The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly activ...The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly active to the polymerization and give high molecular weight polymers. (HNMR)-H-1 spectra and DSC measurement suggest the polymerization is free of decarboxylation. Mechanism study shows that the monomer insertion is via the break of acyl-oxygen bond of DTC.展开更多
The poly（2,2-dimethyltrimethylene carbonate） （PDTC） with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences...The poly（2,2-dimethyltrimethylene carbonate） （PDTC） with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences of monomer/initiator molar ratio, temperature and reaction time on polymerization of DTC were investigated. Under the condition： [DTC]/[I] = 500, 55℃, toluene： 0.5 mL, DTC： 0.6 g, PDTC with Mn = 15600 and PDI = 2.15 was obtained. Through 1H-NMR and 13C-NMR analyses, the structure of PDTC was characterized and a coordination-insertion mechanism was proposed. In addition, the random copolymerization of DTC and caprolactone （CL） initiated by rare-earth borohydride compound was studied. The microstructure of PDTC-co-PCL includes four diads： DTC-CL, CL-CL, DTC-DTC and CL- DTC, which were determined by the specific signals in lH-NMR spectra. Based on the typical signals of the formate （δ = 8.08） and hydroxyl （δ= 3.34） end groups of PDTC-co-PCL, a mechanism involving DTC monomer inserts before CL during the initiation process was presumed. Furthermore, the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry （DSC）. The results support the random structure of PDTC-co-PCL.展开更多
The biphenol based discrete ion-pair rare earth complexes, [Ln（EDBP）2（DME）Na（DME）3] [Ln = Er（1）, Yb（2）, Sm（3）], were prepared and used as catalysts for the ring-opening polymerization （ROP） of 2,2-dimeth...The biphenol based discrete ion-pair rare earth complexes, [Ln（EDBP）2（DME）Na（DME）3] [Ln = Er（1）, Yb（2）, Sm（3）], were prepared and used as catalysts for the ring-opening polymerization （ROP） of 2,2-dimethyltrimethylene carbonate （DTC）. Three complexes show moderate activities for the polymerization, and the catalytic activities increase in the following sequence： （Yb 〈 Er 〈 Sm）. The effect of different ratios of [DTC]/[Ln], polymerization temperature and time on the polymerization was investigated. Moreover, PDTC without ether unit developed from possible CO2 elimination was prepared.展开更多
Single component rare earth aryl oxides substituted by various alkyl groups [Ln(OAr)3] such as methyl,isopropyl,and tertbutyl have been developed to initiate the ring-opening polymerization of 2,2-dimethyltrimethylene...Single component rare earth aryl oxides substituted by various alkyl groups [Ln(OAr)3] such as methyl,isopropyl,and tertbutyl have been developed to initiate the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate(DTC).The catalytic activity of rare earth aryl oxides,characteristics of the ring-opening polymerization as well as the polymerization kinetics and mechanism were intensively examined.The experimental results turn out that the catalytic activity of Ln(OAr)3 changes in good concordance with variation of ligands' structure and number of alkyl groups on benzene ring.The greater the ability of electron-donation of alkyl groups,the greater the catalytic activity.Moreover,the greater the number of substituted alkyls on benzene ring,the greater the catalytic activity.The results show that rare earth tris(2,4,6-tri-tert-butylphenolate)s [Ln(OTTBP)3](Catalyst 1) exhibit rather great activity in all lanthanide aryl oxides.Investigations of the polymerization mechanism by 1H NMR spectroscopy revealed that the DTC monomer inserted into the growing chains with acyloxygen bond cleavage.展开更多
Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethylt...Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.展开更多
The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently p...The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently protected the hepatocytes against carbon tetrachloride (CC14 10 mrnol.L-1) and D-galactosamine (1 mmol.L-1) induced damages. Membranal lipid peroxidation (malondialdehyde, MDA formation) and glutamic pyruvic transaminase (GPT) release from the hepatocytes were markedly decreased. The damage of the cell surfaces of the hepatocytes were also reduced as seen under a scanning electron microscope (SEM). Pretreatment with DDB (300 mg-kg-1) orally ameliorated the reduction of liver glycogen and blood glucose caused by ip injection of D-galactosamine (800 mg-kg-1) in mice. When normal rats were given DDB 300 mg-kg-1 once daily for 10 d, the free ribosomal protein and RNA in the liver increased significantly. These results indicate that DDB is of beneficial effects on both damaged and normal hepatocytes.展开更多
