123-56-8Relevant articles and documents
Unexpected Hydrogenation of C-C-Double Bonds with tert-Butyl Iodide
Jin, Shangde,Liebscher, Juergen
, p. 390 - 392 (1998)
Heating of 3-isobutylidene-2,5-diketopiperazines 1 or 4, maleinimide or 2,3-dichloro-5,6-dicyano-p-benzoquinone with tert-butyl iodide in toluene gave rise to hydrogenation of the conjugated C-C-double bond affording 3-isobutyldiketopiperazines 2(rac) and 3(rac), succinimide, or 2,3-dichloro-5,6-dicyanohydroquinone, respectively. Furthermore, an interesting N-O-migration of a benzoyl group as well as reductive aromatization to pyrazines 5 and 6, respectively, were observed.
Photometric-Potentiometric Evaluation of the Hydrolysis Constants of N-Bromo Compounds
Gottardi, Waldemar
, p. 313 - 322 (1982)
The equilibrium concentrations of all reaction products emerging from the hydrolysis of N-bromo compounds in the presence of bromide and thereby also the hydrolysis constants (K1) have been calculated from the absorbance at 392.8 nm, the pH-value and the initial concentrations of the N-bromo compound and the bromide.The following compounds have been investigated: N-bromo-succinimide: K1 = 2.2E-6, 1,3-dibromo-5,5-dimethylhydantoin: K1 = 1.7E-5, N-bromoacetamide: K1 = 1.8E-6, N-bromo-monochloroacetamide: 5.2E-6, N-bromo-dichloroacetamide: K1 = 8.9E-6 and N-bromo-trichloroacetamide: K1 = 1.8E-5.The precision of the method, which is mainly suited for weak hydrolizing N-bromocompounds (K15-12percent.The reactivities in aqueous solution of the most frequently used N-bromo compounds are compared by means of the calculated HOBr equilibrium concentrations.The differences to be expected on the basis of the latters are at concentrations >1E-5 mol/l rather great, while they can be neglected in very dilute solutions (/=1E-6 mol/l).Keywords: Disinfection; Equilibrium concentrations; N-Halogene compounds; Hydrolysis; Reactivity of N-bromo compounds.
Electrochemical Reduction of N-Bromosuccinimide. Reaction Mechanism for Formation of the Succinimidyl Radical
Barry, John E.,Finkelstein, Manuel,Moore, W. Michael,Ross, Sydney D.,Eberson, Lennart,Joensson, Lennart
, p. 1292 - 1298 (1982)
The electrochemical reduction of N-bromosuccinimide in acetonitrile at a platinum cathode generates the succinimidyl radica;l in an overall process for which the n value is 1.The succinimide anion, generated by two-electron reduction of N-bromosucinimide, is an intermediate in this process, and its electron-transfer reaction with the N-bromo imide generates the radical.The intermediacy of the succinimide anion is demonstrated by trapping experiments in which the anion is captured by alkylating agents to give N-alkylsuccinimides.With increasing capture of the anion the n value for the electrochemical reaction approaches 2 as a limit.The reduction of N-bromosuccinimide by the succinimide anion, added as a quaternary ammonium succinimide, in a purely chemical system has also been studied.Rate constants for the pertinent reactions have been measured, and the reaction mechanisms have been discussed.
Synthesis, characterization and cytotoxic studies of novel 1,2,4-triazole-azomethine conjugates
Mahar, Jamaluddin,Saeed, Aamer,Chaudhry, Gul-e-Saba,Irfan, Madiha,Channar, Pervaiz Ali,Faisal, Muhammad,Larik, Fayaz Ali
, p. 943 - 951 (2020)
Abstract: A series of 1,2,4-triazole-schiff hybrids were synthesized and characterized by mass spectrometry, FTIR and NMR spectroscopy. The compounds were screened for anticancer activity against human breast cancer cell line (MCF-7 and T47D) and human cervical cancer cell line (HeLa). The result indicates that newly synthesized compounds exhibit cytotoxicity to all cell lines studied. In particular, MCF-7 cells were shown to be more sensitive with EC50 50 13.10?μM/ml. To further investigate the mode of cell death, early and late apoptosis studies were done on MCF-7 cells. The externalization of phosphatidylserine and DNA fragmentation supports the apoptosis as the major mode of cell death induced by derivatives on MCF-7 cells. Graphic abstract: [Figure not available: see fulltext.]
Photodecomposition of N-Bromosuccinimide: Radical Chain Carriers and Their Interrelations
Chow, Yuan L.,Zhao, Da-Chuan
, p. 1931 - 1939 (1987)
The direct photolysis of N-bromosuccinimide (NBS) in the absence and presence of bromine and its bromine atom initiated decomposition were investigated by selective irradiation of NBS or Br2 and by critically examining the β-bromopropionyl isocyanate (BPI) yields and the relative selectivity of intermolecular H abstraction from cyclohexane and CH2Cl2.Experimental results showed (i) that direct photolysis of NBS gave extra amounts of BPI, (ii) that the bromine atom initiated NBS decomposition also generated BPI, and (iii) that the interaction of bromine atoms with NBS or the succinimidyl radical with bromine set up a rapid equilibrium of the radicals.In the NBS + Br2 system the relative selectivities of intermolecular H abstraction, kC6H12/kCH2Cl2, were 16-22, practically the same as those for a bromine atom (15-18), and the BPI percent yields decreased systematically as both initial and observed bromine concentrations increased in the range of 1-100 mM.Therefore, the photodecomposition of the NBS + Br2 system involves the succinimidyl radical and bromine atom in a fast equilibrium and as the radical-propagating species, without the need to invoke another radical.The succinimidyl radical generated from direct photolysis of NBS is proposed to be a vibrationally excited hot species that undergoes much faster ring opening than the ground-state species.These results provide a satisfactory explanation to resolve the most recent controversy over the number of radical intermediates involved in the NBS photodecomposition.
