- Biocatalytic chlorination of aromatic hydrocarbons by chloroperoxidase of caldariomyces fumago
-
Chloroperoxidase from Caldariomyces fumago was able to chlorinate 17 of 20 aromatic hydrocarbons assayed in the presence of hydrogen peroxide and chloride ions. Reaction rates varied from 0.6 min-1 for naphthalene to 758 min-1 for 9-methylanthracene. Mono-, di- and tri-chlorinated compounds were obtained from the chloroperoxidase-mediated reaction on aromatic compounds. Dichloroacenaphthene, trichloroacenaphthene 9,10-dichloroanthracene, chloropyrene, dichloropyrene, dichlorobiphenylene and trichlorobiphenylene were identified by mass spectral analyses as products from acenaphthene, anthracene, pyrene and biophenylene respectively. Polycyclic aromatic hydrocarbons with 5 and 6 aromatic rings were also substrates for the chloroperoxidase reaction. The importance of the microbial chlorination of aromatic pollutants and its potential environmental impact are discussed.
- Vazquez-Duhalt, Rafael,Ayala, Marcela,Marquez-Rocha, Facundo J.
-
-
Read Online
- Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
-
A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
- Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
-
supporting information
p. 1621 - 1629
(2020/02/04)
-
- Selective Halogenation Using an Aniline Catalyst
-
Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent-based approach. Unfortunately, a suitable "catalytic" process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N-halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N-halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.
- Samanta, Ramesh C.,Yamamoto, Hisashi
-
supporting information
p. 11976 - 11979
(2015/08/18)
-
- A practical lewis base catalyzed electrophilic chlorination of arenes and heterocycles
-
A mild phosphine sulfide catalyzed electrophilic halogenation of arenes and heterocycles that utilizes inexpensive and readily available N-halosuccinimides is disclosed. This methodology is shown to efficiently chlorinate diverse aromatics, including simple arenes such as anthracene, and heterocycles such as indoles, pyrrolopyrimidines, and imidazoles. Arenes with Lewis acidic moieties also proved amenable, underscoring the mild nature of this chemistry. Lewis base catalysis was also found to improve several diverse aromatic brominations and iodinations.
- Maddox, Sean M.,Nalbandian, Christopher J.,Smith, Davis E.,Gustafson, Jeffrey L.
-
supporting information
p. 1042 - 1045
(2015/03/30)
-
- Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione
-
The Diels-Alder reaction between substituted anthracenes 1a-1j and 4-phenyl-1,2,4-triazoline-3,5 (2) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a. The structure of adduct 3a is proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ? 3a in toluene at 25°C: Keq = 2120 M-1, ΔHf≠ = 58.6 kJ/mol, ΔSf≠ = -97 J/(mol K), ΔVf≠ = -17.2 cm3/mol, ΔHb ≠ = 108.8 kJ/mol, ΔSb≠ = 7.3 J/(mol K), ΔVb≠ = -0.8 cm3/mol, ΔHr-n = -50.2 kJ/mol, ΔSr-n = -104.3 J/(mol K), ΔVr-n = -15.6 cm3/mol. It is concluded that the values of equilibrium constants of the reactions 1a-1j + 2 ? 3a-3j vary within 4 × 101-1011 M-1.
- Kiselev,Kornilov,Kashaeva,Potapova,Krivolapov,Litvinov,Konovalov
-
p. 2073 - 2080
(2015/02/19)
-
- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
-
Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
-
p. 1673 - 1679
(2013/02/22)
-
- Photochemical molecular storage of Cl2, HCl, and COCl 2: Synthesis of organochlorine compounds, salts, ureas, and polycarbonate with photodecomposed chloroform
-
Chloroform is available as not only an organic solvent but also photochemical molecular storage for synthetically important chemicals such as Cl2, HCl, and COCl2. We have succeeded in synthesizing organochlorine compounds, hydrochloric salt of amines, ureas, organic carbonates, and polycarbonate in practical high yields with photodecomposed chloroform.
