Effects of structure on properties of some new aromatic-aliphatic polybenzimidazoles

Polybenzimidazoles were prepared in poly(phosphoric acid) from isophthalic, m- and p-phenylene diacetic, succinic, adipic, suberic, and sebacic acids and 3,3′-diaminobenzidine, 3,3′,4,4′-tetraaminodiphenyl ether and 3,3′,4,4′-tetraaminodiphenylmethane. The thermal, mechanical, and bonding properties were studied. A 3:1 copolymer of isophthalic and m-phenylenediacetic acid with 3,3′-diaminobenzidine showed the best results as far as isothermal oxidation resistance and thermal and processing characteristics.     

Biselenienyl series. II. Synthesis and resolution of 2,2′-dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid

2,2′-Dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid (VI), the first recorded compound of the 3,3′-biselenienyl series, has been prepared and resolved into its optical antipodes by fractional crystallization of its brucine salt. On the basis of the quasi-racemate method of Fredga and the O.R.D. spectra, to the dextrorotatory acid is assigned the R configuration.     

Thermally stable polymers from 1,4,5-naphthalene–tricarboxylic acid and aromatic tetramines

New thermally stable polymers that contained benzimidazole and benzimidazobenzoisoquinoline fragments in polymer chains were synthesized by one-stage cyclopolycondensation of aromatic tetramines (3,3′, 4,4′-tetraminodiphenyl ether, 3,3′,4,4′-tetraminodiphenyl methane, 3,3′,4,4′-tetraminodiphenyl sylfone, and 3,3′-diaminobenzidine) with 1,4,5-naphthalene tricarboxylic acid 4:5–anhydride in polyphosphoric acid and with 1,4,5-naphthalene tricarboxylic acid 4:5–anhydride 1-phenyl ester. All polymers obtained were soluble in concentrated sulfuric acid, 85% phosphoric acid, polyphosphoric acid, methane sylfonic acid. Some were soluble in formic acid. Thermogravimetric analyses indicated that these polymers were stable up to 450–500°C in air. The polymers had good hydrolytic stability.     

Cyclisation of benzils

Treatment of several substituted benzils [3,3′- and 4,4′-dimethyl-; 2,2′-, 3,3′- and 4,4′-dichloro-; 3,3′-dibromo-; 4-(N,N-dimethylamino)-] with an excess of chlorosulfonic acid gave the corresponding 3-chloro-2-phenylbenzofuran disulfonyl dichlorides. Disubstitution was confirmed by microanalytical and spectral data for the corresponding bis(N,N-dimethylaminsulfonamides). The positions of electrophilic substitution were not confirmed with 3,3′-dimethyl-, 2,2′- and 3,3′-dichlorobenzils. With 4,4′-dichlorobenzil, a smaller amount of chlorosulfonic acid enabled the isolation of 3,6,4′-trichloro-2-phenylbenzofuran-5-sulfonyl chloride, which was identified by X-ray analysis of the N,N-dimethylsulfonamide. The cyclisation failed with 3,3′-dimethoxy-, and 3,3′- and 4,4′-dinitrobenzils. The results have been interpreted mechanistically.     

Polymers containing anthraquinone units: Polycondensations 1,2,5,6-tetraaminoanthraquinone with some tetrachloroquinoxaline compounds

New ladder and partial ladder aromatic heteropolymers have been synthesized from 1,2,5,6-tetraaminoanthraquinone, 2,3,7,8-tetrachloro-1,4,6,9-tetraazaanthracene, 2,2′-3,3′-tetrachloro-6,6′-diquinoxaline, 2,2′,3,3′-tetracholoro-6,6′-diquinoxalyl ether and 2,2′,3,3′-tetrachloro-6,6′-diquinoxalyl sulfone. The polycondensations were carried out in solution and in melt. The inherent viscosities of polymers were in the range of 0.1-0.44. These polymers were highly colored, showed good thermal stability and were soluble in concentrated sulfuric acid and methanesulfonic acid. The structures of the polymers were established by comparison with model compounds.     

Syntheses and Promising Properties of Dense Energetic 5,5′‐Dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole and Its Salts

A planar energetic molecule with high density, 5,5′‐dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole ( 4 ), was obtained by the nitration of 5,5′‐diamino‐3,3′‐azo‐1,2,4‐oxadiazole using 100 % nitric acid. In addition, selected nitrogen‐rich salts were prepared. Of them, the neutral compound 4 and its hydroxylammonium salt, 6 , were further confirmed by single‐crystal X‐ray diffraction. Physicochemical and energetic properties including density, thermal stability, and sensitivity were investigated. The energetic performance from the calculated heats of formation and experimental densities indicates that many of them have potential applications as energetic materials.     

