The thermal decompositions of dehydrated or anhydrous bivalent transition metal (Mn, Fe, Co, Ni, Cu, Zn, Cd) and alkali rare
metal (Mg, Ca, Sr, Ba) methanesulfonates were studied by TG/DTG, IR and XRD techniques in dynamic Air at 250–850 °C. The initial
decomposition temperatures were calculated from TG curves for each compound, which show the onsets of mass loss of methanesulfonates
were above 400 °C. For transition metal methanesulfonates, the pyrolysis products at 850 °C were metal oxides. For alkali
rare metal methanesulfonates, the pyrolysis products at 850 °C of Sr and Ba methanesulfonates were sulphates, while those
of Mg and Ca methanesulfonate were mixtures of sulphate and oxide.
Hydrated methanesulfonates Ln(CH3SO3)3nH2O (Ln=La, Ce, Pr, Nd and Yb) and Zn(CH3SO3)2nH2O were synthesized. The effect of atmosphere on thermal decomposition products of these methanesulfonates was investigated.
Thermal decomposition products in air atmosphere of these compounds were characterized by infrared spectrometry, the content
of metallic ion in thermal decomposition products were determined by complexometric titration. The results show that the thermal
decomposition atmosphere has evident effect on decomposition products of hydrated La(III), Pr(III) and Nd(III) methanesulfonates,
and no effect on that of hydrated Ce(III), Yb(III) and Zn(II) methanesulfonates.
The dehydration process of Co(II), Cu(II)
and Zn(II) methanesulfonates was studied by thermogravimetry/derivative thermogravimetry
(TG/DTG) and differential scanning calorimetry (DSC) techniques in dynamic
N2 atmosphere. The TG/DTG curves show that all of them
contain four crystallization water molecules, which are lost in two steps.
The peak temperature and dehydration enthalpies ΔH
were measured from DSC curves for each compound. The effect of procedural
variables on the TG and DSC curves was investigated. In this work, the procedural
variables included heating rate, Al pan state (unsealed and sealed) and sample
Authors:Frederik E. A. Van Waes, Sofie Seghers, Wim Dermaut, Bart Cappuyns, and Christian V. Stevens
An efficient continuous-flow procedure for the synthesis of tribromomethylsulfones and tribromomethanesulfonates has been developed starting from the corresponding methylsulfones or methanesulfonates and potassium hypobromite using a biphasic reaction. Two different continuous-flow systems were used and compared for the bromination reaction. Different derivatives were synthesized in excellent isolated yields in very short reaction times using a small excess of potassium hypobromite. Hypobromite can be synthesized continuously leading to the continuous production of the brominated derivates. With the optimized flow conditions, a throughput of up to 53 g/day was obtained. The bromination reaction in flow has significant advantages compared to the corresponding batch process.
Authors:W.-Y. Liu, X.-J. Yang, P. Li, F. Feng, and L.-Sh. Mao
10-O-(N,N-dimethylaminoethyl)-ginkgolide B (XQ-1) is an intermediate for synthesizing 10-O-(N,N-dimethylaminoethyl)-ginkgolide B methanesulfonate (XQ-1H), which is a novel ginkgolide B derivative and is being developed as a platelet-activating factor antagonist. A specific and rapid liquid chromatographic method was developed for the quantitative analysis of XQ-1 and its three related impurities, which were 10-O-(N,N-dimethylaminoethyl)-11,12-seco-ginkgolide B (imp-1), 10-O-(N,N-dimethylaminoethyl)-11,12-seco-3,14-dehydroginkgolide B (imp-2) and 10-O-(N,N-dimethylaminoethyl)-3,14-dehydroginkgolide B (imp-3) simultaneously in XQ-1 samples. Chromatographic separation was achieved on a CN band stationary phase, with the mobile phase consisting of methanol and 20 mM dipotassium hydrogen phosphate (pH 7.5) (50:50, υ/υ) in isocratic elution. The flow rate was 1.0 mL min−1 and detector was set at 220 nm. The method was optimized by the analysis of the samples generated during the forced degradation studies. The XQ-1, imp-1, imp-2, and imp-3 were completely separated within 15 min. The resolutions (Rs) amongst four target compounds were >2. The developed method was validated with respect to specificity, linearity, accuracy, precision, and robustness. The results indicated that the simultaneous LC determination method was readily utilized as a quality control method for XQ-1 sample.
. E., Roche, H. M., Kunz, B. A.: Elevated intracellular dCPT levels reduce the induction of GC-AT transitions in yeast by ethyl methanesulfonate or N-methyl-N′-nitro-N-nitrosoguanidine but increase alkylation induced GC-CG tranversions. Mutagenesis
tip chromosome aberration assay on N-methyl-N-nitrosourea, meleic hydrazide, sodium azide and ethyl methanesulfonate. Mutation Res. 390, 121-127.
Allium cepa anaphase-telophase root tip chromosome aberration assay on N