- Kuwahara, Yuki,Zhang, Ailing,Soma, Haruka,Tsuda, Akihiko
-
supporting information; experimental part
p. 3376 - 3379
(2012/08/08)
-
- Dynamic Covalent chemistry: A facile room-temperature, reversible, diels-alder reaction between anthracene derivatives and n-phenyltriazolinedione
-
A series of readily accessible, dynamic Diels-Alder reactions that are reversible at room temperature have been developed between anthracene derivatives as dienes and N-phenyl-1,2,4-triazoline-3,5-dione as the dienophile. The adducts formed undergo reversible component exchange to form dynamic libraries of equilibrating cycloadducts. Furthermore, reversible adduct formation allows temperature-dependent modulation of the fluorescent properties of anthracene components; a feature of potential interest for the design of optodynamic polymeric materials by careful selection and manipulation of these simple dienes and dienophiles. Copyright
- Roy, Nabarun,Lehn, Jean-Marie
-
supporting information; experimental part
p. 2419 - 2425
(2012/07/03)
-
- The halogenation of aliphatic C-H bonds with peracetic acid and halide salts
-
Hydrocarbons react with molar concentrations of peracetic acid and halide salts to yield predominantly monohalogenated products under optimum conditions, with chlorination being more oxidatively efficient than bromination. The alkane halogenation proceeds at ambient temperature and does not require a heavy-metal catalyst. The observed reactivity is consistent with a radical mechanism, in which the peracid initially reacts with the halide ions to yield halogen-atom radicals, which ultimately oxidize the hydrocarbon. Although the reactivity proceeds slightly more efficiently in acetonitrile, the halogenation protocol works well in water.
- He, Yu,Goldsmith, Christian R.
-
supporting information; experimental part
p. 1377 - 1380
(2010/08/06)
-
- Comparative study of the reactivity of iodinating agents in solution and solid phase
-
The results of reactions of a series of aromatic substrates with iodine, iodine(I) chloride, and N-iodosuccinimide in solution and solid phase were compared for the first time. In all cases, the general relations holding in the iodination process were similar. Iodine(I) chloride was found to chlorinate anthracene. A high efficiency of solid-phase iodination of β-diketones was demonstrated using dibenzoylmethane as an example.
- Krasnokutskaya,Lesina,Gorlushko,Filimonov
-
p. 855 - 859
(2007/10/03)
-
- Oxidative halogenation of aromatic compounds with metal halides and sodium bismuthate
-
A new mild and efficient method for aromatic halogenation with a wide variety of halides in the presence of sodium bismuthate NaBO3 in AcOH is reported. Metal halides of groups Ia, IIa, IIIa, IVa, Va, and the first row of transition elements are suitable for this method.
- Muathen, Hussni A.
-
p. 164 - 168
(2007/10/03)
-
- Iodination and chlorination of aromatic polycyclic hydrocarbons with iodine monochloride in aqueous sulfuric acid
-
Polycyclic aromatic hydrocarbons when treated with iodine monochloride in water solutions of sulfuric acid afford iodo-and chloroderivatives. Biphenyl, fluorene, acenaphthene, 1-nitronaphthalene undergo iodination. Naphthalene furnishes a mixture of iodo-and chloroderivatives, prevailing the latter. Anthracene and phenanthrene provide only chlorinated products. The iodine monochloride in the sulfuric acid is a stronger iodinating agent than in acetonitrile.
- Chaikovskii,Filimonov
-
p. 1130 - 1133
(2007/10/03)
-
- A convenient synthesis of 9,10-Bis(3-methylphenyl)anthracene on a kilo-lab scale
-
Cross-coupling of 9,10-dihaloanthracene with arylmagnesium halides gave polymers when catalyzed by PdCl2·dppb, but the expected 9,10-diarylanthracene was obtained using NiCl2·dppp as the catalyst. The latter procedure was developed into a large-scale preparation of 9,10-dichloroanthracene.
