Phenyl isocyanate was for the first time successfully polymerized by divalent samarium complex (ArO)2Sm(THF)4. The monomer concentration and temperatur affected the polymerization greatly.
The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such a...The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such as the monomer concentration, the polymerization temperature and time, and the types of solvents on the polymerization of HNCO were studied. Polymerizations of phenyl, i-propyl, p-tolyl, n-butyl and n-octyl isocyanates with La(OAr)_3 were also examined.展开更多
The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were...The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were mainly discussed. It is found that the initiation reaction has a great influence on the apparent catalytic activity. The oligomers can be split into two fractions. The methanol insoluble fraction is mainly composed of dimers, while the methanol soluble fraction is mainly composed of trimers. Neither SmI2 nor SmI2(hmpa)(4)(hmpa = hexamethylphosphoric triamide) shows catalytic activity for the oligomerization of phenyl isocyanate.展开更多
Bis (methylcyclopentadienyl) lanthanide amido complex (MeCp) 2YbNPh2 (THF) reacted with n-hexyl isocyanate (n-nexylNCO) in 1:1 molar ratio to give {(MeC5H4)2Yb[OC(NPh2)N(n-hexyl)] }2(1). Complex 1 was...Bis (methylcyclopentadienyl) lanthanide amido complex (MeCp) 2YbNPh2 (THF) reacted with n-hexyl isocyanate (n-nexylNCO) in 1:1 molar ratio to give {(MeC5H4)2Yb[OC(NPh2)N(n-hexyl)] }2(1). Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533(11) nm, b =2.9533(11) nm, c = 1.5873(6) nm, V= 11.9896(80) nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1(Mo Kα), F(000) =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.展开更多
Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield subs...Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.展开更多
Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plas...Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plasma total proteins, urea and cholesterol. A significant decrease in plasma albumin level was only observed in the 1.0 LD50 group. Urine of MIC intoxicated animals showed presence of protein, bilirubin, elevated urea and urobilinogen, while urine volume was reduced. The hematological and biochemical changes induced by MIC are perhaps the result of fluid loss from the vascular compartment as evidenced by the histopathological observations. This study further substantiates the view that acute toxicity of MIC is mediated in vivo by its effects on vascular beds.展开更多
In the preparation process of crosslinked polyvinyl chloride(c-PVC)foam by isocyanate,the formulated mixture is generally required to be carried out under the condition of isolated water,so as to avoid the mixing diff...In the preparation process of crosslinked polyvinyl chloride(c-PVC)foam by isocyanate,the formulated mixture is generally required to be carried out under the condition of isolated water,so as to avoid the mixing difficulties caused by the reaction between the introduced water and isocyanate.In this paper,NaHCO_(3) was added to the mixture to indirectly introduce water into the system,and the effects of NaHCO_(3) on the cell structure and curing time of c-PVC foam were investigated.The results showed that NaHCO_(3) not only played a role of foaming agent,but also was a good nucleating agent for cells.At the same time,the introduction of NaHCO_(3) held back the exudation of modified diphenylmethane-4,4'-diisocyanate(MDI)on the cell wall.The effects of NaHCO_(3) on the cell structure and aggregation structure of c-PVC foam were studied by thermogravimetric analysis,infrared spectroscopy and scanning electron microscopy.The results showed that decomposition of NaHCO_(3) occurred during the molding stage,which made small amount of MDI react with water to form polyurea,improved the compatibility of MDI with PVC and inhibited the exudation of MDI.展开更多
Currently, industrial production of isocyanates, or diisocyanates in particular, has been exclusively based on phosgene processes. Phosgene is extremely toxic and large amounts of corrosive HC1 are produced as a side ...Currently, industrial production of isocyanates, or diisocyanates in particular, has been exclusively based on phosgene processes. Phosgene is extremely toxic and large amounts of corrosive HC1 are produced as a side product. In the view of environment protection and society safety, development of non-phosgene processes for isocyanates production will be highly desired, and this should be one of the most important missions for green chemistry and catalysis. In this review, efforts for development of non-phosgene method for syntheses of isocyanates, i.e., catalytic syntheses of N-substituted carbamates from nitro- or amino-compounds with CO, dimethyl carbonate (DMC), urea and even CO2 etc. as carbonyl sources, then thermal cracking of N-substituted carbamates to afford corresponding i socyanates, are summarized, and a brief prospect for non-phosgene syntheses of isocyanates is also addressed.展开更多
