Synthesis and properties of cyclic diester based aliphatic copolyesters

Melt polycondensation was used to prepare a systematic series of random and amorphous copolyesters using the following cycloaliphatic diesters: dimethyl‐1,4‐cyclohexane dicarboxylate (DMCD), dimethyl bicyclo[2.2.1]heptane‐1,4‐dicarboxylate (DMCD‐1), dimethyl bicyclo[2.2.2]octane‐1,4‐dicarboxylate (DMCD‐2), dimethyl bicyclo[3.2.2]nonane‐1,5‐dicarboxylate (DMCD‐3), 1,4‐dimethoxycarbonyl‐1,4‐dimethylcyclohexane (DMCD‐M) and the aliphatic diols: ethylene glycol (EG) and 1,4‐cyclohexane dimethanol (CHDM). The polymer compositions were determined by nuclear magnetic resonance (NMR) and the molecular weights were determined using size exclusion chromatography (SEC). The polyesters were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The copolyester based on DMCD‐2 was observed to have a higher glass transition temperature (T_g up to 115 °C) than the other copolyesters of this study. For poly[x(DMCD‐2)y(DMCD) 30(EG)70(CHDM)], T_g increases linearly with increase of DMCD‐2 mole content. DMA showed that all of the cycloaliphatic copolyesters have secondary relaxations, resulting from the conformational transitions of the cyclohexylene rings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2162–2169, 2010     

Thermotropic copolyesters. II. Synthesis and characterization of liquid-crystal copolyesters containing the bicyclo[2.2.2]octane ring system

The syntheses and characterizations of poly(oxy-trans-1,4-cyclohexyleneoxycarbonyl-1,4-bicyclo[2.2.2]octylenecarbonyl) (I) and poly(oxy-trans-1,4-cyclohexyleneoxycarbonyl-1,4-bicyclo[2.2.2]octylenecarbonyl-co-oxy-trans-1,4-cyclohexyleneoxysebacoyl) (II) are described. The polymer systems were characterized by infrared spectroscopy, proton magnetic resonance spectroscopy, solution viscosity, and differential scanning calorimetry. The random copolyester prepared from 1:0.65:0.35 mol of trans-1,4-cyclohexanediol, bicyclo[2.2.2]octane-1,4-dicarbonyl chloride, and sebacoyl chloride, respectively, formed a birefringent fluid state in the melt.     

Thermotropic copolyesters. III. Synthesis and characterization of liquid crystal copolyesters containing the bicyclo[2.2.2]octane ring system

A number of thermotropic copolyesters which contain the bicylo[2.2.2]octane ring system have been synthesized. Because of the stiffening effect of the bicyclo[2.2.2]octane group on the chain, the sebacoyl spacer was used to obtain meltable compositions.     

Thermotropic Copolyesters. 1. Synthesis and Characterization of Liquid Crystal Copolyesters Containing the Bicyclo [2.2.2]octane Ring System

The syntheses and characterizations of poiy[oxy(2-chloro-l,4-phenylene)oxycarbonyl- l,4-bicyclo[2.2.2] octylenecarbonyl-co-oxy(2-chloro-l,4-phenylene)oxysebacoyl] and poly[oxy(2-methyl-l,4-phenylene)oxycarbonyl-l,4-bicyclo[2.2.2]octylenecarbonyl-co-oxy(2-methyl-l,4-phenylene)oxysebacoyl] are described. The resulting random copolyesters were characterized by infrared spectroscopy, proton magnetic resonance spectroscopy, solution viscosity, and differential scanning calorimetry. The random copolyesters formed birefringent fluid states in the melt.     

Diazabicycloalkanes with nitrogen atoms in the nodal positions. 5. Synthesis and some reactions of 2-hydroxymethyl-1,4-diazabicyclo [2.2.2]octane

2-Hydroxymethyl-1,4-diazabicyclo[2.2.2]octane was synthesized by reduction of 1,4-diazabicyclo[2.2.2]octane-2-carboxylic acid or its methyl ester with lithium aluminum hydride in tetrahydrofuran and by hydrolysis or hydrogenation of 2-benzyloxymethyl-1,4-diazabicyclo[2.2.2]octane. Depending on the conditions, 2-hydroxymethyl-1,4-diazabicyclo[2.2.2]octane reacts with methyl iodide to give primarily either a bisquaternary or a monoquaternary derivative. The latter is the only product in its alkylation with methyl esters of benzoic and caproic acids.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1407, October, 1980.     

