- Electron self-exchange kinetics between 2,3-dicyano-5,6-dichloro-p-benzoquinone (DDQ) and its radical anion. Part 1. Solvent dynamical effects
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Rate constants of the electron self-exchange between 2,3-dicyano-5,6-dichloro-p-benzoquinone (DDQ) and its radical anion (DDQ.-) are measured by means of EPR-line-broadening effects in different solvents at T = 293 K. Solvents of different polarity like CHCl3, CH2Cl2, CH3CN, benzonitrile and acetone were used. No correlation is found in the sense of the classical Marcus theory, where In ket should depend linearly on the solvent parameter γ = 1/n2-1/εs (n = refractive index, εs = static relative permittivity of the solvent). The investigated γ-range was 0.270 ≤ γ ≤ 0.530. The diffusion corrected rate constants ket cover a range of 8.9 to 36.7 × 108 M-1 s-1 and clearly show a solvent-dynamical effect, expressed by the longitudinal relaxation time τL dependence of the solvents used. The observed dynamical friction solvent effects clearly indicate an adiabatic reaction behaviour of this electron self-exchange reaction.
- Grampp, Guenter,Landgraf, Stephan,Rasmussen, Kjeld
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- Electronic, infrared, mass spectrometry and thermal studies on the reaction of 2-amino-6-methylpyridine with π-acceptors
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The spectrophotometric characteristics of the solid charge-transfer molecular complexes (CT) formed in the reaction of the electron donor 2-amino-6-methylpyridine (2A6MPy) with the π-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-1,4-benzoq
- Madrahimov, Sherzod,Mostafa, Adel,Yempally, Veeranna,Fadlallah, Joelle,AlQaradawi, Siham Y.
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- Synthetic method for gestrinone drug intermediate dichlorodicyanobenzoquinone
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The invention discloses a synthetic method for the gestrinone drug intermediate dichlorodicyanobenzoquinone. The synthetic method comprises the following steps: adding dicyanodiamine p-dianisole and asodium chloride solution into a reaction vessel, increasing the temperature of the obtained solution, controlling the speed of stirring, and carrying out a reaction; and adding ethyl 3-chloropropionate in batches, raising the temperature, then adding nickel tetracarbonyl powder, carrying out a reaction, carrying out washing with a sodium nitrate solution a plurality of times, then carrying out extraction with a xylene solution a plurality of times, combining extracts, carrying out washing with a propylamine solution, then carrying out recrystallization in a 2-methyl-1-butanol solution, and carrying out dehydration with a dehydrating agent so as to obtain the finished dichlorodicyanobenzoquinone.
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Paragraph 0013; 0016-0027
(2018/07/30)
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- Spectroscopic and thermal investigations on the charge transfer interaction between risperidone as a schizophrenia drug with some traditional π-acceptors: Part 2
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The focus of present investigation was to assess the utility of non-expensive techniques in the evaluation of risperidone (Ris) in solid and solution states with different traditional π-acceptors and subsequent incorporation of the analytical determination into pharmaceutical formulation for a faster release of risperidone. Charge-transfer complexes (CTC) of risperidone with picric acid (PA), 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ), tetracyanoquinodimethane (TCNQ), tetracyano ethylene (TCNE), tetrabromo-p-quinon (BL) and tetrachloro-p-quinon (CL) have been studied spectrophotometrically in absolute methanol at room temperature. The stoichiometries of the complexes were found to be 1:1 ratio by the photometric molar ratio between risperidone and the π-acceptors. The equilibrium constants, molar extinction coefficient (εCT) and spectroscopic-physical parameters (standard free energy (ΔGo), oscillator strength (f), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID)) of the complexes were determined upon the modified Benesi-Hildebrand equation. Risperidone in pure form was applied in this study. The results indicate that the formation constants for the complexes depend on the nature of electron acceptors and donor, and also the spectral studies of the complexes were determined by (infrared, Raman, and 1H NMR) spectra and X-ray powder diffraction (XRD). The most stable mono-protonated form of Ris is characterized by the formation of +NH (pyrimidine ring) intramolecular hydrogen bonded. In the high-wavenumber spectral region ～3400 cm-1, the bands of the +NH stretching vibrations and of the pyrimidine nitrogen atom could be potentially useful to discriminate the investigated forms of Ris. The infrared spectra of both Ris complexes are confirming the participation of +NH pyrimidine ring in the donor-acceptor interaction.
- El-Habeeb, Abeer A.,Al-Saif, Foziah A.,Refat, Moamen S.
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p. 464 - 477
(2013/04/23)
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- Photoinduced electron transfer between acenaphthylene and 1,4-benzoquinones. Formation of dimers of acenaphthylene and 1 : 1-adducts and effect of excitation mode on reactivity of the charge-transfer complexes
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Photochemical reactions of acenaphthylene (ACN) with 1,4-benzoquinones (BQs) of varying reduction potentials in solution have been investigated in order to determine final products and quantum yields of the reactions and to get an insight into the factors
- Haga, Naoki,Takayanagi, Hiroaki,Tokumaru, Katsumi
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p. 734 - 745
(2007/10/03)
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- Anion radical formation in the reaction of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with tribenzylamine in acetonitrile
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Kinetics of the reaction of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with tribenzylamine in acetonitrile has been measured spectrophotometrically. The product of this reaction is a stable anion radical of DDQ. The reaction is relatively slow, due to a considerable steric hindrance in both quinone and amine molecule. Activation parameters indicate a charge separation in the transition state. The mechanism of the reaction has been proposed.