The polymerization of alkyl isocyanates catalyzed by rare earth chloride salen complexes/triisobutyl aluminum(Ln(H2salen)2Cl3·2C2H7OH/Al(i-Bu)3) at room temperature was investigated.The influences of ligand struc...The polymerization of alkyl isocyanates catalyzed by rare earth chloride salen complexes/triisobutyl aluminum(Ln(H2salen)2Cl3·2C2H7OH/Al(i-Bu)3) at room temperature was investigated.The influences of ligand structure,catalyst composition,polymerization temperature,polymerization time,the concentration of catalyst and monomer,and the polymerization solvent on the polymerization of isocyanates were studied.It was found that under the polymerization conditions,examined La(H2salenA)2Cl3·2C2-H7OH/Al(i-Bu)3(H2salenA= N,N'-disalicylideneethylene diamine) is a fairly high efficient catalyst for the polymerization of n-hexyl isocyanate(n-HexNCO) to prepare high molecular weight poly(n-hexyl isocyanate)(PHNCO) with narrower molecular weight distribution at room temperature.PHNCO could be prepared with yield of 74.0%,number-average molecular weight(Mn) of 40.20×104 and MWD of 1.79 under the following optimum conditions:[Al]/[La]=30(molar ratio),[n-HexNCO]/[La]=100(molar ratio),[n-HexNCO]=3.43 mol/L polymerization at 20℃ for 12 h in toluene.In the same polymerization conditions,poly(n-octyl isocyanate)(PONCO) with yield of 67.3%,and poly(n-butyl isocyanate)(PBNCO) with yield of 45.5%,could be prepared respectively.The kinetics of the polymerization of n-HexNCO was also investigated and found to be first-order with respect to both monomer and catalyst concentrations.展开更多
A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF...A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF3CH2O)(3)Y(THF)(3) (7) were synthesized and they have good activity for the oligomerization of phenyl isocyanate. Among-them 5 shows,the highest activity. The conversion is as high as 96.2%, with 1/2500 of the molar ratio of cat. / PhNCO. The main components in oligomer were characterized to be a cyclodimer and a cyclotrimer. The ratio of cyclodimer,to cyclotrimer depends on the lanthanide complexes:used. 7 gave 85.2% cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40 V for 0.5 h, while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat. /PhNCO at 40 degreesC for 4 h.展开更多
The orientation of the addition of 5-amino-3-benzylthio-1,2,4-triazole and its analogues (pyrazole) (1) with the aryl isocyanate can be directed by controlling the reaction temperature and one of the product, 5-amino-...The orientation of the addition of 5-amino-3-benzylthio-1,2,4-triazole and its analogues (pyrazole) (1) with the aryl isocyanate can be directed by controlling the reaction temperature and one of the product, 5-amino-1-arylaminocarbonyl-3-benzylthio-1,2,4-triazole (pyrazole) (2), can rearrange at 170C to another product, 5-arylureylene-3-benzylthio-1,2,4-triazole (pyrazole) (3). A plausible mechanism explanation for this rearrangement reaction was presented. It was suggested that the rearrangement reaction could be referred to the thermodynamics transposition leading to the predominant 5-arylureylene-3-benzylthio-1,2,4-triazole energy preferentially.展开更多
A rod-rod diblock copolymer (diBCP), poly(3-hexylthiophene)-block-poly(furfuryl isocyanate)(P3HT-b-PFIC), was synthesized through the anionic polymerization with an oxyanionic macroinitiator of P3HT. The properties of...A rod-rod diblock copolymer (diBCP), poly(3-hexylthiophene)-block-poly(furfuryl isocyanate)(P3HT-b-PFIC), was synthesized through the anionic polymerization with an oxyanionic macroinitiator of P3HT. The properties of the diBCP (molecular weight, dispersity, composition, thermal stability, UV-visible absorption, and thin film morphology) were determined by various analytical methods. P3HT-b-PFIC was blended with C60 in a toluene solution to prepare a thin film of binary electron donor/acceptor system. Such blending enabled partial conjugation of the two components by the Diels-Alder reaction between furan and C60 at 60℃ for 3 h;the mixture was then spin-cast as a thin film, and annealed at 250℃ for 24 h. Tapping-mode atomic force microscopy (AFM) revealed that P3HT and C60 domains had nanoscale interfaces without a large phase segregation. This result indicated that the microphase separation of C60-functionalized P3HT-b-PFIC preserved even at high temperature provided free C60 molecules with channels to diffuse on the sides of P3HT domain, thus preventing the macroscopic crystallization of free C60 through the interfacial stabilization.展开更多
The reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanate under different equivalents of strong base NaH was studied. Seventeen of new derivatives were obtained whose structures we...The reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanate under different equivalents of strong base NaH was studied. Seventeen of new derivatives were obtained whose structures were characterized by H-1 NMR, IR, MS, elementary analysis and FeCl3 test.展开更多
The bimolecular single collision reaction potential energy surface of an isocyanate NCO radical with a ketene CH2CO molecule was investigated by means of B3LYP and QCISD(T) methods. The computed results indicate tha...The bimolecular single collision reaction potential energy surface of an isocyanate NCO radical with a ketene CH2CO molecule was investigated by means of B3LYP and QCISD(T) methods. The computed results indicate that two possible reaction channels exist on the surface. One is an addition-elimination reaction process, in which the CH2CO molecule is attacked by the nitrogen atom at its methylene carbon atom to lead to the formation of the intermediate OCNCH2CO followed by a C-C rupture channel to the products CH2NCO+CO. The other is a direct hydrogen abstraction channel from CHzCO by the NCO radical to afford the products HCCO+HNCO. Because of a higher barrier in the hydrogen abstraction reaction than in the addition-elimination reaction, the direct hydrogen abstraction pathway can only be considered as a secondary reaction channel in the reaction kinetics of NCO+ CH2CO. The predicted results are in good agreement with previous experimental and theoretical investigations.展开更多
Zeolite imidazole skeleton(ZIF-8)is a promising option for self-cleaning of building exterior walls due to its large specific surface area,high antibacterial activity and low biotoxicity.However,it suffers from low an...Zeolite imidazole skeleton(ZIF-8)is a promising option for self-cleaning of building exterior walls due to its large specific surface area,high antibacterial activity and low biotoxicity.However,it suffers from low antibacterial efficiency and yield under visible light irradiation.To address the issues,we developed the photocatalytic materials T-ZIF-8-TDI(thermally treated-ZIF-8-toluene 2,4-diisocyanate)by modifying ZIF-8 with thermal oxygen sensitization and chemical bonding.The results show that the yield of T-ZIF-8-TDI photocatalytic antibacterial agent is increased to 11.5 times of that of T-ZIF-8,while maintaining the crystal structure of T-ZIF-8 and thermal stability up to 60℃.Furthermore,T-ZIF-8-TDI exhibits extended optical response range to the nearinfrared region,significantly narrowed band gap,improved photogenerated elec tron-hole separation efficiency,reduced recombination rate,and excellent photocatalytic performance.When the concentration of antibacterial agent is 600 mg·L^(-1),the antibacterial rate of Escherichia coli(E.coli)reaches 99.99%irradiated by visible light for30 min,and when the concentration of antibacterial agent is 200 mg·L^(-1),the antibacterial rate of Staphylococcus aureus(S.aureus)reaches 99.99%irradiated by visible light for 25 min.We also analyzed the reasons in detail from the aspects of bacterial species and antibacterial mechanism,and proposed the antibacterial mechanism of·O_(2)^(-)and h^(+)as the main active species.These findings suggest that T-ZIF-8-TDI photocatalytic antibacterial agent has potential for use in self-cleaning of building exterior walls.展开更多
The influence of SO2 on the performance of Ag-Pd/Al2O3 for the selective catalytic reduction (SCR) of NOx with C2H5OH was investigated experimentally. The activity test results suggest that Ag-Pd/Al2O3 shows a small...The influence of SO2 on the performance of Ag-Pd/Al2O3 for the selective catalytic reduction (SCR) of NOx with C2H5OH was investigated experimentally. The activity test results suggest that Ag-Pd/Al2O3 shows a small activity loss in the presence of SO2 when using C2H5OH as a reductant. In situ DRIFTS spectra show that the activity loss originates from the formation of surface sulphate species on the Ag-Pd/Al2O3. The surface sulphate species formation inhibits the formation of nitrate, whereas hardly changes the partial oxidation of C2H5OH. Compared with the NOx reduction by C3H6, an obvious suppression of the surface sulphate species formation was observed by DRIFTS experiment when using C2H5OH as a reductant. This phenomenon reveals the better catalytic performance and strong SO2 tolerance of Ag-Pd/Al2O3-C2H50H system.展开更多
Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.
