Anthracene monosubstituted

The important bluish mixing component 11.22 for whitening polyester is made by Friedel-Crafts acylation of pyrene (Scheme 11.17). This tetracyclic hydrocarbon is not unlike anthracene in its susceptibility to substitution reactions. The most stable bond arrangement in pyrene appears to be that shown as form 11.47a, which contains three benzenoid (b) rings. Canonical form 11.47b, containing only two such rings, contributes to a lesser extent (Scheme 11.18). In all monosubstitutions, pyrene is attacked initially at the 3-position, corresponding to the a-positions in anthracene or naphthalene. 

Soma et al. (12) have generalized the trends for aromatic compound polymerization as follows (1) aromatic compounds with ionization potentials lower than approximately 9.7 eV formg radical cations upon adsorption in the interlayer of transition-metal ion-exchanged montmorillonites, (2) parasubstituted benzenes and biphenyls are sorbed as the radical cations and prevented from coupling reactions due to blockage of the para position, (3) monosubstituted benzenes react to 4,4 -substituted biphenyls which are stably sorbed, (4) benzene, biphenyl, and p-terphenyl polymerized, and (5) biphenyl methane, naphthalene, and anthracene are nonreactive due to hindered access to reaction sites. However, they observed a number of exceptions that did not fit this scheme and these were not explained. 

Exceptional fluorescence properties also characterize the ri.s-isomer 38e. Unsubstituted cis-l,2-di-9-anthrylethylene 38a and its monosubstituted derivatives such as 38b are nonfluorescent at room temperature. By contrast, cis-dianthrylethylene 38e does fluoresce with quantum yields of 0.0018, 0.0042, and 0.0064 in cyclohexane, dichloromethane, and acetonitrile, respectively. The emission is structureless (see Figure 18), and is associated with a solvent-independent Stokes shift of about 6000cm-1. As the molecular geometry of 38e is characterized by overlapping anthracene systems [80], the structureless emission may be attributable to an intramolecular excimer state. 

The photostimulated reaction of 1,8-diiodonaphthalene with p-methyl-benzenethio-late ions in DMSO yields the substituted cyclized product 10-methyl-7-thia-benzo[de] anthracene (31) in moderate yield (Scheme 10.58) [54], The mechanism proposed to explain product 31 involves an intramolecular radical cyclization after monosubstitution in the propagation cycle of the SRN1 process. 

Considering what was said about stabilization energies in our previous discussion of thermochemical mimics, we now turn to aryl halides. There are several conceptual approaches to their thermochemistry one can take. The first is to consider halogenated derivatives of benzene, then of naphthalene, then of the isomeric anthracene and phenan-threne, etc. This approach, perhaps more appropriate for a study of generally substituted aromatic hydrocarbons, is immediately thwarted. Although there are many appropriate derivatives of benzene worthy of discussion, thermochemical data on halogenated naphthalenes are limited to the isomeric 1- and 2-monosubstituted derivatives, and halogenated derivatives of other aromatics remain thermochemically unstudied. 

In normal Diels-Alder reactions benzene and naphthalene usually prove to be quite inert as dienes anthracene adds reactive dienophiles at the central ring. These results are entirely as expected on the basis of the aromaticity of the systems. By contrast, tetrazine diester and 3,6-bistrifluoro-methyltetrazine, due to their low-lying LUMOs and lower resonance energy, will react even with aromatic compounds as dienophiles (Scheme 41) benzene, toluene, anisole, Af,A -dimethylaniline, and methylthiobenzene (226) react at 140°C <81CZ342, 87AG(E)332>. In monosubstituted benzene... 

The samples from South Carolina (Sample 18) and Yosemite National Park (Sample 29) demonstrate a peculiar abundance pattern in the phenanthrene/anthracene series. The nonsubstituted and disubstituted species are both abundant relative to the monosubstituted phenanthrenes/ anthracenes. Information from the mass spectral analysis of other components in these soil extracts indicates the source for these particular PAH is neither combustion nor fossil fuels but rather aromatization of certain natural products (2). 

Anthrylpolyamines 12-15 (Figure 15) were prepared via dmple substitution reactions of 9-(chloromethyl)anthracene. The full emission spectra of 12-15 (all 1 pM) were collected during titration with ds DNA, ss DNA, heparin, and poly-L-glutamate representative titration data from the monitoring of compound 14 at 422 run are drown in Figure 16. Bodi disubstituted anthracenes (14 and 15) exhibit a 6-nm red shift in when bound either to ds DNA or to ss DNA likewise, both monosubstituted anthracenes (12 and 13) show a 14-nm red shift in their emission spectra in the presence of either ds or ss DNA. Interaction of the nucleotide bases with the anthracene is a likely source of the bathochromic shift and the observed CHEQ effect Such n-stacking with ss DNA, seldom observed with intercalating compounds, may result from the favorable entropy effect of electrostatic preassociation (18). 

Experiment [31] demonstrates the monobromination of anthracene to yield one specific monosubstituted product. Other conditions may be used to form other monobrominated anthracenes. Draw the structures of, and name, the possible monobromo-substituted anthracenes that could be prepared in the laboratory. 

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