Dimethyl-anthracene

Dimethyl anthracene and diphenyl isobenzofuran form remarkably stable233 cyclopropanone derivatives (353/354), whilst with other diene components (butadiene, tetracyclone, and fulvene) the primarily formed Diels-Alder adducts either suffer ketalizing attack of the solvent (356 - 357, 359 - 358/360) or undergo irreversible changes such as decarbonylation to 362 or rearrangement to 355. 

Figure 25. Shapes of five alkylated derivatives of adenosine and deoxyadenosine. (a) Adenosine derivative of DMBA (XXXII). (b) Deoxyadenosine derivative of DMBA (XXXIV). No hydrogen atom positions for this diagram, (c) Adenosine derivative of dimethyl anthracene (XXXI). Note the different conformation.

Barnes RL, Birks JB (1966) Excimer fluorescence. X. Spectral studies of 9-methyl and 9,10-dimethyl anthracene. Proc R Soc A Math Phys Eng Sci 291 570-582... 

A more detailed study of the electrochemiluminescence of 9,10-dimethyl-anthracene in dimethylformamide has been carried out by Parker and Short127 who measured the ratio of excimer/molecular fluorescence yields (y°/yp)p in the chemiluminescent spectrum, and (yp/yp)D in the delayed emission spectrum, at different temperatures. The general scheme... 

Fig. 16. Analysis of the central component from the spectrum of 9,10-dimethyl-anthracene positive ion (cf. Fig. 5o and Table 7). Relative intensities are shown by the numbers, the bottom part is drawn to a smaller vertical scale ( ).

Similar results were obtained in the anodic oxidation of 9,10-dimethyl-anthracene S3-). 

Fig. 14.10 9,10-Dimethyl-anthracene (14) and 9,10-bis(chloromethyl)anthracene (15), showing their solid-state Jt-stacking order. 

Two Components. Figures 5 and 6 summarize the least squares analysis of perylene and dimethyl anthracene respectively in the presence of 10- M anthracene. In both cases, the variable component can be easily quantitated in the presence of a one hundred fold excess of anthracene, even when the spectral overlaps... 

Figure 6. Analytical curves for the determination of 1,3-dimethyl anthracene in the presence of anthracene...

E. L. Mackor et al., Trans. Faraday Soc. 54, 66, 186 (1958), have measured for both substituted and condensed aromatics in liquid HF-BFa mixtures by using phase partition to obtain data. II0 in HF-NaBF4 at 0°C is about —8.6, so the system is surprisingly acidic. Their pKj values range from 6.3 for toluene to —1.4 for hexamethyl-benzene and —6.4 for 9,10-dimethyl anthracene. I his last is evidently a reasonably strong base in HF. 

In the method proposed by Valeur monofunctional living monodisperse chains are prepared and deactivated by 9-10-bis(bromomethyl)anthracene. The resultant chains contain dimethyl anthracene in their middle, as shown in Fig. 3 (This figure represents labelled polystyrene, but other polymers can be labelled too). Anthracene is a particularly convenient label since it is rigid and rather small, it has a good quantum yield and it is easy to excite. When it is bounded in 1,9 positions, its... 

Label Effect. In order to assess at least partially the effect of the label on the chain dynamics, we also performed measurements on dilute solutions of 9,10-dimethyl anthracene. The reorientation time for the free dye in cyclohexane was - 10 psec, 50 times faster than the time scale for motion of the labeled chain in cyclohexane. Hence we conclude that the observed correlation functions are not dominated by the hydrodynamic interaction of the chromophore itself with the solvent, but can be attributed to the polymer chain motions. 

Nitrosyl cyanide (109) has been briefly examined as a dienophile by Kirby et alP This intermediate can be generated from nitrosyl chloride and silver cyanide (equation 42) and trapped with 9,10-dimethyl-anthracene to yield adduct (110). As with acyl nitroso compounds, this adduct can be used as a stable source of (109) via a retro Diels-Alder reaction. 

