Showing papers on "Selenourea published in 2002"
TL;DR: In this article, the key structures of diselenides have been established by X-ray crystallography and a reaction mechanism for the formation of 9 is proposed, which takes place when the benzyl residue bears an NO2 group and the phenyl group is not substituted with a strong electron-donating group.
Abstract: The reaction of N-benzylbenzamides 6 with SOCl2 under reflux gave the corresponding N-benzylbenzimidoyl chlorides 7. Further treatment with KSeCN in dry acetone yielded imidoyl isoselenocyanates 3 (Scheme 2). These compounds, obtained in satisfying yields, proved to be stable enough to be purified and analyzed. Reaction of 3 with morpholine in dry acetone led to the corresponding selenourea derivatives 8. On treatment with Et3N, the 4-nitrobenzyl derivatives of type 3 were transformed into bis(2,4-diarylimidazol-5-yl) diselenides 9 (Scheme 3). This transformation takes place only when the benzyl residue bears an NO2 group and the phenyl group is not substituted with a strong electron-donating group. A reaction mechanism for the formation of 9 is proposed in Scheme 4. The key structures have been established by X-ray crystallography.
37 citations
TL;DR: Selenoureas were synthesized by the reaction of carbodiimides with LiAlHSeH in the presence of hydrogen chloride as discussed by the authors, and they were used in the synthesis of carotidimides.
26 citations
TL;DR: It is considered that the storage of urine samples at –20 °C for a short-term (within one month) is safe for Se speciation analysis, and the lower the temperature used for storage the higher the stability of Se species, when other conditions such as light, acidity, and container material are kept constant.
Abstract: The stability of five selenium compounds, selenate, Se(VI), selenourea, SeUr, trimethylselenonium ion, TMSe+, selenomethionine, SeMet, and selenoethionine, SeEt, at concentrations from 30–60 µg L–1 in a pooled human urine, stored in dark at –20 °C, 4 °C, or ambient temperature (ca. 25 °C), without addition of any stabilizing reagent was evaluated. The investigated Se species were determined independently by mixed ion-pair reversed-phase liquid chromatography with inductively coupled plasma mass spectrometric (ICP–MS) detection. The general trend is the lower the temperature used for storage, the higher the stability of Se species, when other conditions such as light, acidity, and container material are kept constant. On the basis of these results it is considered that the storage of urine samples at –20 °C for a short-term (within one month) is safe for Se speciation analysis. Long-term storage of urine samples for speciation analysis should, however, be undertaken with caution.
26 citations
TL;DR: In this article, a density functional analysis of selenourea was performed to understand the extent of electron delocalization in comparison to urea and thiourea. But the analysis was limited to the two types of structures, i.e., C2 symmetry and C-N rotational barrier.
Abstract: Ab initio and density functional calculations have been performed on the different possible structures of selenourea(su), urea(u) and thiourea(tu) to understand the extent of delocalisation in selenourea in comparison to urea and thiourea. Selenourea(su-1) withC2 symmetry has the minima on the potential energy surface at MP2(fu)/6-31+G* level. The C-N rotational barrier in selenourea is 8.69 kcal/mol, which is 0.29 and 0.11 kcal/mol more than that of urea and thiourea respectively at MP2(fu)/6-31+G* level. N-inversion barrier is 0.55 kcal/mol at MP2(fu)6-31+G* level. NBO analysis has been carried out to understand the nature of different interactions responsible for the electron delocalisation.
19 citations
TL;DR: In this article, the upfield shift in 13 C NMR and downfield shifts in 1 H and 15 N NMR for selenourea resonances are consistent with the selenium coordination to Ag(I).
11 citations
2 citations
Patent•
22 Nov 2002TL;DR: The 1,3-Selanazolin derivatives represented by chemical formula 1, wherein R1 to R4 are hydrogen or specified substituents, are prepared by reacting a selenourea and an α-haloacyl halide in a solvent and in the presence of a catalyst.
Abstract: 1,3-Selanazolin derivatives represented by chemical formula 1, wherein R1 to R4 are hydrogen or specified substituents, are prepared by reacting a selenourea and an α-haloacyl halide in a solvent and in the presence of a catalyst, and are useful as anticancer drugs and agrochimicals.
2 citations
TL;DR: In this article, the key structures of diselenides have been established by X-ray crystallography and a reaction mechanism for the formation of 9 is proposed, which takes place when the benzyl residue bears an NO2 group and the phenyl group is not substituted with a strong electron-donating group.
Abstract: The reaction of N-benzylbenzamides 6 with SOCl2 under reflux gave the corresponding N-benzylbenzimidoyl chlorides 7. Further treatment with KSeCN in dry acetone yielded imidoyl isoselenocyanates 3 (Scheme 2). These compounds, obtained in satisfying yields, proved to be stable enough to be purified and analyzed. Reaction of 3 with morpholine in dry acetone led to the corresponding selenourea derivatives 8. On treatment with Et3N, the 4-nitrobenzyl derivatives of type 3 were transformed into bis(2,4-diarylimidazol-5-yl) diselenides 9 (Scheme 3). This transformation takes place only when the benzyl residue bears an NO2 group and the phenyl group is not substituted with a strong electron-donating group. A reaction mechanism for the formation of 9 is proposed in Scheme 4. The key structures have been established by X-ray crystallography.
2 citations
Patent•
13 Dec 2002TL;DR: In this paper, a process for preparing novel 1,3-selanazolin derivatives represented by chemical formula 1 at high yield is described, which includes reaction a selenourea and an α-haloacyl halide in a solvent and in the presence of a catalyst.
Abstract: A process for preparing novel 1,3-selanazolin derivatives represented by chemical formula 1 at high yield. This process includes a step of reacting a selenourea and an α-haloacyl halide in a solvent and in the presence of a catalyst