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
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
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 reaction of isocyanates with aliphatic and aromatic amines in the 1-n-butyl-3- methylimidazolium tetrafluoroborate (bmimBF4) ionic liquid in good to excellent yields is described. Due to its insolubility, the des...The reaction of isocyanates with aliphatic and aromatic amines in the 1-n-butyl-3- methylimidazolium tetrafluoroborate (bmimBF4) ionic liquid in good to excellent yields is described. Due to its insolubility, the desired urea solids could be recovered by simple filtration from the ionic liquid after reaction.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
In search of new anticancer agents, a series of novel 1-benzhydryl-4-(substituted phenylcarboxamide / carbothioamide)-1,4-diazepane derivatives were designed, synthesized and characterized using 1H NMR, LCMS and eleme...In search of new anticancer agents, a series of novel 1-benzhydryl-4-(substituted phenylcarboxamide / carbothioamide)-1,4-diazepane derivatives were designed, synthesized and characterized using 1H NMR, LCMS and elemental analysis. These molecules were evaluated for their anti-cancer activity by trypan blue exclusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on B-cell leukemic cell line, Reh. Carboxamide moiety containing derivatives showed good activity compared to the corresponding carbothioamide derivatives. In particular, 4-benzhydryl-N-(3-chlorophenyl)-1,4-diazepane-1-carboxamide showed good activity with IC50 value of 18 μM.展开更多
Polyamine-based scavenger resins containing 2, 3 and 4 nitrogen atoms have been prepared and their comparative efficacy to scavenge appropriate electrophilic chemicals (acids, acid chlorides, isocyanates and aldehydes...Polyamine-based scavenger resins containing 2, 3 and 4 nitrogen atoms have been prepared and their comparative efficacy to scavenge appropriate electrophilic chemicals (acids, acid chlorides, isocyanates and aldehydes) from solutions has been studied. As expected, the scavenging efficiency is directly proportional to the number of nucleophic nitrogens present on the resin. The results have been compared with the performance of the popular scavenger resin, namely, tris(2-aminoethyl)amine resin, to conclude that the low-cost polyamine resins now prepared can be conveniently used as effectively as the expensive commercial product.展开更多
Fire effluents, in most cases, have an adverse effect on human health and the environment. Exposure to some compounds may show both acute and chronic toxicity. There is a lack of knowledge on the effect of organic pro...Fire effluents, in most cases, have an adverse effect on human health and the environment. Exposure to some compounds may show both acute and chronic toxicity. There is a lack of knowledge on the effect of organic products on the human body in terms of the rate of organic material production in fires and their degree of toxicity. Thus, there is a need to expand the scope of studies about the organic products generated from fires and improve the methods of assessment to be included as part of fire hazard assessment. Different factors can be contributed to this lack of knowledge. For example, the composition of organic products generated from fires changes progressively and rapidly with progression of combustion and in a manner that is dependent on the fire condition. It is difficult to identify individual organic compounds produced during combustion. Another key factor is the lack of suitable instruments for measuring organic products generated from a fire. Also, the lack of procedures that are used to evaluate the lethal concentration limits and the lethal dose for a broad range of organic compounds generated from a fire may be another important factor which can be contributed to this lack of knowledge.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
Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stab...Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The structure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.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.
