The relative basicity of trioctylamine （TOA）, pKa,BS, in protic polar diluent （1-octanol）, non-protic polar diluent [methyl iso-butyl ketone （MIBK）] and inert diluent （CCl4） were determined for 11 mono-carboxy...The relative basicity of trioctylamine （TOA）, pKa,BS, in protic polar diluent （1-octanol）, non-protic polar diluent [methyl iso-butyl ketone （MIBK）] and inert diluent （CCl4） were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted （acidity and hydrophobicity）, pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium （K11） and the system properties （PKa,BS and pKa） was proposed： 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.展开更多
The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐...The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.展开更多
A new aristololactam, aristololactam Ⅶ （1）, was isolated from the root and rhizome of Asarum maximum Hemsl. On the basis of spectroscopic analysis, its structure was identified as 10-amino-7,8-dimethoxy-3,4-methyle...A new aristololactam, aristololactam Ⅶ （1）, was isolated from the root and rhizome of Asarum maximum Hemsl. On the basis of spectroscopic analysis, its structure was identified as 10-amino-7,8-dimethoxy-3,4-methylenedioxy-phenanthrene-1- earboxylie acid laetam.展开更多
An oxidative amidation of tertiary amines with carboxylic acids has been developed in the presence of FeC13- 6H20 as catalyst and oxygen as oxidant. A variety of tertiary amides were obtained in good to excellent yiel...An oxidative amidation of tertiary amines with carboxylic acids has been developed in the presence of FeC13- 6H20 as catalyst and oxygen as oxidant. A variety of tertiary amides were obtained in good to excellent yields from inexpensive and readily available reagents. The possible reaction pathways were investigated.展开更多
Carboxylate as a promising and valuable directing group has attracted a great deal of attention.However,employing it as a traceless direction group has rarely been reported.We developed the ruthenium-catalyzed amidati...Carboxylate as a promising and valuable directing group has attracted a great deal of attention.However,employing it as a traceless direction group has rarely been reported.We developed the ruthenium-catalyzed amidation of substituted benzoic acids with isocyanates via directed C–H functionalization followed by decarboxylation to afford the corresponding metasubstituted N-aryl benzamides,in which the carboxylate serves as a unique,removable directing group.Notably,this protocol can provide an efficient alternative to access meta-substituted N-aryl benzamides,which are much more difficult to prepare than ortho-substituted analogues.展开更多
The electrochemical behavior of nanodiamond （ND） film functionalized with carboxylic acid groups was studied systemati- cally on a glassy carbon （GC） electrode. One stable redox couple corresponding to the carboxy...The electrochemical behavior of nanodiamond （ND） film functionalized with carboxylic acid groups was studied systemati- cally on a glassy carbon （GC） electrode. One stable redox couple corresponding to the carboxylic acid group was observed. At the scan rate of 0.1 V/s, the cathodic and anodic peak potentials were -0.093 V and 0.088 V （vs. Ag/AgCI）, respectively. The carboxylic acid groups on the ND surface were reduced to CH2OH via a four electron redox process. The ND film modified electrode showed favorable electrocatalytic behavior toward the oxidation as well as the reduction of biomolecules, such as tryptophan and nicotinamide adenine dinucleotide.展开更多
基金Supported by the National Natural Science Foundation of China (No. 29836130).
文摘The relative basicity of trioctylamine （TOA）, pKa,BS, in protic polar diluent （1-octanol）, non-protic polar diluent [methyl iso-butyl ketone （MIBK）] and inert diluent （CCl4） were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted （acidity and hydrophobicity）, pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium （K11） and the system properties （PKa,BS and pKa） was proposed： 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.
文摘The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.
基金National Natural Science Foundation of China (Grant No. 30371748)the 985 Project of Peking University and the National Eleventh Five-year Key Technologies R&D Program of China (Grant No. 2006BAI14B01)
文摘A new aristololactam, aristololactam Ⅶ （1）, was isolated from the root and rhizome of Asarum maximum Hemsl. On the basis of spectroscopic analysis, its structure was identified as 10-amino-7,8-dimethoxy-3,4-methylenedioxy-phenanthrene-1- earboxylie acid laetam.
基金financially supported by the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(10XNL017)
文摘An oxidative amidation of tertiary amines with carboxylic acids has been developed in the presence of FeC13- 6H20 as catalyst and oxygen as oxidant. A variety of tertiary amides were obtained in good to excellent yields from inexpensive and readily available reagents. The possible reaction pathways were investigated.
基金supported by the National Natural Science Foundation of China(20906059,21272145)the Shaanxi Innovative Team of Key Science and Technology(2013KCT-17)+1 种基金the Fundamental Research Funds for the Central Universities(GK201503030,GK261001095)the 111 Project,and Canada Research Chair(to CJL)
文摘Carboxylate as a promising and valuable directing group has attracted a great deal of attention.However,employing it as a traceless direction group has rarely been reported.We developed the ruthenium-catalyzed amidation of substituted benzoic acids with isocyanates via directed C–H functionalization followed by decarboxylation to afford the corresponding metasubstituted N-aryl benzamides,in which the carboxylate serves as a unique,removable directing group.Notably,this protocol can provide an efficient alternative to access meta-substituted N-aryl benzamides,which are much more difficult to prepare than ortho-substituted analogues.
基金sponsored by the National Natural Science Foundation of China (21075136)
文摘The electrochemical behavior of nanodiamond （ND） film functionalized with carboxylic acid groups was studied systemati- cally on a glassy carbon （GC） electrode. One stable redox couple corresponding to the carboxylic acid group was observed. At the scan rate of 0.1 V/s, the cathodic and anodic peak potentials were -0.093 V and 0.088 V （vs. Ag/AgCI）, respectively. The carboxylic acid groups on the ND surface were reduced to CH2OH via a four electron redox process. The ND film modified electrode showed favorable electrocatalytic behavior toward the oxidation as well as the reduction of biomolecules, such as tryptophan and nicotinamide adenine dinucleotide.
