The synthesis of dicarboxylie acids containing oxadiazole rings and polyamides derived from them

Novel dicarboxylic acids containing one or two 1,3,4-oxadiazole rings in a molecule were synthesized by the reaction between orthoesters and acid hydrazides These dicarboxylic acids have the following structures: and where R represents a phenylene or an alkylene group and n = 1-4. The polyamides from p-xylylenediamine with these dicarboxylic acids were also prepared. The polymers are generally insoluble in m-cresol but soluble in conc. sulfuric acid. The melting points were estimated at above 350°C. Copolyamides of high molecular weights with aliphatic polyamides were obtained.     

Thermotropic polyamides containing the benzophenone unit

The synthesis and structure-property relationship of fully aromatic homo- and copolyamides are described. They all contain the 3,4′-substituted benzophenone and diphenyl ether moiety in the main chain. The synthesis of the polyamides was performed at low temperatures with silylated aromatic diamines and aromatic acid chlorides. The polymers possess good solubility in dipolar aprotic solvents. They display thermotropic liquid crystalline properties. Based on results obtained by means of polarization microscopy, X-ray scattering, and molecular dynamics simulation a rather unusual structure is proposed. It consists of a superlattice composed alternatingly of smectic B layers and amorphous layers. The formation of smectic B layers is untypical for main-chain LC polymers without aliphatic spacers.     

Syntheses of polyamides containing theophylline and thymine

2-(1,3-Dimethyl-2,6-dioxo-2,6-dihydropurin-7-yl)methylsuccinic acid ( 2a ) and 2-(5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)methylsuccinic acid ( 2b ) were synthesized via the addition reaction of theophylline and thymine, respectively, to dimethyl methylenesuccinate, followed by hydrolysis of the resulting ester. The dicarboxylic acid derivatives 2a and 2b were further converted to their di-p-nitrophenyl esters 3a and 3b , which were allowed to polycondense with diamines such as 1,6-diaminohexane, 1,2-diaminoethane, 3-aminomethylbenzylamine, and piperazine in solutions. The resulting polyamides are white powders with molecular weights in the range of about 2000–6000. The DP of the polyamides varies with the kind of diamines and solvent used. All polyamides are soluble in DMSO and formic acid, the polyamides deriving from esters 3a and 3b and 1,2-diaminoethane and piperazine are also soluble in water.     

Synthesis of polyamides containing cytosine and hypoxanthine

The di(cyanomethyl) methylsuccinate derivative of cytosine and di(p-nitrophenyl) methyl-succinate derivative of hypoxanthine were prepared and polycondensed with a variety of diamines to provide powdery polyamides with molecular weights in the range of 1000–3100. The polyamides are soluble in DMSO and formic acid, but insoluble in ordinary organic solvents.     

Syntheses of polyamides containing uracil and adenine

2-(2,4-Dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)methylsuccinic acid ( 2a ) and 2-(6-aminopurin-9-yl)methylsuccinic acid ( 2b ) were synthesized through the addition reaction of uracil and adenine, respectively, to dimethyl methylenesuccinate, followed by hydrolysis of the resulting dimethyl esters. Dicarboxylic acid 2a was further converted to the corresponding di-p-nitrophenyl ester 3a and dicarboxylic acid 2b was converted to the di(cyanomethyl) ester 3b . The active esters 3a and 3b were polycondensed with diamines such as 1,2-diaminoethane, 1,6-diaminohexane, 4-aminomethylbenzylamine, and piperazine in solution, giving polyamides containing uracil and adenine as the side group. The polyamides were found to have molecular weights in the range of about 1000–5000. The polyamides derived from 1,2-diaminoethane and piperazine were soluble in water.     

Preparation of polyamides containing α-diketone moieties and their transformation into 1,2,4-triazine rings with amidrazones

Polyamides 3–5 containing 1,2,4-triazine rings in the main chain were prepared by condensation of amidrazones 2 with polyamides 1 containing α-diketone moieties, with conversions between 10 and 87%. The thermal stabilities and the solubilities of the resulting polymers 3–5 were enhanced by the introduction of the 1,2,4-triazine rings in the main chain.     

