Preparation and properties of octa-substituted phthalocyanines peripherally substituted with phenyl derivatives

2,3,9,10,16,17,23,24-Octa-substituted phthalocyanines modified with phenyl, tolyl, tert-butylphenyl, and trifluoromethylphenyl groups and their nickel(II) complexes were prepared and characterized. The phthalonitriles with the phenyl derivatives, which are precursors of the phthalocyanines, were synthesized from 4,5-dichlorophthalonitrile and phenyl boronic acids by use of Suzuki-coupling reaction.     

Synthesis of 7,10-dihydroxy-8(E)-octadecenoic acid

We report the synthesis of 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), which has recently also been reported from bioconversion of oleic acid. One hydroxyl of 1,7-heptanediol was protected as tetrahydropyranyl ether, and the other hydroxyl was used for chain extension by two carbonsvia Wittig reaction to give ethyl 9-tetrahydropyranyloxy-2(E)-nonenoate, an α,β-unsaturated ester, which on Dibal-H reduction offered allylic alcohol. The epoxidation at the double bond followed by conversion of the hydroxyl group to chloro gave 9-tetrahydropyranyloxy-2,3-oxirane-1-chlorononane. Treatment of this epoxy nonyl chloride with excess of LiNH₂/liquid NH₃; followed by addition of 1-nonanal, gave 18-tetrahydropyranyloxy-9, 12-dihydroxy-10-octadecyne. The lithium aluminum hydride reduction of the conjugated hydroxy acetylenic bond, protection of hydroxyl groups as benzoates and oxidation of the primary ether group, followed by removal of benzoate groups, gave DOD. IICT Communication No. 2995.     

THERMAL INDUCED HOMOLYTIC SCISSIONS OF LIGNIN INTERUNITARY BONDS IN THE HARDWOOD LIGNIN SOLUTION. AN ESR STUDY COMBINED WITH A SPIN TRAPPING METHOD

An electron spin resonance (ESR) method combined with a spin trapping reagent was successfully applied to trap and characterize unstable free radicals which were generated by heat-treatment of the dimethylsulfoxide (DMSO) solution of a hardwood, Japanese beech (Fagus crenata) lignin. It was found, consequently, that two unstable secondary carbon radicals, ～ CH? in the solution were created and the resulting radicals were trapped as the stable nitroxide spin adducts when the DMSO solution was heat-treated in the presence of a spin trapping reagent: 2,4,6-tri-tert-butylnitrosobenzene (BNB) at ca. 91°C. This means that so-called alkyl phenyl ether bonds, ～ CH-O- phenyl, known as important lignin interunitary bonds were homolytically scissoned by the heat-treatment of the lignin solution. Further the detailed analysis of the observed ESR spectrum revealed that two positions of alkyl phenyl ether bonds, i.e., β-O-4 and/or α-O-4 bonds as the interunitary linkages in the lignin are homolytically scissioned, although the phenoxy radical, Ph-O ? as the counter radical of the secondary carbon radicals was not trapped by the BNB spin trap. This suggests that fairly large steric hindrances operate between the syringyl with two methoxy moieties at the ortho positions and/or guaiacyl moieties with a methoxy moiety at the ortho position, and the BNB molecule bearing two bulky ortho tert-butyl groups in the phenyl ring.     

Copolymerization of glycidol with functionalized phenyl glycidyl ethers

Various copolymers of glycidol with phenyl‐containing comonomers (glycidyl 2‐methylphenyl ether, 2‐biphenylyl glycidyl ether, 4‐tert‐butylphenyl glycidyl ether, methoxyphenyl glycidyl ether, and p‐nitrophenyl glycidyl ether) were synthesized by cationic ring‐opening polymerization, for possible use as nanoparticle coatings. The copolymerization involving p‐nitrophenyl glycidyl ether produced p‐nitrophenol as a byproduct. The copolymers were found to have relatively low average molecular weights and high polydispersities, with glass‐transition temperatures in the ?20 to +10°C range (approximately). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1462–1466, 2005     

Electrophilic Additions to Highly Reactive Enol Ethers. The Particular Role of Resonance in Determining the Kinetic Selectivity Evidenced by Extensive Comparison of Olefin Bromination and Hydration

