Anthracenes 9-methylanthracene

Only one activating group on the alkyne is necessary for the cycloaddition to occur, and the monophosphorylated acetylene reacts as readily as the diphosphorylated one. Dienes such as isoprene, 2,3-dimethyl-l,3-butadiene, cyclopentadiene, l,3-cyclohexadiene, " anthracene, 9-methylanthracene, ° d-methyl-S-propoxyoxazole, l-phenyl-3,4-dimethylphosphole (Scheme 1.25), and a-pyronc have been employed. 

Anthracene 9-methylanthracene, 9-phenylanthracene 9,10-diphenylanthracene benz(a)anthracene Anthraquinone dyes... 

Southworth etaL (1978) reported that elimination rates in the cladoceran Daphnia pulex increased in the order perylene>benz[a]anthracene= methylanthracene > pyrene > phenanthrene > anthracene > naphthalene. Hence, naphthalene often occurs in relatively low concentrations in natural invertebrate populations. Anderson etal. (1976) demonstrated that methyl-derivatives of naphthalene were retained in invertebrates longer than the parent compound owing to a decrease in solubility and rate of volatilization. Varanasi and Malins (1977) reported bioconcentration factors of 2, 8, 17, and 27 for clams Rangia cuneata exposed to naphthalene, methyl-naphthalene, dimethylnaphthalene, and trimethylnaphthalene, respectively. 

Acetic acid, benzene, naphthalene, toluene, styrene, ethyl benzene, propenyl benzene, propylbenzene, methylnaphthalene, ethylnaphthalene, propenylnaphthalene, propylnaphthalene, anthracene, methylanthracene, ethylantbracene, propylanthracene 147... 

The low solubility of fullerene (Ceo) in common organic solvents such as THE, MeCN and DCM interferes with its functionalization, which is a key step for its synthetic applications. Solid state photochemistry is a powerful strategy for overcoming this difficulty. Thus a 1 1 mixture of Cgo and 9-methylanthra-cene (Equation 4.10, R = Me) exposed to a high-pressure mercury lamp gives the adduct 72 (R = Me) with 68% conversion [51]. No 9-methylanthracene dimers were detected. Anthracene does not react with Ceo under these conditions this has been correlated to its ionization potential which is lower than that of the 9-methyl derivative. This suggests that the Diels-Alder reaction proceeds via photo-induced electron transfer from 9-methylanthracene to the triplet excited state of Ceo-... 

The photo-induced single and double Diels-Alder reactions between [60]fullerene and 9-methylanthracene (212) which gave 213 and 214 were performed in the solid state by Mikami and colleagues (equation 60)141. The Diels-Alder reaction was considered to proceed following a photo-induced electron transfer from 9-methylanthracene to fullerene. The higher ionization potential of anthracene should explain its inreactivity toward the cycloaddition reaction with [60]fullerene. 

Pyrolysis of bis(2-ethylhexyl) phthalate in the presence of polyvinyl chloride at 600 °C produced the following compounds methylindene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, biphenyl, dimethylnaphthalene, acenaphthene, fluorene, methylacenaphthene, methylfluorene, phenanthrene, anthracene, methylphenanthrene, methylanthracene, methylpyrene or fluoranthene, and 17 unidentified compounds (Bove and Dalven, 1984). 

An even more pronounced retro-Diels-Alder reaction occurs by using 1,3-di-phenylisobenzofuran (DPIF), 9-methylanthracene or 9,10-dimethylanthracene as dienes [8, 10-12]. The monoadduct of DPIF cannot be isolated from the reaction mixture, while the monoadduct of the 9-methyl- or 9,10-dimethyl- derivatives of anthracene can be isolated at temperatures lower than room temperature [10]. Both anthracene derivatives decompose at room temperature, the adduct with one methyl group within hours, the adduct with two methyl groups within minutes. For DPIF and the anthracene compounds the retro-Diels-Alder reaction seems to be facilitated by steric repulsion due to the bulky groups. However, as shown by Wudl and coworkers [13], the cycloadduct of with isobenzofuran (Scheme 4.2), which was generated in situ from l,4-dihydro-l,4-epoxy-3-phenylisoquinoline, is stable in the solid state as well as in solution and shows no tendency to undergo cycloreversion. 

Electron-donating substituents (e.g., methyl) generally lead to increased relative transformation rates for example, the relative reactivity of anthracene is 1200 compared to 21,000, 6500, and 1600 for 9,10-dimethyl-, 9-methyl-, and 2-methylanthracene, respectively (Table 10.29). Electron-withdrawing substituents, e.g., nitro, decreased rates. These effects are characteristic of electrophilic reactions. 

Figure 2. Gas chromatogram of A, PAH fraction of diesel particulate extract (Sl-C2) and By its HPLC subfraction C (S1-C2). GC conditions 45- X 0.35-mm id SE54 glass capillary column flame ionization detector temperature, 110°C for 2 min, programmed to 170°C at 10°/min, to 212°C at 3°/min, to 278°C at 8°/min. Peak identities 1, phenanthrene 2, anthracene 3-6, methylanthracene/-phenan-threne 7, 2-phenylnaphthalene 8-10, dimethylanthracene/-phenanthrene 11, fluoranthene 12, aceanthrylene/acephenanthrylene 13, pyrene 14-15, trimethylan-thracene/-phenanthrene 16, benzo [ghi]fluoranthene 17, benzo[a/anthracene 18, triphenylene 19, chrysene 20, benzo[b]fluoranthene 21, benzo[]]fluoranthene ...

