Expedient synthesis of N-acyl anthranilamides and β-enamine amides by the Rh(III)-catalyzed amidation of aryl and vinyl C-H bonds with isocyanates

A Rh(III)-catalyzed protocol for the amidation of anilide and enamide C-H bonds with isocyanates has been developed. This method provides direct and efficient syntheses of N-acyl anthranilamides, enamine amides, and pyrimidin-4-one heterocycles.     

Generation of [(IPr)Pd(PR2Cl)] complexes via P-Cl reductive elimination

Treatment of [(IPr)Pd(Cl)(2)(PR(2)H)] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; R = Cy, tBu, or 1-Ad) with NaN(SiMe(3))(2) generated isolable [(IPr)Pd(PR(2)Cl)] complexes (68-75%) that have been crystallographically characterized. The formation of these mixed-ligand Pd(0) species in this manner corresponds to an unusual net dehydrohalogenation/P-Cl reductive elimination sequence.     

Zwitterionic Relatives of Cationic Platinum Group Metal Complexes: Applications in Stoichiometric and Catalytic σ‐Bond Activation

Zwitterionic platinum group metal complexes that feature formal charge separation between a cationic metal fragment and a negatively charged ancillary ligand combine the desirable reactivity profile of related cationic complexes with the broad solubility and solvent tolerance of neutral species. As such, zwitterionic complexes of this type have emerged as attractive candidates for a diversity of applications, most notably involving the breaking and/or forming of E? H and E? C σ bonds involving a main group element E. Important advances in ancillary ligand design are documented that have enabled the construction of platinum group metal zwitterions. Also summarized are the results of stoichiometric and catalytic investigations in which the reactivity of such zwitterions and their more traditionally employed cationic relatives in σ bond activation chemistry are compared and contrasted.     

Elastic steric stabilization of polyethylene-asphalt emulsions by using low molecular weight polybutadiene and devulcanized rubber tire

Emulsions containing 3% polyethylene were stabilized against coalescence in an asphalt medium by low molecular weight virgin polybutadiene and recycled styrene-butadiene stabilizers. The recycled styrene-butadiene steric stabilizer precursor was obtained as a thermo-mechanical devulcanized ground rubber tire in asphalt. The low molecular weight butadiene and styrenebutadiene rubbers were in situ reacted with sulfur in order to increase the compatibility of the stabilizer with the asphalt phase.Because of the high molar volume of the asphalt phase and the similarity in contact energy between stabilizer and matrix phase, it is assumed that the stabilization is caused by entropic effects only. The fundamental aspects of elastic stabilization of polyethylene-asphalt emulsions are discussed. The total interaction free energy profile between the polyethylene particles shows that the efficiency of the steric stabilizer formation reaction can be improved significantly.The use of devulcanized rubber tire as a replacement for the virgin polybutadiene precursor in the in situ stabilization process can significantly reduce the cost of the technology.