Silver-catalyzed unstrained C(CO)–alkyl bond scission via[3+2]/retro-[3+2]cycloaddition of ketones with N-isocyanoiminotriphenylphosphorane

C(CO)–alkyl bonds are ubiquitous in a variety of organic molecules,and their selective activation and functionalization are important for the reconstruction of simple ketones into valuable building blocks.However,due to the thermodynamic and kinetic stability,the cleavage and transformation of the unstrained C(CO)–alkyl bonds remain a significant challenge.Herein,we report a novel silver-catalyzed scission of the unstrained C(CO)–alkyl bond of ketones by reacting with N-isocyanoiminotriphenylphosphorane(NIITP)under mild conditions.This method could transform a variety of unstrained ketones into iminophosphoranes and nitriles in high yields.Experimental and computational studies disclosed the reaction proceeded through an unprecedented[3+2]/retro-[3+2]cycloaddition mechanism.

Silver-catalyzed three-component reaction: synthesis of N^2-substituted 1,2,3-triazoles via direct benzylic amination

A novel Ag(Ⅰ)-catalyzed benzylic amination reaction with in situ generation of NH-1,2,3-triazoles for N^2-substituted 1,2,3 triazole scaffolds is described. This protocol is achieved with easily accessible substrate, broad functional group, good re gioselectivity, thus providing the efficient and practical method to diverse N^2-substituted 1,2,3-triazole rings with moderate t good yields.

Preparation of chloro-functionalized reduced graphene oxide by silver-catalyzed radical reaction

It is well-known that chemical functionalization of graphene has the great significance.We report the development of a new synthesis method of chloro-functionalized reduced graphene oxide（rGOCl）.The rGOCl was prepared by radical reaction,and treatment of carboxyl graphene oxide（GOCOOH） with N-chlorosuccinimide（NCS） at 90℃ for 10 h under an atmosphere of nitrogen,using silver nitrate as catalyst.The morphologies and structures of the prepared materials were investigated by field-emission scanning electron microscopy（FESEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FTIR）,Raman spectroscopy and the thermal gravimetric.Results indicated that the rGOCl can be readily obtained from graphene oxide（GO） in three steps.

Mechanism of silver-influenced bacterial leaching of chalcopyrite, pyrite and a copper ore

The silver catalyzed bioleaching of chalcopyrite, pyrite and a chalcopyrite containing ore from Dexing Copper Mine (China) was investigated. It has been found that silver ions selectively accelerated the rate of copper dissolution from the ore while suppressed the iron leaching. Adding 2.0 g Ag per kg mineral, the copper recovery from chalcopyrite increased from 29.2% (without a catalyst) up to 78.4%, while the iron recovery decreased from 51.0% (no silver) to 27.4%, in the presence of microorganisms. It is believed that the enhancement of chalcopyrite bioleaching by Ag + ions is attributed to the formation of an intermediate, Ag 2S, which was confirmed by X ray diffraction of the solid leach residue of chalcopyrite and the analyses of the cyclic voltammetry for CuFeS 2 electrodes in silver containing 9 K medium. The inhibition of pyrite biooxidation is owing to the formation of metallic silver on the pyrite surface instead of Ag 2S, which was detected by X ray photoelectron spectroscopy (XPS).