54536-24-2Relevant academic research and scientific papers
Rate parameter changes by added albumin in the microsomal oxidative demethylation of deuteriated and non-deuteriated 4-methoxyanisole
Masuda, Masatoshi,Kishimoto, Daisuke,Kurihara, Norio
, p. 806 - 810 (2007/10/03)
Bovine serum albumin (BSA) added to the reaction medium for the oxidative demethylation of 4-methoxyanisole and its 'di-CD3' isotopomer ([d6]methoxyanisole), when catalyzed by liver microsomes from untreated rats, decreased the K(m) values and increased the V(max)/K(m)(= V/K) values. The V(max) values were not markedly altered. The values for the deuterium isotope effect on V(max) and V/K for the reaction with this isotopomer were between 2.2 and 2.8, and that on K(m) was close to unity. The magnitude of the isotope effect was not significantly changed by adding BSA. The intramolecular isotope effect with [mono-CD3]4-methoxyanisole ([d3]methoxyanisole) in liver microsomes from untreated rats was between 10.3 and 10.8, which was not significantly changed by BSA. Liver microsomes from rats treated with phenobarbital resulted in the intramolecular isotope effect value in the absence of BSA being between 7.2 and 9.1, which was not significantly altered by BSA. Based on these data, the calculated apparent rate constant for the enzyme-substrate complex formation was markedly increased by up to about 1.9- and 3.5-fold by 1% and 2% of BSA added, respectively.
A Mechanistic Study of the Thermal Disproportionation Reaction of Quinone Monoketals
Capparelli, Michael P.,Swenton, John S.
, p. 5360 - 5364 (2007/10/02)
Thermolysis of quinone monoketals 1a-d at 180 deg C leads to disproportionation to the p-alkoxyphenols 2a-d and the carbonyl compounds derived from the alcohol moiety of the ketal.The thermolysis of 4,4-dimethoxy-2,5-cyclohexadienone (1a) followed first-order kinetics, and the rate of reaction decreased by a factor of 3.6 when the methoxy groups were replaced with methoxy-d3 groups.The suggested mechanism for the reaction involves reversible dissociation of 1a into a p-methoxyphenoxy-methoxy radical pair, followed by rate-controlling hydrogen atom transfer to give p-methoxyphenol and formaldehyde.Although 1a has a half-life of about 4 h at 180 deg C, the monoethylene glycol ketal of benzoquinone was recovered in > 90percent yield after heating for 24 h at the same temperature.Finally, acid-catalysed exchange of 3,3,6,6-tetramethoxy-1,4-cyclohexadiene with alcohols furnished a convenient route to quinone bisketals not obtainable in good yield via anodic oxidation.