Facile access to some new 3,3′-bipyrazole-ester derivatives utilizing bis-hydrazonoyl chlorides

The 1,3-dipolar cycloaddition reaction of bis-hydrazonoyl chlorides with ethyl propiolate and dimethyl acetylenedicarboxylate afforded diethyl 1,1′-aryl-3,3′-bipyrazole-4,4′-dicarboxylate and tetramethyl 1,1′-diaryl-3,3′-bipyrazole-4,4′,5,5′-tetracarboxylate esters, respectively. Heating the latter two compounds with a mixture of HCl/AcOH furnished the same product: 3,3′-bipyrazole-5,5′-dicarboxylic acid. Reaction of the tetracarboxylate ester with aniline derivatives and with hydrazine gave the corresponding bipyrazole-fused heterocycles. Heating the dicarboxylic acid with 2-aminothiazole gave the corresponding bis-amide derivative. The structures of the products were established by elemental analysis, spectral data, and single-crystal X-ray crystallography.     

Polymers with quinoxaline units. III. Polymers with quinoxaline and thiazine recurring units

Six ladder or partly ladder polymers have been prepared by the condensation reactions of combinations of two diaminodithiophenols, 4,6-diamino-1,3-dithiophenol and 3,3′-dimercaptobenzidine, with three tetrachloroquinoxaline derivatives, 2,3,7,8-tetrachloro-1,4,6,9-tetraazaanthracene, 2,2′,3,3′-tetrachloro-6,6′-bisquinoxaline, and 2,2′,3,3′-tetrachloro-6,6′-diquinoxalyl ether, with the use of dimethylacetamide, hexamethylphos phoramide, and polyphosphoric acid as reaction media. The polymers thus obtained are highly colored, powedery materials which are slightly soluble in methanesulfonic acid and concentrated sulfuric acid. These polymers (η_inh > 1) show good thermal stability.     

3,3′‐Bi(1,2,4‐oxadiazoles) Featuring the Fluorodinitromethyl and Trinitromethyl Groups

Here we report on the preparation of two hydrogen atom free 3,3′‐bi(1,2,4‐oxadiazole) derivatives. 5,5′‐Bis(fluorodinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole) was synthesised by fluorination of diammonium 5,5′‐bis(dinitromethanide)‐3,3′‐bi(1,2,4‐oxadiazole). For our previously reported analogue 5,5′‐bis(trinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole), a new synthetic route starting from new 3,3′‐bi(1,2,4‐oxadiazolyl)‐5,5′‐diacetic acid was developed. In this course also hitherto unknown 5,5′‐dimethyl‐3,3′‐bi(1,2,4‐oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X‐ray diffraction studies were performed and the crystal structures for the 5,5'‐dimethyl and 5,5'‐(fluorodinitromethyl) derivatives are reported. The energetic 5,5'‐(fluorodinitromethyl) and 5,5'‐(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS‐4M enthalpies. With these values and the room‐temperature X‐ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code.     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

Aromatic polyamides and polyimides derived from 3,3′-diaminobiphenyl: Synthesis,characterization, and molecular simulation study

In this article a new synthesis of 3,3′-diaminobiphenyl (3,3′-DABP) is described, along with the preparation and characterization of polyamides and polyimides based on it. Reactivity of this monomer was calculated by a molecular simulation study, using ab initio quantum-mechanical methods. Terephthaloyl and isophthaloyl chloride were used for the synthesis of polyamides, while 3,3′,4,4′-biphenylenetetracarboxylic acid dianhydride and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride were used for the synthesis of polyimides. Medium to high molecular weight polymers were attained, with inherent viscosities near or higher than 1.0 dL/g, the solubility of the 3,3′-DABP polymers was much better than that of the homologous polymers from benzidine (4,4′-DABP), the glass-transition temperatures were lower, by about 40°C, and the thermal resistance, as measured by thermogravimetry, was virtually the same. Amorphous films, made from cast polymer solutions, showed excellent mechanical properties, comparable to conventional aromatic polyamides and polyimides. Theoretical calculations demonstrated that the radius of giration, end-to-end distance and density of poly(3,3′-DABP-isophthalamide) were lower than those of poly(4,4′-DABP-isophthalamide), as a consequence of the chain folding induced in the backbone by the m-substitution in 3,3′-DABP. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4646–4655, 1999     

