- Reproductive toxicity in mink (Mustela vison) chronically exposed to environmentally relevant polychlorinated biphenyl concentrations
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Female mink were exposed to a technical polychlorinated biphenyl (PCB) preparation (Clophen A50 [A50]; 0.1 or 0.3 mg/animal/d), one fraction of A50 containing the non- and mono-ortho-chlorinated congeners (0-1-ortho-chlorobiphenyls [CBs]), another fractio
- Brunstroem,Lund,Bergman,Asplund,Athanassiadis,Athanasiadou,Jensen,Oerberg
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- Mechanism of dehydrochlorination of 2,2-diaryl-1,1,1-trichloroethanes with nitrite and halide anions
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The reactivity of 2,2-diphenyl-1,1,1-trichloroethane toward halide ions in dipolar aprotic solvents has been studied, and the mechanisms of its reactions with nitrite and halide ions have been compared. The results of kinetic and DFT quantum chemical stud
- Kazin,Kuzhin,Sibrikov,Sirik,Guzov,Plakhtinskii
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Read Online
- Kinetic and quantum chemical studies of the mechanism of dehydrochlorination of 2,2-diaryl-1,1,1-trichloroethanes with nitrite ions
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The E2 mechanism has been proposed for the dehydrochlorination of 2,2-diaryl-1,1,1-trichloroethanes with nitrite ion, leading to 2,2-diaryl-1,1-dichloroethenes, on the basis of experimental kinetic study and quantum chemical simulation.
- Kazin,Kuzhin,Sirik,Guzov
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p. 1277 - 1281
(2016/10/26)
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- Photocycloelimination of α,α-dichlorocyclobutanones
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Direct irradiation of a series of α,α-dichlorocyclobutanones in benzene solutions results in photocycloelimination to give 1,1-dichloroalkenes in yields ranging from 30-65%. The α,α-dichlorocyclobutanones were formed in good yields from the [2+2] cycloaddition of the terminal olefins with dichloroketene. This two-step sequence formally represents a "metathesis" of two olefinic functions and provides an easy access to functionalized 1,1-dichloroalkenes. Irradiation of the dichlorocyclobutanones in the solid state led to poor yields of 1,1-dichloroalkenes and polymeric mixtures, however, photoreactions performed in zeolites gave similar yields as those run in benzene solutions.
- Ramnauth, Jailall,Lee-Ruff, Edward
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p. 1245 - 1248
(2007/10/03)
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- Reactions of thioketones with dichlorocarbene
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The reactions of sterically crowded cycloalkanethiones of type 2 with CHCl3/NaOH under phase-transfer catalysis (PTC) with benzyl(triethyl)ammonium chloride (TEBA) as catalyst afforded the corresponding 'gem.-dichlorothiiranes' of type 3 in good yields (cf. Scheme 2 and Table). The desulfurization, which, in some cases, occurred spontaneously, led to (dichloromethylidene)cycloalkanes of type 4. Similar results were obtained using Seyferth's reagent in boiling benzene. In the case of 2,2,6,6-tetramethylcyclohexanethione, reaction under PTC conditions after 3 h yielded only the corresponding dichloromethylidene derivative; on the other hand, workup after 1 h gave (2,2,6,6- tetramethylcyclohexylidene)methanethione (thioketene 9; Scheme 5).
- Mloston, Grzegorz,Romanski, Jaroslaw,Swiatek, Anna,Heimgartner, Heinz
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p. 946 - 956
(2007/10/03)
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- Transformation of ketones into 1-chloro and 1,1-dichloro-1-alkenes by means of a polychloromethane-titanocene(II) system
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The olefination of ketones using the organotitanium species formed from CP2Ti[P(OEt)3]2 and polychloromethane was studied. The reaction of the organotitanium species prepared from carbon tetrachlorlde with ketones produced
- Takeda, Takeshi,Endo, Yumi,Reddy, A. Chandra Sheker,Sasaki, Rika,Fujiwara, Tooru
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p. 2475 - 2486
(2007/10/03)
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- Ramberg-Backlund rearrangement vs. β-Elimination of haloform from trichloro and trifluoromethyl sulfones
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A new and convenient method for the preparation of trichloro and trifluoromethanesulfinates is described. These esters readily undergo rearrangement to the corresponding sulfones at room temperature, in high yields. In contrast to trichloromethyl sulfoxides which undergo base-induced β-elimination of chloroform to sulfines, the corresponding sulfones undergo an unusually facile Ramberg-Backlund rearrangement with formation of dichloromethylene products. Replacement of CCl3 by CF3 results in complete loss of reactivity, even under drastic basic conditions.
