On selection criteria for problems with moving inhomogeneities

We study mechanical problems with multiple solutions and introduce a thermodynamic framework to formulate two different selection criteria in terms of macroscopic energy productions and fluxes. Simple examples for lattice motion are then studied to compare the implications for both resting and moving inhomogeneities.     

Controlled nitroxide‐mediated radical polymerization of methyl and phenyl vinyl ketone

The article describes unprecedented nitroxide‐mediated radical polymerization of methyl and phenyl vinyl ketone (MVK and PVK) using a sterically highly hindered alkoxyamine as initiator/regulator. It is shown that controlled polymerization of PVK is far more difficult to achieve than controlled MVK polymerization. Whereas for MVK high conversion resulting in polyvinyl ketone with low polydispersity index is readily obtained, the PVK polymerization provides good results only in the presence of free nitroxide and styrene as additives. Vinyl ketone polymerizations are analyzed by ESI mass spectrometry. These MS studies provide insights into the problems associated with the controlled nitroxide‐mediated polymerization of PVK. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Metal‐Free Activation of a C(sp)−H Bond of Aryl Acetylenes

C(sp)?H Bond activation of acetylene molecule still remains a challenge for synthetic organic chemists. In practice, acetylenes are activated by strong bases and metals. The first example for activating acetylenic protons under base and metal‐free conditions is reported here. It involves a general method for synthesizing propargylic derivatives of cotarnine. An array of tetrahydroisoquinolines alkaloids was synthesized by C(sp)?H bond activation of aromatic acetylenes with cotarnine at room temperature. A DFT‐based mechanism is proposed for the reaction.