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Liu, Di,Bielawski, Christopher W John Wiley Sons, Ltd 2017 Polymer international Vol.66 No.1
<P><B>Abstract</B></P><P>Azido‐functionalized isotactic polypropylene was prepared via the direct CH azidation of a commercially available polymer using a stable azidoiodinane. Including imidazole or benzimidazole in the reaction mixture was found to significantly improve the yields of the post‐polymerization modification. Although chain cleavage was observed, the methodology afforded high‐molecular‐weight (<I>M</I><SUB>w</SUB> > 100 kDa) functionalized polypropylene containing up to 3 mol% of azido groups and enabled access to polypropylene‐<I>graft</I>‐poly(ethylene glycol) copolymers via azide–alkyne cycloaddition chemistry. © 2016 Society of Chemical Industry</P>
Ionic Liquid Crystals: Versatile Materials
Goossens, Karel,Lava, Kathleen,Bielawski, Christopher W.,Binnemans, Koen American Chemical Society 2016 Chemical reviews Vol.116 No.8
<P>This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the 'state-of-the-art' in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.</P>
Burgess Reagent Facilitated Alcohol Oxidations in DMSO
Sultane, Prakash R.,Bielawski, Christopher W. American Chemical Society 2017 Journal of organic chemistry Vol.82 No.2
<P>The Burgess reagent ([methoxycarbonylsulfamoyl]triethylammonium hydroxide) has historically found utility as a dehydrating agent. Herein we show that, in the presence of dimethyl sulfoxide, the Burgess reagent efficiently and rapidly facilitates the oxidation of a broad range of primary and secondary alcohols to their corresponding aldehydes and ketones in excellent yields and under mild conditions, and can be combined with other transformations (e.g., Wittig olefinations). A mechanism similar to those described for the Pfitzner-Moffatt and Swern oxidations is proposed.</P>
Photoinitiated ring‐opening metathesis polymerization
Joo, Wontae,Chen, Christopher H.,Moerdyk, Jonathan P.,Deschner, Ryan P.,Bielawski, Christopher W.,Willson, Carlton Grant John WileySons, Inc. 2019 Journal of polymer science Part A, Polymer chemist Vol.57 No.17
<P>This study is based on a latent ruthenium catalyst that includes a Schiff base moiety. This catalyst was formulated with a photoacid generator and a ring‐opening metathesis polymerization (ROMP) active monomer such as cyclooctadiene or dicyclopentadiene. Exposure of this mixture to ultraviolet light generates acid that protonates the Schiff base and thereby renders the latent catalyst active, leading to ROMP of the monomer. A resist system based on new photoinitiated ROMP chemistry has been developed. This type of formulation has been used to produce high‐resolution replicas of a transparent mold by imprint lithography.</P>
( Stanfield Youngwon Lee ),( Christopher Bielawski ),정동영,강윤식,이명재,신희종,김미주,성영은 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1
Our work focused on determining if this outer Helmholtz plane reaction does indeedexist and play a significant role in non-precious metal catalysts. A three electrode half-cell was used tomeasure the oxygen reduction reaction activity of a non-precious metal catalystin different alkaline electrolytes. Using electrolytes with different cations altered the hydration energyas well as block or increase access of oxygen to the outer Helmholtzplane. Correlations between hydrationshell size and catalytic activity were observed.
Metal-promoted C1 polymerizations
Cahoon, Collin R.,Bielawski, Christopher W. Elsevier 2018 Coordination chemistry reviews Vol.374 No.-
<P><B>Abstract</B></P> <P>C1 polymerizations provide a means to grow polymer chains one carbon atom at a time. Such methodology enables the synthesis of persubstituted polymers that are challenging to prepare using conventional C2 polymerizations, which typically utilize alkene-based monomers and thus grow polymer chains two carbons at a time. Persubstituted polymers feature higher densities of pendant functional groups and, as such, offer the potential to exhibit enhanced physical and/or chemical properties over their monosubstituted C2 polymer analogues. This review summarizes the various metals that have been used to promote C1 polymerizations in a catalytic or stoichiometric manner. Discussions are stratified according to the monomers used, which are formally carbenes or carbynes and typically employed as their respective ylides, isocyanides, diazo compounds, or geminal di- or trihalides. Emphasis is placed on the scope of the polymerization chemistry, underlying mechanisms, and outstanding opportunities in the field.</P> <P><B>Highlights</B></P> <P> <UL> <LI> C1 polymerizations offer access to highly substituted polymers. </LI> <LI> C1 polymers often exhibit unique properties due to the high densities of functional groups. </LI> <LI> Polymerizations of diazo compounds have been catalyzed by Cu, Au, Pd, and Rh. </LI> <LI> Polymerizations of isocyanides have been catalyzed by Ni, Co, Pd, and Rh. </LI> <LI> Polymerizations of geminal di- and trihalides have been promoted with Mg, Li, Zn, and Na/K. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Elucidating the Mechanism of Reversible Oxiranations via Magnetization Transfer Spectroscopy
Chase, Daniel T.,Moerdyk, Jonathan P.,Bielawski, Christopher W. American Chemical Society 2012 ORGANIC LETTERS Vol.14 No.21
<P>The reversible [2 + 1] cycloadditions between an <I>N</I>,<I>N</I>′-diamidocarbene (DAC) and eight aldehydes were examined using NMR spectroscopy. Variable temperature magnetization transfer experiments revealed higher exchange rates and lower activation barriers when electron-deficient aldehydes were employed. Likewise, competitive equilibrium studies indicated a thermodynamic preference for electron-deficient aryl and sterically unhindered alkyl aldehydes compared to more electron-rich or bulkier substrates. Collectively, these and other data collected were consistent with the oxiranation process proceeding in an asynchronous manner.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2012/orlef7.2012.14.issue-21/ol302596r/production/images/medium/ol-2012-02596r_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol302596r'>ACS Electronic Supporting Info</A></P>