(.alpha.-Haloalkyl)phosphonium salts and sulfur nucleophiles: a new type of reaction mechanism

1987 ◽  
Vol 52 (24) ◽  
pp. 5349-5356 ◽  
Author(s):  
Remo Galli
Keyword(s):  
Reaction Mechanism ◽  
Phosphonium Salts ◽  
New Type

scholarly journals Enzyme catalysis as a chain reaction

1991 ◽  
Vol 279 (3) ◽  
pp. 855-861 ◽  
Author(s):  
S E Szedlacsek ◽  
R G Duggleby ◽  
M O Vlad
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Mechanism ◽  
Point Of View ◽  
Simple Type ◽  
Chain Reaction ◽  
Proposed Model ◽  
New Type ◽  
A Chain ◽  
Theoretical Considerations ◽  
Classical Mechanism

A new type of enzyme kinetic mechanism is suggested by which catalysis may be viewed as a chain reaction. A simple type of one-substrate/one-product reaction mechanism has been analysed from this point of view, and the kinetics, in both the transient and the steady-state phases, has been reconsidered. This analysis, as well as literature data and theoretical considerations, shows that the proposed model is a generalization of the classical ones. As a consequence of the suggested mechanism, the expressions, and in some cases even the significance of classical constants (Km and Vmax.), are altered. Moreover, this mechanism suggests that, between two successive enzyme-binding steps, more than one catalytic act could be accomplished. The reaction catalysed by alcohol dehydrogenase was analysed, and it was shown that this chain-reaction mechanism has a real contribution to the catalytic process, which could become exclusive under particular conditions. Similarly, the mechanism of glycogen phosphorylase is considered, and two partly modified versions of the classical mechanism are proposed. They account for both the existing experimental facts and suggest the possibility of chain-reaction pathways for any polymerase.

scholarly journals Rhodium(III)-Catalyzed [4+2] Annulation via C-H Activation: Synthesis of Multi-Substituted Naphthalenone Sulfoxonium Ylides

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1884 ◽  
Author(s):  
Xiaohan Song ◽  
Xu Han ◽  
Rui Zhang ◽  
Hong Liu ◽  
Jiang Wang
Keyword(s):  
Reaction Mechanism ◽  
Reaction Conditions ◽  
Practical Utility ◽  
Neutral Reaction ◽  
New Type ◽  
Substrate Tolerance

A convenient Rh(III)-catalyzed C-H activation and cascade [4+2] annulation for the synthesis of naphthalenone sulfoxonium ylides has been developed. This method features perfect regioselectivity, mild and redox-neutral reaction conditions, and broad substrate tolerance with good to excellent yields. Preliminary mechanistic experiments were conducted and a plausible reaction mechanism was proposed. The new type naphthalenone sulfoxonium ylides could be further transformed into multi-substituted naphthols, which demonstrates the practical utility of this methodology.

scholarly journals A new electrochemical strategy for the synthesis of a new type of sulfonamide derivatives

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hamed Goljani ◽  
Zahra Tavakkoli ◽  
Ali Sadatnabi ◽  
Mahmood Masoudi-khoram ◽  
Davood Nematollahi
Keyword(s):  
Reaction Mechanism ◽  
Functional Groups ◽  
Disproportionation Reaction ◽  
Carbon Electrodes ◽  
One Pot ◽  
Electrochemical Generation ◽  
Type Reaction ◽  
Second Stage ◽  
Ping Pong ◽  
New Type

Abstract This study is the first report of electrochemical generation of hydroxyimino-cyclohexa-dien-ylidene haloniums and their application in the synthesis of new halo-N-hydroxysulfonamide derivatives. These compounds were obtained in a one-pot process based on the reaction of halonium acceptors with arylsulfinic acids. The method is easy to carry out, as it is performed using the carbon electrodes in a simple undivided cell. The protocol has a broad substrate scope with a tolerance for a variety of functional groups. The proposed mechanism is a ping-pong type reaction mechanism, which in its first stage the halonitroarene is reduced at the cathode to related hydroxylamine and in the second stage the cathodically generated hydroxylamine by oxidation at the anode and participating in disproportionation reaction is converted to the halonium acceptor.