- Dworniczak,Jarczewski
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p. 1739 - 1743
(2007/10/03)
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- Asymmetric synthesis of benzoxazinones
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The present invention provides novel methods for the asymmetric synthesis of (S)-6-chloro-4-cyclopropylethynyl-4-trifluoromethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one of formula (VI-i) STR1 which is useful as a human immunodeficiency virus (HIV) reverse transcriptase inhibitor.
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- Asymmetric synthesis of benzoxazinones
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The present invention provides novel methods for the asymmetric synthesis of (S)-6-chloro-4-cyclopropylethynyl-4-trifluoromethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one of formula (VI-i) STR1 which is useful as a human immunodeficiency virus (HIV) reverse transcriptase inhibitor.
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- Charge-Transfer Complexes of Benzo[b]thiophene with σ- And π-Electron Acceptors
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The spectrophotometric properties of the charge-transfer (CT) complexes of benzo[6]thiophene with iodine at 24°C in different solvents such as cychlohexane, carbon tetrachloride, chloroform, dichloromethane, and 1,2-dichloroethane are studied. In addition the spectrophotometric and thermodynamic properties of the CT complexes of benzo[b]thiophene with tetracyanoethylene, chloranil, 2,3-dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8,-tetracyanoquinodimethane are studied. The results show that the equilibrium and the thermodynamic parameters and the wavelengths of the maximum absorption bands (λmax) of the complexes vary markedly with the solvent. The ionization potential and the donor sites of benzo[b]thiophene are also determined and discussed.
- Ayad, Mohamad M.
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p. 2369 - 2373
(2007/10/03)
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- Halichondrins and related compounds
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Novel chemical compounds that can be used to synthesize halichondrin B and norhalichondrin B, and related derivatives. The total synthesis of halichondrin B and norhalichondrin B is also disclosed.
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- Synthesis of halichondrin B and norhalichondrin B
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Novel chemical compounds that can be used to synthesize halichondrin B and norhalichondrin B, and related derivatives, are described. The synthesis of halichondrin B and norhalichondrin B from these compounds also is described.
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- Energetic Comparison between Photoinduced Electron-Transfer Reactions from NADH Model Compounds to Organic and Inorganic Oxidants and Hydride-Transfer Reactions from NADH Model Compounds to p-Benzoquinone Derivatives
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Kinetics studies on photoinduced electron-transfer reactions from dihydropyridine compounds (PyH2) as being NADH model compounds to organic and inorganic oxidants and hydride-transfer reactions from PyH2 to p-benzoquinone derivatives (Q) in the absence and presence of Mg2+ ion are reported by determining over 150 rate constants.These results, combined with the values of Gibbs energy change of the photoinduced electron-transfer reactions as well as those of each step of the hydride-transfer reactions as being the e--H+-e- sequence, which are determined independently, revealed that the rate constants of the photoinduced electron-transfer reactions obey the Rehm-Weller-Gibbs energy relationship and that the activation barrier of the hydride-transfer reactions from PyH2 to Q is dependent solely on the Gibbs energy changes of the initial electron transfer from PyH2 to Q and the following proton transfer from PyH2.+ to Q.- and thus independent of the Gibbs energy change of the final electron transfer from PyH. to QH..The retarding effect of Mg2+ ion observed on the photoinduced electron transfer and hydride-transfer reactions of PyH2 is ascribed to the positive shifts of the redox potentials of the ground and excited states of PyH2 due to the complex formation with Mg2+ ion.
- Fukuzumi, Shunichi,Koumitsu, Shintaro,Hironaka, Katsuhiko,Tanaka, Toshio
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p. 305 - 316
(2007/10/02)
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- MOLECULAR COMPLEXES OF CYCLOPHANES. XII. ON THE TRANSANNULAR ELECTRONIC INTERACTIONS IN PARACYCLOPHANES
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The interaction of twelve paracyclophane bisazomethynes with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in dichloromethane is described in terms of formation of 1:1 charge-transfer (CT) complexes.Association constants and transition energies of these CT complexes as well as ionization potentials of the donors 1-3 have been determined.On the basis of association constants and wavelengths of maximum absorption, the basicity of the donor 1-3 follow the order; pseudo-gem (1) > pseudo-meta (2) > pseudo-para (3), which could be rationalized in terms of the existence of transannular electronic interactions in this donor system.
- Mourad, Aboul-Fetouh E.,Nour-El-Din, Ahmed M.,Abdel-Nabi, Husham A.
