Naphthacene-5,12-quinones

Quantum yields of phototransformations of phenoxy-substituted naphthacene-quinones depended on the nature of the solvent.59 One can see from Table 7.7 that the replacement of benzene by ethanol led to a decrease in the quantum yield of the ana form. At the same time, the quantum yield of the photodegradation of the ana form increased. 

Zelichenok, A., Buchhol F., Fischer. E., Ratner, J., Krongauz, V., Annesei H-, and Brauchle, C. Photochemistry and multiple holographical recording in polymers with photochromic phenoxy-naphthacene-quinone side-groups. J. Photochem. Phoiobiol. A 1993 76, 135-141. 

A representative plot of AA vs pH is shown in Figure 4. However, whereever such intramolecular stabilisation effect is not present, the pK(l) value goes up, e.g. 9,10-anthraquinone-l,5-disulphonate l,4-diamino-9,10- anthraquinone 1-amino-4-hydroxy-9,10-anthraquinone 5,12-naphthacene quinone, etc. 

Dimethylphthalic anhydride (I) and 1,4-naphthalene-diol pi) were mixed with BO and heated at 190 0 with stirring, to give 2,3-dimethyl-6,ll-dihydroxy-5,12-naphthacene-quinone (III). (Ill) was refluxed with PCl and POCl, followed by the partial dehydrochlorination with Nal In DMF, to give 2,3-dimethyl-5,6,ll,12-tetrachlQrotetracene (IV). (IV) was heated with Na in HMPA at 100°C for 12 h, to give crude DMTTT (V). (V) was washed with H O, MeOH, sublimed and... 

Pentacene diquinone (4) was reduced electrochemically with one Faraday/mole, and the semiquinone salt was precipitated. Four-point-probe measurements were made on pressed pellets at room temperature. The lithium salt and tetramethylammonium salt had a = 1 [4] and a = 0.02 S cm-i, respectively. Such high conductivities are not measured on mono-semiquinones. For example, naphthacene quinone has a < S cm-i. 

A series of polycyclic p-quinones (9,10-anthraquinones 5,12-naphthacene-quinones 6,13-pentacene diones etc.) display a reversible thermochromic reaction in a reducing medixim, for example, on boiling in dimethylform-amide in the presence of potassium borohydfide. Characteristic colors are formed which disappear on cooling, but reappear on heating (37). Polycyclic quinones with a nonterminal quinoid nucleus give, in acetic acid solution with aromatic amines (especially 3,4-dimethoxyaniline) and on heating, blue... 

Methyl, 6,6-dimethyl, and 6-phenylamino derivatives of phenoxynaphtha-cene-5,12-quinone (IIIA) were produced by the interaction of 6,11-diphenoxy-naphthacene-5,12-quinones with the corresponding amines.46... 

Acrylate and styrene polymers as well as polysiloxanes with 11-phenoxy-naphthacene-5,12-quinone side groups (IIIB) were synthesized using the reaction of the active ester copolymers with 6-[(tyrosinebutylester)o-yl]-5,12-naphthacenequi-none.53... 

A comparative study of the efficiency of the photochromic transformations for a series of 6-acetyl-amino-ll-naphthacene-5,12-quinones (Table 7.8) showed that, as for 4 derivatives of 1-phenoxyanthraquinone, the light sensitivity of these compounds decreased with the increasing electron-donor capacity of substituents.46... 

One final interesting application of CAN which exemplifies one of the many possible reactions of qui-nones comes from Hassall and coworkers in their synthesis of 4-demethoxydaunomycinone (47). Thus, oxidation of the boronate (42) with CAN gave the crude quinone (43) which was reacted with trans-1,2-bis(acetoxy)-l,2-dihydrobenzocyclobutene (44) to give the tetracyclic quinone (45) in an impressive 79% overtdl yield. Deacetalization and reductive acetylation to the naphthacene (46), followed by oxidation with anhydrous chromium trioxide and deprotection with boron trichloride afforded the target compound (47 Scheme 10). 

In many cases photophysical effects are much influenced by photochemical reaction. The fluorescence of naphthacene is affected by dimerization and oxidation. Interaction with anthracene and quinones also occurs. The adiabatic photolytic cycloreversion of substituted lipidopterenes into intramolecular exciplexes shows an example involving anthracene derivatives. A series of very detailed papers on conformational effects on the fluorescence and photochemistry of [2/j] 9,10-anthracenophanes have been published by Ferguson and coworkers.It is not possible in this review to summarize this very detailed work... 

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