The solubility of sparingly soluble compounds, particularly when they are present in the finely dispersed state, is difficult to measure, especially at elevated temperature and pressure. To date there have been no simple methods of determination. A quick and very simple method is now presented, termed ‘solubility titration’, based on the idea that if the substance under test is added gradually in small amounts to a solvent or dilute solution, its extinction or light scattering in the u.v/visible region must change abruptly the moment the solubility is exceeded. Such is actually the case, and the solubility is found from the extinction or from the light scattered, at the point indicated by the intersection of two curves. This method was developed specifically to determine the water solubility of commercial disperse dyes under dyeing conditions, i.e. at 130d̀C and elevated pressure (about 400 kPa). Tests gave precise, highly reproducible values.
with potassium carbonate in methanol. Compound 10cr7] was obtained as a mixture of four stereoisomers, since the phosphorus atom is also a stereogenic center and the phosphorylation with 9 proceeded, as expected, in a nonstereoselective fashion. All the compounds reported here are very acid labile, so that chromatography is only possible in the presence of triethylamine.The stereochemistry of 1Oc at the anomeric center is revealed by the doublet for 1-H at 6 = 4.53 (J = 8 Hz) in the 'H NMR spectrum.[*] The configuration at C-2' is assigned on the basis of the I3C NMR signals for C-1' and C-3'. We assume that, by analogy to the NMR datac4] for the acetal glycosides of aldehydes, the signals in the spectrum of the (2'R) epimer lie at lower field for C-I' and higher field for C-3', compared to the corresponding signals of the (2's) isomer.The kinetics of the acid-catalyzed hydrolysis[91 of 1Oc was determined using NMR spectroscopy. The first-order rate constant for deuterolysis at pD = 6.10 in phosphate buffer at 35 " c (0.10 M,Assuming a kDm/kH, value of 1 .5,['01 1Oc has a half-time for hydrolysis of 15 h at pH = 6.2 and 35 "C. This value roughly corresponds to the desired value. Cleavage of 1Oc yields besides glucose and methanol, the diamidophosphate 11 (ketophosphamide)," 'I which, via either elimination or hydrolysis, is converted into the cytotoxic phosphoramide mustard 12 in the cell. This compound is also the active metabolite of the clinically used cytostatic drug cyclophosphamide. [' 21
„Halbverbrückende”︁ CO‐Gruppen charakterisieren die Komplexe 1–3, die alle letztlich aus CuCl und Na[Co(CO)4] bei zunehmender Ammoniakkonzentration entstehen. Rechts ist die Struktur des Cu2Co2‐Komplexes 2 dargestellt; die Pfeile geben an, daß durch NH3 der Komplex an diesen Bindungen unter Bildung von 3 gespalten wird. 2 entsteht analog durch Spaltung von 1.\documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {[({\rm NH}_3)_2 \{ {\rm CuCo}({\rm CO})_4 \} _4]} & {\bf 1}\\ {[\{ ({\rm NH}_3){\rm CuCo}({\rm CO})_4 \} _2]} & {\bf 2} \\ {[({\rm NH}_3)_2 {\rm CuCo}({\rm CO})_4]} & {\bf 3} \\ \end{array} $\end{document}
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