- Kauffman
-
p. 197 - 199
(2007/10/03)
-
- Halogenations of Anthracenes and Dibenz[a,c]anthracene with N-Bromosuccinimide and N-Chlorosuccinimide
-
Halogenation of dibenz[a,c]anthracene (1) by NBS in CCl4 affords the products of 9- and 10-monobromination in the ratio of 9:1. The reaction is accelerated by iodine, and HBr effects rearrangement of 9-bromo product to the sterically less crowded 10-bromo isomer. The mechanism is proposed to involve reversible addition of Br2, followed by elimination of HBr. Reaction of NCS with 1 in CCl4 requires addition of HCl and affords exclusively 9-chlorination. The different reactivities of NBS and NCS are ascribed to the relative amounts of free halogen produced (due to differences in N-X bond strengths involving Br and Cl), and the different sizes of the halogens. Under similar conditions, NCS chlorinates 9-bromoanthracene (2a) to afford 9,10-dichloroanthracene and 9-bromo-10-chloroanthracene in the ratio of 65:35. This reaction ostensibly occurs by addition of Cl2 to 2a, followed by preferential loss of HBr rather than HCl. 9-Methylanthracene (3) affords exclusively 9-(bromomethyl)anthracene with NBS in the absence of iodine, but mainly (67%) 9-bromo-10-methylanthracene in the presence of iodine. Chlorination of 3 with NCS in the presence of HCl also affords mostly (65%) nuclear halogenation. Nuclear bromination of anthracene, 9-methylanthracene, and dibenz[a,c]anthracene by NBS in the absence of added HBr is accelerated by iodine. This effect is probably due to an increase in the amount of bromine produced from NBS in the presence of iodine.
- Duan, Shaoming,Turk, Jeff,Speigle, Joseph,Corbin, Jean,Masnovi, John,Baker, Ronald J.
-
p. 3005 - 3009
(2007/10/03)
-
- Substrate specificity and ionization potential in chloroperoxidase- catalyzed oxidation of diesel fuel
-
Straight-run diesel fuel containing 1.6% of sulfur was enzymatically oxidized with chloroperoxidase from Caldariomyces rumago. Most organosulfides and thiophenes were transformed to form sulfoxides and sulfones. The oxidized organosulfur compounds can be effectively removed by distillation. The resulting fraction after distillation contained only 0.27% sulfur, while the untreated straight-run diesel fuel after the same distillation process still showed 1.27% sulfur. To know the chemical nature of the products, nine organosulfur compounds and 12 polycyclic aromatic compounds (PACs) were transformed by chloroperoxidase in the presence of chloride and hydrogen peroxide. Organosulfur compounds were only oxidized to form sulfoxides and sulfones, and no chlorinated derivatives were detected, except for bithiophene. In contrast, PACs were exclusively chlorinated, and no oxidized derivatives could be found. No enzymatic activity was detected on PACs with an ionization potential higher than 8.52 eV, while in the lower region it was found that the higher the ionization potential of the PAC the lower the specific activity. On the other hand, the substrate ionization potential did not seem to influence chloroperoxidase activity in the oxidation of organosulfur compounds. All organosulfur compounds tested were oxidized by chloroperoxidase. From double-substrate experiments, it appears that organosulfur compounds are oxidized by both compound I and compound X enzyme intermediates, while PACs react only with the halogenating intermediate, compound X. Straight-run diesel fuel containing 1.6% of sulfur was enzymatically oxidized with chloroperoxidase from Caldariomyces fumago. Most organosulfides and thiophenes were transformed to form sulfoxides and sulfones. The oxidized organosulfur compounds can be effectively removed by distillation. The resulting fraction after distillation contained only 0.27% sulfur, while the untreated straight-run diesel fuel after the same distillation process still showed 1.27% sulfur. To know the chemical nature of the products, nine organosulfur compounds and 12 polycyclic aromatic compounds (PACs) were transformed by chloroperoxidase in the presence of chloride and hydrogen peroxide. Organosulfur compounds were only oxidized to form sulfoxides and sulfones, and no chlorinated derivatives were detected, except for bithiophene. In contrast, PACs were exclusively chlorinated, and no oxidized derivatives could be found. No enzymatic activity was detected on PACs with an ionization potential higher than 8.52 eV, while in the lower region it was found that the higher the ionization potential of the PAC the lower the specific activity. On the other hand, the substrate ionization potential did not seem to influence chloroperoxidase activity in the oxidation of organosulfur compounds. All organosulfur compounds tested were oxidized by chloroperoxidase. From double-substrate experiments, it appears that organosulfur compounds are oxidized by both compound I and compound X enzyme intermediates, while PACs react only with the halogenating intermediate, compound X.
