- Bis(dioxolene)(bipyridine)ruthenium Redox Series
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Complexes of the general formula n+ have been prepared where (bpy) is 2,2'-bipyridine and n = -1, 0, +1.The dioxolene ligand is 1,2-dihydroxybenzene (cathechol), 3,5-di-tert-butyl- or 3,4,5,6-tetrachloro-1,2-dihydroxybenzene which may formally exist in the catecholate, semiquinone, or quinone oxidation state.Redox series of up to five members have been prepared by controlled potential electrolysis of the parent species or, in some cases, by chemical oxidation or reduction.Electrochemistry, magnetism, X-ray structural data and ultraviolet, visible and near infrared electronic, resonance Raman, vibrational (FTIR), nuclear magnetic resonance, electron spin resonance and photoelectron spectra, for various members of the redox series, are discussed in terms of theelectronic structures (effective oxidation states, delocalization) of the complexes.Apparent conflicts between results obtained with different techniques are resolved by using a simple, quantitative MO model.
- Lever, A. B. P.,Auburn, Pamela R.,Dodsworth, Elaine S.,Haga, Masa-aki,Liu, Wei,et al.
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- First example of direct transformation of alkylbenzenes to 1,3-benzodioxoles by oxidation with o-chloranil
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The reaction of alkyl-substituted benzenes with o-chloranil at an elevated temperature was found to give 4,5,6,7-tetrachloro-1,3-benzodioxoles via benzylic oxidation and subsequent acetal formation, albeit in poor yields.
- Rahman, Sheikh Maksudur,Kobayashi, Tomoshige
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- Bis(perchlorocatecholato)silane—A Neutral Silicon Lewis Super Acid
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No neutral silicon Lewis super acids are known to date. We report on the synthesis of bis(perchlorocatecholato)silane and verify its Lewis super acidity by computation (DLPNO-CCSD(T)) and experiment (fluoride abstraction from SbF6?). The exceptional affinity towards donors is further demonstrated by, for example, the characterization of an unprecedented SiO4F2 dianion and applied in the first hydrodefluorination reaction catalyzed by a neutral silicon Lewis acid. Given the strength and convenient access to this new Lewis acid, versatile applications might be foreseen.
- Maskey, Rezisha,Sch?dler, Marcel,Legler, Claudia,Greb, Lutz
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Read Online
- Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
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A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
- Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
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p. 4327 - 4337
(2021/05/31)
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- Structure-reactivity studies on hypervalent square-pyramidal dithieno[3,2-b:2′,3′-d]phospholes
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A series of neutral pentacoordinate dithieno[3,2-b:2′,3′-d]phosphole compounds were synthesized by [4 + 1] cycloaddition witho-quinones. Counter to the expected trigonal bipyramidal geometry, the luminescent hypervalent dithienophospholes exhibit square p
- Asok, Nayanthara,Gaffen, Joshua R.,Pradhan, Ekadashi,Zeng, Tao,Baumgartner, Thomas
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p. 2243 - 2252
(2021/02/26)
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- 1-Methyl-1,4-cyclohexadiene as a Traceless Reducing Agent for the Synthesis of Catechols and Hydroquinones
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Pro-aromatic and volatile 1-methyl-1,4-cyclohexadiene (MeCHD) was used for the first time as a valid H-atom source in an innovative method to reduce ortho or para quinones to obtain the corresponding catechols and hydroquinones in good to excellent yields. Notably, the excess of MeCHD and the toluene formed as the oxidation product can be easily removed by evaporation. In some cases, trifluoroacetic acid as a catalyst was added to obtain the desired products. The reaction proceeds in air and under mild conditions, without metal catalysts and sulfur derivatives, resulting in an excellent and competitive method to reduce quinones. The mechanism is attributed to a radical reaction triggered by a hydrogen atom transfer from MeCHD to quinones, or, in the presence of trifluoroacetic acid, to a hydride transfer process.