The title compounds 3,5,6,7-tetrahydro-4H-cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-ones(6) were synthesized by base catalytic reactions of secondary amines with carbodiimides 4, which were obtained from the aza-Witti...The title compounds 3,5,6,7-tetrahydro-4H-cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-ones(6) were synthesized by base catalytic reactions of secondary amines with carbodiimides 4, which were obtained from the aza-Wittig reaction of iminophosphoranes(3) with aromatic isocyanates.展开更多
Oil spills and oil/water wastewater are among the great concerns regarding oil pollution.Existing technologies face many limitations and in some cases are responsible for causing secondary pollution,therefore there is...Oil spills and oil/water wastewater are among the great concerns regarding oil pollution.Existing technologies face many limitations and in some cases are responsible for causing secondary pollution,therefore there is as seek for environmental friendly solutions.Biomass,from which celluloses are highlighted,are being employed for oil/water separation or oil absorbents membranes.Usually,these membranes are obtained by freeze drying of CNF(cellulose nano-fibrils)suspensions followed by chemical modification for hydrophobization,which involves expensive process as chemical vapor deposition and expensive reactants as sylanes,turning these processes hardly scalable.Here,we produced a natural porous structure paper from eucalyptus pulp fibers modified by a dipping and heating process in a blocked diisocyanate solution.After the surface treatment,contact angle with water reached 144°and water absorption reduced seven times,keeping the good oil absorbance.The chemical modification process is simple to be performed and use a very low quantity of reactant estimated to be less than 0.1 wt%based on cellulose.The good mechanical properties of the material allows its use in non usual conditions which can be of great importance depending on the environmental conditions.展开更多
5,6-Dihydrothieno[3',2':4,5]thieno[2,3-d]pyrimidin-4(3H)-ones 6 were synthesized in yields of 71-87% by a consecutive method, which includes aza-Wittig reaction of iminophosphorane 3 with aromatic isocynate to gi...5,6-Dihydrothieno[3',2':4,5]thieno[2,3-d]pyrimidin-4(3H)-ones 6 were synthesized in yields of 71-87% by a consecutive method, which includes aza-Wittig reaction of iminophosphorane 3 with aromatic isocynate to give carbodiimide 4 and subsequent reaction of 4 with various amines, phenols or alcohols in the presence of catalytic amount of sodium ethoxide or solid potassium carbonate. 2009 Ming Wu Ding. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
文摘Phenyl isocyanate was for the first time successfully polymerized by divalent samarium complex (ArO)2Sm(THF)4. The monomer concentration and temperatur affected the polymerization greatly.
文摘The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such as the monomer concentration, the polymerization temperature and time, and the types of solvents on the polymerization of HNCO were studied. Polymerizations of phenyl, i-propyl, p-tolyl, n-butyl and n-octyl isocyanates with La(OAr)_3 were also examined.
文摘The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were mainly discussed. It is found that the initiation reaction has a great influence on the apparent catalytic activity. The oligomers can be split into two fractions. The methanol insoluble fraction is mainly composed of dimers, while the methanol soluble fraction is mainly composed of trimers. Neither SmI2 nor SmI2(hmpa)(4)(hmpa = hexamethylphosphoric triamide) shows catalytic activity for the oligomerization of phenyl isocyanate.
文摘Bis (methylcyclopentadienyl) lanthanide amido complex (MeCp) 2YbNPh2 (THF) reacted with n-hexyl isocyanate (n-nexylNCO) in 1:1 molar ratio to give {(MeC5H4)2Yb[OC(NPh2)N(n-hexyl)] }2(1). Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533(11) nm, b =2.9533(11) nm, c = 1.5873(6) nm, V= 11.9896(80) nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1(Mo Kα), F(000) =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.
文摘Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.
文摘Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plasma total proteins, urea and cholesterol. A significant decrease in plasma albumin level was only observed in the 1.0 LD50 group. Urine of MIC intoxicated animals showed presence of protein, bilirubin, elevated urea and urobilinogen, while urine volume was reduced. The hematological and biochemical changes induced by MIC are perhaps the result of fluid loss from the vascular compartment as evidenced by the histopathological observations. This study further substantiates the view that acute toxicity of MIC is mediated in vivo by its effects on vascular beds.