One-Electron Reduction Potential and Ring Opening of the Succinimidyl Radical in Water
Lind, Johan,Jonsson, Mats,Eriksen, Trygve E.,Merenyi, Gabor,Eberson, Lennart
, p. 1610 - 1614 (1993)
By means of pulse radiolysis in water, N-chlorosuccinimide (SCl) was reduced in a one-electron step to yield the succinimidyl radicals, S*, via the intermediacy of the radical anion, SCl*-.The rate of ring opening of S* was measured to be 8 x 104 s-1.By equilibrium with Cl2*-/2Cl-, the one-electron reduction potential of S* was determined to be 2.22 +/- 0.02 V vs NHE.From this value and other data, the N-H bond strength in succinimide was calculated to be 118 +/- 3 kcal/mol.
Kinetics and mechanism of the reaction of N-chlorosuccinimide with I - and OH-
Agulla,Antelo,Arce,Parajo
, p. 243 - 252 (2005)
In this kinetic study of the reaction between the iodide ion and the N-chlorosuccinimide, we have found that the reaction is first order in N-chlorosuccinimide: namely, first order with respect to the iodide ion and first order with respect to the proton concentration. Based on the experimental results, we propose a mechanism consistent in Cl+ transfer from the N-chlorosuccinimide to the iodide ion. We have found that the reaction presents general acid catalysis with a Broensted exponent value of 0.10. In addition, given that the N-chlorocompounds are not stable in aqueous solution, we have carried out a study on the influence of bases in the presence of N-chlorosuccinimide. We have found that the reaction is first order in hydroxide ion, as well as in the 1,1,1,3,3,3-hexafluoroisopropanoxide ion and the 2,2,2-trifluorethoxide ion. which shows that the reaction is general-base catalyzed.
Polarographic determination of vitamin C after derivatization with o-phenylenediamine
Rodrigues, Jose Antonio,Valente, Ines Maria,Goncalves, Luis Moreira,Pacheco, Joao Grosso,Barros, Aquiles Araujo
, p. 731 - 741 (2010)
A differential pulse polarographic (DPP) method has been developed for the determination of ascorbic acid (AA) and dehydroascorbic acid (DHA), the two main forms of Vitamin C. The method consists of the DPP analysis of a quinoxaline obtained by the derivatization of DHA with o-phenylenediamine. Results using the proposed method correlated well with those obtained by two reference methodologies: the common iodometric method and a published chromatographic methodology. It was also used in the study of Vitamin C degradation in fruit juices, showing that it involves an initial oxidation of AA to DHA, followed by ydrolytic degradation of the latter.
Kinetics of radical-initiated chain bromination of 2-methyl-2-propanol by N-bromosuccinimide in water
Lind, Johan,Jonsson, Mats,Xinhua, Shen,Eriksen, Trygve E.,Merényi, Gábor,Eberson, Lennart
, p. 3503 - 3510 (1993)
The kinetics and product distribution of the radical chain bromination of 2-methyl-2-propanol (RH) by N-bromosuccinimide (SBr) in water have been studied by pulse-radiolytic and γ-radiolytic methods in order to obtain key data for the reactivity of the succinimidyl radical, S?. The products of the reaction after γ-radiolysis are dependent on the concentration of RH, being essentially made up of equal amounts of (CH3)2C(OH)CH2Br and succinimide at [RH] > 0.5 M, while the hydrolyzed ring-opened product, 3-bromopropionamide, increases at the expense of (CH3)2C(OH)CH2Br when the RH concentration is lowered. The chain-propagating steps R? + SBr → RBr + S? (i) and S? + RH → SH + R? (ii) of the S? mediated chain reaction had rate constants ki = (1.8 ± 0.3) × 108 (determined in three ways) and kii = (1 ± 0.5) × 107 M-1 s-1 (determined in four ways), respectively, whereas the corresponding rate constants for the Br? mediated chain under the same conditions were 2.5 × 109 and (5 ± 3) × 103 M-1 s-1. Under pulsed conditions with initial radical concentrations around 10-4 M, the chain length is ≈10. The ratio between kii and the rate constant for ring opening of S?, kiii (S? → ?CH2CH2CONCO), was determined to be 77 M-1, significantly higher than the corresponding value with neopentane as substrate and with dichloromethane as solvent (0.10 M-1). The kii value places S? as having significantly lower reactivity than OH? in hydrogen atom abstraction reactions, whereas a theoretical estimate based on electron affinities puts it in between Cl? and OH?, i.e. at higher reactivity than OH?. This provides kinetic evidence for the II nature of ground state S?. It was also established that Br? complexes rather strongly to SBr according to SBr + Br? → SBr2? (iv). As kiv = (4-7) × 103 M-1 and SBr2? is probably unreactive, the propagation rate of a bromine atom chain is expected to decrease with increasing SBr concentration.
Mechanism of Photoredox-Initiated C-C and C-N Bond Formation by Arylation of IPrAu(I)-CF3 and IPrAu(I)-Succinimide
Kim, Suhong,Toste, F. Dean
, p. 4308 - 4315 (2019)
Herein, we report on the photoredox-initiated gold-mediated C(sp2)-CF3 and C(sp2)-N coupling reactions. By adopting gold as a platform for probing metallaphotoredox catalysis, we demonstrate that cationic gold(III) complexes are the key intermediates of the C-C and C-N coupling reactions. The high-valent gold(III) intermediates are accessed by virtue of photoredox catalysis through a radical chain process. In addition, the bond-forming step of the coupling reactions is the reductive elimination from cationic gold(III) intermediates, which is supported by isolation and crystallographic characterization of key Au(III) intermediates.