- Baschieri, Andrea,Amorati, Riccardo,Valgimigli, Luca,Sambri, Letizia
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p. 13655 - 13664
(2019/10/28)
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- Effect of oxalate and pH on photodegradation of pentachlorophenol in heterogeneous irradiated maghemite System
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Photochemical degradation in the system of iron oxides and oxalic acid (OX) is the important reaction for detoxification of organic pollutants in natural environments, including surface soils, surface water, and even aerosols, and it was more effective at low pH according to previous studies. However, in this study, the photodegradation of pentachlorophenol (PCP) proceeded rapidly at different pH conditions in the system with maghemite and OX under UV light illumination. It was observed that the removal of PCP was 77.7% ± 0.90%, 79.9% ± 0.80% and 74.3% ± 1.50% at initial pH of 3.5, 5.0 and 7.0, respectively. To explore the degradation mechanism, the interaction of OX and maghemite were systematically studied as a function of pH. The presence of OX of 1.2 mM effectively decreased the iso-electric point (iep) of the maghemite from 5.6 to 1.8. The maximum adsorption amount of maghemite adsorbing OX increased with increasing pH value from 208 mmol kg-1 at pH = 3.5 to 293 mmol kg-1 at pH = 9.0. However, PCP (0.0375 mM) inhibited the adsorption of oxalic acid at pH = 3.5 and pH = 5.0 but promoted it at pH = 7.0 and pH = 9.0. When the initial content of OX was 1.2 mM, the highly active compounds of Fe(C2O4)33- as Fe(III) and Fe(C2O4)22- as Fe(II) were the dominant species at different pH. The formation of H2O2 also relied on the value of pH and the concentration range of H2O2 during PCP degradation was 0-1.67 mg L-1, 0-1.16 mg L-1 and 0-0.16 mg L-1at initial pH of 3.5, 5.0 and 7.0, respectively. The low pH conditions favored the iron cycling, the H2O2 generation and the broken of aromatic ring of PCP, so as to enhance the degradation rates of PCP. At the high pH conditions, due to the slowdown of the iron cycling and the decreased amount of H2O2 formation, the direct photolysis was responsible for the enhanced degradation of PCP. The foundation of high photochemical efficiencies of OX and maghemite for PCP degradation at large-scale pH conditions improves the photochemical mechanisms of OX-iron oxide system and is of important for understanding the transformation of organic pollutants in light environments.
- Lan, Qing,Cao, Meiyuan,Ye, Zhijun,Zhu, Jishu,Chen, Manjia,Chen, Xuequan,Liu, Chengshuai
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p. 198 - 206
(2016/07/06)
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- On the redox reaction of 1,2-bis(diphenylphosphino) alkanes toward o -, and p-quinones
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The reaction of 1,2-bis(diphenylphosphino)ethane with substituted o-benzo-quinones afforded new bis(6-hydroxycyclohexa-2,4-dienone) derivatives. Treatment of the same reagent with o-naphthoquinone, phenanthrenequinone, and acenaphthenequinone gave the res
- Boulos, Leila S.,Ewies, Ewies F.,Fahmy, Amin F. M.
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p. 726 - 738
(2013/07/26)
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- Pinacol boronates by direct arene borylation with borenium cations
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Borenium does it direct: A boron analogue of the Friedel-Crafts reaction uses inexpensive catecholatoborenium cations that are sufficiently electrophilic to borylate arenes by electrophilic aromatic substitution. The direct arene borylation proceeds with high regioselectivity for a range of anilines, N-heterocycles, and thiophenes. Subsequent one-pot transesterification provides the synthetically useful pinacol boronate esters (see scheme).
- Del Grosso, Alessandro,Singleton, Paul J.,Muryn, Christopher A.,Ingleson, Michael J.
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supporting information; experimental part
p. 2102 - 2106
(2011/04/22)
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- Photocatalytic removal of pentachlorophenol by means of an enzyme-like molecular imprinted photocatalyst and inhibition of the generation of highly toxic intermediates
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Pentachlorophenol (PCP) is a typical highly-toxic pollutant, and its direct photolysis and conventional photocatalysis may produce more toxic by-products such as dibenzodioxins. It is urgently needed to develop a photocatalytic process able to remove PCP without the generation of highly toxic by-products. To achieve this, enzyme-like molecular-imprinted photocatalysts were prepared by using structural analogues of PCP as pseudo templates. It was found that 2,4-dinitrophenol (DNP) was the best template among the tested analogues. The molecular imprinted polymer (MIP) coated P25 TiO2 photocatalyst DNP-P25 prepared with DNP as the template greatly accelerated the photocatalytic degradation of PCP and depressed the generation of toxic intermediates. It was confirmed that the amino groups at the footprint cavities provided a well-defined micro reaction environment, which made the benzene ring of the adsorbed PCP be better exposed to photo-generated reactive OH radicals, leading to easier cleavage of the benzene ring. Both the intermediate analysis and toxicity evaluation confirmed that the MIP-coated TiO2 can make the photocatalytic degradation a safe and green approach of removing PCP.
