A Case of Tracheitis Sicca with Obstructive Tracheal Crusting In A 7 Year Old Boy.

Tracheitis sicca is a rare condition where there is drying and crusting of tracheal mucosa which may lead to tracheal obstruction and respiratory distress. Reported here is a case of young boy, who presented with cough, cold and respiratory distress worsening over a period of 5 days. On admission the patient was administered with dexamethasone and was intubated. However, saturation was not maintained despite assisted ventilation, and multiple episodes of self extubation always presented with stridor. Hence, otorhinolaryngology reference was taken and decision was taken to perform laryngotracheobronchoscopy. Endoscopy done showed extensive crusting in the trachea causing complete obstruction of airway above the level of carina. The crusting was meticulously removed, sent for culture, and the obstruction was relieved. The patient maintained saturation after the procedure, and was ultimately extubated and discharged.

Selective ozone activation of phenanthrene in liquid CO2.

We demonstrate liquid CO2 (8 °C, 4.4 MPa) as a benign medium to perform safe ozonolysis of phenanthrene at near-ambient temperatures. The ozonolysis products consist of several monomeric oxidation products such as diphenaldehyde, diphenic acid and phenanthrenequinone as well as polymeric structures up to 1130 Da. The observed chemical shifts (1H-6.03 ppm, 13C-104.38 ppm) in 2D-NMR spectra of the products confirm the formation of secondary ozonide. Based on the range of observed products, a Criegee-type mechanism is proposed. The ability to deconstruct phenanthrene and produce oxygenated precursors via this technique is particularly of interest in creating new materials from aromatic moieties.

Ethylene oligomerization using nickel dithiolene complexes Ni(S2C2R2)2 (R=Ph, CF3) and the crystal structure of Ni[S2C2(CF3)2]2.

Nickel bis(dithiolene) complexes have been known for over four decades, yet little is known regarding the chemistry of this important subclass of inorganic coordination complexes in olefin oligomerization or polymerization. We report here that Ni(S(2)C(2)R(2))(2) (R=Ph, CF(3)) are converted to active catalysts for ethylene oligomerization when activated with methylaluminoxane (MAO). The catalyst activity is comparable to some nickel coordination complexes with N-donor ligands under similar conditions. The products are mainly butenes and hexenes, with small amounts of higher oligomers. The product distribution pattern is consistent with a nickel hydride species being the active center, where fast beta-hydride elimination limits the products to mostly butenes and hexenes. The exact nature of the active center and the reaction mechanism remain to be investigated. In addition, we determined the crystal structure for Ni[S(2)C(2)(CF(3))(2)](2). The molecule crystallizes in the P2(1)/n space group and adopts a planar geometry with expected bond lengths and angles. Comparing this structure with that for the donor-acceptor complex with perylene reveals elongation of both the Ni-S and the S-C bonds in the latter, suggesting reduction of Ni[S(2)C(2)(CF(3))(2)](2) may have occurred in the latter.