Synthesis and characterization of polyimides based on new fluorinated 3,3′-diaminobiphenyls

Two new fluorinated diamine monomers, 3,3′-diamino-5,5′-bis(trifluoromethyl)biphenyl and 3,3′-diamino-6,6′-bis(trifluoromethoxy)biphenyl, as well as a known nonfluorinated analog, 3,3′-diaminobiphenyl, were synthesized. Reaction of these diamines with rigid, highly rod-like dianhydrides produced poly(amic acid)s and polyimides, which were spin coated and thermally treated to produce polyimide films for evaluation in electronics applications. It was hoped that these polyimide films would exhibit an ideal combination of low thermal expansion, reduced water absorption, and low dielectric constant but with improved elongation due to the “crankshaft” nature of the 3,3′-biphenyl unit. Unlike polyimide films from analogous 4,4′-diaminobiphenyls, however, the 3,3′-diaminobiphenyl-based polyimides did not yield low in-plane thermal expansion coefficient in spin-coated films. In some cases high elongation was achieved, but with high thermal expansion. These new diamines may nevertheless find utility in polyimides and polyaramides for membrane, fiber, and other applications. Additionally, they may be useful in modifying the properties of polymer backbones via copolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2441–2451, 1997     

Synthesis,characterization, and thermal stability of bismaleimides derived from maleimido benzoic acid

Bismaleimides containing ester, amide, urethane, and imide groups in the backbone were synthesized from maleimido benzoic acid via its acid chloride or isocyanate with 4,4′-dihydroxy-diphenyl-2,2-propane, 3,3′-diamino diphenyl sulfone, and 3,3′,4,4′-benzophenone tetracarboxylic acid anhydride by simple condensation or addition reaction. The new bismaleimides are characterized by IR, ¹H-NMR, and elemental analysis. DSC studies of these bismaleimides indicated a curing exotherm in the temperature range 150–270°C with heat of polymerization 30–50 J/g. Thermogravimetric analysis of the uncured resins showed high thermal stability and char yield for imide containing bismaleimide. The observed char yields of the bismaleimide resins are in accordance with the calculated C/H ratios.     

Self-condensation reaction of aromatic tetraamines in polyphosphoric acid

Ladder and partial ladder polymers have been obtained by self-condensation reactions of 1,2,4,5-tetraaminobenzene, 3,3′,4,4′-tetraaminodiphenyl ether, 3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenyl sulfone in polyphosphoric acid. The products thus obtained are highly colored compounds with good thermal stability. They seem to be made up of polyquinoxaline or dihydrophenazine or a mixture of these two recurring units. They are slightly soluble in methanesulfonic acid and concentrated sulfuric acid and have inherent viscosities in the 0.2 to 0.4 range.     

Polyanthranilides. III. Synthesis and Characterization of Polyamides from 6,6′-Bis[3,1-benzoxazin-2,4-dione]

Ring-scission polymerization of 6,6′-bis[3, 1-benzoxazin-2,4-dione] was studied in presence of such catalysts as aqueous HC1, benzidine-3,3′-dicarboxamide, N-methyl aniline, o-chloroaniline, benzidine-3,3′-dicarboxylic acid, and acid amides under various experimental conditions. It was found that 6,6′-bis[3,1-benzoxazin-2,4-dione] undergoes ring-scission polymerization, affording polyanthranilides in the presence of the first five catalysts under appropriate experimental conditions. The samples are insoluble in all organic solvents including formic acid. They are soluble in sulfuric acid with degradation. They are characterized by IR spectral and thermogravimetric analysis.     