- Ayala, Marcela,Robledo, Norma R.,Lopez-Munguia, Agustin,Vazquez-Duhalt, Rafael
-
p. 2804 - 2809
(2007/10/03)
-
- Solid-state organic reactions proceeding by pulverization: Oxidation and halogenation with iodosobenzene and inorganic solid-supports
-
Pulverization-activation method was employed to accelerate solid-state organic reactions. Crushing and grinding of solid mixtures of hydrogen halide-treated silica gels, iodosobenzene and organic substrates in the absence of a solvent brought about smooth and rapid reactions to give halogenated and/or oxidized products in good yields. Various sulfides were smoothly converted to sulfonyl chlorides in one step in excellent yields. The surface of silica gel activated by pulverization serves as a reaction field on which reagent molecules can effectively encounter with each other.
- Sohmiya, Hajime,Kimura, Takahide,Fujita, Mitsue,Ando, Takashi
-
p. 13737 - 13750
(2007/10/03)
-
- Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
-
Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
- Liu, Lilian Kao,Lin, Ching-Shan
-
-
- Reaction of phosphorus(III, V) chlorides with peri-hydroxy-substituted anthrones, anthraquinones, and naphthoquinones
-
The recently found unusual molecular rearrangement in the series of phosphorylated perihydroxy derivatives of quinones condensed with aromatic rings is investigated.
- Kutyrev,Fomin,Moskva
-
p. 757 - 764
(2007/10/03)
-
- Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate
-
SnCl4/Pb(OAc)4 acts as a safe source of Cl2 for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl4/Pb(OAc)4 under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.
- Muathen, Hussni A.
-
p. 8863 - 8866
(2007/10/03)
-
- Regioselective Catalytic Halogenation of Arenes, mimicking Vanadium Haloperoxidase Reactions
-
Ammonium metavanadate, mimicking vanadate dependent metalloenzymes, efficiently catalyses the halogenation of arenes in moderate to good yields using dilute hydrogen peroxide (30%) as an oxidizing agent, exhibiting remarkable regioselectivity.
- Hegde, Vishnumurthy R.,Pais, Godwin C. G.,Kumar, Rajiv,Kumar, Pradeep,Pandey, Bipin
-
-
- Electrophilic Additions to Tetradehydrodianthracene
-
5,12:6,11-Dibenzenodibenzocyclooctene (tetradehydrodianthracene, TDDA) (1) reacts with halogens to give transannular (anti) 4, 5 and ring-opened (syn) products 6, 7.The product ratio shows a remarkable solvent dependence.Solvents of medium polarity favor anti addition, whereas syn addition is observed both with increasing and decreasing polarity.For instance, chlorine in toluene adds 100percent syn, in dichloroethane 56percent anti, and in trifluoroethanol again 100percent syn.It is concluded that, depending on solvent polarity, three different mechanisms for electrophilic addition are operative. - Keywords: Electrophilic addition / Tetradehydrodianthracene / Solvent effects
- Herges, Rainer,Neumann, Helfried
-
p. 1283 - 1290
(2007/10/02)
-
- The Reaction of Iodine Monochloride with Polycyclic Aromatic Compounds: Polar and Electron Transfer Pathways
-
Several polycyclic aromatic hydrocarbons were treated with iodine monochloride.Although iodination is the predominant reaction of benzenoid arenes, chlorination is the sole reaction with anthracene, phenanthrene and naphthalene compounds (except for 5), whose oxidation half-wave potentials are less than 1.58 V vs Ag/Ag(+) (0.1 M).Arenes with higher potentials are unreactive.Naphthalene (9) and its derivatives with mild electron-withdrawing substituents are chlorinated; the exception (5) yields the 1-iodo product (21).The reaction is first order in substrate and second order in ICl.An electron transfer pathway involving radical cation intermediates is assumed.Ion-pair collapse of the radical cation-ICl intermediates is proposed for the chlorinations and radical-pair collapse for the iodination.