基金This work was supported by the National Natural Science Foundation of China(No.52173050)the National Key Research and Development Program of China(No.2021YFB3702800).
文摘In the preparation process of crosslinked polyvinyl chloride(c-PVC)foam by isocyanate,the formulated mixture is generally required to be carried out under the condition of isolated water,so as to avoid the mixing difficulties caused by the reaction between the introduced water and isocyanate.In this paper,NaHCO_(3) was added to the mixture to indirectly introduce water into the system,and the effects of NaHCO_(3) on the cell structure and curing time of c-PVC foam were investigated.The results showed that NaHCO_(3) not only played a role of foaming agent,but also was a good nucleating agent for cells.At the same time,the introduction of NaHCO_(3) held back the exudation of modified diphenylmethane-4,4'-diisocyanate(MDI)on the cell wall.The effects of NaHCO_(3) on the cell structure and aggregation structure of c-PVC foam were studied by thermogravimetric analysis,infrared spectroscopy and scanning electron microscopy.The results showed that decomposition of NaHCO_(3) occurred during the molding stage,which made small amount of MDI react with water to form polyurea,improved the compatibility of MDI with PVC and inhibited the exudation of MDI.
基金This work was supported by the National Natural Science Foundation of China (No. 21173240).
文摘Currently, industrial production of isocyanates, or diisocyanates in particular, has been exclusively based on phosgene processes. Phosgene is extremely toxic and large amounts of corrosive HC1 are produced as a side product. In the view of environment protection and society safety, development of non-phosgene processes for isocyanates production will be highly desired, and this should be one of the most important missions for green chemistry and catalysis. In this review, efforts for development of non-phosgene method for syntheses of isocyanates, i.e., catalytic syntheses of N-substituted carbamates from nitro- or amino-compounds with CO, dimethyl carbonate (DMC), urea and even CO2 etc. as carbonyl sources, then thermal cracking of N-substituted carbamates to afford corresponding i socyanates, are summarized, and a brief prospect for non-phosgene syntheses of isocyanates is also addressed.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20304011, 20774078 & 20434020)the Special Funds for Major Basic Research Projects (Grant No. 2005CB623802)
文摘The polymerization of alkyl isocyanates catalyzed by rare earth chloride salen complexes/triisobutyl aluminum(Ln(H2salen)2Cl3·2C2H7OH/Al(i-Bu)3) at room temperature was investigated.The influences of ligand structure,catalyst composition,polymerization temperature,polymerization time,the concentration of catalyst and monomer,and the polymerization solvent on the polymerization of isocyanates were studied.It was found that under the polymerization conditions,examined La(H2salenA)2Cl3·2C2-H7OH/Al(i-Bu)3(H2salenA= N,N'-disalicylideneethylene diamine) is a fairly high efficient catalyst for the polymerization of n-hexyl isocyanate(n-HexNCO) to prepare high molecular weight poly(n-hexyl isocyanate)(PHNCO) with narrower molecular weight distribution at room temperature.PHNCO could be prepared with yield of 74.0%,number-average molecular weight(Mn) of 40.20×104 and MWD of 1.79 under the following optimum conditions:[Al]/[La]=30(molar ratio),[n-HexNCO]/[La]=100(molar ratio),[n-HexNCO]=3.43 mol/L polymerization at 20℃ for 12 h in toluene.In the same polymerization conditions,poly(n-octyl isocyanate)(PONCO) with yield of 67.3%,and poly(n-butyl isocyanate)(PBNCO) with yield of 45.5%,could be prepared respectively.The kinetics of the polymerization of n-HexNCO was also investigated and found to be first-order with respect to both monomer and catalyst concentrations.
文摘A series-of lanthanide complexes including (Ind)(3)Sm(THF) (1), [(MeCP)(2)Sm(mu-SPh)(THF)](2),(2), [(MeCp)(2)Y(mu-O-i-Pr)](2) (3), (MeCp)(3)Sm.THF (4), Sm(SPh)(3) (hmpa)(3) (5), [(MeCp)(2)Y(mu-OCH2CF3)](2) (6) and (CF3CH2O)(3)Y(THF)(3) (7) were synthesized and they have good activity for the oligomerization of phenyl isocyanate. Among-them 5 shows,the highest activity. The conversion is as high as 96.2%, with 1/2500 of the molar ratio of cat. / PhNCO. The main components in oligomer were characterized to be a cyclodimer and a cyclotrimer. The ratio of cyclodimer,to cyclotrimer depends on the lanthanide complexes:used. 7 gave 85.2% cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40 V for 0.5 h, while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat. /PhNCO at 40 degreesC for 4 h.