- Shen, Xiantao,Zhu, Lihua,Liu, Guoxia,Tang, Heqing,Liu, Shushen,Li, Weiying
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experimental part
p. 2278 - 2285
(2011/04/23)
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- Chlorinations of derivatives of 2,2,2-trichlorobenzo-1,3,2-dioxaphospholes
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By 31P, 13C, 13C-{1H}, and 1H NMR spectroscopy the chlorination of 4-and 5-methyl-2,2,2- trichlorobenzo-1,3,2-dioxaphosphols was shown to provide in quantitative yield 4-methyl-2,2,2,5-tetrachloroand
- Varaksina,Mironov,Shtyrlina,Dobrynin,Cherkin,Gubaidullin,Litvinov,Konovalov
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experimental part
p. 988 - 999
(2009/06/18)
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- Kinetics of photodegradation and ozonation of pentachlorophenol
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The oxidation of 2,3,4,5,6-pentachlorophenol (PCP) has been carried out by a photodecomposition process using a polychromatic UV irradiation, and by an ozonation process. In the photodegradation process, the pH accelerated the decomposition rate and the approximate first-order rate constants were evaluated, with values between 0.16 ± 0.005 min-1 at pH = 3 and 0.26 ± 0.007 min-1 at pH = 9. A more rigorous kinetic study led to the determination of the quantum yields of the reaction, with values of 200 ± 7 x 10-3 mol/Eins for pH = 3 and 22 ± 1.1 x 10-3 mol/Eins for pH = 9. In the ozonation process, the rate constants for the reaction between ozone and PCP were determined by means of a competition kinetics, with values in the range from 0.67 x 105 to 314 x 105 l/mol s. The specific rate constants for the un-dissociated and dissociated forms of PCP were also calculated. Finally, in both processes, the intermediate reaction products were identified, the most important being tetrachlorocatechol, tetrachlorohydroquinone and tetra-p-chlorobenzoquinone. Free chloride ion released, which was favored at high pHs, was also followed in both processes.
- Benitez, F. Javier,Acero, Juan L.,Real, Francisco J.,Garcia, Juan
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p. 651 - 662
(2007/10/03)
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- Toxicity changes during the UV treatment of pentachlorophenol in dilute aqueous solution
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Pentachlorophenol (PCP) was photolysed using a 1 kW photochemical reactor. The degradation of PCP (0.15 mM) was carried out using both direct UV photolysis and photolysis in the presence of H2O2 (3.0, 6.7, 18.0 and 37.2 mM). The decay of PCP and the formation of photoproducts were followed by high performance liquid chromatography, ion chromatography and UV absorbance detection. The first-order rate constants k1 for the decay of PCP were estimated under various conditions: for direct UV photolysis, k1 = 0.115 min-1; for photolysis in the presence of various concentrations of H2O2, the rate constant increased to a plateau (k1 ? 0.7 min-1) at H2O2 concentrations greater than 6 mM. The correlation between photodegradation and toxicity was studied using a bacterial toxicity test and a 96 h Fathead Minnow toxicity test. In both cases, the toxicity decreased as the concentration of PCP or the total organic chlorine concentration fell. These results indicate that the UV treatment of PCP either does not generate significant levels of acutely toxic intermediates, or any toxic intermediates are rapidly degraded under the specific conditions used in these studies. Pentachlorophenol (PCP) was photolysed using a 1 kW photochemical reactor. The degradation of PCP (0.15 mM) was carried out using both direct UV photolysis and photolysis in the presence of H2O2 (3.0, 6.7, 18.0 and 37.2 mM). The decay of PCP and the formation of photoproducts were followed by high performance liquid chromatography, ion chromatography and UV absorbance detection. The first-order rate constants k1 for the decay of PCP were estimated under various conditions: for direct UV photolysis, k1 = 0.115 min-1; for photolysis in the presence of various concentrations of H2O2, the rate constant increased to a plateau (k1≈0.7 min-1) at H2O2 concentrations greater than 6 mM. The correlation between photodegradation and toxicity was studied using a bacterial toxicity test and a 96 h Fathead Minnow toxicity test. In both cases, the toxicity decreased as the concentration of PCP or the total organic chlorine concentration fell. These results indicate that the UV treatment of PCP either does not generate significant levels of acutely toxic intermediates, or any toxic intermediates are rapidly degraded under the specific conditions used in these studies.
