatalyzed oxidation of naphthalene yields 2-formyldrmamaldehyde and 1,4-naphthoquinone as the primary products (Eq. (45.16)), similarly to what occurs upon direct irradiation of naphthalene in water ... 

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