Naphthalene substitution

Spectrum 8.3 Naphthalene substituted with -CH3 and -CH2-CI groups and expansion. 

Several groups have studied naphthalene substituted anthracene derivatives as hosts or emitter materials in blue OLEDs (121, 202-205) (Scheme 3.63). The Kodak group used ADN as a host and TBP as a dopant in ITO/CuPc/NPD/ADN TBP/Alq3/Mg Ag [241]. They achieved a narrow vibronic emission centered at 465 nm with CIE (0.154, 0.232) and a luminescent efficiency as high as 3.5 cd/A. In comparison, the undoped device shows a broad and featureless bluish-green emission centered at 460 nm with CIE (0.197, 0.257) and an EL efficiency below 2.0 cd/A. The operational lifetimes of the doped device and the undoped device were 4000 and 2000 h at an initial luminance of 636 cd/m2 and 384 cd/m2, respectively. 

SCHEME 3.63 Chemical structures of naphthalene substituted anthracenes. 

H-stacking interactions have also been exploited to orientate olefinic moieties in a geometry suitable for photochemical cycloaddition reactions, and have been invoked by Coates et al. to explain the photodimerization and photopolymerization of mono- and diolefins carrying phenyl and perfiuorophenyl groups [43]. Matsumoto et al. reported the photodimerization of 2-pyridone in co-crystals with naphthalene-substituted monocarboxyhc acids, where the stacking of the naphthalene rings provides carbon-carbon distances appropriate for [4+4] cycloaddition [44]. 

Naphthostyryl 115 (R = R = H) and its numerous N-and naphthalene-substituted derivatives are obtained by acid-catalyzed heterocyclization of peri-aminonaphthoic acids 139. One should notice it is not necessary to isolate these acids since, as a rule, conditions of their formation are suitable for heteroring closure. Syntheses of benzo[crf]indole-2-ones 115 are carried out in a number of ways ... 

In order to better understand the substitution patterns of the reaction of naphthalene-substituted polycarbosilanes with HFA, we examined the reaction of the model compound 2-ethylnaphthalene with HFA under similar reaction conditions as for the functionalization of the naphthalene-substituted parent polycarbosilanes. The reaction of 2-ethylnaphthaIene with excess HFA in the presence of catalytic amounts of AICI3 resulted in the formation of... 

Unsubstituted and o/ -substituted substrates (entries 1-3) give the expected products in good yields. The reader will have noticed that examples in entries 5-9 were chosen to study the regioselectivity of the rearrangement. It was found to be excellent with the exception of 2-naphthalene substituted substrate (entry 9). In the other cases, electronic (entries 5 and 6) or steric factors (entry 7) govern at which position the carbanion is more likely to be formed. 

C. Substitution in the phenyl ring at the a-position raises Jg to 115 °C. Jg in the case of a naphthalene substitution has a value of 135 °C. Jg for biphenyl is 145 °C. Tg of the more sterically hindered poly(a-methylstyrene) is 175 °C and that of polyacenaphthalene is 265 °C. A further illustration of the influence of subtle changes on T g can be seen in the case of poly(butyl methacrylate)s. The normal butyl methacrylate has a T g value of 56 °C, that of secondary butyl methacrylate is 22 °C and that of isobutyl methyacrylate is 43 °C. Once more, the greater the steric interaction the higher the value of T g. 

In radical substitution, an even AH is converted to an intermediate odd AH radical and in nucleophilic substitution to the corresponding anion. Since these differ from the corresponding electrophilic intermediate only in the number of nonbonding electrons, the energies of reaction should be the same in all three cases. The relative reactivities of different even AHs and the orientation of substitution in a given AH, should therefore be the same for all reagents. This is the case. Thus naphthalene substitutes mainly in the 1 position both with electrophiles (e.g., nitration) and with radicals (e.g., phenylation by phenyl radicals, as in the Gomberg reaction) and with nucleophiles (e.g., amination by sodamide, the Chichibabin reaction) i.e.. 

Figure 8.15 Molecular structures of naphthalene-substituted ethenes 32-35.

As might be expected, because pyridine is electron poor compared with benzene, electrophilic substitutions on quinoline and isoquinoline take place at the benzene ring. As with naphthalene, substitution at the carbons next to the ring fusion predominates. 

Behavior similar to that of benzyl chloride is shown by benzyl chlorides and chloromethylated naphthalene substituted in the ring [57], certain N-benzoyllactams [16], and also possibly y-hexachlorane [59], DDT [60], and phenyl vinyl ketone at pH 10.7 [61]. An example of such a reaction investigated in detail is the elimination of a bromine ion from 2-acetyl-5-bromothiophene [17, 34], In the reduction of this compound in alkaline solutions the halfwave potential does not depend on the pH value and, with increase in the electrolyte concentration in the solution, is shifted to positive values this and other evidence is characteristic of the reduction of neutral and (in this case) unprotonated particles (a.g., [4, 10, 17]). 

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