Synthesis of polyphenylene from a cis-dihydrocatechol biologically produced monomer

Abstract

Benzene is oxidized by oxygen utilizing the dioxygenase enzyme contained in the microorganism Pseudomonas putida. Genetic manipulation produced a variant that gave exclusively the initial oxidation product of benzene the cis-dihydrocatechol(2) in practical quantities. Derivatives of the latter, in particular the methyl carbonate, can be obtained pure and are very stable. They polymerize in the absence of solvent with radical initiators to give a polymer (4). The latter is soluble in solvents such as acetone and methylene chloride and readily forms coherent coatings and films. On heating methanol and C 0 2 are expelled and polyphenylene is formed as a coating or film. The aromatization process is catalyzed by bases and can occur well below the glass-transition temperature of the precursor polymer of 185 "C. The aromatization can occur under homogeneous conditions in the basic solvent N-methylpyrrolidone. Surprisingly, these partially aromatized molecules are soluble even at conversion to 30% phenyl groups. The latter studies can be used to measure the glass transition of polyphenylene that was found to be 283 "C. Neutron scattering studies have shown that the precursor polymer is a random coil. Viscosity measurements show that there is a coil-rod transition on aromatization in N-methylpyrrolidone. Crystallographic data on polyphenylene crystallized above its glass transition and the thermal and electrical properties are described.

Aggregation-induced CD effects in chiral poly(2,5-dialkoxy-1,4-phenylene)s

“…All other chemicals are commercially available. (2) 2,5-Dibromohydroquinone (17.04 g, 0.064 mol) and potassium carbonate (35.16 g, 0.254 mol) in 180 ml of dimethylformamide were heated to 70 8C under an argon atmosphere. A solution of 2-(S)-methyl-1-bromobutane (24.03 g, 0.159 mol) in 20 ml of DMF was added.…”

First-principles calculation of the conformation and electronic structure of polyparaphenylene

“…4 Compared to many other conducting polymers which normally have low chemical and thermal stability, poor mechanical strength, or limited possibilities in tuning the wavelength, the wide-gap polymeric PPP is stable in air up to 400°C, 5 and its electronic structure and optical properties can be modified by several chemical methods. [6][7][8][9][10][11][12] Experimentally, the conformation of crystalline PPP as well as the crystalline oligomers of the phenyl ring have been studied extensively. The nuclear configuration is known only for finite oligomers.…”

Saturation Mutagenesis of Burkholderia cepacia R34 2,4-Dinitrotoluene Dioxygenase at DntAc Valine 350 for Synthesizing Nitrohydroquinone, Methylhydroquinone, and Methoxyhydroquinone

“…Dioxygenases are presently used in industrial and pharmaceutical applications, such as the synthesis of cis-(1S,2R)-indandiol from indene with toluene dioxygenase for the human immunodeficiency virus protease inhibitor CRIXIVAN (7), synthesis of indigo from indole with naphthalene dioxygenase (NDO) (4), and synthesis of the heat-stable polymer polyphenylene from benzene by a dioxygenase-catalyzed reaction with Pseudomonas putida (2). These biocatalysts are examples of green chemistry, the synthesis of chemical compounds which reduce the hazardous reagents or by-products that contribute to environmental pollution (1).…”