Preparation of polyamides having 1,2,4-triazine rings in the main chain

Polyamides having 1,2,4-triazine rings in the main chain ( 6 and 7 ) were prepared from 3-substituted 4,4′-(1,2,4-triazine-5,6-diyl)dibenzoic acids ( 5 ) and aromatic diamines. The thermal stability and the solubility of polyamides 6 and 7 were compared with those of structurally identical polyamides (polymers 3 and 4 ) obtained by polymer homologous reaction of polyamides having α-diketone moieties with amidrazones. The effects of introduction of 1,2,4-triazine-5,6-diyl unit in the main chain on the thermal stability and solubility of the polymers are discussed.     

Low temperature elastomeric polyamides containing perfluorinated polyether building blocks

Reductive cleavage of derivatives from tetrafluoroethylene photooxidation resulted in perfluorinated polyethers with α,ω-carboxylic ester groups B . Their condensation with suitable aliphatic and aromatic diamines gave a new class of elastomers, crosslinkable by organic peroxides. A good balance of low temperature elasticity, resistance to solvents, and thermostability was particularly found for aromatic polyamides.     

Polycarbonates and polyesters containing oxadiazole rings

Two new bisphenols containing an oxadiazole ring, 2,5-bis(p-hydroxyphenyl)-1,3,4-oxadiazole and 2,5-bis(m-hydroxyphenyl)-1,3,4-oxadiazole, were synthesized starting from p- and m-hydroxybenzoic acid and hydrazine. Polycarbonates having an inherent viscosity up to 0.5 were obtained by transesterification of the bisphenols with diphenyl carbonate. Similarly, aromatic polyesters were prepared from the corresponding diphenyl esters. These polycarbonates and polyesters were insoluble in all organic solvents, and indicated a high degree of crystallinity. The melting point of all the polymers containing oxadiazole rings were much higher than that of the polymers derived from bisphenol A.     

Synthesis of polyamides containing 4,4′-azodibenzamido units

Four coloured polyamides containing azo-p-phenylene units were synthesised from 4,4′-azodibenzoic acid and four aromatic diamines employing both interfacial and solution polymerization procedures. The polymers were characterized by their UV and IR spectra, by inherent viscosity measurements and by solubility data. The stability in conc. sulfuric acid and the thermal behaviour are discussed.     

Wholly aromatic polyamides containing bridged biphenylylene groups, 2. Copolyamides

A number of wholly aromatic copolyamides containing bridged biphenylylene groups were synthesized from a mixture of aromatic diamines and terephthaloyl chloride, on one hand, and from a mixture of aromatic diacid dichlorides and 1,4-phenylenediamine, on the other hand. Each mixture of diamines and of diacid dichlorides was constituted of a phenylene derivative and a bridged biphenylylene derivative. The copolyamides synthesized were dissolved in high concentration sulfuric acid and spun into fibers. The fibers spun showed fairly high tensile strengths and high initial moduli, but annealing caused further increase in strength and modulus. All the copolyamides studied had very high thermal resistances.     

Preparation and properties of polyamides containing dibenzothiphenediyl and 5,5-dioxodibenzothiophenediyl units

Several new polyamides ( 3a–d , 6a–d , 7a and 7b ) containing dibenzothiophenediyl units were prepared by low temperature solution polycondensation of dibenzothiophenediamines ( 1a, b ) with aromatic diacyl dichlorides ( 2a, b ) or of aromatic diamines ( 5a, b ) with dibenzothiophenediacyl dichlorides ( 4a, b ). Some of the polymers were soluble in polar amide solvents or DMSO. All the polymers possess inherent viscosities in the range of 0,6 to 1 dl/g. Thermal stability and crystallinity were determined. The resulting polyamides were found to be much more stable than the corresponding polymers having open-chain linkages.     

Synthesis and characterization of some novel polyamides containing diacetylene side groups

A series of novel polyamides containing diacetylene groups as side chains were prepared by Cadiot-Chodkiewcz-coupling of polymer precursors bearing 2-propynyloxy side groups with 4-bromo-3-butyn-1-ol. The conversion of the acetylenic groups was in the range of 87.5–96.5% depending on the chemical structure of the polymer backbone. The polymers are highly amorphous and undergo random cross-linking on heating. Thermally treated polymer films show third-order nonlinear optical susceptibility χ(3) of the order of 10⁻¹⁰ esu (= 10⁻¹⁸m⁵/V²).     

