Anthracenes, substituted

The absorption spectrum at 0° has a maximum at 600 nm. Upon rotation of the direction of the incident polarized light by as much as 90°, the absorption intensity decreases. The anisotropy of the absorption spectra reflects the regular orientation of the photogenerated closed-ring isomers and indicates that the photochromic reaction occurred in the single-crystalline phase. The blue color disappeared by irradiation with visible light a > 480 nm). Anthracene-substituted derivatives also showed photochromic properties (01JPC(A)1741). 

Scheme 11.4 Cation sensing by anthracene-substituted azacorand 11.27.19...

Bazan and coworkers also prepared anthracene-substituted swivel cruciforms 33 with binaphthyl cores [44, 45]. They attached the anthracene units to the binaphthyl in the 6,6 -positions by a Suzuki-type cross-coupling reaction (Scheme 3.15). Based on the aforementioned findings that the alkoxy chain length influences the solid-state properties of these types of materials, they produced two de-... 

Scheme 3.15 Synthesis of anthracene-substituted swivel-cruciforms 33 with a binaphthyl core, according to Bazan and coworkers [45],...

A particularly stericahy demanding ligand system with an anthracene substitution was prepared by Trost. The synthesis started from the known Diels— Alder adduct 131 and proceeded via lactone 132 and phosphino acid 133 (not isolated) to 134, which was transformed to either 135 or 136 (Scheme 22). 

Polynuclear aromatic systems are oxidized to the corresponding quinones by ammonium hexanitratocerate(IV) in aqueous THF under mild conditions (25-60 °C) (scheme 1) (Ho et al., 1973). Water is the source of oxygen in the oxidation process. The yields are reasonable, but not very high, and the reaction is only useful for symmetric molecules like naphthalene and anthracene. Substituted and asymmetric substrates give often an intractable mixture of oxidation products (Balanikas et al., 1988). A problem associated with the use of ammonium hexani-tratocerate(IV) is that nitration of the aromatic ring can also occur. Cerium(IV) ammonium... 

PPV-type polymers have been widely investigated for their third-order NLO properties. Polymers 120 and 121 are PPV-type polymers with anthracene substitution in the side-chain. The optical properties of these polymers can be considered as a composition of the interlinked stmcture of diphenylanthracene and derivatized PPV. Phenylanthracene-containing polymers exhibit four vibronic bands in the region of 325-410 nm overlapped with weaker broader absorption at longer wavelength region that arises from the electronic transitions from the main chain. The absorption maxima of the two polymers do not show much variation with maxima at 335, 355, 373, and 394 nm. These values are red-shifted compared... 

Breslow studied the dimerisation of cyclopentadiene and the reaction between substituted maleimides and 9-(hydroxymethyl)anthracene in alcohol-water mixtures. He successfully correlated the rate constant with the solubility of the starting materials for each Diels-Alder reaction. From these relations he estimated the change in solvent accessible surface between initial state and activated complex " . Again, Breslow completely neglects hydrogen bonding interactions, but since he only studied alcohol-water mixtures, the enforced hydrophobic interactions will dominate the behaviour. Recently, also Diels-Alder reactions in dilute salt solutions in aqueous ethanol have been studied and minor rate increases have been observed Lubineau has demonstrated that addition of sugars can induce an extra acceleration of the aqueous Diels-Alder reaction . Also the effect of surfactants on Diels-Alder reactions has been studied. This topic will be extensively reviewed in Chapter 4. 

In an alternative method, the senior component is regarded as substituted by RN=N—, this group R being named as a radical. Thus 2-(7-phenylazo-2-naphthylazo)anthracene is the name by this alternative method for the compound named anthracene-2-azo-2 -naphthalene-7 -azobenzene. 

The reaction of methoxy-substituted 1,4-dihydroatomatic systems is a general one. Other condensed systems react ia a similar manner, for example, 3,6-dimethoxy-1,4,S,8-tetrahydronaphtha1ene and derivatives of anthracene (35) and xanthene (36) (74). The proposed method enables synthesis of the tri-and tetracarbocyanines where the whole chromophore is iategrated iato a rigidizing skeleton. Asymmetrical polymethines can also be obtained similarly. 

Only the reduction products involving the keto groups are of any academic or industrial importance. Complete reduction of the keto groups by ammonia and zinc (von Perger method) gives rise to anthracene in good yields and quaUty (10). This method is of importance since substituted anthracenes can be prepared from the corresponding anthraquinones. Industrially, an important dyestuff intermediate, 3-chloroanthracene-2-carboxyhc acid, (2) is prepared by this method (11) from 3-chloroanthraquinone-2-carboxyhc acid [84-32-2]... 

Many different combinations of carboxyflc acid and hydroxyl groups have been tested to form LCPs. An aromatic stmcture (ben2ene, naphthalene, anthracene, etc) is required that has its functional groups symetricaHy arranged on opposite sides of the molecule. Examples are a 1,4-substituted ben2ene compound or 2,6-substituted naphthalene compound. These monomers are often complex and expensive molecules and account for a significant portion... 

The benzyne adducts prepared from A -methylpyrrole (and A -methylisoindole) are deaminated conveniently by dichlorocarbene generated under phase-transfer conditions (81JOC1025 to give a convenient route to substituted naphthalenes (134) (and anthracenes) (Scheme 49). 

From all symmetrically substituted anthracene and phenanthrene dialdehydes E - H containing 1,2,3-trisubstituted benzene rings,... 

The polycyclic aromatic hydrocarbons such as naphthalene, anthracene, and phenan-threne undergo electrophilic aromatic substitution and are generally more reactive than benzene. One reason is that the activation energy for formation of the c-complex is lower than for benzene because more of the initial resonance stabilization is retained in intermediates that have a fused benzene ring. 

Phenanthrene and anthracene both react preferentially in the center ring. This behavior is expected from simple resonance considerations. The c-complexes that result from substitution in the center ring have two intact benzene rings. The total resonance stabilization of these intermediates is larger than that of the naphthalene system that results if substitution occurs at one of the terminal rings. ... 

Both phenanthrene and anthracene have a tendency to undergo addition reactions under the eonditions involved in eertain eleetrophilic substitutions. For example, in the nitration of anthracene in the presence of hydrochloric acid, an intermediate addition product can be isolated. This is a result of the relatively close balance in resonance stabilization to be regained by elimination (giving an anthracene ring) or addition (resulting in two benzenoid rings). 

As mentioned above, the scope of the Bucherer reaction is limited. It works with anthracenes and phenanthrenes, but only very few examples with substituted benzenes are known. Naphthylamines can be converted into the corresponding naphthols, and these can then be further converted into primary, secondary or tertiary naphthylamines (transamination). Naphthylamines are of importance for... 

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