基金Project supported by the National Natural Science Foundation of China and the Natural Science Foundation of Tianjin.
文摘The orientation of the addition of 5-amino-3-benzylthio-1,2,4-triazole and its analogues (pyrazole) (1) with the aryl isocyanate can be directed by controlling the reaction temperature and one of the product, 5-amino-1-arylaminocarbonyl-3-benzylthio-1,2,4-triazole (pyrazole) (2), can rearrange at 170C to another product, 5-arylureylene-3-benzylthio-1,2,4-triazole (pyrazole) (3). A plausible mechanism explanation for this rearrangement reaction was presented. It was suggested that the rearrangement reaction could be referred to the thermodynamics transposition leading to the predominant 5-arylureylene-3-benzylthio-1,2,4-triazole energy preferentially.
基金financially supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Science, ICT and Future Planning (Nos. NRF-2015R1A2A1A01002493 and NRF-2018R1A2B6003616)supported by “Nobel Research Project” grant for Grubbs Center for Polymers and Catalysis funded by the GIST in 2019
文摘A rod-rod diblock copolymer (diBCP), poly(3-hexylthiophene)-block-poly(furfuryl isocyanate)(P3HT-b-PFIC), was synthesized through the anionic polymerization with an oxyanionic macroinitiator of P3HT. The properties of the diBCP (molecular weight, dispersity, composition, thermal stability, UV-visible absorption, and thin film morphology) were determined by various analytical methods. P3HT-b-PFIC was blended with C60 in a toluene solution to prepare a thin film of binary electron donor/acceptor system. Such blending enabled partial conjugation of the two components by the Diels-Alder reaction between furan and C60 at 60℃ for 3 h;the mixture was then spin-cast as a thin film, and annealed at 250℃ for 24 h. Tapping-mode atomic force microscopy (AFM) revealed that P3HT and C60 domains had nanoscale interfaces without a large phase segregation. This result indicated that the microphase separation of C60-functionalized P3HT-b-PFIC preserved even at high temperature provided free C60 molecules with channels to diffuse on the sides of P3HT domain, thus preventing the macroscopic crystallization of free C60 through the interfacial stabilization.
基金Project supported by the National Natural Science Foundation of China.
文摘The reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanate under different equivalents of strong base NaH was studied. Seventeen of new derivatives were obtained whose structures were characterized by H-1 NMR, IR, MS, elementary analysis and FeCl3 test.
文摘The bimolecular single collision reaction potential energy surface of an isocyanate NCO radical with a ketene CH2CO molecule was investigated by means of B3LYP and QCISD(T) methods. The computed results indicate that two possible reaction channels exist on the surface. One is an addition-elimination reaction process, in which the CH2CO molecule is attacked by the nitrogen atom at its methylene carbon atom to lead to the formation of the intermediate OCNCH2CO followed by a C-C rupture channel to the products CH2NCO+CO. The other is a direct hydrogen abstraction channel from CHzCO by the NCO radical to afford the products HCCO+HNCO. Because of a higher barrier in the hydrogen abstraction reaction than in the addition-elimination reaction, the direct hydrogen abstraction pathway can only be considered as a secondary reaction channel in the reaction kinetics of NCO+ CH2CO. The predicted results are in good agreement with previous experimental and theoretical investigations.
