2 resultados para State Mutual Life Assurance Company (Worcester, Mass.)
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
The rearrangement of methyl 2-(methylthio)benzenesulfonate (1) to the zwitterionic 2-(dimethyl-sulfonium)benzenesulfonate (2) is known to proceed in solution by intermolecular Me transfers. The same rearrangement has been observed to occur in crystalline 1, but the crystal structure shows that the molecular packing is not conducive to intermolecular Me transfer. The reaction has been carried out with mixed crystals composed of 1 and deuteriomethylated (D6)-l. By fast-atom-bombardment mass spectroscopy, it has been shown that the product consists of a 1:2:1 mixture of the non-, tri-, and hexadeuterated species, the mixture expected, if the solid-state reaction proceeds by intermolecular Me transfers. From this result, together with the slower rates of conversion in the single crystal compared with the melt, it can be concluded that the reaction must occur not topochemically but rather at defects such as microcavities, surfaces, and other irregularities in the ordered crystal arrangement.
Resumo:
The long-lived radionuclide 129I (T 1/2 = 15.7 My) occurs in the nature in very low concentrations. Since the middle of our century the environmental levels of 129I have been dramatically changed as a consequence of civil and military use of nuclear fission. Its investigation in environmental materials is of interest for environmental surveillance, retrospective dosimetry and for the use as a natural and man-made fracers of environmental processes. We are comparing two analytical methods which presently are capable of determining 129I in environmental materials, namely radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS). Emphasis is laid upon the quality control and detection capabilities for the analysis of 129I in environmental materials. Some applications are discussed.