The kinetic selectivity of aliphatic enol ethers, EtOCR = CHR' (R and R′ = H or Me), towards electrophiles, I₂, Br₂ and H₃O⁺, is expressed by the kinetic effect of a methyl substituent in the α position with respect to the ethoxy group, k_α-Me/k_H. As expected from the reactivity–selectivity principle, RSP, these selectivities are small, 16, 18 and 330, respectively, as compared to those observed for less reactive olefins. However, a more general comparison of the selectivities of various XCH = CH₂ olefins (X = Br, Me, Ph, OAc, OEt) reveals anomalies in their behavior with respect to the RSP: (i) enol ether iodination and bromination exhibit the same selectivity although their rates differ by 4 powers of ten, (ii) enol acetate and enol ether show similar selectivities in bromination but the rate of acetate is 3 × 10⁵ times smaller than that of ether and (iii) in hydration the selectivities of these two olefins are similar to that of styrene although rates range over 7 powers of ten from styrene to enol ether. In contrast with what was previously observed for homogeneous series of R-substituted styrenes (Ph(R)C = CH₂), there is no reactivity–selectivity relationship for electrophilic additions to XCH = CH₂ olefins. There is a parallelism, however, between the selectivities and the transition-state position estimated by the Brønsted exponents for hydration and by the Winstein–Grunwald coefficients for solvent effects on halogenations. These results are discussed in terms of different resonance effects on transition states and on reactivities which could arise from differences in the relative contributions of thermodynamic and intrinsic kinetic (Hammond effects) factors on the selectivities.     

Biosynthesis of new divinyl ether oxylipins in Ranunculus plants

[1-¹⁴C]Linolenic acid was incubated with homogenates of leaves from the aquatic plants Ranunculus lingua (greater spearwort) or R. peltatus (pond water-crowfoot). Analysis by reversed-phase high-performance liquid radiochromatography demonstrated the formation of a new divinyl ether FA, i.e., 12-[1′(E), 3′(Z)-hexadienyloxy]-9(Z), 11(Z)-dodecadienoic acid [11(Z)-etherolenic acid] as well as a smaller proportion of ω5(Z)-etherolenic acid previously identified in terrestrial Ranunculus plants. The same divinyl ethers were formed upon incubation of 13(S)-hydroperoxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid, a lipoxygenase metabolite of linolenic acid, whereas the isomeric hydroperoxide, 9(S)-hydroperoxy-10(E), 12(Z), 15(Z)-octadecatrienoic acid, was not converted into divinyl ethers in R. lingua or R. peltatus. Incubation of [1-¹⁴C]linoleic acid or 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid produced the divinyl ether 12-[1′(E)-hexenyloxy]-9(Z), 11(Z)-dodecadienoic acid [11(Z)-etheroleic acid] and a smaller amount of ω5(Z)-etheroleic acid. The experiments demonstrated the existence in R. lingua and R. peltatus of a divinyl ether synthase distinct from those previously encountered in higher plants and algae.     

Phase equilibria of vanillins in compressed gases

Solid–liquid phase transitions of vanillin, ethylvanillin, o-vanillin and o-ethylvanillin in compressed hydrocarbons (isobutane and propane), fluorinated hydrocarbons (R23, R134a and R236fa) and sulphur hexafluoride (SF₆) were determined with a modified capillary method in a pressure range between 0.1 and 31.0 MPa. Equilibrium solubilities of vanillins in compressed fluorinated hydrocarbons were determined at temperatures 313.2 and 333.2 K and over a pressure range between 1.1 and 26.0 MPa with a static–analytic method. Experimental solubility data were correlated by a density-based Chrastil model.Results showed that phase equilibria of vanillins in investigated compressed gases are influenced by the type of alchoxy group (methoxy or ethoxy) and the position of OH group (ortho or para), bound to the aromatic ring of solute, as well as the molecular structure of the gas. Three phase SLG curves in p,T-projections mainly exhibited temperature minimums and negative slopes dp/dT, with a maximum melting point depression between 9 and 21 K; all systems with SF₆ exhibited a continuous positive slope dp/dT of approximately 4.5 MPa/K. SLG curves with a temperature maximum at low pressure were observed for systems of o-vanillins with R23. Solubilities of o-vanillins in R23 and R236fa were higher in comparison with p-vanillins, whereas, in the case of R134a, the solubilities were influenced by the alchoxy group bound on aromatic ring: vanillin and o-vanillin with methoxy group are more soluble than vanillins with ethoxy group (ethylvanillin and o-ethylvanillin). The highest solubility of all four vanillins was observed in R236fa.     

