2913-40-8

Upstream product

• 1123-09-7 3,5-dimethyl-2-cyclohexen-1-one 
• 4380-94-3 3,5-dimethyl-1,2,4-benzenetriol 
• 95-68-1 2,4-Xylidine 
• 576-26-1 2.6-dimethylphenol 
• 108-68-9 3,5-Dimethylphenol 
• 527-61-7 2,6-dimethyl-1,4-benzoquinone 
• 41168-76-7 1,3-dimethyl-2,4,5-triacetoxybenzene 

Downstream Products

• 16635-79-3 1,2,3,5-tetraacetoxy-4,6-dimethyl-benzene 
• 6717-01-7 2,6-dihydroxy-3,5-dimethyl-1,4-benzoquinone 
• 4380-94-3 3,5-dimethyl-1,2,4-benzenetriol 
• 3214-57-1 2-methoxy-3,5-dimethyl-2,5-cyclohexadiene-1,4-dione 

Relevant academic research and scientific papers

Kinetic studies of hydroxyquinone formation from water soluble benzoquinones

The kinetics and mechanisms of the redox reactions between hydrogen peroxide and 1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2,6-dimethyl-1,4- benzoquinone, 2-chloro-1,4-benzoquinone and 2,6-dichloro-1,4-benzoquinone were studied in aqueous media using spectrophotometric monitoring. The formation and decay of a hydroxylated 1,4-benzoquinone was detected. The formation of the intermediate was first order with respect to the parent 1,4-benzoquinone and hydrogen peroxide, whereas inverse first order dependence was revealed with respect to the hydrogen ion. The decomposition reaction had two parallel pathways: one was first order with respect to the intermediate, while the other showed second-order dependence. The values of the rate constant measured for the formation step were successfully correlated with both the redox potentials of the substituted quinone-hydroquinone systems and the pKa values of the hydroxylated quinone derivatives. Therefore, electronic effects govern the reactivity of the quinones in this process. NMR and GC-MS measurements were carried out to identify the products in the system. Quantum mechanical calculations were also carried out in these systems.

Photoprocesses of p-Benzoquinones in Aqueous Solution

The photochemistry of 1,4-benzoquinone (BQ) and several derivatives, for example, duroquinone, trimethyl-2,5- or 2,6-dimethyl-, and methyl-BQ in aqueous solution or mixtures with polar media, for example, acetonitrile or 2,2,2-trifluoroethanol, was studied by time-resolved UV-vis spectroscopy after pulses at 248 and 308 nm. The triplet state and the semiquinone radical (?QH/Q?-) of BQs are spectroscopically and kinetically separated intermediates. The radical yield in the absence of H-atom donors is low and significantly increased in the presence of alcohols. Efficient photoinduced charge formation, because of Q?- and H+ after H-atom transfer from 2-propanol to the triplet state, and small effects in the absence of a donor were observed by transient conductivity. The quantum yield of photodecomposition, λirr = 254 nm, is substantial for BQ, MeBQ, and Me2BQs in aqueous solution, but small for Me 4BQ. To account for the efficient photoconversion of BQs into hydrobenzoquinones and 2-hydroxy-1,4-benzoquinones, a novel water-mediated reaction not involving free radicals is proposed as major step. This mechanism is consistent with the prediction that the observed triplet state is monomeric and the yield of Q?-, detected by both transient absorption and conductivity, is low for sub-millimolar BQ, MeBQ, and Me2BQs at pH 5-6. In addition, H-atom abstraction from a polar organic solvent or by self-quenching plays a role in mixtures with water or at enhanced quinone concentration, respectively.