Diazabicycloalkanes with nitrogen atoms in the nodal positions. 3. The benzo[b]-1,4-diazabicyclo [2.2.2]-octene system

Benzo[b]-1,4-diazabicyclo[2.2.2]octene and 4′-methylbenzo[1′,2′-b]-1,4-diazabicyclo[2.2.2]octene were synthesized by the reaction of N-acetyl-6-H- and 6-methyl-1,2,3,4-tetrahydroquinoxalines with ethylene oxide and subsequent cyclization of the N-(β-hydroxyethyl)-N'-acetyl derivatives in refluxing HBr. The errors of the published data on the benzo[b]-1,4-diazabicyclo[2.2.2]octene system are demonstrated. See [1] for communication 2. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 827–830.     

Synthesis of monomers that expand on polymerization. Synthesis and polymerization of 2,6,7-trioxabicyclo[2.2.2]octanes with phenyl groups

2,6,7-Trioxabicyclo[2.2.2]octanes with phenyl group were prepared to obtain monomers which expand on polymerization. 1-Phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane (I) could expand 0.2% during polymerization at a temperature slightly higher than the melting point. 1,4-Diphenyl-2,6,7-trioxabicyclo[2.2.2]octane (II) also expanded as much as 1.4% on polymerization. Further, the hydrolysis of 2,6,7-trioxabicyclo[2.2.2]octanes with p-substituted phenyl groups were investigated to estimate the stability in water.     

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4-bis(carboethoxy)bicyclo[2.2.2]octane, 1,4-bis(hydroxymethyl)bicyclo[2.2.2]-octane and the 1,5-disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4-phenylene and trans-1,4-cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower-melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.     

Synthesis and eutectic behavior of liquid crystalline copolyesters

A series of liquid crystalline copolyesters, derived from 1,4‐hydroxy‐benzoic acid (HBA), 6‐hydroxy‐2‐naphthoic acid (HNA), terephthalic acid (TA), and hydroquinone (HQ), were prepared; crystallization, melting and solid‐state structure of the copolyesters were studied by using differential scanning calorimetry (DSC) and wide‐angle x‐ray diffraction (WAXD). It was found that the variation of melting point of the copolyesters with increasing HBA mol % exhibits eutectic melting behavior at a constant mole ratio of HNA, and the extrapolated eutectic temperature decreases linearly with increasing HNA mol %. WAXD analysis of the copolyesters indicates that the d‐spacing related to three‐dimensional order increases first and then decreases with increasing HBA mol %. The increase of the d‐spacing, consistent with looser packing of chains, leads to the reduction of melting point and most likely accounts for the eutectic behavior observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2171–2177, 2009     

Butylene copolyesters based on aldaric and terephthalic acids. Synthesis and characterization

The synthesis, characterization, and some properties of new copolyesters analogous to poly(butylene terephthalate) (PBT), based on L ‐arabinaric and galactaric acids, are described. These copolyesters were obtained by polycondensation reaction in the melt of mixtures of methyl 2,3,4‐tri‐O‐methyl‐L ‐arabinarate or methyl 2,3,4,5‐tetra‐O‐methyl‐galactarate and dimethyl terephthalate with 1,4‐butanediol. Their weight‐average molecular weights ranged between 10,000 and 34,000, with polydispersities ranging from 1.4 to 2.2. The composition of all the copolymers was analyzed by NMR, and was found to have a statistical microstructure. All these copolyesters were thermally stable, with degradation temperatures well above 300 °C. The melting temperature and crystallinity decreased in both series, and the glass transition temperature increased and decreased respectively, for the PBTGa and PBTAr series with increasing amounts of aldaric units in the copolyester chain. Only PBT‐derived copolyesters containing a maximum of 30% aldaric units showed discrete scattering characteristic of crystalline material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1168–1177, 2009     

Preparation and characterization of aromatic copolyesters containing the o,o′-biphenylene ring system

