Of anthrone

It is prepared by acidifying an alkali solution of anthrone or by reduction of anthraquinone with aluminium powder and concentrated sulphuric acid. 

First, try to draw resonance contributors for both ground state and triplet anthrone. Then display a spin density surface for the triplet state of anthrone. (Note that the spin density surface shows the location of both unpaired electrons, one of which may be in a 7t orbital and one of which may be in a o orbital.) Where are the two unpaired electrons Are they localized or delocalized Given that spin delocalization generally leads to stabilization, would you expect the triplet state of anthrone to be stable ... 

The liquid is filtered with suction through a Gooch crucible with a fixed porous plate (Note 1), and 100 cc. of water is added. The anthrone crystallizes at about io°. After being dried on a porous plate, it melts at about 153° (corr.). The yield is 80 g. (82.5 per cent of the theoretical amount). On rccrystal-lization from a 3 1 mixture (Note 2) of benzene and petroleum ether about 60 g. of anthrone melting at 154-155° (corr.) is obtained (62 per cent of the theoretical amount). 

The proportions do not make much difference as far as the yield is concerned, but the substance is more soluble in mixtures rich in benzene. About 10-12 cc. of the 3 1 mixture is required for each gram of anthrone. The anthrone may be more readily dissolved if it is added to the estimated quantity of hot benzene on the steam bath, and the petroleum ether is then added. About two-thirds of the mother liquor may be distilled off through a condenser and used in later runs. The residual mother liquor deposits about 12 g. of rather impure anthrone. 

In a i-l. beaker equipped with a separatory funnel, a mechanical stirrer, and a thermometer, 20 g. (0.1 mole) of anthrone (p. 8) is dissolved in 300 cc. of glacial acetic acid. While the mixture is kept at 6o and stirred, a solution of 7 cc. of fuming nitric acid (sp. gr. 1.5) in 50 cc. of glacial acetic acid is rim in during one hour. 

Nitroanthrone has been prepared by the nitration of anthracene in isobutyl alcohol,1 and by the nitration of anthrone.2... 

The first evidence of an anionic Diels Alder reaction was given by Rickborn [25a]. The reaction of anthrone with N-methylmaleimide in CHCI3 or THE occurs with low yield [26] (Equation 1.10), while in DMF or in the presence of catalytic amounts of amine (EtsN, Py) the reaction is completed in a few minutes [25]. 

The methylene group of anthrone 64 is acidic by virtue of doubly vinylic activation by the carbonyl group. Thus, treatment with methyl iodide and base leads to the 9,9-dimethyl derivative 65. Grignard reaction with 6-dimethylaminopropyl magnesium chloride... 

Lengthening the side chain produces the antidepressant maprotiline (73), which has a topological relationship to the clinically useful tricyclic antidepressants. The requisite acid is constructed by conjugate addition of the carbanion of anthrone (64) to acrylonitrile, followed by hydrolysis to give 70. Reduction of the carbonyl group with zinc and ammonia gives anthracene 71 by dehydration of the intermediate... 

Moro-Oka et al. (1976) have reported that the oxidation of 9,10-dihydroanthracene by K02 solubilized in DMSO by 18-crown-6 gives mainly the dehydrogenated product, anthracene. Under the same conditions, 1,4-hexadiene is dehydrogenated to benzene. The authors proposed a mechanism in which the superoxide ion acts as a hydrogen-abstracting agent only. The oxidations of anthrone (to anthraquinone), fluorene (to fluorenone), xanthene (to xanthone) and diphenylmethane (to benzophenone) are also initiated by hydrogen abstraction. 

Regiospecific mono-C-alkylation (60-90%) of trimethylsilyl enol ethers is promoted by benzyltriethylammonium fluoride [34, 35]. A similar alkylation of tin(IV) enolates is aided by stoichiometric amount of tetra-n-butylammonium bromide and has been utilized in the synthesis of y-iminoketones [36]. Carbanions from weakly acidic carbon acids can be generated by the reaction of their trimethylsilyl derivatives with tetra-n-butylammonium triphenyldifluorosilicate [37] (see also Section 6.3). Such carbanions react readily with haloalkanes. Tautomeric ketones in which the enol form has a high degree of stabilization are O-alkylated to form the enol ether, e.g. methylation of anthrone produces 9-methoxyanthracene [26],... 

Part XXIII. The Dipole Moments of Some Aliphatic and Aromatic Aldehydes and of Anthrone. J. chem. Soc. (London) 1938, 1444. 

In the presence of ZnCla, Michael addition of anthrone (122) to a,/3-unsaturated ketones has been reported to proceed smoothly, producing mono-adducts (123), whereas bis-adducts (124) are formed in basic solution. ... 

In 2006, Tan and co-workers reported the first asymmetric guanidine catalyzed Diels-Alder addition of anthrone to maleimides (Scheme 75) [130], The authors observed very high yields and enantioselectivities using a derivative of Corey s C2-symmetric bicyclic gnanidine catalyst. The addition of anthrones to maleimide also worked well for snbstitnted anthrones. Interestingly, the anthors observed the oxidized prodnct when the anthrone was substituted at the meto-positions (Scheme 76). 