scholarly journals A Selenamorpholine and Pyrimidine-based Redox-responsive Fluorescent Probe and Its Response Mechanism

2021 ◽  
Author(s):  
Tao Ma ◽  
Yiyun Li ◽  
Ling Ma ◽  
Zhichun Li ◽  
Wenbing Ma ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Peroxide ◽  
Reaction Mechanism ◽  
Detection Limit ◽  
Fluorescent Probe ◽  
Stokes Shift ◽  
Response Mechanism ◽  
Redox Responsive ◽  
New Type ◽  
Electron Withdrawing Group

Abstract A new type of hydrogen peroxide (H2O2) fluorescent probe Pyrimidine-Se was synthesized from selenomorpholine and pyrimidinyl and the large Stokes shift (Δλ>140 nm) was exhibited. The fluorescence intensity of Pyrimidine-Se is very sensitive to pH, and its pKa value is 9.06. While the probe is reacted with H2O2, the selenomorpholine changes from Se (II) to Se (IV), which enhances the electron-withdrawing ability of the Pyrimidine-Se electron-withdrawing group. Based on this, the probe Pyrimidine-Se was used to detect H2O2 by the fluorescence spectrum. The detection limit of the probe Pyrimidine-Se was 1.3 µM. At the same time, we also found that Pyrimidine-Se displayed the reversibility back and forth between H2O2 and GSH. The reaction mechanism with H2O2 was verified by mass spectrometry and simulation on the Gaussian 09 program.

2-Isothiocyanatobenzyltriphenylphosphonium bromides – new type of functionalized heterocumulenes suitable for synthesis of indole derivatives

1987 ◽  
Vol 52 (10) ◽  
pp. 2508-2520 ◽  
Author(s):  
Jozef Gonda ◽  
Pavol Kristian ◽  
Ján Imrich
Keyword(s):  
Nitrogen Atom ◽  
Sulfur Atom ◽  
Mass Spectra ◽  
Wittig Reaction ◽  
Indole Derivatives ◽  
Phosphonium Salts ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrophilic Reactions ◽  
New Type

Reaction of 2-bromomethylphenyl isothiocyanates with triphenylphosphine afforded triphenyl-(2-isothiocyanatobenzyl)phosphonium salts. Their reaction with bases liberated the corresponding carbanions which on intramolecular addition to the N=C=S group gave substituted 3-triphenylphosphoniumindolyl-2-thiolates. These compounds did not react in the Wittig reaction but underwent electrophilic reactions on the sulfur atom or on the indol nitrogen atom. According to a detailed analysis of 1H, 13C, 31P NMR and mass spectra, the indole derivatives exist predominantly in the betaine form. X-Ray diffraction analysis of the unsubstituted betaine, 3-triphenylphosphoniumindolyl-2-thiolate, agrees well with the spectral results.

Studies on phenolic resins. VII. The preparation of a new type of self-crosslinking phenolic resin and the reaction mechanism of the crosslinking

2007 ◽  
Vol 16 (3) ◽  
pp. 1705-1716 ◽  
Author(s):  
Ju Kumanotani ◽  
Toshio Yoshikawa ◽  
Etsuji Kubo ◽  
Isamu Kawanishi ◽  
Takeshi Okamura
Keyword(s):  
Reaction Mechanism ◽  
Phenolic Resin ◽  
Phenolic Resins ◽  
New Type

The reaction mechanism in the system132Xe+56Fe at 5.73 MeV/u: Evidence for a new type of strongly damped collisions

1978 ◽  
Vol 288 (4) ◽  
pp. 391-400 ◽  
Author(s):  
B. Heusch ◽  
C. Volant ◽  
H. Freiesleben ◽  
R. P. Chestnut ◽  
K. D. Hildenbrand ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Strongly Damped Collisions ◽  
New Type ◽  
Strongly Damped
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