21423-86-9Relevant academic research and scientific papers
Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene
Herbinet, Olivier,Rodriguez, Anne,Husson, Benoit,Battin-Leclerc, Frédérique,Wang, Zhandong,Cheng, Zhanjun,Qi, Fei
, p. 668 - 682 (2016/02/23)
The thermal decomposition of cyclopentene was studied in a jet-stirred reactor operated at constant pressure and temperature to provide new experimental information about the formation of the first aromatic rings from cyclic C5 species. Experim
Oxygen-Carbon bond dissociation enthalpies of benzyl phenyl ethers and anisoles. An example of temperature dependent substituent effects
Pratt,De Heer,Mulder,Ingold
, p. 5518 - 5526 (2007/10/03)
For some time it has been assumed that the direction and magnitude of the effects of Y-substituents on the Z-X bond dissociation enthalpies (BDE's) in compounds of the general formula 4-YC6H4Z-X could be correlated with the polarity of the Z-X bond undergoing homolysis. Recently we have shown by DFT calculations on 4-YC6H4CH2-X (X = H, F, Cl, Br) that the effects of Y on CH2-X BDE's are small and roughly equal for each X, despite large changes in C-X bond polarity. We then proposed that when Y have significant effects on Z-X BDE's it is due to their stabilization or destabilization of the radical. This proposal has been examined by studying 4-YC6H4O-X BDE's for X = H, CH3, and CH2C6H5 both by theory and experiment. The magnitudes of the effects of Y on O-X BDE's were quantified by Hammett type plots of ΔBDE's vs σ+ (Y). Calculations reveal that changes in O-X BDE's induced by changing Y are large and essentially identical (ρ+ = 6.7-6.9 kcal mol-1) for these three classes of compounds. The calculated ρ+ values are close to those obtained experimentally for X = H at ca. 300 K and for X = CH2C6H5 at ca. 550 K. However, early literature reports of the effects of Y on O-X BDE's for X = CH3 with measurements made at ca. 1000 K gave ρ+ ≈ 3 kcal mol-1. We have confirmed some of these earlier, high-temperature O-CH3 BDE's and propose that at 1000 K, conjugating groups such as -OCH3 are essentially free rotors, and no longer lie mainly in the plane of the aromatic ring. As a consequence, the 298 K DFT-calculated ΔBDE for 4-OCH3-anisole of -6.1 kcal mol-1 decreases to -3.8 kcal mol-1 for free rotation, in agreement with the ca. 1000 K experimental value. In contrast, high-temperature O-CH3 ΔBDE's for three anisoles with strongly hindered substituent rotation are essentially identical to those that would be observed at ambient temperatures. We conclude that substituent effects measured at elevated temperatures may differ substantially from those appropriate for 298 K.
Thermal decomposition of the halide and pseudohalide derivatives of bis(cyclopentadienyl)titanium(IV)
Brown, Gilbert M.
, p. 3028 - 3032 (2008/10/08)
The thermal decomposition reactions of Ti(Cp)2(X)2, where Cp is η5-C5H5 and X is Cl-, Br-, NCS-, NCO-, and N3-, were studied at atmospheric pressure by temperature-programmed pyrolysis with analysis of the evolved gas by mass spectroscopy. The gas evolution versus temperature profile showed that the compounds decomposed in a single, sharp, symmetrical step with the loss of cyclopentadiene observed from all compounds. The pseudohalide-containing compounds evolved products of the breakdown of this moiety simultaneously with C5H6. The gas evolution versus temperature profiles were used to measure ΔH? for the decomposition of the azide and cyanate compounds. The compound Ti(Cp)2(N3)2 was used for the chemical vapor deposition of titanium-containing films on quartz or CaF2 substrates at 400°C. Additional pyrolysis converts the film to an adherent, chemically resistant, refractory material. The infrared spectrum of the initial deposition product on a CaF2 substrate was obtained. Chemical analysis and IR spectroscopy suggest the film contains a large excess of carbon over that required for stoichiometric TiC. Hydrocarbon evolution probably occurs by a hydrogen abstraction mechanism, which leads to dehydrogenation of coordinated cyclopentadienyl. This dehydrogenated ring system appears to be the source of the excess carbon in the solid film.
PHOTOCHEMISTRY OF α,α-DISUBSTITUTED BICYCLIC CYCLOBUTANONES - A POTENTIAL THERMAL-PHOTOCHEMICAL METATHESIS REACTION
Lee-Ruff, Edward,Hopkinson, Alan C.,Kazarians-Moghaddam, Hira
, p. 2067 - 2070 (2007/10/02)
Under certain conditions the photolysis of α,α-disubstituted cyclobutanones give terminal olefinic esters.A two-stage thermal photochemical metathesis is described.