- Turner, Dean E.,O'Malley, Robert F.,Sardella, Dennis J.,Barinelli, Lucio S.,Kaul, Pushkar
-
p. 7335 - 7340
(2007/10/02)
-
- TeCl4 in organic synthesis. Elimination reactions
-
TeCl4 has been shown to react smoothly with unsaturated or halogenated cyclohydrocarbons.With cyclohexene, alkylcyclohexenes, halogenocyclohexenes, halogenocyclohexanes or unsaturated polycyclic compounds at elevated temperatures (ca 80 deg C), aromatization takes place as the only process, whereas at room temperature, addition products of halogenation or halogenotelluration are also formed.With conjugated dienes only chlorine-containing products are obtained with TeCl4, whereas dienes with separated double bonds undergo addition of TeCl4 to the double bond.An ionicpathway for the addition and aromatization reactions is suggested.
- Albeck, Michael,Tamary, Tova
-
-
- Structural Effects Controlling the Rate of the Retro-Diels-Alder Reaction in Anthracene Cycloadducts
-
We have undertaken a fairly broad study of how the structure of an anthracene cycloadduct affects the rate of its cycloreversion reaction.Based on the rate constants for retro-Diels-Alder (rDA) reactions of a variety of anthracene-type adducts conducted in diphenyl ether, we draw the following conclusions.The rDA reaction of anthracene cycloadducts is influenced by diene substituents in the following ways: (1) electron-donating groups increase the reaction rate, and the accelerating effect is subject to geometric modulation for a conjugating substituent like dimethylamino; (2) electron-withdrawing groups may decrease or increase the reaction rate , although the effect is rarely large; and (3) steric acceleration is relatively small and demonstrates an unprecedented bell-shaped structure-reactivity profile.Peripheral substitution of the adduct with siloxy groups results in a significant acceleration, even though the groups are three bonds removed from the reaction site.The same reaction is influenced by dienophile substituents in the following ways: (1) electron-withdrawing groups increase the rate of the reaction; (2) strongly conjugating substituents make the reaction much faster than predicted by classical electron-withdrawing or -donating ability due to a change to polar mechanism; and (3) there is no observable steric effect.
- Chung, Yongseog,Duerr, Brook F.,McKelvey, Timothy A.,Nanjappan, P.,Czarnik, Anthony W.
-
p. 1018 - 1032
(2007/10/02)
-
- Halogenation Using Quaternary Ammonium Polyhalides. XIX. Aromatic Chlorination of Arenes with Benzyltrimethylammonium Tetrachloroiodate
-
The reaction of arenes with a calculated amount of benzyltrimethylammonium tetrachloroiodate in acetic acid at room temperature or at 70 deg C gave nuclear chloro-substituted arenes in fairly good yields.