Preparation of regularly Sequenced polyamides,containing definite numbers of oxyethylene units

Polyamides 3 containing constant and definite numbers of oxyethylene units were prepared by condensation polymerization of suitable diamines and diesters, both of which containing oxyethylene units. The polymer structure was determined by IR and ¹H NMR spectroscopy. Almost all polymers are crystals melting at ≈ 40°C and show a complexation ability towards alkalimetal cations. It was also found that diesters containing oxyethylene units show a higher condensation rate than alkylene diesters, which is explained by an inductive effect of the ether oxygene. However, no remarkable difference in the condensation rate was found between diamines containing oxyethylene units and the corresponding aliphatic diamines.     

Stability of solutions of aromatic polyamides containing carborane units in the main chain

The stability of aromatic polyamide chains containing 1,7-dicarba-closo-dodecaborane units was investigated in dilute solution by viscometry and sedimentation analysis at 25°C. Traces of impurities in dimethylformamide bring about degradation of the polymer and formation of polyanions, which become manifest in the viscosity by the polyelectrolyte effect. Neutral salts suppress this effect. Degradation is not hindered in an inert atmosphere. The solutions in N,N-dimethylacetamide and N-methyl-2-pyrrolidone are also unstable. No degradation occurs in solutions in tetrahydrofuran stabilized with 2,6-di-tert-butyl-4-methylphenol. Hence, reliable measurements of the molecular characteristics of this polymer can be carried out only in stabilized peroxide-free tetrahydrofuran.     

Solitary bone cyst of the radius containing Liesegang's rings

The authors describe the case of a 33-year-old man with a solitary cystic lesion of the left distal radius with central radiodensities that radiographically suggested a chondroid matrix. Curettage of the lesion revealed numerous calcospherites with a lamellar structure. This lamellar pattern is thought to be a result of alternating precipitation and diffusion of supersaturated solutions. This biochemical process has been called the Liesegang's phenomenon, and the structures have been termed Liesegang's rings. The presence of these structures in this benign lesion contributed to atypical roentgenographic and pathologic findings.     

Synthesis and characterization of some aliphatic polyamides containing 4,4′-azodiphenylene units

Polyamides containing azo groups were prepared by the phosphorylation method from 4,4′-diaminoazobenzene and malonic, succinic, glutaric, adipic, azelaic, sebacic, or chlorosuccinic acid. The polymers were characterized by their viscosity and solubility, and by UV-visible and IR spectroscopy, TG, and DTA.     

Synthesis and characterization of new cardo polyamides and polyimides containing tert‐butylcyclohexylidene units

A new cardo diamine monomer, 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐4‐tert‐butylcyclohexane containing tert‐butylcyclohexylidene units was prepared in three steps from 4‐tert‐butylcyclohexanone. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce polyamides and polyimides, respectively. All the polymers, characterized by X‐ray diffraction, are amorphous. These cardo polymers exhibit good solubility in a variety of solvents. Almost all polymers are soluble in N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, and even in tetrahydrofuran (THF) and cyclohexanone. The polymers show glass transition temperatures between 244–310°C and decomposition temperatures at 10% mass loss ranging from 486–526°C in nitrogen. The tough and flexible polymer films have tensile strength of 77–137 MPa, elongations at break of 5–14%, and tensile moduli of 2.0–2.6 GPa.     

Synthesis and characterization of some new polyamides containing azomethine groups in the polymer backbone, 2

New aromatic polyamides containing azomethine groups in the backbone and also having different linking groups like ? CH₂? , ? CH₂? CH₂? , and ? O? were synthesized by reacting 4,4′-[1,4-phenylenebis(methylidynenitrilo)]dibenzoyl dichloride (2) with some diamines 1a – d, 4, and 6 by the low temperature solution polycondensation method. The physical, spectral, and thermal properties of the synthesized polyamides were investigated. The effect of the nature of different linking groups on the properties of these aromatic polymides was explored by comparing their spectral and thermal data.