Anthracene salt

Kobayashi investigated a self-assembled boronic ester cavitand capsule for photochemical reaction of 2,6-diacetoxyanthracene. Tsuda found a self-assembled helical anthracene nanofiber in a vortex. Chou examined rotational behaviors and fluorescence energy transfer of N-l- and N-2-anthryl succinimide derivatives. " Reversible photoinduced twisting of molecular crystal microribbons via [4 - - 4] photocycloaddition of 9-anthra-cenecarboxylic acid. Reversible single walled carbon nanotubes of 1,3-bis(9-anthracenylmethyl)imidazolium chloride was examined as a functionalized anthracene salts.Karatsu reported the intramolecular photodimerization of 9-substituted anthracene derivatives (253) tethered by oligosilanes giving [4 + 4] and [2 - - 4]cycloadducts (254), (255), and (256). ... 

Picrates, Many aromatic hydrocarbons (and other classes of organic compounds) form molecular compounds with picric acid, for example, naphthalene picrate CioHg.CgH2(N02)30H. Some picrates, e.g., anthracene picrate, are so unstable as to be decomposed by many, particularly hydroxylic, solvents they therefore cannot be easily recrystaUised. Their preparation may be accomplished in such non-hydroxylic solvents as chloroform, benzene or ether. The picrates of hydrocarbons can be readily separated into their constituents by warming with dilute ammonia solution and filtering (if the hydrocarbon is a solid) through a moist filter paper. The filtrate contains the picric acid as the ammonium salt, and the hydrocarbon is left on the filter paper. 

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. 

TNSf (potassium salt) Ethanol 0.48 Anthracene 0.51 POPOP... 

Hypochlorites, salts of Urea, amines, anthracene, carbon, carbon tetrachloride, ethanol, glycerol, mercaptans, organic sulfides, sulfur, thiols... 

Methylene thiirane is obtained by thermolysis of several spirothiirane derivatives which are formally Diels-Alder adducts of methylenethiirane and cyclopentadiene or anthracene <78JA7436). They were prepared via lithio-2-(methylthio)-l,3-oxazolines (c/. Scheme 121). A novel synthesis of the allene episulfide derivatives, 2-isopropylidene-3,3- dimethylthiirane (good yield) or its 5-oxide (poor yield), involves irradiation of 2,2,3,3-tetramethyl-cyclopropanethione or its 5-oxide (81AG293). Substituents on the thiirane ring may be modified to give new thiiranes (Section 5.06.3.9). The synthesis of thiirane 1-oxides and thiirane 1,1-dioxides by oxidation is discussed in Section 5.06.3.3.8 and the synthesis of 5-alkylthiiranium salts by alkylation of thiiranes is discussed in Section 5.06.3.3.4. Thiirene 1-oxides and 1,1-dioxides may be obtained by dehydrohalogenation of 2-halothiirane 1-oxides and 1,1-dioxides (Section 5.06.4.1.2). 

Coke (coal tar), high temperature pitch Coke (coal tar), mixed coal-high temperature pitch Coke (coal tar), low temperature, high temperature pitch Diaminotoluene o-Dianisidine Salts of o-dianisidine o-Dianisidine-based azodyes Diarsenic trioxide Diazomethane Dibenz(a,/i)anthracene 1,2-Dibromo-3-chloropropane... 

Aryl bromides were also perfluoroethylated under these conditions [205] The key to improved yields was the azeotropic removal of water from the sodium perfluoroalkylcarboxylate [205] Partial success was achieved with sodium hepta-fluorobutyrate [204] Related work with halonaphthalene and anthracenes has been reported [206 207] The main limitation of this sodium perfluoroalkylcarboxylate methodology is the need for 2 to 4 equivalents of the salt to achieve reasonable yields A trifluoromethylcopper solution can be prepared by the reaction of bis(tri-fluoromethyl)mercury with copper powder in /V-methylpyrrolidone (NMP) at 140 °C [208] (equation 138) or by the reaction of N-trifluoromethyl-A-nitro-sotnfluoromethane sulfonamide with activated copper in dipolar aprotic solvents [209] This trifluoromethylcopper solution can be used to trifluoromethylate aro matic [209], benzylic [209], and heterocyclic halides [209]... 

Rideout and Breslow first reported [2a] the kinetic data for the accelerating effect of water, for the Diels Alder reactions of cyclopentadiene with methyl vinyl ketone and acrylonitrile and the cycloaddition of anthracene-9-carbinol with N-ethylmaleimide, giving impetus to research in this area (Table 6.1). The reaction in water is 28 to 740 times faster than in the apolar hydrocarbon isooctane. By adding lithium chloride (salting-out agent) the reaction rate increases 2.5 times further, while the presence of guanidinium chloride decreases it. The authors suggested that this exceptional effect of water is the result of a combination of two factors the polarity of the medium and the... 

Table 6.2 Sodium and guanidinium salt effects (relative reaction rates) of Diels-Alder reaction of anthracene-9-carbinol and N-ethylmaleimide...