Poly[oxy-2,2′-diphenyleneoxyisophthaloyl-b-oxy(2-methyl-1,3-phenylene)oxyterephthaloyl] I, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-methyl-1,3-phenylene)oxyterephthaloyl] II, poly(oxy-2,2′-diphenyleneoxyisophthaloyl-b-oxy-2,2′-diphenyleneoxyterephthaloyl) III, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-methyl-1,4-phenylene)oxyterephthaloyl] IV, poly[oxy2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-chloro-1,4-phenylene)oxyterephthaloyl] V, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-co-oxy(2-chloro-1,4-phenylene)oxyterephthaloyl] VI, and poly[oxy-2,2′-diphenyleneoxyterephthaloyl-co-oxy(2-methyl-1,4-phenylene)oxyterephthaloyl] VII have been synthesized and characterized. Random copolyester VI appears to form a birefringent fluid phase above the melting temperature.     

Novel copolyesters containing naphthalene structure. I. From bis(hydroxyalkyl)naphthalate and bis[4-(2-hydroxyethoxy)aryl] compounds

Copolyesters containing naphthalene structure were synthesized from bis(hydroxyethyl)naphthalate (BHEN) or bis(hydroxybutyl)naphthalate (BHBN) and various aralkyloxy diols. The starting bis[4-(2-hydroxyethoxy)aryl] compounds were derived from a nucleophilic substitution of various bisphenols with ethylene carbonate in the presence of KI. Copolyesters having intrinsic viscosities of 0.45–0.60 dL/g were obtained by the melt polycondensation in the presence of metallic catalysts. The effect of reaction temperature and time on the formation of copolyesters were investigated to obtain an optimum condition for copolyesters manufacturing. Most copolyesters have better solubilities than polyethylene naphthalate (PEN) or polybutylene naphthalate (PBN) in aprotic solvents, such as N-methyl-2-pyrrolidone or m-cresol. The thermal properties of the copolyesters were investigated by the differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Glass transition temperatures (T_g) of copolyesters result from BHEN were in the range of 90–141°C, and 10% weight loss in nitrogen were all above 460°C. Another series of copolyesters result from BHBN have T_g in the range of 75–135°C, and 10% weight loss in nitrogen of over 420°C. © 1996 John Wiley & Sons, Inc.     

Novel bicyclo[2.2.2]octanyl-1,4-benzodiazepinones. Their syntheses and rearrangement to bicyclooct-2-enylbenzimidazoles

The synthesis of the novel bicyclo[2.2.2]octanyl[1,4]benzodiazepinone ring system (IV) and its facile acid catalysed rearrangement to the corresponding bicyclo[2.2.2]oct-2-enylbenzirnid-azole system (IX) is described.     

Pyrimidine derivatives XII. A convenient preparation of 6-formylpyrimidinedione and 2- and 3-formylpyridine derivatives from corresponding nitrooxymethyl derivatives

The convenient preparation of 6-fomylpyrimidinedione derivatives and 2- and 3-formylpyridine are described. Thus, 5-bromo-1,3-dimethyl- ( 1a ), 5-bromo-3-methyl-1-(2-nitrooxyethyl)- ( 1b ), and 5-bromo-3-methyl-1-(3-nitrooxypropyl)-2,4(1H,3H)-pyrimidine-dione ( 1c ) were converted to the corresponding 6-formyl compounds 2a, 2b , and 2c , respectively, in excellent yields by the reaction with triethylamine and 1,4-diazabicyclo[2.2.2]octane. These 6-formylpyrimidinedione derivatives are key intermediates for the preparation of 6-carbon-carbon substituted compounds, which are expected to be potential antitumor and antiviral agents. Similarly, 2-(and 3-)formylpyridine ( 9a (and 9b )) were obtained by the reaction of 2-(and 3)nitrooxymethylpyridine ( 8a (and 8b )) with 1,4-diazabicyclo[2.2.2]octane.     

Synthese und Struktur von Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octan – Eine neue Käfigverbindung mit dem Sn(P2)3Sn-Gerüst

Synthesis and Structure of Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane – a New Cage Compound with the Sn(P₂)₃Sn Skeleton The reaction of the diphosphide K₂[(tBuP)₂] 1 with SnCl₄ leads by a redox process mainly to (tBuP)_3,4 and other sideproducts. However, at the same time a threefold [2 + 1]-cyclocondensation reaction takes place yielding the new cage compound hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane, ClSn(tBuP? PtBu)₃SnCl 2 . 2 could be obtained in a pure form and characterized ³¹P and ¹¹⁹Sn NMR spectroscopically; 2 was also characterized by a single crystal structure analysis.     