Synthesis and properties of aromatic polyimides derived from 2,2,′3,3′‐biphenyltetracarboxylic dianhydride

2,2,′3,3′‐Biphenyltetracarboxylic dianhydride (2,2,′3,3′‐BPDA) was prepared by a coupling reaction of dimethyl 3‐iodophthalate. The X‐ray single‐crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,′4,4′‐BPDA. This dianhydride was reacted with aromatic diamines in a polar aprotic solvent such as N,N‐dimethylacetamide (DMAc) to form polyamic acid intermediates, which imidized chemically to polyimides with inherent viscosities of 0.34–0.55 dL/g, depending on the diamine used. The polyimides from 2,2,′3,3′‐BPDA exhibited a good solubility and were dissolved in polar aprotic solvents and polychlorocarbons. These polyimides have high glass transition temperatures above 283°C. Thermogravimetric analyses indicated that these polyimides were fairly stable up to 500°C, and the 5% weight loss temperatures were recorded in the range of 534–583°C in nitrogen atmosphere and 537–561°C in air atmosphere. All polyimides were amorphous according to X‐ray determination. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1425–1433, 1999     

Novel polybenzoxazinones with tricyclic fused-rings

A series of polybenzoxazinones containing phenoxathiin and phenoxaphosphine units were prepared from tricyclic diacid chlorides and 4,4′-diaminobiphenyl-3,3′-dicarboxylic acid and 4,4′-diamino-3,3′-diphenylmethane dicarboxylic acid. The low temperature solution polymerization technique afforded polyamic acid which subsequently underwent cyclization along the polymer chain in a solvent mixture of refluxing N,N′-dimethylacetamide, acetic anhydride, and pyridine to give polybenzoxazinones in moderate yields. The polymers thus obtained had inherent viscosities in the range of 0.15–0.23 dL/g, were sparingly soluble in N-methyl-2-pyrrolidone, and were found to be thermally more stable than the corresponding open-chain polymer with diphenylether linkage.     

Ni(0)-Catalyzed Dimerization of o-Keto Carboxylic Acid Pseudochlorides

Russian Journal of Organic Chemistry - A new protocol of the synthesis of 3,3′-diaryl-3,3′-diphthalides by dehalogenation of o-keto carboxylic acid pseudochlorides is implemented. The...     

Synthesis of corrosion-inhibiting polythioesters

Binary condensation copolymers of five monomers known to be corrosion inhibitors were synthesized by solution polymerization. The copolymers synthesized were poly(1,2-ethanedithiol-thiodiglycolate), poly(1,3-propanedithiol-3,3′-thiodipropionate), poly(1,2-ethanedithiol-3,3′-thiodipropionate), and poly(2,5-dimercapto-1,3,4-thiadiazole-3,3′-thiodipropionate). Yields ranged from 77 to 89% and molecular weights from 10,100 to 24,300. Attempts to produce the condensation copolymers of thiodiglycolic acid chloride and 1,3-propanedithiol or 2,5-dimercapto-1,3,4-thiadiazole failed, yielding only telomeric products. The copolymers that were synthesized demonstrated significant corrosion-inhibitory properties on steel samples in salt water.     

Chelating Polymers. II. Amino Acetic Acid Chelating Polymers Derived from Hydroxyarylamino Acetic Acids

The prototype dimeric chelating compounds 3,3′-methylenebis-[N(4-hydroxyphenyl) iminodiacetic acid] and 3,3′-methylenebis-[N(4-methoxyphenyl) iminodiacetic acid] were synthesized and characterized by composition analysis, infrared spectroscopy, and potentiometric titration data. Their chelating characteristics with Cu(II), Ni(II), Co(II), and Zn(l1) ions were established by composition analysis and comparative infrared spectroscopy.

The results suggest chelation and structures of the usual iminodiacetatometal complex type for the Ni(II), Co(II), and Zn(I1) compounds of 3,3′methylenebis-[N-(4-hydroxyphenyl) iminodiacetic acid] and for the Cu(I1, Ni(II), and Co(I1) compounds of 3,3′-methylenebis-[N-(4-methoxyphenyl) iminodiacetic acid]. The composition analysis of each of these compounds indicates 1:2:2 mole ratios of ligand to metal ion to water. Square planar structures are proposed wherein the two iminodiacetatometal chelate moieties are essentially independent of each other.

The composition analysis of the Cu(II) compound of 3,3′-methylenebis-[N-(4-hydroxyphenyl) iminodiacetic acid] indicates a 1:2:1 mole ratio of ligand to metal ion to water. Structures are proposed in which some of the carboxylate groups are bridges between two metal coordination centers.

The composition analysis of the Zn(II) compound of 3,3′-methylenebis-[N-(4-methoxyphenyl) iminodiacetic acid] indicates a 1:1 mole ratio of ligand to metal ion. A structure is proposed in which both nitrogen atoms and two of the four carboxylate groups of the dimeric ligand are coordinated to the same metal ion.

A preliminary investigation was made of oligomeric compounds analogous to the prototype dimeric compounds.