- Ho, Te-Fu L.,Bolton, James R.
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p. 489 - 497
(2007/10/03)
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- New 2-pyrazolines of anticipated molluscicidal activity
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A facile one-pot synthesis of 1-substituted carbamoyl- or thiocarbamoyl-2-pyrazolines 6 is described. The synthesis as well as molluscicidal activity of 1,3,5-triaryl- and 1-acetyl-3,5-diaryl-2-pyrazolines (2 and 4) are also outlined.
- Mishriky, Nawal,Asaad, Fahmy M.,Ibrahim, Yehia A.,Girgis, Adel S.
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p. 935 - 940
(2007/10/03)
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- New 2-pyrazolines of anticipated molluscicidal activity
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A facile one-pot synthesis of 1-substituted carbamoyl or thiocarbamoyl-2-pyrazolines 6 is described. Also, the synthesis as well as the molluscicidal activity of 1,3,5-triaryl- (2), 1-acetyl-3,5-diaryl- (4) 2-pyrazolines are outlined.
- Mishriky,Asaad,Ibrahim,Girgis
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p. 544 - 548
(2007/10/03)
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- N-Arylisoindolines: Charge-transfer Complexation and Novel Synthesis of 2'-Arylspiro-3'-ones
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N-Arylisoindolines 1a-d and tetrachloro-1,2-benzoquinone 2 interact to give the title products 14.
- Hassan, Alaa A.
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p. 498 - 499
(2007/10/03)
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- Reactions of Ethoxycarbonylmethylene(triphenyl)phosphorane with some ortho-Quinones in the Presence of Triphenylphosphine, Alcohols and Acetic Anhydride
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The reactions of ortho-quinones 1a, 1c and 1d with ylide 2 in the presence of triphenylphosphine afforded the ylides 11a, 11c and 11d and compound 12.The reactions of 1a and 1c with 2 in refluxing methanol or ethanol gave compounds 16 and 17 respectively, while the reactions of 1a-d with 2 in acetic anhydride yielded the acetates 18a, 18b, 18d and 19b, 19d, the furan derivative 24 and the ylide 25.Compounds 8 and 9 were also obtained in most of the above reactions.Wittig reactions of the ylides 11a, 11c with p-nitrobenzaldehyde and of ylide 2 with coumarins 8a and 29 resulted in compounds 14a, 14c, 26 and 30 respectively.The transformations of compounds 18, 19 into 8, 9 as well as of compound 26 into 28 were also studied.
- Nicolaides, Demetrios N.,Adamopoulos, Spyros G.,Lefkaditis, Demetrios A.,Litinas, Konstantinos E.,Tarantili, Petroula V.
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p. 283 - 290
(2007/10/02)
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- Reactions of lignin model compounds with pulp bleaching chemicals. Cannizzaro-type reaction of tetrachloro-o-benzoquinone with alkali
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Reaction of tetrachloro-o-benzoquinone 1 with aqueous sodium hydroxide resulted in a Cannizzaro-type disproportionation into tetrachloromuconic acid and tetrachlorocatechol.The tetrachloromuconic acid was isolated and identified by X-ray crystallography as the methyl ester of the cyclized lactone 3.Crystals of C7H3Cl3O4, 4, are orthorombic, a = 9.991(2), b = 7.981(1), c = 24.626(2) Angstroem, Z = 8, space group Pna21.The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.033 for 1609 reflections with I >= 3?(I).
- McKague, A. Bruce,Reeve, Douglas W.,Rettig, Steven J.,Trotter, James
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p. 1706 - 1710
(2007/10/02)
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- Reactions of 4-Chloro-9H-xanthene-9-thione with Tetrachloro-o-benzoquinone
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Thiones are usually converted to the corresponding ketones by oxidizing agents.Also high potential halogenated o-quinones oxidize thiones to the corresponding ketones.When 9H-thioxanthene-9-thione was subjected to the action of tetrachloro-o-benzoquinone the in presence of oxygen, it was oxidized to 9H-thioxanthen-9-one.Meanwhile tetrachloro- and tetrabromo-o-benzoquinones were found to react with diazoalkanes giving the corresponding cyclic acetals.
