Direct and sensitized photolysis of 1,4-benzoquinone diazides in organic solvents

Samsonova, L. V.; Никифоров, Г. А.

doi:10.1007/bf01141701

Cited by 2 publications

(2 citation statements)

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“…Benzoquinone (BQ) belongs to a large class of quinonic compounds commonly used for dye production. Quinones have been used as analytical reagents, 1 polymer modifiers, 2 photoresistors, 3 catalysts, 4 herbicides, 5 fungicides, 5,6 and plantgrowth regulators. 7 BQ is also broadly used in tanning, dyes, 1 cosmetics, 8 and nonprescription forms of skin lightening cosmetics.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Benzoquinone (BQ) belongs to a large class of quinonic compounds commonly used for dye production. Quinones have been used as analytical reagents, polymer modifiers, photoresistors, catalysts, herbicides, fungicides, , and plant-growth regulators . BQ is also broadly used in tanning, dyes, cosmetics, and nonprescription forms of skin lightening cosmetics. − The widespread domestic and industrial use of BQ and its products results in a significant human population being exposed to quinones.…”

Section: Introductionmentioning

confidence: 99%

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Substituent Effects on the Reactivity of Benzoquinone Derivatives with Thiols

Mbiya

Chipinda

Siegel

et al. 2012

Chem. Res. Toxicol.

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Benzoquinone (BQ) is an extremely potent electrophilic contact allergen that haptenates endogenous proteins through Michael addition (MA). It is also hypothesized that BQ may haptenate proteins via free radical formation. The objective of this study was to assess the inductive effects (activating and deactivating) of substituents on BQ reactivity and mechanistic pathway of covalent binding to a nucleophilic thiol. The BQ binding of Cys34 on human serum albumin was studied and for reactivity studies, nitrobenzenethiol (NBT) was used as a surrogate for protein binding of the BQ and benzoquinone derivatives (BQD). Stopped flow techniques were used to determine pseudo-first order rate constants (k) of methyl, t-butyl and chlorine substituted BQD reactions with NBT whereas electron pair resonance (EPR) studies were performed to investigate the presence a free radical mediated binding mechanism of BQD. Characterization of adducts was performed using mass spectrometry and nuclear magnetic resonance spectroscopy (NMR). The rate constant values demonstrated the chlorine substituted (activated) BQD to be more reactive toward NBT than the methyl and t-butyl substituted (deactivated) BQD, and this correlated with the respective EPR intensities. The EPR signal, however, was quenched in the presence of NBT suggesting MA as the dominant reaction pathway. MS and NMR results confirmed adduct formation to be a result of MA onto the BQ ring with vinylic substitution also occurring for chlorine substituted derivatives. The binding positions on BQ and NBT:BQ(D) stoichiometric ratios were affected by whether the inductive effects of the substituents on the ring were positive or negative. The reactivity of BQ and BQD is discussed in terms of the potential relationship to potential allergenic potency.

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