Naphthalene spontaneous aromatization

Aromatization of preMAP Metabolites. Another spontaneous aromatization process has been observed for preMAP metabolites. PreMAP metabolites of naphthalene (77) and phenanthrene (78) have been shown to spontaneously aromatize to the parent hydrocarbon. The decomposition of 9,10-dihydro-9-hydroxy-10-( cysteinyl)phenanthrene has been proposed to occur through a thiiranium ion as shown in Equation 14. The isolation of the 9,10-dihydrodiol, and a phenol... 

Condensation of benzotriazole with 2-carboxybenzaldehyde gives 3-(benzotriazol-l-yl)phthalide 795 (Scheme 127). The anion derived from phthalide 795 adds to the ft-carbon atom of a,( -unsaturated carbonyl compounds E to produce anion 796 that by intramolecular nucleophilic attack on the phthalide carbonyl group is converted to anion 797. Spontaneous expulsion of benzotriazole from molecules 797 followed by aromatization leads to 1,4-dihydroxy-naphthalenes 798 <1997SC3951>. 

Spin-spin coupling in nmr, 242 Spontaneous reaction, 36 Stability, heat of combustion, 90 of radicals, 61 resonance, 24 Staggered conformation, 51 Stereoisomers, 69 Stereomers, conformational, 80 Stereoselective reactions, 91 Steric strain, 54, 126 Stilbene, 218 Strain, torsional, 54, 167 Structure of benzene, 189 cyclooctatetraene, 195 Substitution, ally lie, 105 in arenes, 205 in naphthalene, 213 nucleophilic aromatic, 215 ... 

The first clear example of cyclometallation of sp C-H bonds was shown by Chart and Davidson" and Cotton and coworkers in the case of the ruthenium complex [Ru(dmpe)2] [dmpe = l,2-bis-(dimethylphosphino)ethane]. This complex was found to spontaneously cyclometallate the C-H a bond of the methyl group on the phosphorous through a pentacoordinate hypercarbon intermediate to provide a dimer"" [Eq. (6.62)]. Tlie same complex also reacts with the aromatic C-H bond of naphthalene... 

In later work it was shown that water-soluble antennas could be made by copolymerizing aa oinatic monomers such as vinyl naphthalene and naphthylmethyl methacrylate with polyelectrolytes such as acrylic acid [3,4]. The high efficiency of these antennas in dilute aqueous base was attributed to the hypercoiling of the poly-(acrylic acid) chain to give a pseudo micellar stincture such as that illustrated schematically in Figure 2. We believe that such structures are formed spontaneously in solution due to the hydro-phobic interactions of the large aromatic ccmiponents stabilized by the interaction of water with the hydrophillic carboxyl anions. 

Related cyclization reactions are the formation of zethrene (134) [69], which was the product of all attempts to prepare the corresponding bisnaphthalenediyne system 132 (Scheme 8-16). Also, l,6-dehydro[10]annulene (40) [19], already an aromatic system, spontaneously cyclizes to give naphthalene via 1,5-dehydronaphthalene (135) at low temperature [19] (Scheme 8-17). 

The tellurepin (29) spontaneously eliminates tellurium over 2-3 days in solution at room temperature to give naphthalene in a manner similar to borepins and benzophosphepines <91CC802>. Higher temperatures (about 200 °C) are required to eliminate selenium from (30) <72JHC1427> and from (19) <84JHC1321> to give the aromatic products (31) and (32), respectively. 

Hexagonally ordered silica, SBA-15, were also fabricated with PANI to prepare PANI/hexagonally ordered silica nanocomposite, which was used to extract polycyclic aromatic hydrocarbons from aqueous solutions, including naphthalenes, biphenyl, acenaphthene, anthracene, pyrene, and so on [37]. The same nanocomposite exhibited selective adsorption toward 2,4-dini-trophenol in aqueous solution in the presence of phenol with the adsorption capacity of 55.0 mg/g [38]. Chemical oxidation of aniline on hexagonal mesoporous silica (HMS) was carried out to generate PANI/HMS nanocomposite for Ni(II) elimination from aqueous solutions [39]. This process was spontaneous and endothermic and can be applied to Freimdlich isotherm and a pseudo-second-order kinetic. The removal efficiency was 99.87% for 50 mg/L Ni(II) solution, and the maximum sorption capacity can reach 253.17 mg/g at 300 mg/L Ni(II) solution. 2,6-Dichlorophenol can be selective removed from aquatic environment by PANI/silica gel composite [40]. A spontaneous and endothermic process was also observed with a Langmuir isotherm. 

Ferroelectric liquid crystals having a heterocyclic pyrimidine, pyrazine, or pyridazine ring have been developed. Phenylpyrimidine systems show a characteristic low rotational viscosity, and fused aromatics, such as fluorene, fluorenone, or naphthalene, have been discussed from the viewpoint of dipole moment, spontaneous polarization, and orientability. 

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