Neutral hydrolysis and imidazole-catalysed decomposition of bis(4-nitrophenyl) oxalate. 1,1′-Oxalyldiimidazole as an intermediate

Kinetics and mechanism of aminolysis of aliphatic esters in aprotic solvents

“…It appeared that activation enthalpies for all the esters are slightly negative and nearly independent of the substituents in the acyl group while the relative rate of the reaction is determined foremost by the entropy factor. Comparison of this conclusion with those made by Neuvonen 6 for ester hydrolysis in acetonitrile, where similar changes in structure caused a decrease in the DH ≠ obsd value from 32.7 to À18.9 kJ mol À1 , demonstrates a completely different behaviour of esters in the reactions.…”

The chemiluminescent peroxyoxalate system: state of the art almost 50 years from its discovery

“…A second imidazole molecule acts as a general-base catalyst in the deprotonation of the acylimidazolium cation inducing the release of a phenolate unit; thereby explaining the secondorder dependence of the rate constants on the imidazole concentration, observed previously. 40 The role of ODI as reactive intermediate in the PO system was then investigated by Hadd and coworkers from Birks' research group, 46 in a systematic study of the chemiluminescence reaction kinetics for mixtures of ODI and hydrogen peroxide in the presence of an activator, using imidazole, lutidine and collidine as catalysts. The kinetic of the reaction of TCPO with hydrogen peroxide catalyzed by imidazole was studied in details by Stevani and coworkers, 37 which employed a wide range of imidazole concentrations and measured the reaction rates both by UV-Vis spectroscopy and by observing the light emission intensity.…”

“…39 The authors studied this system in several experimental conditions, and were able to propose a reaction mechanism, including several speculative high-energy intermediate structures (see below). In order to obtain more detailed information on the mechanism of base catalysis in the PO system, Neuvonen 40 studied the kinetics of neutral and imidazole-catalyzed hydrolysis of bis(4-nitrophenyl)oxalate (4-NPO), following the reaction progress by observing the 4-nitrophenol UV absorption at 310 nm. The rate of neutral hydrolysis of 4-NPO in aqueous acetonitrile solution was shown to correspondent to the release of the second equivalent of 4-nitrophenol, since the release of the first equivalent appeared to be considerably faster.…”

Theoretical studies on the relative reactivities of aryl thiol, thiono and dithio carbonates and carbamates

“…The aminolysis of aryl thiol, thiono and dithio esters , carbonates and carbamates, 1-3, where Y, Y =O or S, and R=H, alkyl, aryl or arylalkyl group, has been a subject of numerous experimental [1][2][3][4][5][6][7][8] and theoretical studies [9][10][11][12][13][14] because of the importance of this process in chemistry and biochemistry. It has been shown that there are five factors that influence the nucleofugality of the leaving group, Y Ar [18].…”