ABSTRACT
Three synthetic routes to 5-substituted 1,3-diazacyclohexane derivatives 1 are reported. The first method involves treatment of 1, 3-diaminopropan-2-ol 2 with paraformaldehyde to yield 5-hydroxy-1, 3-diazacyclohexane 3. A second method is based on the condensation of 2-bromo-2-nitro-1,3-propanediol with tert-butylamine and formaldehyde to yield 1,3-di-tert-butyl-5-bromo-5-nitro-1, 3-diazacyclohexane 22. The third method relies on the cycloalkylation of methylenebisacetamide with 3-chloro-2-chloromethyl-2-propene to provide 5-exomethylene-1, 3-diacetyl-1,3-diazacyclohexane 28. Functional group manipulations of 3, 22, and 28 provide a number of novel 1,3-diazacyclohexanes functionalized at the 5-position.
ABSTRACT
Chalcopyrite in contact with water is thermodynamically unstable in the presence of oxygen. Oxidation of chalcopyrite may take place due to various factors, e.g., geological environment, mining/comminution, and storage. In this work oxidation of chalcopyrite has been investigated through interfacial electrokinetics. The characteristics of samples obtained from different geological locations as well as the effects of ageing and laboratory oxidation have been delineated. Variation of the solid-liquid ratio was found to have a significant effect on the zeta-potential characteristics of chalcopyrite. The role of constituent metal ions, namely copper and iron, has been studied in the absence and presence of externally added metal ions. The results indicated that the ratio of Cu/Fe on the surface of oxidized chalcopyrite determines the Stern layer potential and under appropriate solution chemistry conditions influences charge reversals. The mineral surfaces, thus, could be either copper-rich or iron-rich as reflected by a shift in pHiep(s). The observed charge reversals have been explained on the basis of a model proposed by James and Healy. Copyright 1997 Academic Press. Copyright 1997Academic Press
