Chemical trapping experiments support a cation-radical mechanism for the oxidative polymerization of aniline

Ding, Yong; Padías, Anne Buyle; Hall, H. K.

doi:10.1002/(sici)1099-0518(19990715)37:14<2569::aid-pola30>3.0.co;2-n

Cited by 61 publications

(18 citation statements)

References 48 publications

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“…At the same time, PANI is readily formed in the presence of electron-enriched arenes (1,3-and 1,4-dimethoxybenzene) well known as "traps" of nitrenium cations. This f a c t p r o v e s t h a t oxidation of aniline proceeds via a radical cation site (Ding at al., 1999).…”

Section: The Active Site Of Polymerizationmentioning

confidence: 99%

Oxidative Polymerization of Aniline: Molecular Synthesis of Polyaniline and the Formation of Supramolecular Structures

Sapurina¹,

Shishov²

2012

New Polymers for Special Applications

104

128

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Section: The Active Site Of Polymerizationmentioning

confidence: 99%

Oxidative Polymerization of Aniline: Molecular Synthesis of Polyaniline and the Formation of Supramolecular Structures

Sapurina¹,

Shishov²

2012

New Polymers for Special Applications

104

128

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“…attention because of their suspected roles in carcinogenesis [30][31][32][33][34][35] and in the synthesis of conducting polymers. [36][37][38] For substituted nitrenium ions, the prevailing view is that the ∆E ST is determined by both steric and electronic factors. For the parent system (NH 2 + ), the singlet state has a bent geometry with a bond angle of 107°, whereas the triplet is quasilinear, having an equilibrium bond angle of 150°and a very low barrier to inversion.…”

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confidence: 99%

Effect of meta Electron-Donating Groups on the Electronic Structure of Substituted Phenyl Nitrenium Ions

2004

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Density functional theory (UB3LYP/6-31G(d,p)) was used to determine substituent effects on the singlet-triplet-state energy gap for 21 meta-substituted phenylnitrenium ions. It was found that strongly electron-donating substituents stabilize the triplet state relative to the singlet state. With sufficiently strong meta electron donors (e.g., m,m'-diaminophenylnitrenium ion) the triplet is predicted to be the ground state. Analysis of equilibrium geometries, Kohn-Sham orbital distributions, and Mulliken spin densities for the triplet states of this series of nitrenium ions leads to the conclusion that there are two spatially distinct types of low-energy triplet states. Simple arylnitrenium ions such as phenylnitrenium ions as well as those having electron-withdrawing or weakly donating meta substituents have lowest-energy triplet states that are n,pi in nature. That is, one singly occupied molecular orbital is orthogonal to the plane of the phenyl ring and one is coplanar. These n,pi triplets are generally characterized by large ArNH bond angles (ca. 130-132 degrees ) and an NH bond that is perpendicular to the plane of the phenyl ring. In contrast, meta donor arylnitrenium ions have a lowest-energy triplet state best described as pi,pi. That is, both singly occupied molecular orbitals are orthogonal to the aromatic ring. Such pi,pi states are characterized by NH bonds that are coplanar with the phenyl ring and have ArNH bond angles that are more acute (ca. 110-111 degrees ). These triplet nitrenium ions have electronic structures analogous to those of meta-benzoquinodimethane derivatives.

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“…The initial pH value of the system was about 6.6, above the pK a of aniline (4.6). [19,20] The pH value quickly decreased to around 4.0 within 10 min, as the oxidation polymerization proceeded, and a large number of round plates were yielded in this period.…”

Section: On-line Detection Of the Morphology And Ph Valuementioning

confidence: 99%

Fabrication of Polyaniline: Nail/Spindle‐Shaped Morphology

Leng

Zhou

2011

Macro Chemistry & Physics

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Nail/spindle‐shaped polyaniline is synthesized by chemically oxidizing aniline with ammonium persulfate in a near‐neutral aqueous medium using PVP as the stabilizing agent. The type of dispersing agent, APS content and aniline concentration have obvious impacts on the morphology of the resulting polyaniline. Typically, in the concentration ranges of 1.5–6 × 10−4 M PVP and 0.02–0.05 M aniline and for molar ratios [APS]:[aniline] of 0.4:1 to 0.8:1, nail/spindle‐shaped polyaniline can be obtained. A possible mechanism is proposed to elucidate the formation process.magnified image

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Chemical trapping experiments support a cation-radical mechanism for the oxidative polymerization of aniline

Cited by 61 publications

References 48 publications

Oxidative Polymerization of Aniline: Molecular Synthesis of Polyaniline and the Formation of Supramolecular Structures

Oxidative Polymerization of Aniline: Molecular Synthesis of Polyaniline and the Formation of Supramolecular Structures

Effect of meta Electron-Donating Groups on the Electronic Structure of Substituted Phenyl Nitrenium Ions

Fabrication of Polyaniline: Nail/Spindle‐Shaped Morphology

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