The oxidation of an anthracene suspension in sulfuric acid conducted in the presence of cerium salts can serve as an example of mediated oxidation. In the bulk solution the Ce" ions chemically oxidize anthracene to anthraquinone. The resulting Ce ions are then reoxided at the anode to Ce". Thus, the net result of the electrochemical reaction is the oxidation of anthracene, even though the electrochemical steps themselves involve only cerium ions, not anthracene. Since the cerium ions are regenerated continuously, a small amount will suffice to oxidize large amounts of anthracene. 

Another recent application to the activation of transition metals was reported (247) by Bonnemann, Bogdavovic, and co-workers, in which an extremely reactive Mg species was used to reduce metal salts in the presence of cyclopentadiene, 1,5-cyclo-octadiene, and other ligands to form their metal complexes. The reactive Mg species, characterized as Mg(THF)3 (anthracene), was produced from Mg powder in THF solutions containing a catalytic amount of anthracene by use of an ultrasonic cleaning bath. A plausible scheme for this reaction has been suggested ... 

Other selected examples include tris(tetramethylethylene diamine-sodium)-9,9-dianthryl 143,154 alkali metal salts of 9,10-bis(diisopropylsilyl)anthracene 144,155 as well as the closely related naked 9,10-bis(trimethylsilyl)anthra-cene radical anion 145.156 This chemistry is further extended to the solvent-shared and solvent-separated alkali metal salts of perylene radical anions and dianions 146, 147,156 while other examples focus on alkali metal salts of 1,2-diphenylbenzene and tetraphenylethylene derivatives, where reduction with potassium in diglyme afforded contact molecules with extensive 7r-bonding, [l,2-Ph2C6H4K(diglyme)] 148.157 Extensive 7r-coordination is also observed in (1,1,4,4 tetraphenylbutadiene-2,3-diyl)tetracesiumbis(diglyme)bis(methoxyethanolate) 149.158... 

Although organic anion radicals are oxygen sensitive, they have been isolated as crystalline salts from a variety of electron acceptors (e.g., chloranil, tetracyanoethylene, tetracyanoquinodimethane, perylene, naphthalene, anthracene, tetraphenylethylene, etc.) and their structures have been established by X-ray crystallography.180... 

Effect of Viscosity on the Rate of Photosensitization of Diaryliodonium Salts by Anthracene... 

Photosensitization of diaryliodonium salts by anthracene occurs by a photoredox reaction in which an electron is transferred from an excited singlet or triplet state of the anthracene to the diaryliodonium initiator.13"15,17 The lifetimes of the anthracene singlet and triplet states are on the order of nanoseconds and microseconds respectively, and the bimolecular electron transfer reactions between the anthracene and the initiator are limited by the rate of diffusion of reactants, which in turn depends upon the system viscosity. In this contribution, we have studied the effects of viscosity on the rate of the photosensitization reaction of diaryliodonium salts by anthracene. Using steady-state fluorescence spectroscopy, we have characterized the photosensitization rate in propanol/glycerol solutions of varying viscosities. The results were analyzed using numerical solutions of the photophysical kinetic equations in conjunction with the mathematical relationships provided by the Smoluchowski16 theory for the rate constants of the diffusion-controlled bimolecular reactions. 

Materials. The 1-propanol, glycerol and anthracene were obtained from Aldrich Chemical Company and were used as received. As in a previous study,17 a commercially available bis-(4-dodecylphenyl) iodonium hexafluoroantimonate salt (UV9310C GE Silicones) was used as the initiator. In this initiator, various dodecyl isomers have been attached to the phenyl rings of the diphenyliodonium salt to impart solubility in the monomer and do not effect the reactivity of the initiator.1 All studies were performed with an order of magnitude excess of initiator relative to anthracene. 

Figure 1. Representative anthracene fluorescence profile during the photosensitization of diaryliodonium salts in pure propanol at 30°C.

Figure 2. Profile of anthracene fluorescence at 425 nm obtained during photosensitization of diaryliodonium salt in pure propanol at 30°C.

Here A, lA, and3A represent anthracene in the ground state, the first excited singlet state and first excited triplet state, respectively. In addition, I represents the onium salt initiation, while Rs and Rt correspond to the reactive centers formed by reaction of the onium salt with the excited singlet and triplet state anthracene, respectively. 

The discrepancies between the experimental data and the behavior predicted using the Smoluchowski-Stokes-Einstein model for ksenfluor and ksenphos likely arise from the inadequacies of the simple Smoluchowski-Stokes-Einstein analysis for application to the anthracene/diaryliodonium salt molecular system. For example, the Smoluchowski analysis assumes that the reacting molecules are spherical in... 

The experimental and simulation results presented here indicate that the system viscosity has an important effect on the overall rate of the photosensitization of diary liodonium salts by anthracene. These studies reveal that as the viscosity of the solvent is increased from 1 to 1000 cP, the overall rate of the photosensitization reaction decreases by an order of magnitude. This decrease in reaction rate is qualitatively explained using the Smoluchowski-Stokes-Einstein model for the rate constants of the bimolecular, diffusion-controlled elementary reactions in the numerical solution of the kinetic photophysical equations. A more quantitative fit between the experimental data and the simulation results was obtained by scaling the bimolecular rate constants by rj"07 rather than the rf1 as suggested by the Smoluchowski-Stokes-Einstein analysis. These simulation results provide a semi-empirical correlation which may be used to estimate the effective photosensitization rate constant for viscosities ranging from 1 to 1000 cP. 

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