- Donor-Acceptor (Electronic) Coupling in the Precursor Complex to Organic Electron Transfer: Intermolecular and Intramolecular Self-Exchange between Phenothiazine Redox Centers
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Intermolecular electron transfer (ET) between the free phenothiazine donor (PH) and its cation radical (PH.+) proceeds via the [1:1] precursor complex (PH)2.+ which is transiently observed for the first time by its diagnostic (charge-resonance) absorption band in the near-IR region. Similar intervalence (optical) transitions are also observed in mixed-valence cation radicals with the generic representation: P(br)P .+, in which two phenothiazine redox centers are interlinked by p-phenylene, o-xylylene, and o-phenylene (br) bridges. Mulliken-Hush analysis of the intervalence (charge-resonance) bands afford reliable values of the electronic coupling element HIV based on the separation parameters for (P/P.+) centers estimated from some X-ray structures of the intermolecular (PH)2.+ and the intramolecular P(br)P .+ systems. The values of HIV, together with the reorganization energies λ derived from the intervalence transitions, yield activation barriers ΔGET? and first-order rate constants kET for electron-transfer based on the Marcus-Hush (two-state) formalism. Such theoretically based values of the intrinsic barrier and ET rate constants agree with the experimental activation barrier (E a) and the self-exchange rate constant (kSE) independently determined by ESR line broadening measurements. This convergence validates the use of the two-state model to adequately evaluate the critical electronic coupling elements between (P/P.+) redox centers in both (a) intermolecular ET via the precursor complex and (b) intramolecular ET within bridged mixed-valence cation radicals. Important to intermolecular ET mechanism is the intervention of the strongly coupled precursor complex since it leads to electron-transfer rates of self-exchange that are 2 orders of magnitude faster (and activation barrier that is substantially lower) than otherwise predicted solely on the basis of Marcus reorganization energy.
- Sun, Duoli,Rosokha, Sergiy V.,Kochi, Jay K.
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- Synthesis and properties of phenothiazine derivatives. 2. Spectral (ESR and IR) characteristics of the radical-cations of the phenothiazine N-derivatives
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The temperature dependence of the ESR spectra of the radical-cations of the N-derivatives of phenothiazine were studied in the range of 200-393 K (o-xylene). It was established that at temperatures of 323-333 K the nature of the HFS varies from doublet to quartet with approximate intensity ratios of 1:2:2:1, and this transformation is irreversible. A hypothesis explaining the results is proposed. IR spectroscopy was used to confirm the proposed mechanism of localization of the unpaired electron.
- Tomilin,Shchegolikhin,Sanaeva,Klyakin,Ryabkina,Konovalova
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- Transition-Metal-Free and Base-Promoted Carbon-Heteroatom Bond Formation via C-N Cleavage of Benzyl Ammonium Salts
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A facile and general method for constructing carbon-heteroatom (C-P, C-O, C-S, and C-N) bonds via C-N cleavage of benzyl ammonium salts under transition-metal-free conditions was reported. The combination of t-BuOK and 18-crown-6 enabled a wide range of substituted benzyl ammonium salts to couple readily with different kinds of heteroatom nucleophiles, i.e. hydrogen phosphoryl compounds, alcohols, thiols, and amines. Good functional group tolerance was demonstrated. The scale-up reaction and one-pot synthesis were also successfully performed.
- Liu, Long,Tang, Yuanyuan,Wang, Kunyu,Huang, Tianzeng,Chen, Tieqiao
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p. 4159 - 4170
(2021/03/09)
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- Non-directed copper-catalyzed regioselective C-H sulfonylation of phenothiazines
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We develop a simple and general method for sulfonylation of phenothiazines under Cu(i) catalysis. The broad scope of aryl/alkyl sulfonyl chlorides was applicable to produce C3 sulfonylation products of phenothiazines in moderate to good yields. The further transformation of the sulfonylation products was successful, which afforded valuable polyheterocycles.