- Kajigaeshi, Shoji,Ueda, Yasuhiro,Fujisaki, Shizuo,Kakinami, Takaaki
-
p. 2096 - 2098
(2007/10/02)
-
- Sulphuryl Chloride as an Electrophile. Part 5. Chlorination of Some Anthracene Derivatives; Molecular Orbital Modelling of Substituent Effects
-
The rates of electrophilic attack at C-10 of some 9-substituted anthracenes (9-H, Br, CHO, CN, NO2, OMe, or Bz) by sulphuryl chloride have been measured (in PhCl 298 K).The substituent effects roughly parallel those expected from considering the simpler p-XC6H4 system (ρ -1.51; r 0.975); better agreement (ρ -1.23 +/- 0.05; r 0.994) comes by using Dewar's FMMF treatment.MNDO calculations of the energy and optimised geometry of the intermediate ?-complex show a folded structure which allows a degree of sp3 character of the C-10 atom while maintaining sufficient delocalisation of the extended ?-system in the anthracenium ion.The Bell-Eyring-Polyani principle is followed with a linear correlation between the difference in the calculated energy between each reactant and its ?-complex and the experimentally observed change in free energy during attack by Clδ+.
- Bolton, Roger,Hibbert, Brynn D.,Parand, Simin
-
p. 981 - 984
(2007/10/02)
-
- Carbon-13 NMR Spectroscopic Study of Substituted Anthracene Dications
-
A series of substituted anthracenes (2-10 and 20-21) were oxidized by SbF5/SO2ClF at 0 to -30 deg C to their dications (11-19 and 22-23), which were observed by carbon-13 NMR spectroscopy.In the studied anthracene dications substantial positive charge was found to be localized at C9 and C10 positions.Methyl substitution in these dications was found to deshield the α-carbons as compared to their shielding effect in the corresponding monocations.The proportionality factor of (13)C chemical shift to electron density was found to be 174.1-217.0 ppm/e-, clearly proving the dicationic nature of the ions.
- Olah, George A.,Singh, Brij P.
-
p. 4830 - 4835
(2007/10/02)
-
- Adiabatic S1 9,10-Dichloroanthracene Formation from Electronically Excited 9,10-Dichloroanthracene/1,3-Cyclohexadiene Photoadducts
-
The photochemistry and fluorescence of the two major photoadducts of 9,10-dichloroanthracene (DCA) and 1,3-cyclohexadiene (CHD) are described.The 1,2-adduct, 1,2-A (?s + 2?s> to the 1,2-positions of DCA),gives DCA and CHD as main photoproducts in several solvents, φ-1,2-A ca. φDCA ca. φCHD ca. 0.3.It exhibits fluorescence characteristic of the naphthalene moiety (350-435 nm) and, in addition, gives DCA fluorescence (390-560 nm).The pronounced oxygen quenching effect of the latter shows that cleavage of singlet excited 1,2-A, 11,2-A*, is in part adiabatic, φ1DCA* ca. 0.007-0.015.The 9,10-adduct, 9,10-A (?s + 4?s> to the 9,10-position of DCA), is efficiently destroyed by light, φ-9,10-A ca. 1.0, but gives several products in addition to DCA and CHD, φDCA ca. φCHD ca. 0.11.Its fluorescence is identical with DCA fluorescence, corresponding to φ1DCA* ca 0.0041-0.0068, depending on the solvent.The observations are discussed by using the current theoretical model for electrocyclic photochemical reactions.They suggest that if pericyclic minima are involved in adduct photocleavage and formation, they are isolated in the potential energy surface and do not readily interconvert.
- Smothers, William K.,Saltiel, Jack
-
p. 2794 - 2799
(2007/10/02)
-
- Reactions of Phenanthrenes with Nitrogendioxid in UV Light
-
The compounds 2-7 were isolated from solutions of phenanthrene (1) and nitrogendioxide in carbon tetrachloride after irradiation with UV light having long wavelengths (λ > 290 nm).With the help of spectroscopical methods the proposed structures are derived.Radical mechanisms are proposed for these reactions. - Key words: Phenanthrene, Nitrogendioxid, UV Light
- Barlas, H.,Parlar, H.,Kotzias, D.,Korte, F.
