The simple spectrophotometric method for the determination of esters has been developed. The procedure is based on the quantitative determination of ferric hydroxamate generated from the reaction of esters, hydroxylam...The simple spectrophotometric method for the determination of esters has been developed. The procedure is based on the quantitative determination of ferric hydroxamate generated from the reaction of esters, hydroxylamine hydrochloride in basic solution at 120℃, and ferric chloride. The formed complex was monitored through absorbance at 517 nm. The parameters affecting the absorbance value were explored for optimum analytical performance. The optimum conditions were 1.50 mL of 0.5 M hydroxylamine hydrochloride, 0.40 mL of 6 M sodium hydroxide, 1.00 mL of 3 M hydrochloric acid and 0.50 mL of 5 % ferric chloride. The method exhibits linear response up to 7.50% wt. and a detection limit of 0.23% wt. The linear range and working range were used at the same range 1.25 to 7.50% wt. The proposed method can be applied to biodiesel （B 100） for measuring the esters quantity in the percentage unit of biodiesel oil.展开更多
Rhodium(III)-catalyzed coupling between ketoximes and alkynes via C–H activation and annulation typically followed the[4+2]selectivity to afford isoquinolines.By designing alkynes bearing a highly electron-withdrawin...Rhodium(III)-catalyzed coupling between ketoximes and alkynes via C–H activation and annulation typically followed the[4+2]selectivity to afford isoquinolines.By designing alkynes bearing a highly electron-withdrawing group and under substrate control,we have successfully switched the selectivity of the coupling between oximes and alkynes to the alternative[3+2]annulation,leading to the efficient synthesis of indenamines.This process features good regioselectivity for both substrates,high efficiency,broad substrate scope,and excellent functional group tolerance.展开更多
文摘The simple spectrophotometric method for the determination of esters has been developed. The procedure is based on the quantitative determination of ferric hydroxamate generated from the reaction of esters, hydroxylamine hydrochloride in basic solution at 120℃, and ferric chloride. The formed complex was monitored through absorbance at 517 nm. The parameters affecting the absorbance value were explored for optimum analytical performance. The optimum conditions were 1.50 mL of 0.5 M hydroxylamine hydrochloride, 0.40 mL of 6 M sodium hydroxide, 1.00 mL of 3 M hydrochloric acid and 0.50 mL of 5 % ferric chloride. The method exhibits linear response up to 7.50% wt. and a detection limit of 0.23% wt. The linear range and working range were used at the same range 1.25 to 7.50% wt. The proposed method can be applied to biodiesel （B 100） for measuring the esters quantity in the percentage unit of biodiesel oil.
基金supported by the Dalian Institute of Chemical Physics,Chinese Academy of Sciencesthe National Natural Science Foundation of China(21472186,21272231)
文摘Rhodium(III)-catalyzed coupling between ketoximes and alkynes via C–H activation and annulation typically followed the[4+2]selectivity to afford isoquinolines.By designing alkynes bearing a highly electron-withdrawing group and under substrate control,we have successfully switched the selectivity of the coupling between oximes and alkynes to the alternative[3+2]annulation,leading to the efficient synthesis of indenamines.This process features good regioselectivity for both substrates,high efficiency,broad substrate scope,and excellent functional group tolerance.