- Liu, Caiyan,Shen, Yongli,Yuan, Kedong
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supporting information
p. 5009 - 5013
(2019/06/03)
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- Base Catalysis Enables Access to α,α-Difluoroalkylthioethers
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A nucleophilic addition reaction of aryl thiols to readily available β,β-difluorostyrenes provides α,α-difluoroalkylthioethers. The reaction proceeds through an unstable anionic intermediate, prone to eliminate fluoride and generate α-fluorovinylthioethers. However, the use of base catalysis overcomes the facile β-fluoride elimination, generating α,α-difluoroalkylthioethers in excellent yields and selectivities.
- Orsi, Douglas L.,Easley, Brandon J.,Lick, Ashley M.,Altman, Ryan A.
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supporting information
p. 1570 - 1573
(2017/04/13)
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- Pd-Catalyzed double N-arylation of primary amines to synthesize phenoxazines and phenothiazines
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An efficient and versatile Pd-catalyzed tandem C-N bond formation between aryl halides and primary amines is developed. The transformation allows a one-pot synthesis of phenoxazine and phenothiazine derivatives with a broad range of substitution patterns from readily available precursors.
- Zhang, Lu,Huang, Xin,Zhen, Shan,Zhao, Jing,Li, Heng,Yuan, Bingxin,Yang, Guanyu
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p. 6306 - 6309
(2017/08/10)
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- An efficient ultrasound-assisted synthesis of n-alkyl derivatives of carbazole, indole, and phenothiazine
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Heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen such as carbazole, indole, and phenothiazine can be efficiently alkylated in DMSO or N,N-DMF under ultrasonic irradiation in the presence of potassium hydroxide as a base. In almost all cases, a dramatic reduction of the reaction time results and a clear yield increase accompanied by an improved quality of the products occurs.
- Zhao, Sanhu,Kang, Jin,Du, Yuting,Kang, Jingyan,Zhao, Xiaoni,Xu, Yinfeng,Chen, Ruixi,Wang, Qianqian,Shi, Xitao
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supporting information
p. 683 - 689
(2014/06/10)
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- POLYMERIZATION INHIBITOR COMPOSITION AND METHOD OF INHIBITING POLYMERIZATION OF DISTILLABLE MONOMERS
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The present invention relates to a polymerization inhibitor composition and a method of inhibiting polymerization of distillable monomers in liquid and evaporated/condensed phases with the polymerization inhibitor composition. The polymerization inhibitor composition is useful for inhibiting polymerization of the distillable monomers during manufacture, purification (e.g., distillation), handling, and storage thereof.
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Page/Page column 10
(2011/12/13)
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- The role of phase transfer catalysis in the microwave-assisted N-benzylation of amides, imides and N-heterocycles
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The effect of triethylbenzylammonium chloride (TEBAC) was studied on the outcome of the microwaveassisted solid-liquid phase N-alkylation of amides, imides and N-heterocycles using benzyl halides and K2CO3. It was found that while the benzylation of amides may be somewhat promoted by the presence of TEBAC, succinimide and benzimidazole are so reactive that there is no need to use the catalyst. At the same time, the outcome of the benzylation of phenothiazine may be significantly influenced by the presence or absence of TEBAC in respect of N-versus C-alkylation.
- Greiner, Istvan,Sypaseuth, Fanni Daruny,Gruen, Alajos,Karsai, Eva,Keglevich, Gyoergy
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experimental part
p. 529 - 534
(2010/04/23)
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- Palladium-catalyzed three-component approach to promazine with formation of one carbon-sulfur and two carbon-nitrogen bonds
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(Chemical Presented) Zip it up! The use of a Pd/dppf catalyst gives access to the tricyclic phenothiazine scaffold starting from 1-bromo-2-iodobenzenes, aliphatic or aromatic amines, and 2-bromothiophenols in a single reaction flask (see scheme; dppf=1,1′-bis(diphenylphosphanyl) ferrocene; dba=dibenzylidineacetone). This transformation involves thioether formation and subsequent intermolecular and intramolecular aryl amination reactions. The reaction occurs in good overall yield and selectivity.
