Anthracene, oxidation preparation

Anthraqiiinone may also be prepared by the oxidation of pure anthracene with a solution of chromium trioxide in glacial acetic acid ... 

Methylene thiirane is obtained by thermolysis of several spirothiirane derivatives which are formally Diels-Alder adducts of methylenethiirane and cyclopentadiene or anthracene <78JA7436). They were prepared via lithio-2-(methylthio)-l,3-oxazolines (c/. Scheme 121). A novel synthesis of the allene episulfide derivatives, 2-isopropylidene-3,3- dimethylthiirane (good yield) or its 5-oxide (poor yield), involves irradiation of 2,2,3,3-tetramethyl-cyclopropanethione or its 5-oxide (81AG293). Substituents on the thiirane ring may be modified to give new thiiranes (Section 5.06.3.9). The synthesis of thiirane 1-oxides and thiirane 1,1-dioxides by oxidation is discussed in Section 5.06.3.3.8 and the synthesis of 5-alkylthiiranium salts by alkylation of thiiranes is discussed in Section 5.06.3.3.4. Thiirene 1-oxides and 1,1-dioxides may be obtained by dehydrohalogenation of 2-halothiirane 1-oxides and 1,1-dioxides (Section 5.06.4.1.2). 

Also important is the choice of a suitable redox system for the indirect electroreaction of particular substrates. For instance, toluene can be oxidized with Mn(III) or Ce(IV) to benzaldehyde, whilst with Cr(VI) benzoic acid is obtained. On the other hand, anthraquinone is commercially prepared from anthracene by employing chromic acid oxidation. 

Eventually, cis-l,2-di-9-anthrylethylene was prepared, as originally planned, by catalytic hydrogenation of bis-9-anthrylacetylene 53 [148]. Also, thanks to the appearance of a suitable oxidant for the conversion of primary and secondary alcohols into aldehydes and ketones [149], the synthesis of l,2-di-9-anthrylethanol 127 has been accomplished [51]. Numerous other chromophorically substituted anthracenes discussed in Sections II and III then became available as a matter of consequence. In retrospect, I feel gratefully indebted not only to my co-workers for their collaboration, but also to those numerous authors from whose earlier published efforts in the area of anthracene chemistry we have benefitted in our photochemical... 

Methyl anthraquinone has been obtained by the oxidation of /3-methyl anthracene by several investigators 1 and material of the same origin, obtained by the benzene-extraction of crude commercial anthraquinone,2 has been fully described. As regards the synthesis from phthalic anhydride and toluene, both the preparation and properties of />-toluyl-o-benzoic acid 3 and the complete synthesis 4 have been the subject of several papers. This acid has also been prepared from o-carbomethoxy benzoyl chloride and toluene.5 The phthalic anhydride synthesis of anthraquinone derivatives in general has received considerable attention. An account of this work, together with extensive references, is given by Barnett.6... 

The following unimportant preparative methods may be mentioned the production of /3-methyl anthraquinone by the reduction of 2-bromo-3-methyl anthraquinone 7 the oxidation of /3-methyl anthracene-7-carboxylic acid 8 and the reduction of 2-methyl anthraquinonyl-i-diazonium sulfate.9... 

The cis- 1,2-glycols, obtainable from the parent aromatic hydrocarbon by osmium tetroxide hydroxylation, can be converted to the corresponding trans-1,2-glycols by oxidation-reduction, using a mixture of dimethyl sulfoxide, sulfur trioxide, and pyridine, followed by lithium aluminum hydride reduction. The trans- 1,2-glycols can be dehydrated to arene oxides using DMF-DMA as mentioned above. Benzo[a]pyrene 4,5-oxide (28) and 7,12-dimethylbenz[a]anthracene 5,6-oxide (30) have been prepared by this method in 68 and 80% yields, respectively.18... 

The first arene oxides to be synthesized (1964) were obtained by the cyclization of appropriate seco derivatives. 0,0-Diformylbiphenyl derivatives, when treated with Mark s reagent [tris(dimethylamino)phosphine], gave arene oxides [Eq. (3)]. Thus K-region epoxides from phenanthrene and its analogs, benz[a]anthracene and its 7,12-dimethyl analog, have been prepared.34... 

Naphthalene 1,2-oxide (136), a non-K-region epoxide, shows low thermal stability. Anthracene 1,2-oxide, on the other hand, is stable at ambient temperatures for several weeks. Preparation of (+ )-(lR,2S)-anthracene 1,2-oxide (137), using the above method, constitutes the first example of preparation of an optically pure arene oxide. However, the non-K-region oxides of phenanthrene, namely, its 1,2- and 3,4-oxides (47 and 48), obtained from chiral precursors, racemize fast.66 Perturbational molecular orbital calculations indicate that epoxide-oxepin valence tautomerism is possible. However, the oxepin could not be detected by NMR. 

The (+H, 2-epoxides of naphthalene (138) and anthracene (137) can be prepared using a similar sequence from the corresponding (—)-menthoxy-acetyl derivatives of frans-2-bromo- 1-hydroxy-1,2,3,4-tetrahydronaph-thalene and anthracene, whereas the (—)-epoxides (136 and 139) are obtainable from the (+ )-menthoxyacetyl derivatives.67 The configurations of these compounds are determined by NMR analyses and correlation with alcohols of known configuration. Solid oxide 138 is unstable, whereas... 

As with 141, the ( + )- and (-)-benz[a]anthracene 8,9-oxides are prepared by the same sequence in optically pure form. The configuration of (—)-benz[a]anthracene 8,9-oxide (148) is unequivocally assigned as SS,9R by configurational correlation with the tetrahydrobenz[o]anthracene 149, whose absolute configuration is determined by X-ray crystallography.72... 

Based on this sequence, Blum et a/.158 have reported a general synthesis of unsubstituted K-region arene imines from the corresponding arene oxides. K-Imines of benz[a] anthracene, 7-methylbenz[a]anthracene, dibenz [a,/i] anthracene, and benzo[a] pyrene have been prepared. Azido alcohol formation from these oxides is generally nonregiospecific and both possible regioisomers of the azido alcohols are formed in different proportions. 

Quinones of the more reactive, polycyclic, aromatic systems can usually be obtained by direct oxidation, which is best carried out with chromium(vi) compounds under acidic conditions. In this way 1,4-naphthoquinone, 9,10-anthraquinone and 9,10-phenanthraquinone are prepared from naphthalene, anthracene and phenanthrene respectively (Expt 6.128). Also included in this section is the reduction of anthraquinone with tin and acid to give anthrone, probably by the sequence of steps formulated below. 

Anthracene-benzene biplanemers (119) were prepared through the electrolytic oxidative decarboxylation of (4 + 4) photocycloadducts between substituted anthracenes and 1,2-dihydrophthalic anhydrides [165,166] (Scheme 36). Chemiluminescence was observed for 119 only in the solid state at > 120°C, but not in a liquid phase, whereas 119 (X = F or Cl, Y = Z = H) were not chemiluminescent [167], Efficient chemiluminescence was observed in the photocycloreversion of all biplanemers tested in both phases. 

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