Laser flash photolysis of aziridines. Spectroscopic and kinetic characterization of azomethine ylides. Their [3 + 2] cyclization with alkenes and protonation by water–alcohols to yield iminium ions 1

1998 ◽  
pp. 2735-2740 ◽  
Author(s):  
Carsten Gaebert ◽  
Christian Siegner ◽  
Jochen Mattay ◽  
Marion Toubartz ◽  
Steen Steenken
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Azomethine Ylides ◽  
Kinetic Characterization ◽  
Iminium Ions

Formation and nucleophilic capture of N-nitrosiminium ions

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1148-1161 ◽  
Author(s):  
Latifa Chahoua ◽  
Alain Vigroux ◽  
Yvonne Chiang ◽  
James C Fishbein
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Aqueous Media ◽  
Laser Flash ◽  
Azide Ion ◽  
Iminium Ions ◽  
Nucleophilic Trapping

A study of the solvolysis of a series of (N-nitrosomethylamino)arylmethyl esters and azides and the products of nucleophilic trapping of the corresponding N-nitrosiminium ion intermediates in aqueous media, 25°C, ionic strength 1 M is reported. Structure-reactivity data for the forward and reverse reactions have been obtained. In three cases, the rate constants for reactions of the cations with nucleophiles have been measured directly by laser flash photolysis. The data allow a comparison of the degree to which the N-methyl-N-nitroso functionality enhances cation stability from a thermodynamic and kinetic perspective. It has been possible to deduce that the carbon basicity of azide ion is less than 1 kcal/mol greater than that of acetate ion.Key words: nitrosiminium ions, α-acetoxynitrosamines, carbocations, iminium ions, nucleophilicity.

Generation of α,β-Unsaturated Iminium Ions by Laser Flash Photolysis

2011 ◽  
Vol 50 (42) ◽  
pp. 9953-9956 ◽  
Author(s):  
Sami Lakhdar ◽  
Johannes Ammer ◽  
Herbert Mayr
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Iminium Ions

scholarly journals Fragmentation of a dioxolanyl radical via nonstatistical reaction dynamics: characterization of the vinyloxy radical by ns time-resolved laser flash photolysis

2018 ◽  
Vol 20 (30) ◽  
pp. 19819-19828
Author(s):  
Götz Bucher ◽  
Mukul Lal ◽  
Anup Rana ◽  
Michael Schmittel
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Reaction Dynamics ◽  
Laser Flash ◽  
Time Resolved

Photolysis of a dioxolanyl Barton ester results in formation of the vinyloxy radical, via nonstatistical reaction dynamics. The nonstatistical reaction involves ester cleavage, CO2 loss and fragmentation of the intermediate dioxolanyl radical.

Formation and Direct Detection of Non-Conjugated Triplet 1,2-Biradical from β,γ-Vinylarylketone

2015 ◽  
Vol 68 (11) ◽  
pp. 1707 ◽  
Author(s):  
H. Dushanee M. Sriyarathne ◽  
Kosala R. S. Thenna-Hewa ◽  
Tianeka Scott ◽  
Anna D. Gudmundsdottir
Keyword(s):  
Rate Constant ◽  
Density Functional ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Direct Detection ◽  
Density Functional Theory Calculations ◽  
Laser Flash ◽  
Triplet Excited State ◽  
Functional Theory

Laser flash photolysis of 2-methyl-1-phenylbut-3-en-1-one (1) conducted at irradiation wavelengths of 266 and 308 nm results in the formation of triplet 1,2-biradical 2 that has λmax at 370 and 480 nm. Biradical 2 is formed with a rate constant of 1.1 × 107 s–1 and decays with a rate constant of 2.3 × 105 s–1. Isoprene-quenching studies support the notion that biradical 2 is formed by energy transfer from the triplet-excited state of the ketone chromophore of 1. Density functional theory calculations were used to verify the characterization of triplet biradical 2 and validate the mechanism for its formation. Thus, it has been demonstrated that intramolecular sensitization of simple alkenes can be used to form triplet 1,2-biradicals with the two radical centres localized on the adjacent carbon atoms.

CHARACTERIZATION OF A MICROSECOND INTERMEDIATE IN THE LASER FLASH PHOTOLYSIS OF SMALL PHYTOCHROME FROM OAT

1980 ◽  
Vol 31 (4) ◽  
pp. 417-420 ◽  
Author(s):  
Silvia E. Braslavsky, ◽  
J. Ioan Matthews, ◽  
Hans J. Herbert, ◽  
Jacob Kok ◽  
Carel J. P. Spruit ◽  
...  
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash
Sign in / Sign up

Export Citation Format

Share Document