- Zeid, Ibrahim,El-Sakka, Ibrahim,Yassin, Salah,Abass, Atif
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p. 196 - 198
(2007/10/02)
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- THE REACTION OF TETRACHLORO-o-BENZOQUINONE WITH THE SULFIDES OF TRIPHENYLARSINE AND TRIPHENYLSTIBINE
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The reaction of tetrachloro-o-benzoquinone (1) with triphenylarsine sulfide gives a hydrogen-bonded complex of the corresponding hydroquinone and triphenylarsine oxide (5).The same quinone reacts with triphenylstibine sulfide yielding the cyclic adduct (9).In both cases, elemental sulfur is the other product.Possible reaction mechanisms are considered and the structural assignments are based on analytical, chemical and spectroscopic results.
- Sidky, M. M.,Mahran, M. R.,Abdou, W. M.
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p. 129 - 136
(2007/10/02)
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- Reaction of spiro with hydroxylamine and active methylene compounds
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The reactivity of the title spiranes (1) towards cleavage by different nucleophiles in ethanolic solutions has been investigated.The spiranes are cleaved by ethyl p-aminobenzoate to give 2-aryl-3-(4-methoxycarbonylphenyl)-3H-quinazoline-4-thiones (2b-d) t
- Latif, N.,Zeid, I. F.,Mishriky, N.,Assad, F. M.
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- Mesoionic Six-membered Heterocycles, III. - Reactions of o-Quinonoid Compounds with 6-Oxo-6H-1,3-diazin-1-ium-4-olates
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Mesoionic 6-oxo-6H-1,3-diazin-1-ium-4-olates 9 react with tetrachloro-o-benzoquinone (2, R=Cl) to give 1 : 1 adducts 12 which can formally be derived from ketene tautomers 13 of 9.The structure of 12f has been clarified by X-ray crystallography.
- Friedrichsen, Willy,Schmidt, Regine,Hummel, Gerrit J. van,Ham, Dirk M. W. van den
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p. 521 - 531
(2007/10/02)
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- Carbonyl and Thiocarbonyl Compounds: Part XV-Synthesis of Spiro and Quinazolinone Anils
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Tetrachloro-o-benzoquinone reacts with 2,3-diarylquinazoline-4(3H)-thiones (4a-c) to give spiro (5).The latter are cleaved with mineral acids to give 2,3-diarylquinazolin-4(3H)-ones (4d-f).Reaction of 5 with anilines affords the hitherto unknown quinazolinoneanils (6) together with tetrachlorocatechol.Reaction mechanisms are discussed.
- Latif, N.,Mishriky, N.,Assad, Fahmy M.
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p. 118 - 120
(2007/10/02)
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- Reactions of Mesoionic Five-Membered Heterocycles with o-Quinonoid Compounds, IV. Mono- and Tricyclic 1,3-Thiazolium-4-olates, 1,3-Dithiolylium-4-olates
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Monocyclic 1,3-thiazolium-4-olates (10) react with o-quinonoid compounds to give cycloadducts (12,13); tricyclic 1,3-thiazolium-4-olates (14,15) yield compounds (17,18,19,20) which can formally be derived from a ketene tautomer (C). 1,3-Dithiolylium-4-olates are borderline cases; both (32) and adducts (34) were obtained. - Keywords: o-Quinones, Heterocycles
- Friedrichsen, Willy,Schroeer, Wolf-D.,Schwarz, Ingo,Boettcher, Andreas
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p. 609 - 621
(2007/10/02)
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- Newer Carbamates from Vanillin and Their Molluscicidal, Larvicidal and Antimicrobial Activities
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Vanillin, vanillal-p-methylacetophenone (1a), N-vanillalaniline (2c) and vanillalnitromethane (2e) react with isocyanates to give the corresponding phenyl carbamates of pesticidal importance.O-Acetylvanillal-p-methylacetophenone (1b) reacts with tetrahalo
- Latif, N.,Mishriky, N.,Girgis, N. S.,Arnos, S.
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p. 301 - 304
(2007/10/02)
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