84369-94-8Relevant academic research and scientific papers
Gas-Phase Thermolysis of Pyrazolines, 2. Electronic Structure and Gas-Phase Thermolysis of 4,5-Dihydro-3H-pyrazoles Studied by Photoelectron Spectroscopy, Semiempirical Quantum-Chemical Calculations, and Flash Vacuum Pyrolysis
Kindermann, Markus Karl,Kowski, Klaus,Muchall, Heidi M.,Rademacher, Paul
, p. 2675 - 2682 (2007/10/02)
The PE spectra of the 4,5-dihydro-3H-pyrazoles 1, 2, of 2,5-dihydro-1,3,4-oxadiazole 3, and 2,5-dihydro-1,3,4-thiadiazole 4 have been recorded.Based on HAM/3, MNDO, AM1, and PM3 calculations, the ionization potentials have been assigned to molecular orbitals.The gas-phase thermolyses of 1-4 have been studied by PE-controlled gas analysis.Extrusion of molecular nitrogen leads to reactive species which cyclize to three-membered rings of different stability.At higher temperatures and in flash vacuum pyrolysis, consecutive reactions may lead to smaller acyclic molecules.The cyclopropanol 7, obtained by denitrogenation of 2, is thermally rather stable.Its PE spectrum has been recorded and analyzed. - Key Words: Electronic structure / PE spectroscopy / Gas-phase thermolysis / 3H-Pyrazoles, 4,5-dihydro- / 1,3,4-Oxadiazole, 2,5-dihydro- / 1,3,4-Thiadiazole, 2,5-dihydro- / Cyclopropanol, 2,2,3,3-tetramethyl-
Reaction of carbonyl ylides with chloroform
Bekhazi, Michel,Lawrynowicz, Witold,Warkentin, John
, p. 1507 - 1510 (2007/10/02)
Carbonyl ylides 2, generated by thermolysis of alkoxyoxadiazolines 1 in chloroform, react with chloroform to form ketals (3) of 1,1,1-trichloropropanone.The isotope effect at 80 deg C, determined by analysis of products from thermolysis of 1 in mixed solvent (CHCl3/CDCl3, both in large excess) was estimated to be kH/kD = 5.A mechanism involving concerted C-Cl and C-H bond formation between the ylide C atoms and the Cl and H atoms of chloroform is proposed.The ketals of 1,1,1-trichloropropanone are the first to be reported. Key words: carbonyl ylide, reaction with chloroform; chloroform, reaction with carbonyl ylides; ketals, of 1,1,1-trichloropropanone; 1,1,1-trichloropropanone, ketals of
Reactions of Carbenes with Acetone. Reversible Thermal Formation and Fragmentation of Carbonyl Ylides and Their Cycloaddition to Acetone
Bekhazi, Michel,Warkentin, John
, p. 1289 - 1292 (2007/10/02)
2-Methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline (1) undergoes thermal decomposition in solution to form a carbonyl ylide intermediate.In acetone-d6 a portion of the ylide is trapped by cycloaddition but a large fraction undergoes fragmentation, either to methyl acetate and 1-methylethylidene or to acetone and 1-methoxyethylidene.Both carbenes react with acetone-d6 at the carbonyl oxygen to generate carbonyl ylides and they also insert into C-D bonds of the ketone.The carbonyl ylides themselves react with acetone by a 1,3-cycloaddition processes.
Thermolysis of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline
Hitchcock, A. P.,Zweep, S.,Steel, T.,Bekhazi, M.,Warkentin, J.
, p. 2914 - 2917 (2007/10/02)
The principal product of gas phase thermal decomposition of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline (methoxyoxadiazoline) was found to be 1-methoxy--ethane (vinyl ether).This arises from a selective 1,4-hydrogen shift in the carbonyl ylide intermediate.Fragmentation of the carbonyl ylide is the dominant process in the solution thermolysis of methoxyoxadiazoline.The phase and temperature dependence of this thermolysis is discussed in terms of the probable structure of the carbonyl ylide intermediate.