- Dahl, Troels,Tornoe, Christian W.,Bang-Andersen, Benny,Nielsen, Poul,Jorgensen, Morten
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supporting information; scheme or table
p. 1726 - 1728
(2009/02/06)
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- Negative kinetic temperature effect on the hydride transfer from NADH analogue BNAH to the radical cation of N-benzylphenothiazine in acetonitrile
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The reaction rates of 1-(p-substituted benzyl)-1,4-dihydronicotinamide (G-BNAH) with N-benzylphenothiazine radical cation (PTZ?+) in acetonitrile were determined. The results show that the reaction rates (k obs) decreased from 2.80 × 107 to 2.16 × 107 M-1 s-1 for G = H as the reaction temperature increased from 298 to 318 K. The activation enthalpies of the reactions were estimated according to Eyring equation to give negative values (-3.4 to -2.9 kcal/mol). Investigation of the reaction intermediate shows that the charge-transfer complex (CT-complex) between G-BNAH and PTZ ?+ was formed in front of the hydride transfer from G-BNAH to PTZ?+. The formation enthalpy of the CT-complex was estimated by using the Benesi-Hildebrand equation to give the values from -6.4 to -6.0 kcal/mol when the substituent G in G-BNAH changes from CH3O to Br. Detailed thermodynamic analyses on each elementary step in the possible reaction pathways suggest that the hydride transfer from G-BNAH to PTZ?+ occurs by a concerted hydride transfer via a CT-complex. The effective charge distribution on the pyridine ring in G-BNAH at the various stages-the reactant G-BNAH, the charge-transfer complex, the transition-state, and the product G-BNA+-was estimated by using the method of Hammett-type linear free energy analysis, and the results show that the pyridine ring carries relative effective positive charges of 0.35 in the CT-complex and 0.45 in the transition state, respectively, which indicates that the concerted hydride transfer from G-BNAH to PTZ?+ was practically performed by the initial charge (-0.35) transfer from G-BNAH to PTZ?+ and then followed by the transfer of hydrogen atom with partial negative charge (-0.65). It is evident that the present work would be helpful in understanding the nature of the negative temperature effect, especially on the reaction of NADH coenzyme with the drug phenothiazine in vivo.
- Zhu, Xiao-Qing,Zhang, Jian-Yu,Cheng, Jin-Pei
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p. 7007 - 7015
(2007/10/03)
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- Organophotoreceptor with charge transport material having a hydrazone group linked to an epoxy group and a heterocyclic ring
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Improved organophotoreceptor comprises an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (a) a charge transport material having the formula where R1 and R2 are, independently, H, an alkyl group, an alkaryl group, or an aryl group; X is a linking group having the formula —(CH2)m—, branched or linear, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, C═O, O═S═O, a heterocyclic group, an aromatic group, urethane, urea, an ester group, a NR3 group, a CHR4 group, or a CR5R6 group where R3, R4, R5, and R6 are, independently, H, hydroxyl group, thiol group, an alkyl group, an alkaryl group, a heterocyclic group, or an aryl group; E is an epoxy group; and Z is a phenothiazine group, a phenoxazine group, a phenoxathiin group, a dibenzo(1,4)dioxin group, a thianthrene group, or a phenazine group; and (b) a charge generating compound. Corresponding electrophotographic apparatuses and imaging methods are described.
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- Interaction of N-substituted phenothiazines with halogen-containing solvents
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ESR spectroscopy was used to study the interaction of several N-substituted phenothiazines with halogen-containing solvents (CCl4, CHCl3, CH2Br2). The dissolution of phenothiazines in these solvents was found to be associated with an ESR signal indicating the presence of an oxidation-reduction reaction in which the halogen-containing compounds act as acceptors, and the phenothiazines act as electron donors. The HFS of the ESR spectra of the cation radicals obtained was studied. 1996 Plenum Publishing Corporation.
