Reactions of diterpenoids on solid supports II. Behavior of di- and tricyclic diterpenoids on alumina containing oxidants
The behavior of epimanool (1), epimanool oil, larixol (2), cis-abienol (3) and methyl dehydroabietate (4) on alumina impregnated with oxidants (H2CrO4 and KMnO4) has been studied. This has led to the methyl ketone (5) and norambrenolide (8) - precursors of the perfume substances 14,15,17-trinorlabdane-8,13-dione (6), 8α-hydroxy-14,15-bisnorlabd-II-en-13-one (7), and methyl 7-oxodehydroabietate (14). α-Levantenolide (11) has been synthesized in one stage from cis-abienol (3)for the first time.
Oxidising supported reagents-II-influence of the chemical and textural properties of the K2Cr2O7 supported reagents on the oxidation of menthol
Abstract We have analyzed the influence of the chemical and textural properties of the solid supports as well as the oxidising K2Cr2O7 supported reagent on the oxidation of menthol to menthone—as a reaction test—. The most active K2Cr2O7 supported reagents are obtained with amorphous solid supports with large surface areas or with microcrystalline solids, with great amounts of oxidising sites titrated by phenothiazine.
Refinement of crystal structure parameters using convergent‐beam electron diffraction: the low‐temperature phase of SrTiO3
The method to refine crystal structure parameters (atom positions and Debye–Waller factors) using convergent-beam electron diffraction (CBED), which is applicable to crystal structure analysis of a small specimen area down to a few nm in diameter, is studied. The line profiles of higher-order Laue-zone reflections are recorded using imaging plates. Theoretical intensities are calculated based on the dynamical theory of electron diffraction with the aid of the generalized Bethe approximation to shorten calculation time. The structural parameters are determined by fitting the experimental profiles with the theoretical ones using a nonlinear least-squares method. The present method has been applied to the low-temperature phase of SrTiO3. The structural parameter or the rotation angle of the oxygen octahedron has been determined to be \varphi = 1.12 (4)°, which shows good agreement with that obtained from electron spin resonance experiments.