Laplante and Pottler (1982) observed fluorescence oscillations upon irradiating the 9,10-dimethyl anthracene/chloroform systems continuously. Fluorescence oscillations were found to occur immediately after the reaction was started. However, initial oscillations were usually found to be of horatian nature and periodic oscillations were obtained following a horatian initial period. In some cases the periodic behavior was not reproducible even though the nonperiodic oscillatory behavior could be reproduced. Experiments were carried out to determine the effect of e.g., excitation wavelength, substrate concentration and specificity. The mechanism has not yet been elucidated. 

Dimethyl anthracene/Chloroform Solutions. J. Phys. Chem. 86, 4759-4766... 

Later the same authors61 published a study on the reactivities of a number of electrogenerated radical cations toward St and isobutyl vinyl ether (IBVE). The reactivity comparison was made among 9-phenylanthracene (9PA), 9,10-dimethyl-anthracene (DMA), 9,10-diphenylanthracene (DPA), 1,3,6,8-tetraphenylpyrene (TPP), rubrene (RU), triphenylene (TP), perylene (p). The stability of the ion radicals, in the absence of the monomers, is in the order ... 

Similar observations led to analogous expressions for the reactions involving 1,2-dimethyl-anthracene, DMA, or pyrene, n, as the electron acceptors1045. The combined constants, 2KDMA and k2Kx, derived from these studies... 

Foote reactivity indices (ft) have been measured for rubrene and 9,10-dimethyl-anthracene undergoing autophotoperoxidation in a range of solvents for which , has been measured. The variation in /3-values (about a factor of 40) is almost entirely due to the solvent dependence of t 0,. Thus = 1// t 0i varies by less than a factor of 2 ( is the singlet oxygen addition rate constant). However, for... 

C.iii. Nitroso-Type Compounds. Nitroso compounds (R—N=0) show reactivity as dienophiles in Diels-Alder reactions, giving heterocyclic rings. In Kibayashi s synthesis of fasicularin, " for example, hydroxamic acid 180 was treated with tetrapropylammonium periodate in the presence of 9,10-dimethyl-anthracene to give transient acylnitroso compound 181, and the resultant Diels Alder product 182 was formed in 84% yield. In this particular example, the Diels-Alder adduct essentially "protected" the acyl nitroso unit, which was used in a subsequent reaction. 

For the formulation of the lattice dynamics in a molecular crystal, only six coupled equations of motion are necessary three for translation and three for rotation of a single molecule, if all the molecules in the unit cell are connected by symmetry operations. (This assumption does not hold e.g. for dipolar disorder in dimethyl-naphthalene or dimethyl-anthracene crystals (see Sect. 5.7).) The translational-rotational displacements u(lk) of the kth molecule in the Ith unit cell are taken to be given by propagating plane waves u(lfe) = U(fk)e F Here, S2(K)... 

Dunethyl-naphthalene (DMN) and 2,3-Dimethyl-anthracene (DMA) These two molecules crystallise similarly to naphthalene and anthracene (see Chap. 4.2.4). In particular, they form macroscopically apparently perfect single crystals. The lattice parameters of the triclinic 2,3-DMA crystal at room temperature are a =... 

The diminution of electrode fouling in oxido-reductive mode is shown in Fig. 22. Other ECL systems were also examined and sonoelectrochemical enhancement was observed for luminol (3-aminophthalhydrazide). This system has been thoroughly studied for the detection of low concentrations of residual hydrogen peroxide in contact-lens cleaning solutions. The ECL intensity of 9,10-diphenyl-anthracene in sonicated DMF solutions was increased by factors of 20-30 depending on the concentration of the solutions, ultrasound power, and fre-quencyT Similar effects were observed from l,5-diphenyl-3-styrylpyrazoline, rubrene, 9,10-dimethyl-anthracene, and perylene. ... 

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