- Braverman, Samuel,Zafrani, Yossi
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p. 1901 - 1912
(2007/10/03)
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- Free radical elimination and oxidation of 1, 1, 1-trichloro-2, 2-bis(p-substituted phenyl)ethanes
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The reaction of 1, 1, 1-trichloro-2, 2-bis(p-substituted-phenyl)ethanes with bromine in carbon tetrachloride under nitrogen atmosphere and in the presence of light results in the formation of 1, 1-dichloro-2, 2-bis(p-substituted-phenyl)ethylenes. Whereas an identical reaction conducted under oxygen atmosphere, leads to the formation of benzophenone derivatives.
- Bennur, Shankar C.,Talawar, Mahadev B.,Laddi, Umesh V.,Nome, Faruk
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- x - a highly reactive titanium hydride and an active species in the McMurry reaction
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The complex reacts with catalytically-prepared solid magnesium hydride (MgH2*) or dissolved magnesium hydride (MgH'2) with evolution of hydrogen to give a highly reactive titanium hydride, x (1).The well-known low valent titanium species, obtained by reduction of TiCl3 with LiAlH4, utilized in the McMurry reaction, has been shown to be 1.An X-ray absorption spectroscopy study (EXAFS) of 1 reveals that the Ti absorber is surrounded by O (from THF) and Cl atoms plus two types of Ti neighbors.Possible structural models for 1 compatible with the EXAFS results are proposed.Complex 1 is an active reagent for the coupling reaction of benzophenone to give tetraphenylethene.During the reaction hydrogen is liberated and the inorganic side product has been shown to be titanium(III) oxychloride; thus the McMurry reaction employing 1 as the reagent can be described by . On the basis of these results, a new interpretation of the mechanism for the McMurry reaction is presented.Complex 1 also undergoes a number of carbenoid type reactions, which may proceed via a "titanium carbenoid" intermediate 9a-c. Key words: Titanium; Hydride; Magnesium; EXAFS
- Aleandri, Lorraine E.,Becke, Sigurd,Bogdanovic, Borislav,Jones, Deborah J.,Roziere, Jacques
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- Pseudophase Ion-Exchange Model Applied to Kinetics in Aqueous Micelles under Extreme Conditions: A Simple Modification
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The dehydrochlorination of 1,1-diphenyl-2,2,2-trichloroethane (DTE) with hydroxide ion was studied in the presence of hexadecyltrimethylammonium hydroxide (CTAOH) micelles at 25.0 deg C, under conditions where the pseudophase ion-exchange model (PPIE) normally fails (high sodium hydroxide and salt concentrations).A simple modification of the model, which includes the variable degree of dissociation concept and the contribution of the counterion in the aqueous phase to the interfacial counterion concentration, allows the application of the PPIE model to all ranges of counterion concentrations in the presence and absence of added salts.
- Ferreira, Ligia Catarina Mello,Zucco, Cesar,Zanette, Dino,Nome, Faruk
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p. 9058 - 9061
(2007/10/02)
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- A facile method for the preparation of 1,1-dichloroolefins using benzenesulfonyl chloride as a chlorenium ion source
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Reaction of the lithio anion derived from diethyl methylphosphonate with benzenesulfonyl chloride gives directly the (diethylphosphoryl)dichloromethyllithium. In situ reaction with aldehydes or ketones gives in high yields of 1,1-dichloroolefins in a convenient one-pot procedure.
