On the structure of macromolecules obtained by oxidative polymerization of polyhydroxyphenols and quinones

Cataldo, Franco

doi:10.1002/(sici)1097-0126(199808)46:4<263::aid-pi983>3.0.co;2-0

Cited by 30 publications

(32 citation statements)

References 8 publications

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“…The oxidative polymerisation of benzoquinone in water [15,16] at the interphase between organic and aqueous phase is the mostimportant side reaction: a small amount of quinone diffuses into the aqueous phase an leading to high-molecular species of humic acid type [16]. After 90 minutes of irradiation 37% of the consumed benzoquinone were converted to hydroquinone.…”

Section: 4-benzoquinone In a Direct Methan Fuel Cell (Dmfc)mentioning

confidence: 99%

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1,4-Hydroquinone is a Hydrogen Reservoir for Fuel Cells and Recyclable via Photocatalytic Water Splitting

Wilke¹,

Schneider²,

Kleinermanns³

2013

OJPC

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Photocatalytic splitting of water was carried out in a two-phase system. Nanocrystalline titanium dioxide was used as photocatalyst and potassium hexacyanoferrate(III)/(II) as electron transporter. Generated hydrogen was chemically stored by use of a 1,4-benzoquinone/1,4-hydroquinone system, which was used as a recyclable fuel in a commercialised direct methanol fuel cell (DMFC). The electrical output of the cell was about half compared to methanol. The conversion process for water splitting and recombination in a fuel cell was monitored by UV-Vis spectroscopy and compared to a simulated spectrum. Products of side reactions, which lead to a decrease of the overall efficiency, were identified based on UV-Vis investigations. A proof of principle for the use of quinoide systems as a recyclable hydrogen storage system in a photocatalytic water splitting and fuel cell cyclic process was given.

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Section: 4-benzoquinone In a Direct Methan Fuel Cell (Dmfc)mentioning

confidence: 99%

“…Condensation of benzoquinone leads to a wide variety of highmolecular products of humic acid type, which show a wide absorption in the range of 300nm to 500 nm [16].…”

Section: 4-benzoquinone In a Direct Methan Fuel Cell (Dmfc)mentioning

confidence: 99%

1,4-Hydroquinone is a Hydrogen Reservoir for Fuel Cells and Recyclable via Photocatalytic Water Splitting

Wilke¹,

Schneider²,

Kleinermanns³

2013

OJPC

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“…This structure is similar to lignin, one of the major constituents of the organic matter of soil. 21 The SHA synthesis presented an excellent performance, yielding 76.36% in weight of polymerized parabenzoquinone. Table 1 lists the results of the elemental analysis and the ash content, indicating that the SHA contained a large amount of oxygen exceeding 40% (values calculated by difference), which is similar to the amount of oxygen found in natural humic acid, which also contains more than 40% of oxygen.…”

Section: Obtaining Natural and Synthetic Humic Acidsmentioning

confidence: 99%

“…21 The reason for synthesizing these polymers was that the information obtained from these synthetic precursors can be used to shed light on the complex structure of natural humic acids.…”

Section: Obtaining Natural and Synthetic Humic Acidsmentioning

confidence: 99%

“…This structure can be described by a sequence of phenyl rings having three hydroxyl groups per ring intercalated by monohydroxylated quinone units (Figure 1). 21 The presence of the carboxylic group is derived from the degradation of the aromatic ring during polymerization. This structure is similar to lignin, one of the major constituents of the organic matter of soil.…”

Section: Obtaining Natural and Synthetic Humic Acidsmentioning

confidence: 99%

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Electron paramagnetic resonance characterization of a humic acid-type polymer model

Barriquello¹,

Saab²,

Filho³

et al. 2010

J. Braz. Chem. Soc.

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Modelos de ácidos húmicos do tipo poliméricos tem mostrado semelhanças químicas com os ácidos húmicos naturais (AH). Devido à complexidade das substâncias húmicas (SH), esses modelos de ácidos húmicos do tipo poliméricos, no qual os sítios ligantes podem ser melhores definidos, podem ser usados no estudo de metais e outras aplicações. Neste estudo, obteve-se um polímero com características análogas às dos AH coletados em área de cultivo com sistema plantio direto por 9 anos, por meio de reações de síntese, através da polimerização oxidativa em meio alcalino utilizando como precursor a para-benzoquinona. Foi realizado um estudo do ácido húmico (AH) e do ácido húmico sintético (AHS) utilizando espectroscopia de ressonância paramagnética eletrônica (RPE Humic acid-type polymer models have been shown to be similar to natural humic acids (HA) in terms of chemical properties. Due to the complexity of humic substances (HS), this humic acid-type polymer models, in which the ligand sites are better defined, can be used in the study of metals and for other applications. In this study, a polymer with characteristics analogous to those of humic acids isolated from soil surface cultivated using a no-tillage system for nine years, was obtained by means of synthesis reactions, through oxidative polymerization in an alkaline medium using para-benzoquinone as precursor. An EPR spectroscopy study was made of natural humic acids (HA) and synthetic humic acids (SHA). A semiquinone-type free radical signal was detected in the SHA. The spectra showed similar signals for HA from soil and synthetic HA complexed with Fe 3+ , Cu 2+ and Mn 2+ ions.

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Redox‐active LBL films via in situ template polymerization of hydroquinone

Guan

Zhang

2013

J of Applied Polymer Sci

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New redox-active hydrogel thin films with poly(hydroquinone) (PHQ) as polymeric redox couple and chitosan hydrogel as matrix are synthesized. Single-component layer-by-layer films of chitosan are first fabricated in a uniform and reproducible manner, which is proved by UV and AFM studies. The chitosan films are then treated in acidic hydroquinone (HQ) solution to introduce PHQ. In situ generation of PHQ in the films is proved by UV and FTIR spectroscopy. PHQ formation also results in an increased film roughness and thickness. We confirmed that oxygen acts as oxidant and chitosan acts as template in the polymerization of HQ. Cyclic voltammogram of the film presents two oxidation peaks at 0.21 and 0.75 V and one reduction peak at À0.15 V(vs Ag/AgCl), indicating the film, which is originally not redox-active, becomes redox-active after the introduction of PHQ. The new redox-active films may find applications in amperometric biosensors.

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On the structure of macromolecules obtained by oxidative polymerization of polyhydroxyphenols and quinones

Cited by 30 publications

References 8 publications

1,4-Hydroquinone is a Hydrogen Reservoir for Fuel Cells and Recyclable via Photocatalytic Water Splitting

1,4-Hydroquinone is a Hydrogen Reservoir for Fuel Cells and Recyclable via Photocatalytic Water Splitting

Electron paramagnetic resonance characterization of a humic acid-type polymer model

Redox‐active LBL films via in situ template polymerization of hydroquinone

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