Year 2007, Month 6 (Section Full Articles, Page 1234)
Comparative thermolysis of β- and α-pinenes in supercritical ethanol: the reaction characterization and enantiomeric ratios of products
A. M. Chibiryaev, A. Yermakova, I. V. Kozhevnikov, O. I. Sal´nikova, and V. I. Anikeev
The thermolysis of β-pinene and the cothermolysis of an equimolar mixture of β- and α-pinenes in supercritical ethanol were carried out. The reaction of βpinene affords β-myrcene as the major product (>70%). Considerable differences in the temperature dependence of the reaction rate were revealed for the transformations of β-pinene into β-myrcene and of α-pinene into limonene. The preexponential factors and the activation energies were calculated. The enantiomeric ratios of the thermolysis products of β and αpinenes and limonene were estimated. The starting monoterpenes do not undergo racemization during thermolysis. The thermolysis of enantiomerically pure α-pinene affords racemic (±)-limonene, whereas (–)-β-pinene gives (–)-limonene. The enantiomeric ratio in the latter remains equal to the enantiomeric purity of the starting β-pinene.
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