Photo-CIDNP. Investigation of ?,?-Unsaturated Ketones: Evidence for Temperature-dependent S1vs. T2 Reactivities of Cyclopent-2-enyl Methyl Ketones

1979 ◽  
Vol 62 (6) ◽  
pp. 1952-1965 ◽  
Author(s):  
Andreas Henne ◽  
Nancy P. Y. Siew ◽  
Kurt Schaffner
Keyword(s):  
Methyl Ketones ◽  
Temperature Dependent ◽  
Unsaturated Ketones

CONFORMATIONAL EQUILIBRIA IN OPEN-CHAIN α,β-UNSATURATED KETONES

1961 ◽  
Vol 39 (11) ◽  
pp. 2225-2235 ◽  
Author(s):  
K. Noack ◽  
R. Norman Jones
Keyword(s):  
Raman Spectra ◽  
Equilibrium Mixture ◽  
Infrared And Raman Spectra ◽  
Temperature Dependent ◽  
Trans Form ◽  
Open Chain ◽  
Unsaturated Ketones ◽  
Conformational Isomers ◽  
Alkyl Substitution ◽  
Conformational Equilibria

The infrared and Raman spectra of trans-Δ3-penten-2-one have been measured over the temperature range +30° to −75° and +85° to +5° respectively. The temperature-dependent changes observed in the spectra indicate that this ketone exists as an equilibrium mixture of s-cis and s-trans conformational isomers in the liquid state. The s-trans form is the more stable and is present exclusively in the crystalline solid.Similar measurements have been carried out on Δ3-buten-2-one. The infrared and Raman spectra of this ketone also exhibit temperature effects that can be explained by a similar equilibrium, though the evidence is not as conclusive as for trans-Δ3-penten-2-one.The influence of alkyl substitution at the α- and β-carbon atoms on the relative stability of the s-cis and s-trans forms of α,β-unsaturated ketones is discussed.

scholarly journals Experimental and computational kinetics investigations for the reactions of Cl atoms with series of unsaturated ketones in gas phase

2017 ◽  
Author(s):  
Siripina Vijayakumar ◽  
Avinash Kumar ◽  
Balla Rajakuma
Keyword(s):  
Gas Phase ◽  
State Theory ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Unsaturated Ketones ◽  
Temperature Range ◽  
Computational Calculations ◽  
Temperature Rate ◽  
Cl Atoms

Abstract. Temperature dependent rate coefficients for the gas phase reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one were measured over the temperature range of 298–363 K relative to 1-pentene, 1,3-butadiene and isoprene. Gas Chromatography (GC) was used to measure the concentrations of the organics. The derived temperature dependent Arrhenius expressions are k4-hexen-3-one+Cl (298–363 K) = (2.82 ± 1.76)×10−12exp [(1556 ± 438)/T] cm3 molecule−1 s−1 and k5-hexen-2-one+Cl (298–363 K) = (4.6 ± 2.4)×10−11exp[(646 ± 171)/T] cm3 molecule−1 s−1. The corresponding room temperature rate coefficients are (5.54 ± 0.41)×10−10 cm3 molecule−1 s−1 and (4.00 ± 0.37)×10−10 cm3 molecule−1 s−1 for the reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one respectively. To understand the mechanism of Cl atom reactions with unsaturated ketones, computational calculations were performed for the reactions of Cl atoms with 4-hexen-3-one, 5-hexen-2-one and 3-penten-2-one over the temperature range of 275–400 K using Canonical Variational Transition state theory (CVT) with Small Curvature Tunneling (SCT) in combination with CCSD(T)/6-31+G(d, p)//MP2/6-311++G(d, p) level of theory. Atmospheric implications, reaction mechanism and feasibility of the title reactions are discussed in this manuscript.

Methods for preparation of heterobifunctional nitroxides: α,β-unsaturated ketones, β-ketoesters, cyano-nitro-derivatives

1982 ◽  
Vol 60 (12) ◽  
pp. 1432-1438 ◽  
Author(s):  
H. Olga Hankovszky ◽  
Kálmán Hideg ◽  
László Lex ◽  
Gyula Kulcsár ◽  
H. Anna Halász
Keyword(s):  
Methyl Ketones ◽  
Reaction Products ◽  
Unsaturated Ketones ◽  
Nitro Derivatives

The reactions of 1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-carboxaldehyde (1), 1-oxyl-2,2,5,5-tetramethyl-3-cyano-3-pyrroline (2), ethyl 1-oxy(-2,2,5,5-tetramethyl-3-pyrroline-3-carbonyl carbonate (3), and N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-carbonyl)imidazolide (4) are investigated with several nucleophiles (dialkylcadmium, diethyl sodio-malonate, magnesium enolate of ethyl hydrogen malonate, nitromethane-anion) to obtain α,β-unsaturated ketones, β-ketoesters, or conjugated reaction products. Aldehyde 1 is reacted with several methyl ketones (acetylmethylene-triphenylphosphorane, acetophenone, 2-acetylpyridine, 4-phenyl-3-butyn-2-one) to give spin labeled polyenones. The reaction of 4-(1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-yl)-2-buten-2-one (24a) with ethylenediamine gives 7,14-bis-(1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-yl)-5,12-dimethyl-1,4,8,11-tetraazatetradeca-7,14-diene biradical (25).

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