A pathway for biosynthesis of divinyl ether fatty acids in green leaves

[1-¹⁴C]α-Linolenic acid was incubated with a particulate fraction of homogenate of leaves of the meadow buttercup (Ranunculus acris L.). The main product was a divinyl ether fatty acid, which was identified as 12-[1′(Z),3′(Z)-hexadienyloxy]-9(Z), 11(E)-dodecadienoic acid. Addition of glutathione peroxidase and reduced glutathione to incubations of α-linolenic acid almost completely suppressed formation of the divinyl ether acid and resulted in the appearance of 13(S)-hydroxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid as the main product. This result, together with the finding that 13(S)-hydroperoxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid served as an efficient precursor of the divinyl ether fatty acid, indicated that divinyl ether biosynthesis in leaves of R. acris occurred by a two-step pathway involving an ω6-lipoxygenase and a divinyl ether synthase. Incubations of isomeric hydroperoxides derived from α-linolenic and linoleic acids with the enzyme preparation from R. acris showed that 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid was transformed into the divinyl ether 12-[1′(Z)-hexenyloxy]-9(Z), 11(E)-dodecadienoic acid. In contrast, neither the 9(S)-hydroperoxides of linoleic or α-linolenic acids nor the 13(R)-hydroperoxide of α-linolenic acid served as precursors of divinyl ethers.     

Aqueous Biphasic Hydroformylation of Higher Olefins Catalyzed by Rhodium Complexes with Amphiphilic Ligands of Sulfonated Triphenylphosphine Analog

The catalytic performances of rhodium complexes with three new amphiphilic phosphine ligands, bis-(3-sodium sulfonatophenyl)-(4-tert-butylphenyl)-phosphine (3), phenyl-(3-sodium sulfonatophenyl)-(4-tert-butyl-phenyl)-phosphine (4) and bis-(4-tert-butylphenyl)-(3-sodium sulfonatophenyl) phosphine (5), in hydroformylation of 1-hexene, 1-octene and 1-dodecene have been studied. The steric attributes of free ligands are investigated by Tolman's cone angle method through geometric optimizations. The results reveal that the new phosphines are surface-active as the typical surfactants and the corresponding rhodium complexes show significant enhancements in the reaction rate and higher selectivities toward the normal aldehydes in comparison with those obtained by triphenylphosphine trisulfonate (TPPTS)- and triphenylphosphine disulfonate (TPPDS) rhodium complexes under identical conditions.     

Synthesis, characterization, thermal and flame retardant properties of novel aryl phosphinate diglycidyl ether cured with anhydride

A novel aryl phosphinate diglycidyl ether, 10-(2′,5′-diglycidyl ether phenyl)-9,10-dihydro-9-oxa-l0-phosphaphenanthrene-10-oxide (DHQEP), was synthesized. The structure of the diglycidyl ether was characterized by elemental analysis, mass, FTIR, ¹H, ¹³C, ³¹P NMR spectroscopies and X-ray single crystal analysis. In addition, compositions of the diglycidyl ether with three curing agents, e.g. phthalic anhydride (PA), hexahydrophthalic anhydride (HHPA), and aryl phosphinate anhydride (DMSA), were used for making a comparison of its heat and flame retardancy with that of DER331 and DEN438. The resulting aryl phosphinate epoxy-resin composites demonstrated a higher limiting oxygen index (LOT) value as well as a higher char yield, confirming the effectiveness of aryl phosphinate epoxide as a flame retardant for epoxy resins.     

Synthesis of graft polyethers by ring-opening copolymerization of epoxy-terminated poly(ethylene glycol) with epoxides

The copolymerization of epoxy-terminated poly(ethylene glycol methyl ether) (CH₃PEG–epoxide) with low molecular weight epoxides such as phenyl ether (PGE) was carried out to prepare the PEG graft polyethers. Potassium tert-butoxide was the most favorable catalyst used to obtain the graft polyethers. The apparent number-average molecular weight (M_n ) of the graft polyethers decreased with increase in PGE concentration because PGE acted as both solvent and comonomer. The composition of the graft polyethers (PGE/CH₃PGE), however, increased with increase in PGE concentration and was almost consistent with the feed ratio of the two monomers. The graft polyethers whose composition was over 10 were insoluble in water. The M_n of the graft polyethers was little affected by the reaction temperature, but more affected by the presence of solvent. Besides PGE, n-butyl glycidyl ether and styrene oxide were effective as comonomers. CH₃PEG–epoxide hardly polymerized in tert-butyl alcohol. © 1994 John Wiley & Sons, Inc.     

