No abstract

Epoxidation of styrene under heterogeneous catalyzed conditions provides environmentally friendly routes to produce styrene oxide, an important synthetic intermediate for synthesis of perfumes, epoxy resins, plasticizers, drugs, sweeteners and fine chemicals. The present review explores epoxidation of styrene under heterogeneous catalysed conditions using a variety of catalysts such as metal nanoparticles, metal oxides (of group 12 and 13 metals, transition metals, rare earth metals), transition metals and complexes, polyoxometallates, microporous and mesoporous materials (zeolites, modified zeolites, organic/inorganic porous hybrid materials, porous metal oxides, SBA 15) and polymers using hydrogen peroxide (H2O2), tert‐butyl hydroperoxide (TBHP), air or oxygen as oxidants.The use of salen based transition metal complexes and of chiral porphyrins as catalysts in asymmetric epoxidation of styrene is also reviewed. The reaction mechanism studies of most of these reactions suggest an intermediate formation of a reactive metal‐oxygen species, by interactions between the catalyst and oxidant.

BackgroundCentral Nervous System (CNS) lymphoma is a rare presentation of post-transplantation lymphoproliferative disorder (PTLD).MethodsThis single center retrospective study reviewed presentations, management and outcomes of CNS lymphomas in kidney transplant patients transplanted 1968 to 2015, and reviews relevant current literature.ResultsWe identified 5773 adult kidney transplant recipients of who 90 had a PTLD diagnosis confirmed. CNS disease was diagnosed in 6/90 (7%). Median age at presentation was 60 years and time from transplant 4.5 years. Immunosuppression at diagnosis included mycophenolate mofetil and prednisolone without calcineurin inhibitor in 5/6 patients. Histological analysis diagnosed monomorphic disease in 5/6, and one polymorphic case with tissue positive for Epstein-barr virus (EBV) in 5/6 cases. Despite this 2/4 EBV positive cases had no detectable EBV in peripheral blood or CSF at diagnosis. Treatment strategies included reduction in immunosuppression in all, chemotherapy (n=5), radiotherapy (n=3), Cytotoxic T-Lymphocytes and Craniotomy (n=2). Patient survival was 40% at 1 year with CTL treated patients surviving beyond three years from diagnosis.ConclusionThis study supports observational data suggesting MMF treated patients without CNI may have increased risk of disease. Peripheral blood screening for EBV DNAemia does not seem helpful in early identification of those at risk.

Zn­(NCO)2·2NH3 catalyst has been synthesized, characterized by X-ray diffraction and IR spectroscopy, and used as a catalyst for the cyclization of urea and ethylene glycol (EG) to ethylene carbonate (EC) for the first time. A maximum yield of 40% has been obtained with a urea/EG mole ratio of 1:1.5 and a temperature of 150 ± 2 °C. An attempt has been made to predict the mechanism of the reaction with the help of density functional theory calculations. Our calculations suggest the reaction to be a consecutive one. In the first step, urea decomposes to ammonia and isocyanic acid (HNCO). HNCO reacts with EG to produce 2-hydroxyethyl carbamate (2-HEC). At the last step, 2-HEC cyclizes over Zn­(NCO)2·2NH3 to EC. Calculations suggest the cyclization of 2-HEC to follow a charge-controlled intramolecular nucleophilic elimination cyclization path.