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p. 381 - 384
(2007/10/02)
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- Electron Donor-Acceptor Complexes of Some Aromatic Hydrocarbons with Chlorosubstituted Quinones
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Electron donor-acceptor interactions between fluorene, 2-bromofluorene, t-stilbene and pyrene as electron donors and chloranil and 2,3-dichloro-5,6-dicyano-p-benzoquinone as electron acceptors have been examined by electronic spectroscopy.The spectroscopic and thermodynamic parameters of the complexes are reported.Among all the donors studied, pyrene appears to be the strongest electron donor towards both the electron acceptors.
- Dwivedi, P. C.,Agarwal, Rama
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p. 1015 - 1017
(2007/10/02)
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- STUDIES OF THE CHARGE-TRANSPHER COMPLEXES OF AZOXY COMPOUNDS WITH ?-ACCEPTORS
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Charge-transfer complexes of aryl azoxy compounds with some ?-acceptors in dichloromethane were studied spectrophotometrically at 25 deg C in the visible region.The spectroscopic data indicate that the complexes are not strong in nature and the Ph-N=-->O group is resposible for the complexation with ?-acceptors.Comparison with nitrones has been made.The 1H NMR and IR spectra of some solid complexes differ in important respects from those of either component taken separately.The effect of temperature on the stability of the complexes is discussed.Job's method shows that the stoicheiometric ratio of the complexes is 1:1.
- El-Din, Ahmed Moukhtar Nour
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p. 401 - 404
(2007/10/02)
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- ?-? Molecular Complexes with Nitrones: PartIV - Substituent Effect in the Complexation of Aryl Nitrones with Tetracyanoethylene and 1,4-Benzoquinones
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Charge-transfer complexes of some substituted nitrones with tetracyanoethylene and 1,4-benzoquinones have been studied spectrophotometrically.The stoichiometry and apparent formation constants of the complexes have been determined.From the energies of the charge-transfer transitions, the ionization potentials of the donors have been obtained.
- Nour El-Din, Ahmed M.
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p. 511 - 512
(2007/10/02)
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- One-electron Reduction Potentials of Several Electron Acceptor Molecules and Cation Radicals of Donors
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Reversible one-electron reduction potential values of several electron acceptor molecules and cation radicals of donors were estimated by means of the equilibrium constant of electron transfer reaction between ion radicals in acetonitrile solution, and the results were compared with the observed electrochemical data.
- Iida, Yoichi
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p. 2673 - 2674
(2007/10/02)
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- Intermediates for the production of quinones
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A novel method for producing hydroquinone and quinone derivatives by a regio- and stereo-specific coupling reaction of hydroquinone derivative having a terminal activated (poly)prenyl side chain with a prenyl derivative. This method can provide in good yield various hydroquinone and quinone derivatives having any prenyl length of the side chain.
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- 2,2-Difluoro-13,14-didehydro-11-deoxy-17-phenyl-18,19,20-trinor-PGE2 compounds
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This invention comprises certain analogs of the prostaglandins in which the double bond between C-13 and C-14 is replaced by a triple bond. Also provided in this invention, are novel chemical processes and novel chemical intermediates useful in the preparation of the above prostaglandin analogs. These prostaglandin analogs exhibit prostaglandin-like activity, and are accordingly useful for the same pharmacological purposes as the prostaglandins. Among these purposes are blood pressure lowering, labor induction at term, reproductive-cycle regulation, gastric antisecretory action, and the like.
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- 13,14-Didehydro-PGA1 compounds
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This invention comprises certain analogs of the prostaglandins in which the double bond between C-13 and C-14 is replaced by a triple bond. Also provided in this invention are novel chemical processes and novel chemical intermediates useful in the preparation of the above prostaglandin analogs. These prostaglandin analogs exhibit prostaglandin-like activity, and are accordingly useful for the same pharmacological purposes as the prostaglandins. Among these purposes are blood pressure lowering, labor induction at term, reproductive-cycle regulation, gastric antisecretory action, and the like.
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- 13,14-Didehydro-PG analogs
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This invention comprises certain analogs of the prostaglandins in which the double bond between C-13 and C-14 is replaced by a triple bond. Also provided in this invention, are novel chemical processes and novel chemical intermediates useful in the preparation of the above prostaglandin analogs. These prostaglandin analogs exhibit prostaglandin-like activity, and are accordingly useful for the same pharmacological purposes as the prostaglandins. Among these purposes are blood pressure lowering, labor induction at term, reproductive-cycle regulation, gastric antisecretory action, and the like.
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- 13,14-Didehydro-PG3 compounds
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This invention comprises certain analogs of the prostaglandins in which the double bond between C-13 and C-14 is replaced by a triple bond. Also provided in this invention, are novel chemical processes and novel chemical intermediates useful in the preparation of the above prostaglandin analogs. These prostaglandin analogs exhibit prostaglandin-like activity, and are accordingly useful for the same pharmacological purposes as the prostaglandins. Among these purposes are blood pressure lowering, labor induction at term, reproductive-cycle regulation, gastric antisecretory action, and the like.
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