- Lee,Shin,Oh
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p. 1657 - 1661
(2007/10/02)
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- The Influence of Crown Ethers and Cryptands on the Kinetics and Mechanism of Elimination Reaction of HCl from 1,1,1-Trichloro-2,2-Diphenylethane by iso-PrOK in Isopropanol Solvent
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The influence of crown ethers (15C5 and 18C6) and cryptands (221 and 222) on the rate, deuterium kinetic isotope effect, activation parameters and mechanism of the elimination reaction of 1,1,1-trichloro-2,2-diphenylethane by iso-PrOK in isopropanol solve
- Schroeder, G.
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p. 579 - 585
(2007/10/02)
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- SYNTHESES AND MASS SPECTRAL REARRANGEMENTS OF UNSATURATED BIS-SULPHIDES AND BIS-SULPHONES
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The synthesis of (E)- and (Z)-1,2-bis(p-fluorophenylsulphenyl)stilbenes (2a and 2b) and 1,2-bis(p-fluorophenylsulfonyl)stilbenes (3a and 3b) was carried out and their configurations were consistent with their stereospecific synthesis.The isomeric 1,1-bis(p-fluorophenylsulphenyl)- and 1,1-bis(p-fluorophenylsulphonyl)-2,2-bis(phenyl)ethylenes (8 and 9) were also synthesised and configurations were established by degradative oxidation.Mass spectral rearrangements of all these compounds were examined.Mass spectra of 1,1-bis-sulphide and 1,1-bis-sulphone bears close relationship with those of (E)- and (Z)-isomeric counterparts.Smiles-type rearrangement observed in 1,2-bis-sulphides was absent in 1,2-bis-sulphones.McLafferty-type rearrangement involving hydrogen migration, from aryl group was noticed in both bis-sulphides and bis-sulphones.Vinyl migration to the sulphone oxygen predominates over aryl migration in three isomeric bis-sulphones.
- Peeran, S. G.,Reddy, G. Hanumantha
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- Solvolysis rates in mixed organic solvents: II. Kinetics of dehydrochlorination of 1,1,1-trichloro-2,2-diphenylethane by base in methanol/isopropanol mixed solvents
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The kinetics of dehydrochlorination of 1,1,1-trichloro-2,2-diphenylethane by methoxide and isopropoxide ions in methanol-isopropanol solutions have been studied over the temperature range 30 to 50 deg C.The rate of the reaction is first order with respect
- Mousa, M. A.,Diefallah, E. M.,Shaaban, A. F.,Azab, M. M.
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p. 1177 - 1184
(2007/10/02)
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- Reaction of α,β-Unsaturated Carboxylic Acids with Manganese(III) Acetate in the Presence of Chloride Ion
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The reaction of 3-phenylpropenoic acids with manganese(III) acetate - Cl- complex yielded 1,2,2-trichloro-1-phenylethanes, 1-acetoxy-2,2-dichloro-1-phenylethanes, and 2,2-dichloro-1-phenylethanols. (E)-2,3-Diphenylpropenoic acids gave 2,2-dichloro-1,2-diphenylethanones and 2-acetoxy-1,2-diphenylethanones. 3,3-Diphenylpropenoic acids yielded 2,2-dichloro-1,1-diphenylethenes, 1-acetoxy-2,2-dichloro-1,1-diphenylethanes, 2,2-dichloro-1,1-diphenyl-1-ethanols, and 2-hydroxy-2,2-diphenylethanal.Fluorenylideneacetic acid gave 9-chloro-9-(dichloromethyl)fluorene, 9-acetoxy-9-(dichloromethyl)fluorene, and 9-fluorenone. 1-Cyclohexenecarboxylic acid yielded 1,2-dichlorocyclohexanecarboxylic acid and 1-acetoxy-2-chlorocyclohexanecarboxylic acid.The reaction can be explained in terms of a free-radical mechanism involving manganese(III) acetate - Cl- complexation, addition of Cl. radical, decarboxylation, and the oxidation of chloroethenes which are the reaction intermediates.
- Yonemura, Hiroshi,Nishino, Hiroshi,Kurosawa, Kazu
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p. 3153 - 3160
(2007/10/02)
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