Figure 1. Gas chromatogram of PAH in a work atmosphere a, particulate PAH b, gaseous PAH. The peak identities are 1, naphthalene 2, 2-methylnaphthalene 3, 1 -methylnaphthalene 4, biphenyl 5, acenaphthene 6, dibenzofuran 7, fluorene 8, 2-methylfluorene 9, 1-methylfluorene 10, dibenzothiophene 11, phenanthrene 12, anthracene 13, methylphenanthrene/methylanthracene 14, methylphenan-threne/methylanthracene 15, 2-methylanthracene 16, 4,5-methylenephenanthrene 17, methylphenanthrene/methylanthracene 18,1-methylphenanthrene 19, fluoranthene 20, benzo(def)dibenzothiophene 21, pyrene 22, ethylmethylenephena-threne 23, benzo(a)fluorene 24, benzofb)fluorene 25, 4-methylpyrene 26, meth-ylpyrene 27, 1-methylpyrene 28, benzothionaphthene 29, benzo(c)phenanthrene 30, benzophenanthridine 31, benzo(2i)anthracene 32, chrysene/triphenylene 33, benzo(b)fluoranthene 34, benzof])fluoranthene 35, benzo(k)fluoranthene 36, ben-zo(c)pyrene 37, benzofa)pyrene 38, perylene 39, indenof 1,2,3-cd)pyrene 40, dibenz(a, /a,h)anthracenes 41, benzofghi)perylene 42, anthanthrene 43, coro-...

In some molecules, the interaction can develop into a stronger force and the interplanar distance further reduced to form stable photodimers through covalent bonds. For example, anthracene forms a photodimer and no excimer emission is observed, whereas some of its derivatives with bulky substituents which hinder close approach give excimer fluorescence. In 9-methylanthracene both photodimer formation and excimer emission is observed. 9, 10-diphenylanthracene neither forms a photodimer nor emits excimer fluorescence due to steric hindrance. These observations are tabulated in the Table 6.3, which shows that the nature of the excited state is also important. 

The T values of the methyl carbon nucleus in 1-methylnaphthalene and 9-methyl-anthracene are interpreted accordingly in 1-methylnaphthalene the peri proton forces a preferred conformation of the methyl group and thereby inhibits its rotation. On the other hand, in 9-methylanthracene two energetically equivalent pm H- -CHj interactions occur, so that methyl rotation is less hindered because there is no preferred conformation [148],... 

The chemical deactivation of photoexcited anthracenes by dimerization usually proceeds by 4re + 4re cycloaddition [8]. However, exceptions to this rule have become known in recent years [8], and a multitude of steps, including the formation of metastable intermediates such as excimers, may actually be involved in a seemingly simple photochemical reaction such as the dimerization of 9-methylanthracene [9, 10]. Moreover, substitution of the anthracene chromophore may affect and alter its excited state properties in a profound manner for a variety of reasons. For example, in 9-tert-butylanthracene the aromatic ring system is geometrically distorted [11,12] and, consequently, photoexcitation results in the formation of the terf-butyl-substituted Dewar anthracene [13-15], The analogous photochemical isomerization of decamethylanthracene [16] probably is attributable to similar deviations from molecular planarity. 

Dimethylanthracene cation Anthracene anion 9-Methylanthracene anion... 

Propiolactone H-Nitroscmethylurea 10-Chlorcmethyl-9-methylanthracene Dibenz la,h] anthracene-5,6-oocide 5-Nitro-2-furamidoxime Chlornaphazin... 

In the case of electronic spectroscopy in molecular crystals, the first singlet state of the isotopic mixed crystal of anthracene has been investigated in reflectivity and shown to be of amalgamation type.129 Actually, while the gap of resonances A = va — vg) is about 70 cm-1, the excitonic bandwidth is estimated at 500 cm-1. Very few mixed crystals have been investigated in the whole range of concentrations,120 whereas examples of low concentrations (of impurities, for instance) are very numerous The anthracene crystal contains j8-methylanthracene naturally and shows an impurity level below the excitonic band.120 (This does not suffice, however, to predict that a mixed anthracene-j8-methylanthracene crystal will be of the persistence type.)... 

The reactions of Cp(Sm(THF)2 with a variety of alkenes in hexane or toluene solvent to produce allyl and alkene products have been studied. Binuclear Sm complexes have been synthesized [159] by the reaction of Cp Sm with pyrene, anthracene, 2,3-benzanthracene, 9-methylanthracene. The structure of the complex [(Cp Sm)2(/r-/73 /73-CioHi4)] is shown in Fig. 6.16. 

Hydrogermylation of naphthalene, phenanthrene, anthracene and 9-Me-anthracene to form 69-71 proceed in the usual way, in accordance with equations 55-57. Reactions with anthracene and 9-methylanthracene (MA) in benzene solution at inert atmosphere lead to a single isomer of 9-trichlorogermyl-9-methyl-9,10-dihydroanthracene 71 (R = Me) in close to quantitative yield. The structure of 71 shows that protonation takes place in the 10 position of MA in accordance with the orientation effect of the Me group, as happens in the reactions of MA with classical superacids which give a stable <7-complex. ... 

With nickel(II) 2-ethylhexanoate and triethylaluminum, tetralin (59) is obtained by hydrogenation of naphthalene (55). Polycyclic aromatics, such as anthracene (57 equation 8), 9-methylanthracene and 9-trifluoroacetylanthracene, are partially hydrogenated to 1,2,3,4-tetrahydroanthracene derivatives by use of [Rh(DPPE)(arene)]+ in methanol and by ruthenium hydride complexes having triphenylphosphine ligands... 

A study of Livingston and Wei (102) showed that the dimerization reaction of anthracene is occurring via the singlet excited state although it may be partially due to triplet reaction based on the effect of oxygen on the quantum yield of cyclomerl-zatlon. Recent results (105), however, indicate that dimerization of 9-methylanthracene occurs via excited state complex formation from the singlet excited state. 

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