Thermally induced homolytic scissions of interunitary bonds in a softwood lignin solution: A spin‐trapping study

Unstable chemical species, that is, radicals generated by the thermal treatment of a dimethyl sulfoxide (DMSO) solution of the lignin of a softwood, Yezo spruce (Picea jezoensis Carr.), were studied in detail with an electron spin resonance (ESR) method combined with a spin‐trapping technique. An unstable secondary carbon radical (～CH ·) in the solution was trapped as a stable nitroxide spin adduct [R? (N? O ·)? CH～ (R = tert‐butyl benzene)] when the DMSO solution was heat‐treated in the presence of a spin‐trapping reagent [2,4,6‐tri‐tert‐butylnitrosobenzene (BNB)] at about 40°C. This meant that alkyl phenyl ether bonds (～CH? O‐phenyl), known as interunitary lignin bonds, were homolytically scissioned by the thermal treatment in the lignin solution. A detailed analysis of the ESR spectrum revealed that three kinds of radicals—primary (～CH₂ ·), secondary (～CH ·), and tertiary (～C ·) carbon radicals—were trapped as stable spin adducts at about 60°C, although the phenoxy radical (Ph? O ·) was not trapped by the BNB spin trap as the counter radical of the secondary carbon radical. This suggested that a fairly large steric hindrance existed between the so‐called guaiacoxy radical with a methoxy group in the ortho position and the BNB molecule bearing two butyl groups as bulky moieties in the ortho positions. However, the phenoxy radicals in the lignin solution were stable up to about 60°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2136–2141, 2004     

Antioxidant synergism between butylated hydroxyanisole and butylated hydroxytoluene

Decay of the 2,6-di-tert-butyl-4-methylphenoxy radical [butylated hydroxytoluene (BHT)-radical] in the presence of butylated hydroxyanisole (BHA) was investigated in 1,2-dimethoxyethane with or without triethylamine. BHT-radical was conveniently generated by dissociation of its unstable dimer in solution. The products were BHT, 3,3′-di-tert-butyl-5,5′-dimethoxy-2,2′-dihydroxybiphenyl (BHA-dimer), 2,6-di-tert-butyl-p-quinone methide (QM), 1,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)ethane, and 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone. The reaction without added triethylamine gave larger quantities of the last two products and BHA (recovery), whereas the reaction with it provided larger quantities of the first two products. The marked difference in the product distribution can be accounted for by a series of reactions including reversible dehydrogenation of BHA with BHT-radical, which generates 2-tert-butyl-4-methoxyphenoxy radical (BHA-radical) and BHT, reversible dimerization of BHA-radical, which affords an intermediarybis(cyclohexadienone), and spontaneous and base-catalyzed prototropic rearrangement of the intermediate into BHA-dimer. Products of coupling between BHT-radical and BHA-radical were not obtained. BHA was found to undergo facile acid-catalyzed addition to QM, providing two isomericbis(hydroxyphenyl)methanes. The results help to elucidate the mechanism of antioxidant synergism between BHA and BHT and may suggest that the synergism can be affected by base or acid.     

Investigation of charge transport properties in conducting copolymers of aniline with 3‐aminobenzenesulfonic acid for their applications as antistatic encapsulation materials blended with low‐density polyethylene

The electrostatic charge dissipative (ESD) properties of conducting self‐doped and PTSA-doped copolymers of aniline (AA), o‐methoxyaniline (methoxy AA) and o‐ethoxyaniline (ethoxy AA) with 3‐aminobenzenesulfonic acid (3‐ABSA) blended with low‐density polyethylene (LDPE) were investigated in the presence of external dopant p‐toluenesulfonic acid (PTSA). Blending of copolymers with LDPE was carried out in a twin‐screw extruder by melt blending by loading 1.0 and 2.0 wt% of conducting copolymer in the LDPE matrix. The conductivity of the blown polymers blended with LDPE was in the range 10^?12–10^?6 S cm^?1, showing their potential use as antistatic materials for the encapsulation of electronic equipment. The DC conductivity of all self‐doped homopolymers and PTSA‐doped copolymers was measured in the range 100–373 K. The room temperature conductivity (S cm^?1) of self‐doped copolymers was: poly(3‐ABSA‐co‐AA), 7.73 × 10^?4; poly(3‐ABSA‐co‐methoxy AA), 3.06 × 10^?6; poly(3‐ABSA‐co‐ethoxy AA), 2.99 × 10^?7; and of PTSA‐doped copolymers was: poly(3‐ABSA‐co‐AA), 4.34 × 10^?2; poly(3‐ABSA‐co‐methoxy AA), 9.90 × 10^?5; poly(3‐ABSA‐co‐ethoxy AA), 1.10 × 10^?5. The observed conduction mechanism for all the samples could be explained in terms of Mott's variable range hopping model; however, ESD properties are dependent upon the electrical conductivity. The antistatic decay time is least for the PTSA‐doped poly(3‐ABSA‐co‐AA), which has maximum conductivity among all the samples. © 2013 Society of Chemical Industry     

