Synthesis and reactions of N-methylbenzylammonium fluorochromate(VI) on silica gel, a selective and efficient heterogeneous oxidant.
N-Methylbenzylammonium fluorochromate(VI) (MBAFC) is easily synthesized by addition of N-methylbenzylamine to an aqueous solution of CrO3 and HF. MBAFC shows selectivity in the oxidation of aryl alcohols to their corresponding aldehydes and ketones under mild conditions. The durability, ease of work up and efficiency of MBAFC are considerably increased upon its absorption on silica gel.
Oxidation of benzhydrol by tributylammonium chlorochromate: a kinetic and mechanistic study
The kinetics of oxidation of benzhydrols (BH) by tributylammonium chlorochromate (TriBACC) to the corresponding benzophenones have been studied. The reaction is first order each in the concentration of TriBACC, benzhydrol and H+. The oxidation of (α-C–D) benzhydrol indicates the presence of a primary kinetic isotope effect. The reaction rate have been determined at different temperatures and activation parameters calculated. With an increase in the amount of acetic acid in its aqueous mixture, the rate increases. The reaction does not induce polymerization of acrylonitrile. A mechanism involving hydride ion transfer has been proposed.
Taphonomy of Isisfordia duncani specimens from the Lower Cretaceous (upper Albian) portion of the Winton Formation, Isisford, central-west Queensland
Taphonomic analysis of fossil material can benefit from including the results of actualistic decay experiments. This is crucial in determining the autochthony or allochthony of fossils of juvenile and adult Isisfordia duncani, a basal eusuchian from the Lower Cretaceous (upper Albian) distal-fluvial-deltaic lower Winton Formation near Isisford. The taphonomic characteristics of the I. duncani fossils were documented using a combination of traditional taphonomic analysis alongside already published actualistic decay data from juvenile Crocodylus porosus carcasses. We found that the I. duncani holotype, paratypes and referred specimens show little signs of weathering and no signs of abrasion. Disarticulated skeletal elements are often found in close proximity to the rest of the otherwise articulated skeleton. The isolated and disarticulated skeletal elements identified, commonly cranial, maxillary and mandibular elements, are typical of lag deposits. The holotype QM F36211 and paratype QM F34642 were classified as autochthonous, and the remaining I. duncani paratypes and referred specimens are parautochthonous. We propose that I. duncani inhabited upper and lower delta plains near the Eromanga Sea in life. Their carcasses were buried in sediment-laden floodwaters in delta plain overbank and distributary channel deposits. Future studies should refer to I. duncani as a brackish water tolerant species.