Polymerization of Phenyl Isocyanate by Divalent Samarium Complex (ArO)_2Sm(THF)_4 (ArO=2,6-di-tert-butyl-4-methylphenoxo)

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.

Polymerization of n-Hexyl Isocyanate Initiated by Novel Rare Earth Tris(2,6-di-tert-butyl-4-methylphenolate)

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.

Study on Oligomerization of Phenyl Isocyanate Catalyzed by Bis(methylcyclopentadienyl)samarium Complex

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.

Reaction of Bis(Methylcyclopentadienyl) Lanthanide Amido Complex with n-Hexyl isocyanate-Synthesis and Characterization of {(MeC_5H_4)_2YbOC(NPh_2)N(n-hexyl)}_2

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.

LOW-VALENT TITANIUM INDUCED REDUCTIVE REACTION OF THIOCYANATES AND ISOCYANATE

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.

Acute Toxicity of Methyl Isocyanate in Mammals. Ⅳ Biochemical and Hematological Changes in Rabbits

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.

Introduction and Influence of Water in the Preparation of Crosslinked PVC Foam by Isocyanate

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.

Important Green Chemistry and Catalysis： Non-phosgene Syntheses of Isocyanates - Thermal Cracking Way

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.

Room temperature polymerization of alkyl isocyanates catalyzed by rare earth Schiff base complexes

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.

Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

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.

Regioselective addtion of 5-amino-3-benzylthio-l,2,4-triazole and its analogues with aryl isocyanates

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.

Synthesis of a Rod-rod Diblock Copolymer, Poly (3-hexylthiophene)-block-poly(furfuryl isocyanate), through the Anionic Polymerization with an Oxyanionic Macroinitiator

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.

Studies on the reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanates and the synthesis of corresponding derivatives

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.

Theoretical Study on the Reaction Mechanism of Ketene CH2CO with Isocyanate NCO Radical

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.

Effect of SO_2 on the performance of Ag-Pd/Al_2O_3 for the selective catalytic reduction of NOx with C_2H_5OH

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.

The Synthesis of Cyclic Amino Acids

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.

Efficient Synthesis of 3,5,6,7-Tetrahydro-4H-cyclopenta [4,5] thieno [2,3-d] Pyrimidin-4-ones

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.

Efficient synthesis of 5,6-dihydrothieno[3′,2′:4,5]-thieno[2,3-d]pyrimidin-4(3H)-ones via an iminophosphorane

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.

Synthesis and Properties of Novel Polyurethane-Imide Elastomers

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.

Insertion Reactions of PhEtCCO and PhNCO into Ln-S (Ln=Er, Y, Yb) Bond of [Cp_2Ln(μ-SEt)]_2

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.