926-09-0Relevant articles and documents
Keto-difluoromethylation of aromatic alkenes by photoredox catalysis: Step-economical synthesis of α-CF2H-substituted ketones in flow
Nakayama, Yoshiki,Ando, Gaku,Abe, Manabu,Koike, Takashi,Akita, Munetaka
, p. 6555 - 6563 (2019)
A step-economical method for synthesis of α-CF2H-substituted ketones from readily available alkene feedstocks has been developed. Radical difluoromethylation of aromatic alkenes combining DMSO oxidation and photoredox catalysis is a key to the successful transformation. Electrochemical analysis, laser flash photolysis (LFP), and density functional theory (DFT) calculations reveal that N-tosyl-S-difluoromethyl-S-phenylsulfoximine serves as the best CF2H radical source among analogous sulfone-based CF2H reagents. The present photocatalytic keto-difluoromethylation has been applied to flow synthesis and easily scaled up to gram-scale synthesis within a reasonable reaction time. Furthermore, potentials of the α-CF2H-substituted ketones for useful synthetic intermediates are shown; e.g., synthesis of the CF2H-containing α-hydroxyamide with the same carbon skeleton as that of the anticonvulsant active CF3-analogue, is disclosed. Additionally, mechanistic studies are also discussed in detail.
Reaction of OH with Dimethyl Sulfide (DMS). 1. Equilibrium Constant for OH + DMS Reaction and the Kinetics of the OH*DMS + O2 Reaction
Barone, Stephen B.,Turnipseed, Andrew A.,Ravishankara, A. R.
, p. 14694 - 14702 (2007/10/03)
The formation of a weakly bound adduct in the reaction of OH with DMS-d6 was observed between 217 and 240 K using the technique of pulsed laser photolysis/pulsed laser-induced fluorescence.The equilibrium constant for this process, OH + DMS-d6 OH*DMS-d6, was measured as a function of temperature.The bond strength of this adduct was determined to be 10.7 +/- 2.5 kcal mol-1.The weakly bound adduct was observed to react rapidly with O2.The rate constant for the reaction OH*DMS-d6 + O2 -> products was determined to be (1.00 +/- 0.33)E-12 cm3 molecules-1 s-1, independent of pressure and temperature.The atmospheric implications of the formation of this adduct and its reaction with O2 to the mechanism of DMS oxidation in the atmosphere are discussed.
THERMODYNAMICS OF S THEREFORE S2 sigma /1 sigma * THREE-ELECTRON BONDS AND DEPROTONATION KINETICS OF THIOETHER RADICAL CATIONS IN AQUEOUS SOLUTION.
Moenig,Goslich,Asmus
, p. 115 - 121 (2007/10/02)
These experiments on the determination of K//1 and the associated rate constants were conducted at various temperatures and thus provided for the first time experimentally determined thermodynamic parameters ( DELTA H** does not equal and DELTA S** does not equal ) for the unimolecular dissociation of the three-electron bond. This in turn will allow an experimental estimate for the sulfur-sulfur bond strength in (R//2S therefore SR//2)** plus . Up to now only a theoretical ab-initio value has been published, namely 130 kJ mol** minus **1 for the simplest congeneric species with all R equals H. The kinetic and thermodynamic results substantiate previous conclusions on the electronic structure and relative stability of S therefore S bonded radicals and corroborate some theoretical calculations.