Fluordiazadiphosphetidine, 16. Mitt.

The reaction of (CH₃NPF₃)₂ with NH₃ and primary aliphatic and aromatic amines in the molar ratio 3:2 yields (CH₄NPF₄)₂ and the monoamino substituted fluordiaza-diphosphetidines. These react with N-Trimethylsilyl-methylamine to the mixed diamino substituted compounds.With 1,4-Diazabicyclo[2.2.2]octan as HF-acceptor a second step of nucleophilic substitution with NH₃ and primary amines is possible. In the case of ammonia a by- product has been identified as the 1:1 adduct of (CH₃NPF₂NH₂)₂ with 1,4-diazabicyclo[2.2.2]octan.

Herrn Prof. Dr.O. Hromatka zum 80. Geburtstag gewidmet.     

Thermal and pyrolysis studies of copolyesters

Random copolyesters of dimethyl terephthalate (DMT), ethylene glycol (EG), and butane-1,4-diol (BD) and the homopolyesters poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) have been subjected to degradation and pyrolysis studies. Differential thermal analysis (DTA) showed that the decomposition temperature is dependent on the percentage of EG and BD present in the copolyesters. Thermal volatilization analysis (TVA) also showed that the decomposition temperature is dependent on the percentage of EG and BD present in the copolyesters. The trend for the decomposition temperatures obtained from TVA studies for these copolyesters is similar to such other thermal properties as melting temperature T_m, ΔH_f, ΔH_c, etc. The subambient thermal volatilization analysis (SATVA) curves obtained for these polymers are also presented. The SATVA curve is the fingerprint of the total volatile products formed during the degradation in high vacuum. The isothermal pyrolysis of these materials was carried out in high vacuum at 450°C. The products formed were separated in a gas chromatograph and were subsequently identified in a mass spectrometer. The major pyrolysis products from PBT were butadiene and tetrahydrofuran, whereas those from PET were ethylene and acetaldehyde. The ratio of acetaldehyde to ethylene increases with the EG content in the copolyester, suggesting a different decomposition mechanism compared to the decomposition mechanism of PBT and PET.     

Interaction between Exocyclic s-cis-Butadiene and Homoconjugated Functions. Preparation and Diels-Alder Reactivity of Remotely Substituted 2,3-Dimethylidenebicyclo[2.2.2]octanes

The preparations of 5,6-dimethylidene-2exo-bicyclo[2.2.2]octanol ( 8 ), its endo isomer 9 , 5,6-dimethylidene-2-bicyclo[2.2.2]octanone ( 10 ) and 2 exo, 3 exo-epoxy-5,6dimethylidenebicyclo[2.2.2]octane ( 11 ) are described. The kinetics of their cycloaddition to tetracyanoethylene has been measured in toluene at 25° together with those of 2,3-dimethylidenebicyclo[2.2.2]octane ( 7 ) and 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene (12). The effects of remote substitution on the Diels-Alder reactivity of 2,3-dimethyl idenebicyclo[2.2.2]octanes are compared with those observed in the 2,3-dimethylidenenorbornane series ( 1–6 ).     

Efficient Baylis-Hillman Reaction via a 1,4-Diazabicyclo[2.2.2]octane-based Ionic Catalyst

A novel ionic catalyst, 1-butyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride based on 1,4-diazabicyclo[2.2.2]octane was synthesized and applied in the Baylis-Hillman reaction, which occurred readily at room temperature to afford the corresponding adducts in good yield. The ionic catalyst could be recycled for seven runs without diminution in its catalytic activity.     

Efficient <Emphasis Type="Italic">Baylis-Hillman</Emphasis> Reaction <Emphasis Type="Italic">via</Emphasis> a 1,4-Diazabicyclo[2.2.2]octane-based Ionic Catalyst

Summary. A novel ionic catalyst, 1-butyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride based on 1,4-diazabicyclo[2.2.2]octane was synthesized and applied in the Baylis-Hillman reaction, which occurred readily at room temperature to afford the corresponding adducts in good yield. The ionic catalyst could be recycled for seven runs without diminution in its catalytic activity.