Carbenoid Polycondensation

Structure of a reactive gold carbenoid.

A formal gold-for-chromium transmetalation allowed the gold carbenoid species [Cy3 PAuCAr2 ]NTf2 (11) (Ar=pMeOC6 H4 -) to be obtained in crystalline form. The structure in the solid state suggests that there is only little back donation of electron density from gold to the carbene center of 11 and hence very modest AuC double-bond character; rather, it is the organic ligand framework that is r...

Nickel (0) Catalyzed Kumada Chain Transfer Polycondensation

Fast screening of polycondensation catalyst, Determination of the kinetic data of catalyzed polycondensation in polyethylene terephthalate synthesis

Differential scanning calorimetry (DSC) belongs to the family of thermal analysis methods. In general thermal analysis is the determination of substance properties in dependence on temperature. Thermodynamic data (heat capacity, phase transition, enthalpy) and kinetic data can be determined by methods of thermal analysis. The greatest advantage of thermal analysis is the easy handling and the o...

Gold Carbene or Carbenoid: Is There a Difference?

By reviewing the recent progress on the elucidation of the structure of gold carbenes and the definitions of metal carbenes and carbenoids, we recommend to use the term gold carbene to describe gold carbene-like intermediates, regardless of whether the carbene or carbocation extreme resonance dominates. Gold carbenes, because of the weak metal-to-carbene π-back-donation and their strongly elect...

Titanium carbenoid-mediated cyclopropanation of allylic alcohols: selectivity and mechanism.

A new method for the chemo- and stereoselective conversion of allylic alcohols into the corresponding cyclopropane derivatives has been developed. The cyclopropanation reaction was carried out with an unprecedented titanium carbenoid generated in situ from Nugent's reagent, manganese and methylene diiodide. The reaction involving the participation of an allylic hydroxyl group, proceeded with co...