Exo conformers of N‐(pyridin‐2‐yl)‐ and N‐(pyridin‐3‐yl)norbornene‐5,6‐dicarboximide crystals

Two isomeric pyridine‐substituted norbornenedicarboximide derivatives, namely N‐(pyridin‐2‐yl)‐exo‐norbornene‐5,6‐dicarboximide, (I), and N‐(pyridin‐3‐yl)‐exo‐norbornene‐5,6‐dicarboximide, (II), both C₁₄H₁₂N₂O₄, have been crystallized and their structures unequivocally determined by single‐crystal X‐ray diffraction. The molecules consist of norbornene moieties fused to a dicarboximide ring substituted at the N atom by either pyridin‐2‐yl or pyridin‐3‐yl in an anti configuration with respect to the double bond, thus affording exo isomers. In both compounds, the asymmetric unit consists of two independent molecules (Z′ = 2). In compound (I), the pyridine rings of the two independent molecules adopt different conformations, i.e. syn and anti, with respect to the methylene bridge. The intermolecular contacts of (I) are dominated by C—H...O interactions. In contrast, in compound (II), the pyridine rings of both molecules have an anti conformation and the two independent molecules are linked by carbonyl–carbonyl interactions, as well as by C—H...O and C—H...N contacts.     

Metathesis polymerization of N-aryl norbornene dicarboximides. I

Metathesis polymerization of N-phenyl-exo-norbornene dicarboximide and ortho/meta/para methyl substituted phenyl nadimides was carried out using WCl₆/tetramethyltin. Structural characterization was done by FTIR, ¹H- and ¹³C-NMR. A mixture of cis and trans double bond structures were introduced in the backbone during polymerization. The cis content was higher (52 to 65%). In the DSC scan of poly(N-o-tolyl nadimide), two exotherms were observed at 240 and 270°C while in other samples only one exothermic transition was observed above 240°C. These exotherms disappeared in the second heating cycle. The T_g of the polymers, as determined in the second heating cycle, was highest in poly(N-o-tolyl nadimide) and lowest in poly(N-m-tolyl nadimide). The polymers were stable up to 443 ± 3°C and decomposed above this temperature in a single step. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2917–2924, 1997     

Polynorbornene with pentafluorophenyl imide side chain groups: Synthesis and sulfonation

The mixtures of exo‐endo‐monomers and isomerically pure endo‐monomers of N‐pentafluorophenyl‐norbornene‐5,6‐dicarboximide ( 2a ) and N‐phenyl‐norbornene‐5,6‐dicarboximide ( 2b ) were synthesized and polymerized via ring opening metathesis polymerization using bis(tricyclohexylphosphine) benzylidene ruthenium ( IV ) dichloride ( I ) and tricyclohexylphosphine [1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene][benzylidene] ruthenium dichloride ( II ). Ring opening metathesis polymerization of mixtures of exo‐endo‐monomers ( 2a ) and ( 2b ) and pure endo‐ 2b gave the corresponding high molecular weights poly(N‐pentafluorophenyl‐norbornene‐5,6‐dicarboximide) ( 3a ) and poly(N‐phenyl‐norbornene‐5,6‐dicarboximide) ( 3b ). The isomerically pure endo‐ 2a did not polymerize by I in these conditions, since I is the least active catalyst and endo‐ 2a is the least active monomer because of the intramolecular complex formation between the Ru active center and the fluorine atom of ring‐opened endo‐ 2a on the one hand and steric hindrances caused by the pentafluorinated ring on the other. The quantitative hydrogenation of the polymer 3a , at room temperature and 115 bar, was achieved by a Wilkinson's catalyst. The new polynorbornene bearing highly fluorinated sulfonic acid groups (5) was obtained by the reaction of the hydrogenated poly(N‐pentafluorophenyl‐norbornene‐5,6‐dicarboximide) (4) with sodium 4‐hydroxybenzenesulfonate dihydrate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2925–2933, 2010     

“PMR”聚酰亚胺的封端剂

研究了十四种不饱和羧酸酐的 N-苯基二酰亚胺的热聚合反应,以此作为“PMR”聚酰亚胺封端剂的选择。对结构与热聚合活性的关系进行了讨论。对其中五种热聚合速度较快的化合物,研究了它们的酸酯与苯胺在无水乙醇浓溶液中的反应动力学,求得反应速度常数、活化能和半衰期。     

Preparation and characterization of polyimide alternating copolymers incorporating N,N′-bis-(4-anilino)-1,2,4,5-benzene bis(dicarboximide)

N,N′-Di-(4-anilino)-1,2,4,5-benzene bis(dicarboximide) was prepared in a three-step synthesis and purified by heating the resulting solid to 200°C. Condensation of the diamino-diimide with several dianhydrides (BPDA, BTDA, and 6-FDA) yielded polyamic acid-imides that could be either thermally or chemically cured to the corresponding alternating copolyimides. Imidization of the polyamic acid-imide to the final polyimide was monitored by FTIR for samples coated on silicon wafers before being thermally cured. Polyimides prepared by chemical imidization were found by thermogravimetric analysis to be stable to temperatures of 600°C. © 1997 John Wiley & Sons, Inc.     

The effect of fluorine atoms on gas transport properties of new polynorbornene dicarboximides

The new N-4-trifluoromethylphenyl-norbornene-5,6-dicarboximide (2a) and N-3,5-bis(trifluoromethyl)phenyl-norbornene-5,6-dicarboximide (2b) mixtures of exo and endo monomers were synthesized and polymerized via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II) to produce the corresponding polynorbornene dicarboximides Poly-2a and Poly-2b, respectively. The transport of five gases He, N₂, O₂, CO₂ and CH₄ across membranes prepared from Poly-2a was determined at 35 °C using a constant volume permeation cell. The gas transport properties of the fluorine containing polymer Poly-2a were compared with those found for membranes from non-fluorinated poly(N-phenyl-exo-endo-norbornene-5,6-dicarboximide) (P-PhNDI). Gas permeability, diffusion and solubility coefficients of the fluorine containing polynorbornene Poly-2a were up to an order of magnitude larger than those of the non-fluorinated one. Poly-2a was found to have one of the largest gas transport coefficients reported to date in glassy polynorbornene dicarboximides.