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 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
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
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
Novel polyurethane-imide elastomers were prepared from isocyanates (hexamethylene, and 4,4’-dicyclohexyl diisocyanates), polytetramethylene glycol (PTMG1000, Mw = 1000), pyromellitic dianhydride, and 4,4’-diphenylme...Novel polyurethane-imide elastomers were prepared from isocyanates (hexamethylene, and 4,4’-dicyclohexyl diisocyanates), polytetramethylene glycol (PTMG1000, Mw = 1000), pyromellitic dianhydride, and 4,4’-diphenylmethane diamine. The formation of PUIEs was confirmed by Fourier transform infrared spectroscopy. The resultant films were studied through X-ray diffraction analysis, contact angle measurement, atomic force microscopy, solubility and swelling tests, tensile test, differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis.展开更多
The reactivity of lanthanocene thiolates [Cp2Ln(μ-SEt)]2(Ln = Er, Y, Yb) with PhEtCCO and with PhNCO was examined. Treatment of [ Cp2Ln(μ-SEt)]2 with PhEtCCO gives the α-thiolate-substituted enolate complexes...The reactivity of lanthanocene thiolates [Cp2Ln(μ-SEt)]2(Ln = Er, Y, Yb) with PhEtCCO and with PhNCO was examined. Treatment of [ Cp2Ln(μ-SEt)]2 with PhEtCCO gives the α-thiolate-substituted enolate complexes [ Cp2Ln (μ-η^1 :η^3-OC(SEt)CPhEt)]2(Ln = Yb, Y), while [Cp2Ln(μ-SEt)]2 react with PhNCO to give the lanthanocene amido derivatives [Cp2Ln(OC(SEt)NPh )]2(Ln = Er, Yb). In both cases, the insertion reaction is independent of the stoichiometric ratio and the nature of lanthanides, demonstrating that lanthanocene thiolates are high reactive toward PhEtCCO and PhNCO under the conditions involved. All complexes are characterized by elemental analysis and spectroscopic properties, of which the structures of ytterbium enolate and erbium amido are also determined by X-ray single crystal diffraction analysis, indicating that both of them are centrosymmetric binuclear structures.展开更多
Treatment of Cp3Y with EtSH, followed by reaction with an equivalent of PhNCO, yielded the dinuclear complex [Cp2Y(μ-η^1:η^3-OC(SEt)NPh)]2. The structure was characterized by elemental analysis, IR, MS and sin...Treatment of Cp3Y with EtSH, followed by reaction with an equivalent of PhNCO, yielded the dinuclear complex [Cp2Y(μ-η^1:η^3-OC(SEt)NPh)]2. The structure was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction analysis. The title compound crystallizes in triclinic, space group P1^- with a = 8.643(3), b = 10.752(4), c = 11.161(4)A°, α= 117.840(5), β = 94.086(5), γ= 101.008(5)°, V = 884.8(6) A°^3, Z = 1, Mr = 798.66 (C38H40N2O2S2Y2), λ(MoKα) = 0.710730 .A°, ,μ= 3.417 mm^-1, Dc = 1.499 g/cm^3, F(000) = 408, the final R = 0.0453 and wR = 0.1007 for 3067 unique reflections (Rint = 0.0317) with 2357 observed ones (I 〉 2σ(I)). X-ray analysis reveals an unusual bonding mode of the OC(SEt)NPh ligand and the OCN fragment acts as a both bridging and side-on chelating ligand. Each yttrium atom is coordinated by two η^5-cyclopentadienyl groups, one chelating η^3-OC(SEt)NPh ligand and one bridging O atom from another η^3-OC(SEt)NPh ligand.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
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.
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 reaction of isocyanates with aliphatic and aromatic amines in the 1-n-butyl-3- methylimidazolium tetrafluoroborate (bmimBF4) ionic liquid in good to excellent yields is described. Due to its insolubility, the desired urea solids could be recovered by simple filtration from the ionic liquid after reaction.
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.
文摘In search of new anticancer agents, a series of novel 1-benzhydryl-4-(substituted phenylcarboxamide / carbothioamide)-1,4-diazepane derivatives were designed, synthesized and characterized using 1H NMR, LCMS and elemental analysis. These molecules were evaluated for their anti-cancer activity by trypan blue exclusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on B-cell leukemic cell line, Reh. Carboxamide moiety containing derivatives showed good activity compared to the corresponding carbothioamide derivatives. In particular, 4-benzhydryl-N-(3-chlorophenyl)-1,4-diazepane-1-carboxamide showed good activity with IC50 value of 18 μM.
文摘Polyamine-based scavenger resins containing 2, 3 and 4 nitrogen atoms have been prepared and their comparative efficacy to scavenge appropriate electrophilic chemicals (acids, acid chlorides, isocyanates and aldehydes) from solutions has been studied. As expected, the scavenging efficiency is directly proportional to the number of nucleophic nitrogens present on the resin. The results have been compared with the performance of the popular scavenger resin, namely, tris(2-aminoethyl)amine resin, to conclude that the low-cost polyamine resins now prepared can be conveniently used as effectively as the expensive commercial product.