-
p. 486 - 489
(2007/10/02)
-
- Polar and Non-polar Cycloadditions of 1,3-Butadiene and Cyclopentadiene to Anthracenes
-
The photoadditions of anthracene (1a) and 9-anthracenecarbonitrile (1b) with 1,3-butadiene (2) lead to very different ratios of - and -adducts.This and, in contrast to the behavior of 1a, the complete suppression of photo-Diels-Alder additions between 1b, c, d and cyclopentadiene (9) at 0 deg C are readily rationalized as an effect of hybridization in terms of the well established and successful diradical mechanism.At higher temperatures the -adducts 11 undergo suprafacial 1,3-shifts into Diels-Alder adducts 12 and -cycloreversions into 1 and 9.At such temperatures, added 1,3-dienes (or 1 and 9 generated in situ) combine with 11 to give well defined polycyclic adducts.Spectroscopic and quenching data are discussed.
- Kaupp, Gerd,Grueter, Heinz-Willi
-
p. 1458 - 1471
(2007/10/02)
-
- N-Chloro- and NN-Dichloro-derivatives of Some Phosphinic Amides: Preparation and Reactions with Anthracene, Anisole, and Triphenylarsine
-
1-Amino-2,2,3,4,4-pentamethylphosphetan 1-oxide (5) and di-t-butylphosphinic amide (9) can be converted into the N-monochloro- and NN-dichloro-derivatives with t-butyl or sodium hypochlorite.The N-monochloroamides partially disprportionate in solution.They can be prepared conveniently by evaporation of the solvent from a solution containing equimolar amounts of the appropriate amide and NN-dichloroamide.The N-monochloro- and NN-dichloro-derivatives of (5) are reduced to the amide by sodium methoxide in methanol; no rearrangement (ring-expansion) is observed.They react with anthracene to give 9-chloro- and 9,10-dichloro-anthracene and with anisole to give chloroanisole (mainly the para-isomer).Triphenylarsine reacts with the NN-dichloroamide to give (after reductive work-up) an arsoranylideneamine, which can also be prepared from the amide (5) and diacetoxytriphenylarsorane.
- Harger, Martin J. P.,Stephen, Michael A.
-
p. 705 - 711
(2007/10/02)
-
- The Dithiole Series. Part 7. Synthesis of Compounds containing Condensed Ring Systems related to 1,6,6aλ4-Trithiapentalene.
-
1,8-Dichloro- and 1,8-dichloro-4,5-dinitro-anthraquinone react with sodium sulphide in boiling aqueous N,N-dimethylformamide to give, respectively, 5H-1,9,9aλ4-trithiapentalenoanthracen-5-one and its 4,6-diamino derivative.Under the same conditions, 1,4,5,8-tetrachloroanthraquinone gives 1,4,4aλ4,5,8,8aλ4-hexathiadipentalenoanthracene, and 2,2',6,6'-tetrachlorobenzophenone gives a low yield of 1,5,9,9aλ4-tetrapentalenoanthracene.
- Davidson, Stephen,Grinter, Trevor J.,Leaver, Derek,Steven, James H.
-
p. 3172 - 3182
(2007/10/02)
-
- BINARY PHASE CHLORINATION OF AROMATIC HYDROCARBONS WITH SOLID COPPER(II) CHLORIDE: REACTION MECHANISM.
-
Anthracene is selectively chlorinated with solid copper(II) chloride to give a quantitative yield of 9-chloroanthracene. The tentative reaction mechanisms so far proposed fail to explain the nonreactivity of some other hydrocarbon homologues, e. g. naphthalene and phenanthrene, toward copper(II) chloride. The present study revealed that the oxidative half-wave potentials (E//1/////2//0//x) of all reactive hydrocarbon homologues were less than 1. 26 V. On the basis of this finding the authors postulate a reaction mechanism involving one electron transfer from hydrocarbon to copper(II) chloride.
- Tanimoto,Kushioka,Kitagawa,Maruyama
-
p. 3586 - 3591
(2007/10/05)
-