Experiment 15-2 9,-Dihydroanthracene

Howard and Ingold studied this equilibrium reaction in experiments on the oxidation of tetralin and 9,10—dihydroanthracene in the presence of specially added triphenylmethyl hydroperoxide[41]. They estimated the equilibrium constant K to be equal to 60 atm-1 (8 x 103 L mol-1, 303 K). This value is close to T=25atm-1 at 300 K (A/7=38kJ mol-1), which was found in the solid crystal lattice permeable to dioxygen [84], The reversible addition of dioxygen to the diphenylmethyl radical absorbed on MFI zeolite was evidenced and studied recently by the EPR technique [85],... 

An attempt was made to determine the amount of hydrogen peroxide formed and correlate it with the amount of anthracene. An experiment was made with oxygen at atmospheric pressure and a reaction temperature of —20°C., so that any hydrogen peroxide formed would be less likely to decompose. The solid product (88% recovery of dihydroanthracene) was isolated and found to contain 1 mmole of anthracene. The... 

Studies in this field are just beginning, and the number of publications hardly exceeds a dozen. The most interesting results were obtained by the research groups of Yamada [160-162], Neumann [163,164] and Kozhevnikov [165, 166], Using various type catalysts (Ru porphyrene complexes, polyoxometalates, supported metals), the authors conducted selective oxidations of various types. These include epoxidation of alkenes, oxidation of alcohols, oxidation of alkylaromatics, oxidation and aromatiza-tion of dihydroanthracenes, and some other reactions. The experiments were typically conducted at 373—423 K under 1.0 MPa pressure of nitrous oxide. 

An anionic 1,4-silyl migration from C to C was observed during the lithiation of 9,10-dihydroanthracene (DHA) derivatives (equation 140)349 - 353. Typically, treatment of DHA 212 (R=SiMe3) with butyllithium followed by hydrolysis gave only ds-9,10-bis(trimethylsilyl)-DHA 213 (R=SiMe3, E=H) stereospecifically. The crossover and deuterium labeling experiments confirmed the intramolecular and irreversible feature of the... 

The results of this investigation of hydrogen transfer are presented in table 9.3. The experiment with thermal treatment of pure anthracene (E.l) demonstrated that a significant amount of dihydroanthracene was found in the used anthracene after thermal treatment. Therefore, it is important to use this fact in the discussion of the results. Experiment RE.3 is a reproducibility experiment in comparison with E.3. It is evident that the experimental method has a good reproducibility (relative divergence 4%). 

The results of the inhibited oxidation experiments with polypropylene are summarized in Tables I and II. A few experiments where 9,10-dihydroanthracene was used as the substrate are summarized in Table III. 

In this experiment the metal-free carbon nanotubes acted directly as a support and active phase for the liquid-phase ODH of dihydroanthracene to anthracene at low temperature. The results are compared with those obtained on other catalysts. Oxidative dehydrogenation of dihydroanthracene in the liquid-phase was carried out over different CNT-based materials. The results are presented in Table 7.3. The test was also performed on an exfoliated graphite material for comparison. The results clearly showed that the reaction was chemically selective whatever... 

Recently, a clathrate system was announced in which the host entraps mixed guests, and the stoichiometry is controlled by the relative concentrations of the guests in the starting mixture. The host, rra i.v-9,10-dihydroxy-9,10-Z /.s (/ ferr-butylphenyl)-9,10-dihydroanthracene (N) forms inclusion compounds with dimethylformanide (A) and dimethylsulfoxide (B) of the type H nA (4-n)B, such that n varies from 0 to The results of competition experiments are given in Fig. 2, which shows that the stoichiometry of the inclusion compounds varies in discrete steps, giving rise to five distinct compounds H 4A, H 3A B, H 2A 2B, H A 3B, and H 4B. 

After last year s preliminary report on the synthesis of pentatetraene by a retro-Diels-Alder reaction involving flash thermolysis of (131), Ripoll has now published the full details and has also shown that the similar decomposition of ll-vinylidene-9,10-ethano-9,10-dihydroanthracene (132) at 750°C-10mm-Hg pressure gives an 85% yield of butatriene (133). To complement these developments, a timely publication has appeared on the theoretical basis and the instrumentation necessary for flash thermolyses, suitable for such experiments on a preparative scale. 

EXPERIMENT 15 Diels-Alder Reaction 9,10-Dihydroanthracene-9,10-a,p-succinic Acid Anhydride 269... 

Dihydroanthracene is also formed in an interesting fashion. The initial step is the reduction of 9-CH3AN by emim-, a reaction exothermic by 9 kcal mob in the IL, to form the radical anion 9-CH3AN and emim+. Proton transfer from HCl and emim+ (deuterium labehng experiments) foUowed by further reduction yields the observed product. 

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