Aim To analyze the fragmentation patterns of diquaternary dipiperaziniumscontaining dithiocarboxyl groups. Methods Positive ion electrospray ionization mass spectrometry inconjunction with tandem mass spectrometry (ES...Aim To analyze the fragmentation patterns of diquaternary dipiperaziniumscontaining dithiocarboxyl groups. Methods Positive ion electrospray ionization mass spectrometry inconjunction with tandem mass spectrometry (ESI-MS^n) was used. Results The fragment ion [M^(2+) Cl^-]^+ showed characteristic double peaks with high intensity instead of the parent molecular ionbeing detected. And [M^(2+) - CH_3^+ ]^+ ion had relatively low intensity. Meanwhile, [M^(2+) Cl^- -Cl^- - PhCH_2^+ ]^+ species had the highest intensity as the base peak, which was originated from[M^(2+) Cl^- ]^+, The detailed fragmentation mechanisms are supported with the tandem massspectrometry.展开更多
A series of multi-hydroxyl bis-(quaternary ammonium)ionic liquids(Ils1‒7)was prepared as bifunctional catalysts for the chemical fixation of CO_(2).All these ionic liquid compounds were efficient for the catalytic syn...A series of multi-hydroxyl bis-(quaternary ammonium)ionic liquids(Ils1‒7)was prepared as bifunctional catalysts for the chemical fixation of CO_(2).All these ionic liquid compounds were efficient for the catalytic synthesis of cyclic carbonates and oxazolidinones via the cycloaddition reactions between CO_(2) and epoxides or aziridines with excellent yield and high selectivity in the absence of co-catalyst,metal and solvent.Due to the synergistic effects of hydroxyl groups and halogen anion,the cycloaddition reactions proceeded smoothly either at atmospheric pressure or room temperature.The selectivity for substituted oxazolidinones at 5-and 4-positions can be tuned via changing the reaction conditions.Finally,possible mechanisms including the activation of both CO_(2) and epoxide or aziridines were proposed based on the literatures and experimental results.展开更多
文摘Aim To analyze the fragmentation patterns of diquaternary dipiperaziniumscontaining dithiocarboxyl groups. Methods Positive ion electrospray ionization mass spectrometry inconjunction with tandem mass spectrometry (ESI-MS^n) was used. Results The fragment ion [M^(2+) Cl^-]^+ showed characteristic double peaks with high intensity instead of the parent molecular ionbeing detected. And [M^(2+) - CH_3^+ ]^+ ion had relatively low intensity. Meanwhile, [M^(2+) Cl^- -Cl^- - PhCH_2^+ ]^+ species had the highest intensity as the base peak, which was originated from[M^(2+) Cl^- ]^+, The detailed fragmentation mechanisms are supported with the tandem massspectrometry.
文摘A series of multi-hydroxyl bis-(quaternary ammonium)ionic liquids(Ils1‒7)was prepared as bifunctional catalysts for the chemical fixation of CO_(2).All these ionic liquid compounds were efficient for the catalytic synthesis of cyclic carbonates and oxazolidinones via the cycloaddition reactions between CO_(2) and epoxides or aziridines with excellent yield and high selectivity in the absence of co-catalyst,metal and solvent.Due to the synergistic effects of hydroxyl groups and halogen anion,the cycloaddition reactions proceeded smoothly either at atmospheric pressure or room temperature.The selectivity for substituted oxazolidinones at 5-and 4-positions can be tuned via changing the reaction conditions.Finally,possible mechanisms including the activation of both CO_(2) and epoxide or aziridines were proposed based on the literatures and experimental results.
