Synthesis and characterization of thianthrene‐containing poly(benzoxazole)s

Johnson, Randy A.; Mathias, Lon J.

doi:10.1002/pola.1995.080331118

Cited by 12 publications

(11 citation statements)

References 5 publications

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“…Another option could be Michael addition of the NHC to the a,b-unsaturated system (to give 25), which would offer another means of initiation in the absence of an NHC-Si interaction. [37] Such NHC addition reactions have been previously reported in other organocatalytic pathways [38] and may be relevant here.…”

Section: Mechanistic Understandingsupporting

confidence: 74%

N‐Heterocyclic Carbene Mediated Activation of Tetravalent Silicon Compounds: A Critical Evaluation

Fuchter

2010

Chemistry A European J

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An overview of the recent bibliography concerning the N-heterocyclic carbene (NHC)-mediated activation of tetravalent silicon compounds is presented. Diverse reactions are discussed, such as the NHC-mediated addition of silyl pronucleophiles to a variety of electrophiles, NHC-promoted organic and inorganic polymerisation and the reduction of CO(2) by hydrosilanes as facilitated by NHCs. The review concludes with a discussion of the current knowledge regarding the role of Lewis acid-base NHC-Si interactions in the mechanistic course of these reactions.

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Section: Mechanistic Understandingsupporting

confidence: 74%

N‐Heterocyclic Carbene Mediated Activation of Tetravalent Silicon Compounds: A Critical Evaluation

Fuchter

2010

Chemistry A European J

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“…Thianthrene groups have also been incorporated into the backbone of conjugated aromatic polymers for applications in light‐emitting diodes 26, 27. The thianthrene group has also been incorporated into the backbones of poly(benzoxazole)s28 to increase solubility. Polydithiathianthrenes have been made in which the backbone of the polymer consists completely of thianthrene units 29.…”

Section: Introductionmentioning

confidence: 99%

Thianthrene as an activating group for the synthesis of poly(aryl ether thianthrene)s by nucleophilic aromatic substitution

Edson

Knauss

2004

J. Polym. Sci. A Polym. Chem.

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A method for the preparation of poly(aryl ether thianthrene)s has been developed in which the aryl ether linkage is generated in the polymer‐forming reaction. The thianthrene heterocycle is sufficiently electron‐withdrawing to allow fluoro displacement with phenoxides by nucleophilic aromatic substitution. The monomer for this reaction, 2,7‐difluorothianthrene, can be synthesized in a moderate yield by a simple reaction sequence. Semiempirical calculations at the PM3 level suggest that 2,7‐difluorothianthrene is sufficiently activated, whereas NMR spectroscopy (1H and 13C) indicates that the monomer is only slightly activated or (19F) not sufficiently activated for nucleophilic aromatic substitution. Model reactions with p‐cresol have demonstrated that the fluorine atoms on 2,7‐difluorothianthrene are readily displaced by phenoxides in high yields, and the process has been deemed suitable for polymer‐forming reactions. High‐molecular‐weight polymers have been produced from bisphenol A, bisphenol AF, and 4,4′‐biphenol. The polymers have been characterized with gel permeation chromatography, NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The glass‐transition temperatures for the polymers of different compositions and molecular weights range from 138 to 181 °C, and all the polymers have shown high thermooxidative stability, with 5% weight loss values in an air environment approaching 500 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6353–6363, 2004

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“…The first is a two‐step process that involves the initial formation of poly( o ‐hydroxy amide)s from bis( o ‐aminophenol)s or their silylated derivatives with aromatic diacid chlorides followed by thermal cyclodehydration to PBOs in solid state or in solution 7, 10, 21–24. The second is a one‐step route directly producing PBOs by the melt polycondensation of bis( o ‐aminophenol)s with aromatic diacid diphenyl esters25 and by the solution polycondensation with aromatic diacids,14, 26–29 poly(terephthalic acid anhydride),30 or 1,4‐bis(trichloromethyl)benzene31 in acidic media such as poly(phosphoric acid) and phosphorus pentoxide/methanesulfonic acid. Furthermore, another facile method has been reported for the preparation of PBOs, that is, the one‐step polycondensation method from nitrile‐bearing o ‐aminophenols32 and from monomer pairs of bis( o ‐aminophenol)s and dinitriles 33.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

Hsiao

2001

J. Polym. Sci. A Polym. Chem.

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Three new bis(ether-acyl chloride) monomers, 1,1-bis[4-(4-chloroformylphenoxy)phenyl]cyclohexane (1a), 5,5-bis[4-(4-chloroformylphenoxy)phenyl]-4,7-methanohexahydroindan (1b), and 9,9-bis[4-(4-chloroformylphenoxy)phenyl]fluorene (1c), were synthesized from readily available compounds. Aromatic polybenzoxazoles bearing ether and cardo groups were obtained by the low-temperature solution polycondensation of the bis(ether-acyl chloride)s with three bis(aminophenol)s and the subsequent thermal cyclodehydration of the resultant poly(o-hydroxy amide)s. The intermediate poly(o-hydroxy amide)s exhibited inherent viscosities in the range of 0.35-0.71 dL/g. All of the poly(o-hydroxy amide)s were amorphous and soluble in many organic polar solvents, and most of them could afford flexible and tough films by solvent casting. The poly(o-hydroxy amide)s exhibited glass-transition temperatures (T g 's) in the range of 141-169°C and could be thermally converted into the corresponding polybenzoxazoles approximately in the region of 240 -350°C, as indicated by the DSC thermograms.Flexible and tough films of polybenzoxazoles could be obtained by thermal cyclodehydration of the poly(o-hydroxy amide) films. All the polybenzoxazoles were amorphous and showed an enhanced T g but a dramatically decreased solubility as compared with their poly(o-hydroxy amide) precursors. They exhibited T g 's of 215-272°C by DSC and showed insignificant weight loss before 500°C in nitrogen or air.

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Synthesis and characterization of thianthrene‐containing poly(benzoxazole)s

Cited by 12 publications

References 5 publications

N‐Heterocyclic Carbene Mediated Activation of Tetravalent Silicon Compounds: A Critical Evaluation

N‐Heterocyclic Carbene Mediated Activation of Tetravalent Silicon Compounds: A Critical Evaluation

Thianthrene as an activating group for the synthesis of poly(aryl ether thianthrene)s by nucleophilic aromatic substitution

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

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