- Oxidation of aromatic anils by sodium perborate in aqueous acetic Acid Medium
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The kinetics of oxidation of 9 meta- and 15 para- substituted aromatic anils by sodium perborate were investigated in aqueous acetic acid medium. The reaction was second order with respect to aromatic anil and first order with respect to the sodium perborate. The increase of [H+] in this oxidation retards the rate of the reaction. The observed rate constant for the substituents were plotted against the Hammett constant, δ and a non-linear concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus δwas attributed to the transition state whereas the non-linear concave upward curve was observed for the substituents in the benzaldehyde moiety and a non-linear concave upward curve was observed for the substituents in the combination of aniline and benzaldehyde moiety. The electron withdrawing substituents fall on one side of the curve, having a negative ρvalue and the electron releasing substituents fall on the other side, with a positive ρvalue and a suitable mechanism was proposed.
- Venkatesh,Karunakaran
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p. 739 - 744
(2014/06/09)
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- Kinetic investigation of oxidation of aromatic anils by potassium peroxymonosulfate in aqueous acidic medium
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The kinetics of oxidation of aromatic anils to benzaldehyde and azobenzene by potassium peroxymonosulfate has been studied in aqueous acetic acid medium. The low dielectric constant of the medium facilitates the reactivity. It has been found that the variation in the ionic strength of the reaction has a negligible effect on the rate. Similarly, polymerization was not observed when acrylonitrile was added to the reaction mixture. This observation rules out the formation of any free radical in the reaction. The added Mn(II) increases the rate of the reaction, which indicates the involvement of two-electron transfer. Highly negative ΔS# values indicate a structured transition state. The deviation of the Hammett plot was noted, and a concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus σ is attributed to the transition state whereas the concave upward curve was observed for the substituents in the benzaldehyde moiety and in the combination of aniline and benzaldehyde moieties, and a suitable mechanism was proposed.
- Venkatesh,Karunakaran
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p. 542 - 550
(2013/07/26)
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- Synthesis of aminophosphonates with a primary amino group
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Mono- and dinitro-substituted aromatic Shiff bases were reacted with diisopropyl hydrogen phosphite in the presence of the boron trifluoride-ether complex to obtain the corresponding α-aminophosphonates. Reduction of the nitro groups in the resulting phos
- Gavrilov
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p. 1708 - 1711
(2007/10/03)
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- SUBSTITUENT EFFECTS ON THE 31P, 13C, AND 1H NMR CHEMICAL SHIFTS OF SUBSTITUTED DIPHENYL 1-PHENYLAMINO-1-PHENYLMETHANEPHOSPHONATES AND THEIR ANIONS
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For a series of thirty-five novel diphenyl 1-phenylamino-1-phenylmethanephosphonates, substituted in the meta and para positions on the anilino and/or aryl ring, 31P chemical shifts show a good linear correlation with Hammett ?n and Taft ?0 parameters, the 31P nucleus being better shielded in the case of electron withdrawing substituents.The same pattern is observed for the phosphonate anions, except when para phenyl substituents can interact with the phosphorus atom by direct resonance.This inverse relationship is due to a field effect of the substituent dipole which polarizes ?-electron clouds in the molecule.A corresponding shift in ?-electron density is likewise observed for 13C resonances of the two diastereotopic phenoxy groups, the phenylamino and phenyl moieties.Vicinal CH-NH coupling is shown to be dependent on the rate of NH proton exchange as influenced by resonance, temperature and solvent effects.
- Smith, Scott J.,Zimmer, Hans,Fluck, Ekkehard,Fischer, Peter
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p. 105 - 120
(2007/10/02)
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