Studies of tetrazoles as rubber chemicals. I. Preparation and characterization of reactive antioxidants based on tetrazoles

The novel reactive antioxidants based on tetrazoles that are stable at room temperature and convertible into the highly reactive nitrileimines by pyrolysis were prepared and the reactivity for carbon–carbon double bonds was evaluated. Antioxidants, i.e., 2-substituted phenyl-5-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)tetrazoles (PHPT) were prepared with the reaction of p-toluenesulfonylhydrazone of 3,5-di-tert-butyl-4-hydroxybenzaldehyde and substituted phenyl diazonium chloride in a mixed solvent of pyridine, ethanol, and water at ?10°C to ?20°C in 31-61% yields. To evaluate the reactivities of PHPT for carbon–carbon double bonds, m-chloro-substituted PHPT was pyrolyzed in an excess of styrene at 160–170°C for 0.5 h to give the 1-(3′-chlorophenyl)-3-(3″,5″-di-tert-butyl-4″-hydroxyphenyl)-5-phenyl-2-pyridazoline in a 44.1% yield by 1,3-dipolar addition reaction of the nitrileimine formed from the m-chloro-substituted PHPT. The thermogravimetric analysis of a mixture of proton isomer of PHPT and liquid polybutadiene showed that PHPT attached to liquid polybutadiene with an accompanying evolution of nitrogen.     

Design and synthesis of novel cyclooxygenase-1 inhibitors as analgesics: 5-amino-2-ethoxy-N-(substituted-phenyl)benzamides

We previously found that N‐(4‐aminophenyl)‐4‐trifluoromethylbenzamide (TFAP), a COX‐1 inhibitor, exhibits an analgesic effect without causing gastric damage. Unfortunately, TFAP causes reddish purple coloration of urine, and its analgesic effect is less potent than that of indomethacin. Herein we describe our study focusing on the development of 4‐ and 5‐amino‐2‐alkoxy‐N‐phenylbenzamide scaffolds, designed on the basis of the structures of TFAP and parsalmide, another known COX‐1 inhibitory analgesic agent. 5‐Amino‐2‐ethoxy‐N‐(2‐ or 3‐substituted phenyl)benzamide derivatives exhibited analgesic activity in a murine acetic acid induced writhing test. Among these compounds, 5‐amino‐2‐ethoxy‐N‐(2‐methoxyphenyl)benzamide ( 9 v ) possesses potent COX‐1 inhibitory and analgesic activities, similar to those of indomethacin. In addition, 5‐amino‐2‐ethoxy‐N‐(3‐trifluoromethylphenyl)benzamide ( 9 g ) showed a more potent analgesic effect than indomethacin or 9 v without causing apparent gastric damage or coloration of urine, although its COX‐1 inhibitory activity was weaker than that of indomethacin or 9 v . Thus, 9 g and 9 v appear to be promising candidates for analgesic agents and are attractive lead compounds for further development of COX‐1 inhibitors.     

Two‐component photoresists containing thermally crosslinkable photoacid generators

Bis{4‐[2′‐(vinyloxy)ethoxy]phenyl}‐4‐methoxyphenylsulfonium triflate (TPS‐2VE‐Tf) and tris{4‐[2′‐(vinyloxy)ethoxy]phenyl}sulfonium triflate (TPS‐3VE‐Tf) were synthesized as thermally crosslinkable photoacid generators (PAGs) and used in a two‐component chemically amplified photoresist system. The photoresist films formulated with poly(p‐hydroxystyrene) (PHS) as a binder polymer and a thermally crosslinkable PAG are insolubilized in aqueous base by prebaking due to the thermal crosslinking reaction between PHS and the PAG. The insolubilization temperature of the resists and conversion of vinyl ether groups are greatly influenced by the PAG concentration and prebaking temperature, respectively. Upon exposure to deep UV and subsequent postexposure bake, the crosslinks are cleaved by photogenerated acid, leading to effective solubilization of the exposed areas. Photoresists containing TPS‐2VE‐Tf and TPS‐3VE‐Tf exhibited sensitivities of 12 and 45 mJ/cm², respectively. Positive‐tone images were obtained using a 2.38 wt% aqueous tetramethylammonium hydroxide developer.     

