NMR investigation of aniline oligomers produced in the oxidation of aniline in alkaline medium

Křı́ž, Jaroslav; Konyushenko, Elena N.; Stejskal, Jaroslav

doi:10.1002/pi.3079

Cited by 21 publications

(15 citation statements)

References 44 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The differences between GPC and MALDI-TOF analysis results can be explained as the standards used in GPC detection is very different in nature of polyaniline [33], and the MALDI-TOF method has been usually shown to be less efficient when detecting PANI with much higher molecular mass [33,34]. By referring to the literature study, we propose that OANI-B may have molecular structure containing some phenazine-like units and O0Q0N-like groups [8,12,15], as schematically shown in Scheme 1.…”

Section: Resultsmentioning

confidence: 90%

“…As the aniline COP is an autocatalytic process, where the later produced polymers are more prone to grow from active sites on the as-formed products [10], and it was said that in contrast to PANI, aniline oligomers are capable of forming ordered extended structures [11]. Recently, more and more efforts have been made to carefully examine the structures of oligomeric intermediates produced during aniline COP process [8,[12][13][14][15][16]]. However, the specific self-assembly behaviors of aniline oligomers and PANI molecules are still shown to be partially known, due to the special aniline COP course.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Self-assembly of aniline oligomers in aqueous medium

Feng

et al. 2012

Colloid Polym Sci

View full text Add to dashboard Cite

By dissolving branched or linear aniline oligomers in polar solvent and introducing their stock solution into an aqueous acidic medium, sheet-like as well as wire-like supramolecular structures with well-defined morphology were obtained, respectively. These oligomeric supramolecular structures were constructed via a post-synthetic precipitation process, indicating that aniline oligomers are capable of selfassembling in an aqueous medium, which is similar to the reaction medium of aniline chemical polymerization. Possible formation mechanisms of these supramolecular structures were proposed, i.e., sheet-like products were probably constructed by collapsed molecular chains of aniline oligomers with branched units through π-π stacking and hydrogen bonding, whereas formation of the wire-like products was attributed to "oriented-attachment" of collapsed molecular chains of linear aniline oligomers. The findings obtained in this study are supposed to provide useful clues for uncovering the formation mechanism of polyaniline micro-/nanostructures.

show abstract

Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Self-assembly of aniline oligomers in aqueous medium

Feng

et al. 2012

Colloid Polym Sci

View full text Add to dashboard Cite

show abstract

“…Furthermore, the formation of oxygen-containing products (arylhydroxylamine, nitrosoarene, nitroarene, azoxyarene, amino-phenols, benzoquinones, and oligomers containing such structures) is also possible (Ćirić-Marjanović 2013b; Kříž et al 2011; Surwade et al 2009; Zhou et al 2015). The main product as well as the product distribution after the reaction is completed are very dependent on the reaction conditions: this includes such characteristics like the type of oxidant, the concentration of the oxidant, the concentration of the arylamine, the ratio between the oxidant and the arylamine, the solvent type, the presence of co-solvent, the ratio between the solvent and the co-solvent, and the presence and concentration of reaction-controlling templates (Ćirić-Marjanović 2013b; Rakić et al 2015; Walde and Guo 2011).…”

Section: Introductionmentioning

confidence: 99%

Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives

et al. 2016

View full text Add to dashboard Cite

The literature concerning the oxidative oligomerization and polymerization of various arylamines, e.g., aniline, substituted anilines, aminonaphthalene and its derivatives, catalyzed by oxidoreductases, such as laccases and peroxidases, in aqueous, organic, and mixed aqueous organic monophasic or biphasic media, is reviewed. An overview of template-free as well as template-assisted enzymatic syntheses of oligomers and polymers of arylamines is given. Special attention is paid to mechanistic aspects of these biocatalytic processes. Because of the nontoxicity of oxidoreductases and their high catalytic efficiency, as well as high selectivity of enzymatic oligomerizations/polymerizations under mild conditions—using mainly water as a solvent and often resulting in minimal byproduct formation—enzymatic oligomerizations and polymerizations of arylamines are environmentally friendly and significantly contribute to a “green” chemistry of conducting and redox-active oligomers and polymers. Current and potential future applications of enzymatic polymerization processes and enzymatically synthesized oligo/polyarylamines are discussed.

show abstract

“…They form mainly due to the head‐to‐tail (C–N) coupling of aniline units, but in alkaline and neutral environments hydrazobenzene and azobenzene are found as a result of head‐to‐head coupling (N–N) . According to various spectroscopies, mass spectroscopy, 1 H NMR, 13 C NMR, 15 N NMR and XRD analyses, aniline oxidation products prepared under alkaline conditions are chemically heterogeneous and contain linear and cyclic fragments with amino and imino groups, as well as oxygen‐containing groups . Such products have molecular weights up to 3000 g mol −1 , are amorphous and are partially soluble in aqueous and organic solvents.…”

Section: Oxidative Polymerization Of Anilinementioning

confidence: 99%

“…In addition, hydrolysis becomes operational in the presence of water and oxidant. Aminophenols and benzoquinones are the products of this hydrolysis . As the regioselectivity of electrophilic substitution is low, aniline oxidation leads to a heterogeneous chain structure.…”

Section: Mechanism Of Aniline Oxidationmentioning

confidence: 99%

Conjugated polyaniline as a result of the benzidine rearrangement

Sapurina

Теньковцев

Stejskal

2015

Polymer International

Self Cite

View full text Add to dashboard Cite

Abstract:The mechanism of the oxidative polymerization of aniline is reviewed on the basis of the experimental evidence and reaction schemes proposed in the literature. It is demonstrated that the balance between the non-protonated and protonated forms of the monomer and the growing chain is responsible for the diversity of the molecular structure, morphology and properties of aniline oxidation products. Various forms are oxidized by two oxidation mechanisms: (1) chain reaction of electrophilic substitution and (2) coupling of cation-radical centres. At pH > 2.5, the non-protonated reagents are oxidized with a chain reaction controlled by electrophilic substitution of the aromatic ring. The reaction leads to the formation of non-conducting aniline oligomers with heterogeneous molecular structures. At pH = 2.5-4, the electrophilic substitution is reduced because of the protonation of the aniline, and the cyclic dimer, phenazine, becomes the main product of the oxidation. The growth of the conjugated chain proceeds at pH < 2.5, when the reactants are protonated. The reaction proceeds through coupling between the terminal cation radical and the monomer cation radical with formation of a -complex. The transformation of the -complex into a para-substituted monomer unit is thermodynamically controlled and is produced through an intramolecular benzidine (semidine) rearrangement. The regular structure of the growing chains is a result of the high regioselectivity of the sigmatropic rearrangements and significant energy gain attained by the formation of protonated polyconjugated chains in the agglomerated state.

show abstract

NMR investigation of aniline oligomers produced in the oxidation of aniline in alkaline medium

Cited by 21 publications

References 44 publications

Self-assembly of aniline oligomers in aqueous medium

Self-assembly of aniline oligomers in aqueous medium

Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives

Conjugated polyaniline as a result of the benzidine rearrangement

Contact Info

Product

Resources

About