673-84-7Relevant academic research and scientific papers
Kinetic and mechanistic study on the thermal isomerization of ocimene in the liquid phase
He, Jindong,Xie, Meng,Tang, Xiangyang,Qi, Xin
scheme or table, p. 373 - 378 (2012/07/30)
The rate of thermal isomerization of ocimene in the liquid phase has been investigated in the range 90-150°C. The rate constant for the disappearance of ocimene may be expressed by k=1.3×1010e -11994.2/T(min-1), from which we can infer that the activation energy is 99.7kJmol-1 and the pre-exponential factor is 1.3×1010min-1. The half-life for the disappearance of ocimene may be expressed by t1/2=5.2×10-11e 11994.2/T(min). The conclusion has been supported by the study results that the ocimene is safe when temperature is below 100°C. A discussion of the mechanism concerning the conversion is included. Copyright
Thermolysis of α-pinene in supercritical lower alcohols
Chibiryaev,Anikeev,Yermakova,Mikenin,Kozhevnikov,Sal'nikova
, p. 987 - 992 (2008/02/01)
Thermal isomerization of α-pinene in supercritical solvents, viz., ethanol, methanol, and propan-1-ol, was carried out, and differences in the rate and selectivity of the process were revealed. In supercritical ethanol the reaction rate increases sharply and the selectivity remains unchanged with an increase in the temperature (from 290 to 390°C) or pressure (from 90 to 270 atm). The main reaction products are limonene, isomeric alloocimenes, and pyronenes. The selectivity for limonene in propan-1-ol is higher than in other alcohols when the conversion of α-pinene not higher than 50%. In supercritical ethanol (430°C, 120 atm, 140 s) limonene is more stable than α-pinene (conversion 8%).
The kinetics, stereochemistry, and deuterium isotope effects in the α-pinene pyrolysis. Evidence for incursion of multiple conformations of a diradical
Gajewski, Joseph J,Kuchuk, Ilya,Hawkins, Christopher,Stine, Robert
, p. 6943 - 6950 (2007/10/03)
Pyrolysis of optically active α-pinene gave 95% racemic limonene (dipentene), alloocimine, racemic α-pinene, α-pyronene. Activation parameters are reported. Pyrolysis of (S) syn-6-trideuteriomethyl α-pinene at 256.7°C for 2400s gave dipentene with twice as much deuterium as hydrogen transfer with kH/kD=1.49 and alloocimine with a Z and E trideuteriomethyl ratio of ca. 5 with kH/kD=0.89. The isotope effect on loss of starting material was 1.16. Separation of the enantiomers of α-pinene from 3600s pyrolyses at 256.7°C followed by NMR analysis revealed that the ratio of the R-syn to R-anti to S-anti isomers is 4.6:3.7:1 at roughly two half-lives. Kinetic analysis reveals that the previously proposed mechanism for all conversions involving slow interconversion of two diradicals with Cs symmetry is not consistent with the distribution of the ??-pinene isomers, particularly the formation of more suprafacial-retention product (R-anti) than bond-rotated isomer (S-anti). Inclusion of another Cs species (ignoring the deuteriums) that would be intermediate between the originally proposed Cs species, appears more consistent with the observations.
Photosensitized Geometric Isomerization of Alloocimene. The Triplet Torsitional Potential Surface of a Conjugated Ttriene
Butt, Yondani C. C.,Singh, Anil K.,Baretz, Bruce H.,Liu, R. S. H.
, p. 2091 - 2097 (2007/10/02)
The photostationary state compositions and quantum yields of the benzophenone-sensitized geometric isomerization of alloocimene, a model triene, have been studied in detail.The results arte discussed in terms of two reaction schemes for four isomer systems (one for steady-state concentrations of isomers and one for partially eequilibrated isomeric triplets).A triplet torsional potential surface of the triene is also presented which was constructed to reflect the photochemical properties of the triene.From quenching data, the average lifetime of an alloocimene triplet at room temperature was determined to be 2E-7 s.