N-chloro-2,2-dichloroacetamide(N-Cl-DCAM)is an emerging nitrogenous disinfection by-product(N-DBP)which can occur in drinking water.In this study,an analytical method based on liquid chromatography with tandem mass sp...N-chloro-2,2-dichloroacetamide(N-Cl-DCAM)is an emerging nitrogenous disinfection by-product(N-DBP)which can occur in drinking water.In this study,an analytical method based on liquid chromatography with tandem mass spectrometry(LC-MS/MS)was developed to validate the concentration of N-Cl-DCAM,which was found to be 1.5µg/L in the effluent of a waterworks receiving raw water from Taihu Lake,China.The changes of N-Cl-DCAM formation potential(N-Cl-DCAMFP)in the drinking water treatment process and the removal efficiency of its precursors in each unit were evaluated.Non-polar organics accounted for the majority of N-Cl-DCAM precursors,accounting for 70%of the N-Cl-DCAM FP.The effect of conventional water treatment processes on the removal of N-Cl-DCAM precursors was found to be unsatisfactory due to their poor performance in the removal of low molecular weight(MW)or non-polar organics.In the ozonation integrated with biological activated carbon(O_(3)-BAC)process,the ozonation had little influence on the decrease of N-Cl-DCAM FP.The removal efficiency of precursors by a new BAC filter,in which the granular activated carbon(GAC)had only been used for four months was higher than that achieved by an old BAC filter in which the GAC had been used for two years.The different removal efficiencies of precursors were mainly due to the different adsorption capacities of GAC for individual precursors.Low MW or non-polar organics were predominantly removed by GAC,rather than biodegradation by microorganisms attached to GAC particles.展开更多
文摘The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly active to the polymerization and give high molecular weight polymers. (HNMR)-H-1 spectra and DSC measurement suggest the polymerization is free of decarboxylation. Mechanism study shows that the monomer insertion is via the break of acyl-oxygen bond of DTC.
基金supported by the National Natural Science Foundation(Nos.20674071,20774078)the Special Funds for Major State Basic Research Projects(No.2005CB623802)
文摘The poly（2,2-dimethyltrimethylene carbonate） （PDTC） with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences of monomer/initiator molar ratio, temperature and reaction time on polymerization of DTC were investigated. Under the condition： [DTC]/[I] = 500, 55℃, toluene： 0.5 mL, DTC： 0.6 g, PDTC with Mn = 15600 and PDI = 2.15 was obtained. Through 1H-NMR and 13C-NMR analyses, the structure of PDTC was characterized and a coordination-insertion mechanism was proposed. In addition, the random copolymerization of DTC and caprolactone （CL） initiated by rare-earth borohydride compound was studied. The microstructure of PDTC-co-PCL includes four diads： DTC-CL, CL-CL, DTC-DTC and CL- DTC, which were determined by the specific signals in lH-NMR spectra. Based on the typical signals of the formate （δ = 8.08） and hydroxyl （δ= 3.34） end groups of PDTC-co-PCL, a mechanism involving DTC monomer inserts before CL during the initiation process was presumed. Furthermore, the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry （DSC）. The results support the random structure of PDTC-co-PCL.
基金supported by the National Natural Science Foundation(No.20674071)the Special Funds for Major State Basic Research Projects(No.2005CB623802)
文摘The biphenol based discrete ion-pair rare earth complexes, [Ln（EDBP）2（DME）Na（DME）3] [Ln = Er（1）, Yb（2）, Sm（3）], were prepared and used as catalysts for the ring-opening polymerization （ROP） of 2,2-dimethyltrimethylene carbonate （DTC）. Three complexes show moderate activities for the polymerization, and the catalytic activities increase in the following sequence： （Yb 〈 Er 〈 Sm）. The effect of different ratios of [DTC]/[Ln], polymerization temperature and time on the polymerization was investigated. Moreover, PDTC without ether unit developed from possible CO2 elimination was prepared.
