Biimidazole-sensitized photooxidation of leuco triphenylmethane dyes

MacLachlan, Alexander; Riem, R. H.

doi:10.1021/jo00815a017

Cited by 24 publications

(4 citation statements)

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“…The high stability of the trityl cation in polymer Ic may be contributed to the extensive delocalization of the charge onto the phenyl rings and TPA via resonance as shown in Scheme . The halocarbon‐sensitized photooxidation mechanism of triphenylmethane have already be described 40, 41. The new absorption band at 698 nm of Ic in Figure 11(b) is another strong evidence that the methine protons of TPA derivatives‐benzaldehyde polymers could be completely eliminated by UV light, which Sato also reported the similar absorption result by the reaction of polymer Ib with oxidant 42…”

Section: Resultssupporting

confidence: 52%

Novel aromatic polymers from benzaldehyde and triphenylamine derivatives: Synthesis, electrochromic, and photochemical properties

Liou

Chang

Lin

et al. 2009

J. Polym. Sci. A Polym. Chem.

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A series of novel triphenylamine-based polymers were synthesized from benzaldehyde and triphenylamine derivatives. All the polymers having high molecular weight are readily soluble in many organic solvents and could be solution-cast into amorphous films. They had glass transition temperatures (T g s) in the range of 193-217 C, and 10% weight loss temperatures in excess of 475 C. Cyclic voltammograms of all polymers showed reversible oxidation redox peaks and E onset around 0.42-0.90 V, indicating that the polymers are electrochemically active and stable. In addition, all these polymers revealed photochemical characteristics in conformity with their electrochromic characteristics.

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Section: Resultssupporting

confidence: 52%

Novel aromatic polymers from benzaldehyde and triphenylamine derivatives: Synthesis, electrochromic, and photochemical properties

Liou

Chang

Lin

et al. 2009

J. Polym. Sci. A Polym. Chem.

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“…5. With 2,6-Di-iert-butylphenol (9).-A solution prepared in the dark from 1.3 g of 9, 1.5 g of biimidazole lb, and 100 ml of benzene was irradiated 1 hr, 6 in. from a sun lamp.…”

Section: Methodsmentioning

confidence: 99%

“…Examples of representative reactions are the subject of mechanistic studies reported in subsequent papers. [9][10][11][12][13] Radicals 2 do not react with aromatic hydrocarbons, aliphatic alcohols, oxygen, or vinyl monomers at rates which compete detectably with dimerization or the oxidation reactions studied. Thus, benzene and methanol could be used as solvents under conditions employed without observing side products due to their presence.…”

mentioning

confidence: 99%

Reactions of triarylimidazolyl free radicals

Coraor¹,

Cescon²,

Dessauer³

et al. 1971

J. Org. Chem.

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was also 10-4 M in leuco crystal violet and 2 X 10~1 234 M in toluenesulfonic acid. From the amount of crystal violet dye obtained as determined spectrally, and from the reaction stoichiometry (1 mol of dye per biimidazole dissociated) and quantum yield of unity,9 both experimentally determined, radical concentration immediately after the flash was obtained.Rates of Triarylimidazolyl Radical Dimerization.-A Perkin-Elmer "Spectrachord" Model 400A was set up in a dark room to record absorbance (at of each radical) vs. time. A solution of biimidazole in carefully purified benzene was irradiated until a steady state was established and absorbance was recorded for several half-lives and determined eventual!)-at "t = ® ." From the usual second-order expression, the slope of 1/A. plotted vs. t gave k/e (cell length = 1 cm) reported in Table I. From these values k was calculated.Extreme care was necessary to free solvents of impurities which react with radicals. Normally, three distillations of reagent grade solvent sufficed. Even with carefully purified solvents, radical dimerization was not the exclusive fate of radicals in the media studied. A small but detectable deviation from strict second-order was apparent sometime during the second half-life4 and A" was slightly greater than A measured prior to irradiation. Rate constants were taken from the first half-life.Rates in 50:50 vol methanol-benzene were measured both in the spectrometer and in the flash photolysis apparatus used to determine extinction coefficients. An oscillographic trace of absorbance vs. time was photographed.

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“…[29][30][31][32] The mechanism of the bisimidazole-sensitized photooxidation of leuco Crystal Violet has been studied. 33 The first step of the reaction involves an electronexchange reaction between 2-(o-chlorophenyl)-4,5-diphenylimidazolyl radical 18 (generated from the corresponding dimer) and the leuco dye, forming a solvated electron and a radical cation 26,34,35 19. Decay of the radical cation results in the formation of a dye cation 20 and a hydrogen atom.…”

Section: Via Oxidationmentioning

confidence: 99%