Hydrolysis of the oxidate of anthrone resulted in the precipitation of anthraquinone (m.p. 263-268°C.). Extraction of the aqueous filtrate with chloroform yielded the DMSO adduct (1 to 1) of anthraquinone (m.p. 158-158.5°C.) (recrystallized from a chloroform-cyclohexane mixture). 

A sample of the monohydroperoxide, previously reported by Bickel and Kooyman (2), was obtained by autoxidation of 9,10-dihydroanthra-cene in benzene under ultraviolet irradiation. When this compound was treated under nitrogen with benzyltrimethylammonium hydroxide, it decomposed to give a mixture of anthracene and anthrone. (Under acidic conditions, it decomposed entirely to anthracene.) A fresh sample of the hydroperoxide was then oxidized. The physical appearance of the reaction mixture was similar to that in the oxidation of anthrone. The product was analyzed, and the conversion to anthraquinone was only 59%. Again, other oxidation products or anthrone may have contributed to the anthraquinone estimate. 

Dr. Russell Is it possible that the oxidation of 9,10-dihydroanthra-cene is more exothermic than that of anthrone and that the heat generated could have accounted for the high yield of anthraquinone in the 2-hour reaction ... 

D-glucose, and 5-(hydroxymethyl)-2-furaldehyde with anthrone lends support to these conclusions, and further indicates the complexity of the overall reaction. In the reaction of either D-fructose or 5-(hy-droxymethyl)-2-furaldehyde with anthrone, at least nine compounds were observed, three of which were condensation products of anthrone itself. The other products had absorption maxima ranging from 490 to 770 nm (in sulfuric acid solution and under the conditions of the anthrone reaction). One of the prominent pigments, having a blue color ( max 620 nm) and a postulated structure corresponding to compound 123, was isolated and characterized by its nuclear magnetic... 

The hrst step in the preparation of the antidepressant maprotiline (33-5) takes advantage of the acidity of anthrone protons for incorporation of the side chain. Thus treatment of (30-1) with ethyl acrylate and a relatively mild base leads to the Michael adduct saponihcation of the ester group gives the corresponding acid (33-1). The ketone group is then reduced by means of zinc and ammonium hydroxide. Dehydration of the hrst-formed alcohol under acidic conditions leads to the formation of fully aromatic anthracene (33-2). Diels-Alder addition of ethylene under high pressure leads to the addition across the 9,10 positions and the formation of the central 2,2,2-bicyclooctyl moiety (33-3). The hnal steps involve the construction of the typical antidepressant side chain. The acid in (33-3) is thus converted to an acid chloride and that function reacted with methylamine to form the amide (33-4). Reduction to a secondary amine completes the synthesis of (33-5) [33]. 

At room temperature, add 4 ml of anthrone reagent, each to sample and standards. Vortex and let stand for 10 min, vortex again and leave for another 10 min before measuring the OD. 

Fig. 4 (a) Structures of aromatic polyketides produced by A. arborescens. (b) Proposed enzyme reaction mechanism of PCS, (c) OKS, and (d) PKS3. A hypothetical scheme for the involvement of OKS and as yet unidentified ketoreductase in the biosynthesis of anthrones and anthraquinones is also included... 

The thermochromic ethylene 373 has been efficiently prepared in 96% yield by the microwave promoted condensation of anthrone with thioxanthone (Equation 83) <2003JCM260>. 

In conjugated systems, y-condensation can occur, as in the case of anthrone (Eq. 9).31... 

Samsel, E. P., and Aldrich, J. C. (1957). Application of anthrone test to determination of cellulose derivatives in non-aqueous media. Anal. Chem. 29 574-576. 

Good yields of substitution product 30 (75%) were also obtained in the reaction of 1-Adi with the anion of anthrone (29) (equation 42)124. 

In the photostimulated reaction of Phi with the monoanion of acetylacetone or with the diethylmalonate anion, no substitution products were found. On the other hand, in the reaction of anthrone anion (29) with Phi a 95% yield of the substitution product (126) was formed (equation 86)169. 

C. Add 2 to 5 mg of sample to 20 mL of a 0.1% solution of anthrone in 75% sulfuric acid, and heat on a steam bath. The solution turns blue-green within 5 min. 

B. Take 2 mL of the solution separated from the solid in Identification Test A, and add 1 mL of anthrone TS carefully down the inside of the test tube. The boundary surface of the two layers turns to blue or green. 

Anthrone TS Carefully dissolve about 0.1 g of anthrone in 100 g of sulfuric acid. Use a freshly prepared solution. 

The problem then is the route to hydrogen peroxide in the present case. Insertion of ozone into a carbon—hydrogen bond has been postulated by White and Bailey (14) to explain the ozonation of benzaldehydes, by Price and Tumolo (15) in the ozonation studies of ethers, and by Batter-bee and Bailey (16) in their studies on the ozonation of anthrone. We postulate a similar intermediate to explain the formation of hydrogen peroxide and subsequently the diaminoperoxide VII. 

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