- Tomilin,Konovalova,Yuzhalkin,Klyakin,Sanaeva
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p. 246 - 248
(2007/10/03)
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- Cation radicals of N-substituted phenothiazines
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The reaction of N-substituted phenothiazines with certain acceptors (halogenated solvents CHCl3, CH2Br2, CCl4, o-chloranil, AlCl3, SnCl4, concentrated H2SO4, concentrated HNO3 in HClO4) has been studied by EPR spectroscopy. The hyperfine structure in the EPR spectra of the cation radicals is analyzed. To interpret the EPR spectra obtained in terms of the MNDO-PM3 method we carried out a calculation of the electronic structure of phenothiazine cation radicals containing N-CH3 and N-CH2R substituents. In these radical systems, there are significant steric hindrances to conformational rotation of the CH2 substituent around the N-C bond leading to a conformation with magnetically non-equivalent protons in the methylene group. 1996 Plenum Publishing Corporation.
- Tomilin,Konovalova,Yuzhalkin,Ryabkina,Sanaeva
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p. 365 - 370
(2007/10/03)
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- THE EFFECT OF THE STRUCTURE OF THE SUBSTITUENT IN POSITION TEN ON THE VOLTAMMETRIC BEHAVIOUR OF PHENOTHIAZINE DERIVATIVES
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The electrochemical oxidation of seven derivatives of phenothiazine substituted in position 10 on the phenothiazine skeleton has been studied in acetonitrile, using a platinum disc electrode.The electron donor properties of the derivatives that depend on the substituent structure and the presence of nucleophiles in acetonitrile were followed.The diffusion coefficients for the formation of the radical cations were from 10-5 to 10-6 cm2 s-1 and depended on the concentration of the acid in acetonitrile medium.A determination of these substances has beenproposed, using differential pulse voltammetry, with a detection limit of 1*10-7 mol l-1.
- Zimova, Nad'a,Nemec, Ivan,Ehlova, Miroslava,Waisser, Karel
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- SN2 Reactions of Nitranions with Benzyl Chlorides
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The rates of SN2 reactions of 19 nitranions with PhCH2Cl and 9 nitranions with m-CF3C6H4CH2Cl were measured in Me2SO at 25 deg C.Bronsted plots of log k vs. pKHA for reactions of anion families derived from carbazoles, phenothiazines, and diphenylamines with PhCH2Cl are linear with slopes of 0.32-0.33.Extension of the carbazole and phenothiazine family lines, which are collinear, provided a reference line by which nucleophilicities of other nitranions could be assessed at constant basicity.Nitranions of varied structural types were found to have remarkably similar nucleophilicities when compared at the same basicities.Steric effects caused rates of reactions of ArAr'N(1-) ions and acetanilide ion to be retarded slightly and that of benzanilide ion to be retarded appreciably.Evidence is presented to show that nitranions, like carbanions, utilize the electron pair in a p orbital for bonding to an electrophile whereas pyridines utilize a nonbonded electron pair.Comparisons with literature data for neutral nitrigen nucleophiles, such as n-BuNH2 and PhNH2, indicate that they are 10-100 times more reactive than nitranion nucleophiles of comparable basicity.The order of nucleophilicities toward PhCH2Cl of anion families with different donor atoms when compared at the same basicity was found to be the following: 9-methylfluoredine ion family (25) > 2-naphthoxide ion family (3) > carbazole ion family (1.0).The results show that basicity is the primary factor in controlling nucleophilicities of nitranions, carbanions, and oxanions of diverse structural types in SN2 reactions.Donor atom, solvation, and steric effects generally play a secondary role.
- Bordwell, Frederick G.,Hughes, David L.
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p. 3234 - 3240
(2007/10/02)
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