The mass spectra of several structurally related ring B seco 5-keto compounds (I to VII) have been examined. The mass spectra of I, II, III and IV are conspicuous by an intense peak at m/e112(C7H12O) and those of V (highest mass peak at [M ? CH3COOH]), VI and VII by a prominent peak at m/e 100 (C7H10O), which apparently results from McLafferty rearrangement involving 5-keto function and an appropriate γ-hydrogen at C-8 and C-11. This rearrangement, leading to the aforementioned ions, is of diagnostic value in the characterisation of such compounds. The mass spectrum of VIII exhibits a prominent ion peak at m/e 332 (C23H40O) resulting from McLafferty rearrangement involving the 5-keto function and C2? H. This offers an excellent means of differentiating between the isomeric acids (III and VIII). The fragmentation pathways suggested are supported by accurate mass measurement of the salient fragment ions and in some cases by appropriate metastable peaks. 相似文献
We report here the experimental evaluation of crossed-second-order (CSO) effects in the field shift of8F and6F terms of 4f6(7F)6s configuration of singly ionised samarium. Our experimental value of CSO field shift difference between8F and6F terms for148Sm and154Sm is ?11.8(3.2) mK, which is in good agreement with the theoretical value of ?13.8 mK evaluated using known parameters. 相似文献
Summary [RuCl2(CO)2]n reacts with the Schiff base 1-acetylferrocenethiosemicarbazone, [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)] to give [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)RuCl2(CO)2] and with 1-acetylferrocenesemicarbazone [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)] to give [Fe(-Cp)(-C5H4MeC=NN-HCSNH2)RuCl2-(CO) 2]. Spectroscopic data indicate that the Schiff bases act as bidentate ligands and coordinate to ruthenium via the hydrazinic N and either the S or O atoms, respectively, giving stable heterobimetallic complexes, which have been characterized by i.r. and 1H-n.m.r. spectroscopies, and elemental analyses.Part of this work was presented at the First International Conference in Chemistry and its applications in Doha, Qatar, 1993. 相似文献
The present work aims to investigate the feasibility of oxalic acid-choline chloride deep eutectic solvent (OA-ChCl DES), which serves as a promising green solvent that utilized in the acidic deep eutectic solvent (DES) hydrolysis. Oxalic acid-choline chloride DES cellulose nanocrystal (OA-ChCl DES CNC) was isolated from the bleached DES treated pulp (BP) through the acidic DES hydrolysis using 1:1 molar ratio of OA-ChCl DES. The functional groups, crystallinity index, morphological structure, particle size, zeta potential, thermal stability and surface chemistry of the OA-ChCl DES CNC were compared with the sulphuric acid cellulose nanocrystal (SA-CNC) that prepared via sulphuric acid hydrolysis. The findings revealed the presence of negatively charged carboxyl groups on OA-ChCl DES CNC surface after the acidic DES hydrolysis. The physicochemical analyses verified that the OA-ChCl DES CNC was in nano-sized range with polydispersity index (PdI) of 0.56, indicating slightly monodispersed nanoparticles. A stable OA-ChCl DES CNC colloidal suspension with zeta potential value of ?52.1?±?5.2 mV was obtained. The OA-ChCl DES CNC outweighed the SA-CNC in term of thermal stability (288 °C) despite having a slightly lower crystallinity index (76.7%). In fact, the OA-ChCl DES CNC with a yield of 55.1% was achieved through the acidic DES hydrolysis, suggesting that the OA-ChCl DES was capable of promoting efficient cleavage of strong hydrogen bonds in BP.
Bis‐hydrazonoyl chloride 1 reacts regioselectively with 3‐mercapto‐1,2,4‐triazole 2a , 2,3‐dihydro‐3‐thioxo‐1,2,4‐triazin‐5(4H)‐one 2b and 2‐mercaptobenzimidazole 2c to give the hitherto unknown annelated 2,3‐bis‐(phenylhydrazono)thiazoles 6a‐c , respectively. Reactions of 1 with the methylthio derivatives of such heterocycles afforded the annelated 3,3′‐bis‐(1,2,4‐triazoles) 11a‐c , respectively. Similar reaction of 1 with 2‐phenylamino‐4(3H)‐pyrimidinones 4 gave 2,3‐bis(phenylhydrazono)imidazo[1,2‐a]pyrimidin‐5(1H)‐ones 16 . Oxidation of 6c yielded the corresponding bis(phenylazo) derivative 15 . The regiochemistry of the studied reactions is discussed. 相似文献
A convenient and efficient method for the estimation of cobalt(II) ions in the presence of other metal ions is described. Interference of metal ions such as iron(II), iron(III), nickel(II), manganese(II), and copper(II) have been investigated. Only iron(III) ions seriously affect this determination. Copper(II) and nickel(II) ions do not interfere if present in a molar-ratio less than 1:2 in the cobalt(II) ion solution. Cobalt(II)-nickel(II) and cobalt(II)-copper(II) binary mixtures can be efficiently analyzed at selective wavelengths. 相似文献
A routine procedure has been developed for the simultaneous determination of uranium and thorium in high concentration thorium ores. INAA is used to determine the uranium and thorium concentration. However, for very low concentrations of uranium a radiochemical procedure based on the use of NPy/benzene as an extractant has to be employed. The precision and accuracy of the method has been determined by analyzing IAEA and NBL standard thorium/uranium ores. 相似文献
Nitroarenes were chemoselectively reduced to the corresponding amines using zinc and aqueous ammonium salts in ionic liquids as a safe and recyclable reaction medium. Our results specify the effect of ammonium salts in the process; the combination of Zn/NH4Cl in [bmim][PF6] or Zn/HCO2NH4 in [bmim][BF4] were the suitable conditions for the reduction of nitroarenes. Azobenzenes were also smoothly reduced to hydrazobenzenes with Zn/HCO2NH4 (aq.) in recyclable [bmim][BF4] without any over reduction to the corresponding anilines. 相似文献
The results from a proficiency test exercise for the determination of natural levels of radionuclides in mushroom reference
material carried out by laboratories in six different countries are discussed. These laboratories submitted data on seven
radionuclides, namely 134Cs, 137Cs, 40K, 90Sr, 241Am, 226Ra, and 210Po. However, only the data received for three of these radionuclides could be statistically evaluated to obtain consensus
mean values and confidence intervals (at a significance level of 0.05). The contents of 134Cs, 137Cs and 40K were quantified as 4.4, 2,899 and 1,136 Bq/kg, respectively. 相似文献