基金support from the Natural Science Foundation of Shanxi Province (Grant No 2006011069)the Opening Foundation of Key Laboratory of Shanxi Province (Grant No 2009011059-7)
文摘Single component rare earth aryl oxides substituted by various alkyl groups [Ln(OAr)3] such as methyl,isopropyl,and tertbutyl have been developed to initiate the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate(DTC).The catalytic activity of rare earth aryl oxides,characteristics of the ring-opening polymerization as well as the polymerization kinetics and mechanism were intensively examined.The experimental results turn out that the catalytic activity of Ln(OAr)3 changes in good concordance with variation of ligands' structure and number of alkyl groups on benzene ring.The greater the ability of electron-donation of alkyl groups,the greater the catalytic activity.Moreover,the greater the number of substituted alkyls on benzene ring,the greater the catalytic activity.The results show that rare earth tris(2,4,6-tri-tert-butylphenolate)s [Ln(OTTBP)3](Catalyst 1) exhibit rather great activity in all lanthanide aryl oxides.Investigations of the polymerization mechanism by 1H NMR spectroscopy revealed that the DTC monomer inserted into the growing chains with acyloxygen bond cleavage.
基金Supported by the National Natural Science Foundation of China (Grant no. 20434020)the Special Fund for Major State Basic Research Project (Grant No. G2005CB623802)the Committee of Science and Technology of Zhejiang Prov-ince
文摘Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.
文摘The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently protected the hepatocytes against carbon tetrachloride (CC14 10 mrnol.L-1) and D-galactosamine (1 mmol.L-1) induced damages. Membranal lipid peroxidation (malondialdehyde, MDA formation) and glutamic pyruvic transaminase (GPT) release from the hepatocytes were markedly decreased. The damage of the cell surfaces of the hepatocytes were also reduced as seen under a scanning electron microscope (SEM). Pretreatment with DDB (300 mg-kg-1) orally ameliorated the reduction of liver glycogen and blood glucose caused by ip injection of D-galactosamine (800 mg-kg-1) in mice. When normal rats were given DDB 300 mg-kg-1 once daily for 10 d, the free ribosomal protein and RNA in the liver increased significantly. These results indicate that DDB is of beneficial effects on both damaged and normal hepatocytes.
基金the National Natural Science Foundation of China(Grant No.51978238)the Science and Technology Development Plans of Ministry of Housing and Urban-Rural Development(2020-K-036)+1 种基金the Six Talent Peaks Project in Jiangsu Province(JNHB-004)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘N-chloro-2,2-dichloroacetamide(N-Cl-DCAM)is an emerging nitrogenous disinfection by-product(N-DBP)which can occur in drinking water.In this study,an analytical method based on liquid chromatography with tandem mass spectrometry(LC-MS/MS)was developed to validate the concentration of N-Cl-DCAM,which was found to be 1.5µg/L in the effluent of a waterworks receiving raw water from Taihu Lake,China.The changes of N-Cl-DCAM formation potential(N-Cl-DCAMFP)in the drinking water treatment process and the removal efficiency of its precursors in each unit were evaluated.Non-polar organics accounted for the majority of N-Cl-DCAM precursors,accounting for 70%of the N-Cl-DCAM FP.The effect of conventional water treatment processes on the removal of N-Cl-DCAM precursors was found to be unsatisfactory due to their poor performance in the removal of low molecular weight(MW)or non-polar organics.In the ozonation integrated with biological activated carbon(O_(3)-BAC)process,the ozonation had little influence on the decrease of N-Cl-DCAM FP.The removal efficiency of precursors by a new BAC filter,in which the granular activated carbon(GAC)had only been used for four months was higher than that achieved by an old BAC filter in which the GAC had been used for two years.The different removal efficiencies of precursors were mainly due to the different adsorption capacities of GAC for individual precursors.Low MW or non-polar organics were predominantly removed by GAC,rather than biodegradation by microorganisms attached to GAC particles.
