3844-63-1Relevant academic research and scientific papers
Solvent-induced changes in nitrosation mechnisms. Part 3. The effects of tetrahydrofuran-water and dimethyl sulfoxide-water mixtures on the nitrosation of ureas
Herves, P.,Leis, J. R.
, p. 2035 - 2040 (2007/10/03)
Kinetic studies of the nitrosation of 1,3-dimethylurea and 2-imidazolidone in tetrahydrofuran-water and dimethyl sulfoxide-water mixtures have been carried out.In tetrahydrofuran-water mixtures, the results obtained show that the kinetic characteristics of the reaction depend on the proportion of tetrahydrofuran in the medium.At low concentrations of organic solvent, the reaction is not catalysed by chloride ions and the reaction mechanism is probably the same as in pure water.At very high proportions of tetrahydrofuran (more than 80percent by weight), there is a change in the reaction mechanism.Halide ions catalyse the process, which is interpreted in terms of formation of the corresponding nitrosyl halides which act as efficient nitrosating agents of ureas.In dimethyl sulfoxide-water mixtures the results obtained show that the addition of the organic solvent up to 85percent by weight of dimethyl sulfoxide inhibits the reaction rate, which increases slightly upon further increasing the proportion of dimethyl sulfoxide.However, unlike other organic solvents in dimethyl sulfoxide-water mixtures we did not observe catalysis by halide ions.The reaction mechanism seems to be the same as in pure water, with the proton transfer from the protonated nitroso compound to the medium being the rate limiting step.
ALKALINE HYDROLYSIS OF N-NITROSO-2-IMIDAZOLIDONE
Castro, Albino,Leis, J. Ramon,Pena, M. Elena,Tato, Jose Vazquez
, p. 117 - 122 (2007/10/02)
The hydrolysis of N-nitroso-2-imidazolidone has been studied kinetically between pH 8.3 and 12.6.This nitroso compound has an acid-base equilibrium whose constant has been determined spectrophotometrically (pKa 11.45).Only the acid form is reactive.At pH - and is subject to general base catalysis.These results are interpreted in terms of a mechanism involving an initial steady-state hydrate whose decomposition by base leads to the final products.At pH > 10 reaction paths of orders one and two in OH- appear.The second-order term reflects general base catalysis superimposed on a first-order term in OH- (the bases dimethylamine, sarcosine, piperidine, and HPO42- have been used).The results are interpreted by an initial OH- attack on the carbonyl group of the nitroso compound to give an intermediate which in the rate-controlling step reacts with bases, among them water (which explains the first-order term with respect to OH-).The low value of the Broensted relation (β ca.O) and the fact that the intermediate possesses no proton yielding a low pKa value suggest that there is inverse classical general base catalysis.
