An efficient, transition-metal free, and practical approach to cis-bis(boryl)alkenes from various alkynes was disclosed in the presence of a catalytic amount of K_2CO_3 under mild conditions. Meanwhile, tetrasubstitut...An efficient, transition-metal free, and practical approach to cis-bis(boryl)alkenes from various alkynes was disclosed in the presence of a catalytic amount of K_2CO_3 under mild conditions. Meanwhile, tetrasubstituted alkenes and phenanthrene derivatives were readily constructed from the target diborylalkenes via Suzuki-Miyaura cross coupling.展开更多
The mechanical properties and phase morphologies of cis-1,4-butadiene rubber（BR） blended with polyethylene（PE） at different blend ratios were studied. The tensile test results show that the PE exhibits excellent r...The mechanical properties and phase morphologies of cis-1,4-butadiene rubber（BR） blended with polyethylene（PE） at different blend ratios were studied. The tensile test results show that the PE exhibits excellent reinforcing capabilities towards BR. Blending BR with PE results in a remarkable enhancement of tensile strength, modulus and the elongation at break simultaneously. An increment of tensile strength from 1.11 MPa to 16.26 MPa was achieved by incorporation of 40 wt% PE in the blends. The modulus and elongation at break of 40/60 PE/BR blends are also about 5 times higher than those of the pure BR treated under exactly the same conditions. The tear test indicates that the tear strength also increases with the increase of PE content. It reaches 58.38 MPa for the 40/60 PE/BR blend, which is approximately 10 times higher than that of the pure BR. Morphological study demonstrates that the PE forms elongated microdomains finely dispersed in the BR matrix when its content is over 30 wt%, which corresponds to the remarkably enhanced mechanical properties.According to the results, reinforcement mechanism of PE toward BR dependent on the microstructure has been discussed and two different mechanisms have been proposed.展开更多
（-）-7-Isopropyl-cis-l-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π- azaelectrocyclization, has been prepared previously by two methods. Each however involved using...（-）-7-Isopropyl-cis-l-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π- azaelectrocyclization, has been prepared previously by two methods. Each however involved using of one extreme condition, i.e. high temperature or high pressure, for the respective reaction. A modified reaction route employed mild condition for synthesis was presented in this report.展开更多
The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst system.This system exhibited high activity and high ...The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst system.This system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=20 °C,98.2%;Tp=-20 °C,> 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582 kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum alkyls.Dynamic investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.展开更多
基金supported by the National Natural Science Foundation(21772046)Program of Innovative Research Team of Huaqiao University(Z14X0047)+2 种基金the Recruitment Program of Global Experts(1000 Talents Plan)the Natural Science Foundation of Fujian Province(2016J01064)Postgraduates’ Innovative Fund in Scientific Research of Huaqiao University for K.Z
文摘An efficient, transition-metal free, and practical approach to cis-bis(boryl)alkenes from various alkynes was disclosed in the presence of a catalytic amount of K_2CO_3 under mild conditions. Meanwhile, tetrasubstituted alkenes and phenanthrene derivatives were readily constructed from the target diborylalkenes via Suzuki-Miyaura cross coupling.
基金financially supported by the National Natural Science Foundation of China(Nos.51221002 and 21174014)
文摘The mechanical properties and phase morphologies of cis-1,4-butadiene rubber（BR） blended with polyethylene（PE） at different blend ratios were studied. The tensile test results show that the PE exhibits excellent reinforcing capabilities towards BR. Blending BR with PE results in a remarkable enhancement of tensile strength, modulus and the elongation at break simultaneously. An increment of tensile strength from 1.11 MPa to 16.26 MPa was achieved by incorporation of 40 wt% PE in the blends. The modulus and elongation at break of 40/60 PE/BR blends are also about 5 times higher than those of the pure BR treated under exactly the same conditions. The tear test indicates that the tear strength also increases with the increase of PE content. It reaches 58.38 MPa for the 40/60 PE/BR blend, which is approximately 10 times higher than that of the pure BR. Morphological study demonstrates that the PE forms elongated microdomains finely dispersed in the BR matrix when its content is over 30 wt%, which corresponds to the remarkably enhanced mechanical properties.According to the results, reinforcement mechanism of PE toward BR dependent on the microstructure has been discussed and two different mechanisms have been proposed.
文摘（-）-7-Isopropyl-cis-l-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π- azaelectrocyclization, has been prepared previously by two methods. Each however involved using of one extreme condition, i.e. high temperature or high pressure, for the respective reaction. A modified reaction route employed mild condition for synthesis was presented in this report.
基金supported by the National Natural Science Foundation of China (20674081,20934006) the Ministry of Science and Technology of China (2005CB623802,2009AA03Z501).
文摘The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst system.This system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=20 °C,98.2%;Tp=-20 °C,> 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582 kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum alkyls.Dynamic investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.