Synthesis and properties of novel poly(aryl ether ketone)s containing imide linkages in the main chains

A new monomer containing imide linkages, bis[4-(p-phenoxybenzoyl)-1,2-benzenedioyl]-N,N,N′,N′-4,4′-diaminodiphenyl ether (BPBDADPE), was prepared by the Friedel–Crafts reaction of bis(4-chloroformyl-1,2-benzenedioyl)-N,N,N′,N′-4,4′-diaminodiphenyl ether (BCBDADPE) with diphenyl ether (DPE). Novel poly(aryl ether ketone)s containing imide linkages in the main chains (PEK-I) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of DPE and BPBDADPE. The polymers were characterized by different physico-chemical techniques. The polymers with 10–40 mol% BPBDADPE are semicrystalline and had increased T _gs over commercially available poly(ether ether ketone) (PEEK) and poly(ether ketone ketone) (PEKK) (70/30) due to the incorporation of imide linkages in the main chains. The polymers IV and V with 30–40 mol% BPBDADPE had not only high T _gs of 182–183 °C, but also moderate T _ms of 341–343 °C, having good potential for melt processing and exhibited high thermal stability and good resistance to common organic solvents.     

New investigation of 1‐substituted imidazole derivatives as thermal latent catalysts for epoxy‐phenolic resins

Novel 1‐substituted imidazole derivatives ( 4 – 10 ) were synthesized by imidazole and the corresponding substituted reagents (chloromethylpivalate, diphenylphosphinicchloride, di‐tert‐butyldicarbonate, 1,1′‐oxalylchloride, pyrazine, phneylisocyanat, and p‐toluensulfonylchloride). Polymerization of diglycidyl ether of bisphenol A (DGEBA) with 1‐substituted imidazole derivatives, two commercial available catalysts (imidazole and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole) and N‐benzylpyrazinium hexafluoroantimonate were investigated as model reactions of epoxy resin systems with respect to the thermal latency and storage stability of the catalysts. The catalytic activity of 1‐substituted imidazole derivatives 4 – 10 depended on the steric and withdrawing electronic effect of the substitution groups. To characterize the cure activation energy and the viscosity‐storage time, the order of thermally latent activity is 1‐tosylimidazole ( 6 ) > 1,1′‐oxalyldiimidazole ( 8 ) > N‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) > 1‐tritylimidazole ( 9 ) > N‐phenyl‐imidazole‐1‐carboxamide ( 5 ) > 3‐(diphenylphosphinoyl)imidazole ( 7 ) > tert‐butyl‐1H‐imidazole‐1‐carboxylate ( 4 ) > 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole (2E4MZ, 2 ) > 1‐[(pivalyloxy)methyl]imidazol ( 10 ) > imidazole ( 1 ). In comparison with commercially available catalysts imidazole ( 1 ) and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole ( 2 ) and a cationic latent catalyst N‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) as the standard compounds, in addition to 1‐[(pivalyloxy)methyl]imidazole ( 10 ), the 1‐substituted imidazole derivatives ( 4 – 9 ) revealed better thermal latency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Heat stable and organosoluble polyimides containing laterally-attached phenoxy phenylene groups

In this research a diamine monomer containing two phenoxy phenylene lateral groups, 2,2′-bis[(p-phenoxy phenyl)]-4,4′-diaminodiphenyl ether (PPAPE) was used to prepare novel wholly aromatic polyimides by thermal or chemical two-step polycondensation reactions. Comonomers including pyromellitic dianhydride (PMDA), 4,4′-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) were used for the polyimidization reactions. A reference polyimide was also prepared by the reaction of 4,4′-diaminodiphenyl ether (DADPE) with pyromellitic dianhydride (PMDA). The limited viscosity numbers as well as [`(M)]<sub>n</sub> \overline{M}_n and [`(M)]_w \overline{M}_w values of the resulting polymers were determined. All PPAPE-resulted polyimides had excellent organosolubility in common polar solvents. A low crystallinity extent was only observed using their wide-angle X-ray diffractograms (WAXD). The prepared hinged polyimides could also be cast into transparent and flexible films. The glass transition temperatures of the resulting polyimides were determined by differential scanning calorimetry (DSC) analyses. The thermograms obtained from thermogravimetric analyses (TGA) showed that the phenoxy phenylene lateral groups attached to the macromolecular backbones had no substantial diminishing effect on the thermal stability of these structurally-modified polyimides.