基金financially supported by the Projects of the Research and Development Project of New Materials and Chemical Engineering Research Institute of Shanxi Zhejiang University(No.2021SX-AT010)the National Natural Science Foundation of China(No.21972103)Innovation and entrepreneurship training program for college students(No.202110112012)。
文摘Zeolite imidazole skeleton(ZIF-8)is a promising option for self-cleaning of building exterior walls due to its large specific surface area,high antibacterial activity and low biotoxicity.However,it suffers from low antibacterial efficiency and yield under visible light irradiation.To address the issues,we developed the photocatalytic materials T-ZIF-8-TDI(thermally treated-ZIF-8-toluene 2,4-diisocyanate)by modifying ZIF-8 with thermal oxygen sensitization and chemical bonding.The results show that the yield of T-ZIF-8-TDI photocatalytic antibacterial agent is increased to 11.5 times of that of T-ZIF-8,while maintaining the crystal structure of T-ZIF-8 and thermal stability up to 60℃.Furthermore,T-ZIF-8-TDI exhibits extended optical response range to the nearinfrared region,significantly narrowed band gap,improved photogenerated elec tron-hole separation efficiency,reduced recombination rate,and excellent photocatalytic performance.When the concentration of antibacterial agent is 600 mg·L^(-1),the antibacterial rate of Escherichia coli(E.coli)reaches 99.99%irradiated by visible light for30 min,and when the concentration of antibacterial agent is 200 mg·L^(-1),the antibacterial rate of Staphylococcus aureus(S.aureus)reaches 99.99%irradiated by visible light for 25 min.We also analyzed the reasons in detail from the aspects of bacterial species and antibacterial mechanism,and proposed the antibacterial mechanism of·O_(2)^(-)and h^(+)as the main active species.These findings suggest that T-ZIF-8-TDI photocatalytic antibacterial agent has potential for use in self-cleaning of building exterior walls.
基金The Key Program of the National Natural Science Foundation of China (No. 20437010) and the National Science Fund forDistinguished Young Scholars of China (No. 20425722)
文摘The influence of SO2 on the performance of Ag-Pd/Al2O3 for the selective catalytic reduction (SCR) of NOx with C2H5OH was investigated experimentally. The activity test results suggest that Ag-Pd/Al2O3 shows a small activity loss in the presence of SO2 when using C2H5OH as a reductant. In situ DRIFTS spectra show that the activity loss originates from the formation of surface sulphate species on the Ag-Pd/Al2O3. The surface sulphate species formation inhibits the formation of nitrate, whereas hardly changes the partial oxidation of C2H5OH. Compared with the NOx reduction by C3H6, an obvious suppression of the surface sulphate species formation was observed by DRIFTS experiment when using C2H5OH as a reductant. This phenomenon reveals the better catalytic performance and strong SO2 tolerance of Ag-Pd/Al2O3-C2H50H system.
基金the National Natural Science Foundation of China(No.20272001)
文摘Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.
基金the National Natural Science Foundation of China(No.20772041)the Opening Foundation of the Key Labo-ratory of Three Gorges University of China(No.2006NP01)the Key Project of Chinese Ministry of Education(No.107082)
文摘The title compounds 3,5,6,7-tetrahydro-4H-cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-ones(6) were synthesized by base catalytic reactions of secondary amines with carbodiimides 4, which were obtained from the aza-Wittig reaction of iminophosphoranes(3) with aromatic isocyanates.
基金This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil(CAPES)—Finance Code 001.Authors also acknowledge CNPq for financial support in special for the doctoral fellowship granted to G.S(CNPq Proc.140249/2017-6).AJFC acknowledge CNPq for research funding project#03847/2019-0.
文摘Oil spills and oil/water wastewater are among the great concerns regarding oil pollution.Existing technologies face many limitations and in some cases are responsible for causing secondary pollution,therefore there is as seek for environmental friendly solutions.Biomass,from which celluloses are highlighted,are being employed for oil/water separation or oil absorbents membranes.Usually,these membranes are obtained by freeze drying of CNF(cellulose nano-fibrils)suspensions followed by chemical modification for hydrophobization,which involves expensive process as chemical vapor deposition and expensive reactants as sylanes,turning these processes hardly scalable.Here,we produced a natural porous structure paper from eucalyptus pulp fibers modified by a dipping and heating process in a blocked diisocyanate solution.After the surface treatment,contact angle with water reached 144°and water absorption reduced seven times,keeping the good oil absorbance.The chemical modification process is simple to be performed and use a very low quantity of reactant estimated to be less than 0.1 wt%based on cellulose.The good mechanical properties of the material allows its use in non usual conditions which can be of great importance depending on the environmental conditions.
基金support of this work by the National Natural Science Foundation of China(No.20772041)Key Project of Science and Technology of Ministry of Education of China(No.107082)
文摘5,6-Dihydrothieno[3',2':4,5]thieno[2,3-d]pyrimidin-4(3H)-ones 6 were synthesized in yields of 71-87% by a consecutive method, which includes aza-Wittig reaction of iminophosphorane 3 with aromatic isocynate to give carbodiimide 4 and subsequent reaction of 4 with various amines, phenols or alcohols in the presence of catalytic amount of sodium ethoxide or solid potassium carbonate. 2009 Ming Wu Ding. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.