文摘Fire effluents, in most cases, have an adverse effect on human health and the environment. Exposure to some compounds may show both acute and chronic toxicity. There is a lack of knowledge on the effect of organic products on the human body in terms of the rate of organic material production in fires and their degree of toxicity. Thus, there is a need to expand the scope of studies about the organic products generated from fires and improve the methods of assessment to be included as part of fire hazard assessment. Different factors can be contributed to this lack of knowledge. For example, the composition of organic products generated from fires changes progressively and rapidly with progression of combustion and in a manner that is dependent on the fire condition. It is difficult to identify individual organic compounds produced during combustion. Another key factor is the lack of suitable instruments for measuring organic products generated from a fire. Also, the lack of procedures that are used to evaluate the lethal concentration limits and the lethal dose for a broad range of organic compounds generated from a fire may be another important factor which can be contributed to this lack of knowledge.
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 work cited in this review was supported by the National Natural Science Foundation of China (No, 928700801 and No 2880201)
文摘Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The structure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.
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.
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.
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.
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.
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.
文摘Novel polyurethane-imide elastomers were prepared from isocyanates (hexamethylene, and 4,4’-dicyclohexyl diisocyanates), polytetramethylene glycol (PTMG1000, Mw = 1000), pyromellitic dianhydride, and 4,4’-diphenylmethane diamine. The formation of PUIEs was confirmed by Fourier transform infrared spectroscopy. The resultant films were studied through X-ray diffraction analysis, contact angle measurement, atomic force microscopy, solubility and swelling tests, tensile test, differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis.
文摘The reactivity of lanthanocene thiolates [Cp2Ln(μ-SEt)]2(Ln = Er, Y, Yb) with PhEtCCO and with PhNCO was examined. Treatment of [ Cp2Ln(μ-SEt)]2 with PhEtCCO gives the α-thiolate-substituted enolate complexes [ Cp2Ln (μ-η^1 :η^3-OC(SEt)CPhEt)]2(Ln = Yb, Y), while [Cp2Ln(μ-SEt)]2 react with PhNCO to give the lanthanocene amido derivatives [Cp2Ln(OC(SEt)NPh )]2(Ln = Er, Yb). In both cases, the insertion reaction is independent of the stoichiometric ratio and the nature of lanthanides, demonstrating that lanthanocene thiolates are high reactive toward PhEtCCO and PhNCO under the conditions involved. All complexes are characterized by elemental analysis and spectroscopic properties, of which the structures of ytterbium enolate and erbium amido are also determined by X-ray single crystal diffraction analysis, indicating that both of them are centrosymmetric binuclear structures.
基金This work was supported by the National Natural Science Foundation of China (No. 20372016)
文摘Treatment of Cp3Y with EtSH, followed by reaction with an equivalent of PhNCO, yielded the dinuclear complex [Cp2Y(μ-η^1:η^3-OC(SEt)NPh)]2. The structure was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction analysis. The title compound crystallizes in triclinic, space group P1^- with a = 8.643(3), b = 10.752(4), c = 11.161(4)A°, α= 117.840(5), β = 94.086(5), γ= 101.008(5)°, V = 884.8(6) A°^3, Z = 1, Mr = 798.66 (C38H40N2O2S2Y2), λ(MoKα) = 0.710730 .A°, ,μ= 3.417 mm^-1, Dc = 1.499 g/cm^3, F(000) = 408, the final R = 0.0453 and wR = 0.1007 for 3067 unique reflections (Rint = 0.0317) with 2357 observed ones (I 〉 2σ(I)). X-ray analysis reveals an unusual bonding mode of the OC(SEt)NPh ligand and the OCN fragment acts as a both bridging and side-on chelating ligand. Each yttrium atom is coordinated by two η^5-cyclopentadienyl groups, one chelating η^3-OC(SEt)NPh ligand and one bridging O atom from another η^3-OC(SEt)NPh ligand.
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.