Fragmentation routes table

TMS-derivatization of steroids with a 3-keto-androst-l-ene or 3-keto-androst-4-ene yields enol-TMS ethers with 3-hydroxy-l, 3-diene or 3-hydroxy-2,4-diene structure that give rise to mass spectra containing a characteristic fragment ion at m/z 194 (Table 3.4) as shown for testosterone in Figure A fragmentation route including the fis-... 

The five routes presented (A-E) can be detected in the mass spectra of all 3-hydroxytropane esters. However, their contribution to the general fragmentation may vary widely. Table XIII shows the relative intensities of the characteristic peaks, corresponding to the ions a-g given below for atropine 26 (Fig. 8). Route A strongly dominates the fragmentation of pyranotropane alkaloids, leading in the case of strobiline (112), for example, to the ion m/z 162 (ion e) (base peak) (Scheme 30). 

As can be seen in Table XIII, the presence of supplementary functional groups often strongly influences the fragmentation pattern. For example, a hydroxyl group at C-6 or C-7 position generally strongly favors the cleavage of the ethylene derivative (Routes A and E) (53,63,166,171). The substituents... 

Interest in these compounds—mainly for use as weakly coordinating anions—has grown rapidly in the last decade. Many synthetic routes to CBnHi2 and its derivatives are shown in Table 17 (Figures 4 and 5). The structures of CBnH12 and its derivatives determined experimentally are summarized in Table 18. The table shows one column for cations where the anions are regarded as discrete entities within the crystal lattice and the other for cations where the anions are viewed as a fragment of a molecule or polymer in the solid state. 

Fragmentation of the molecules of macrobicyclic boron-capped iron(II) tris-dioximates in the gas phase occurs mainly by an alternative scheme compared with the reactions in solution [292]. Excited molecules of the complexes that gained from a cascade of reactions sufficient energy for rupture of bonds with fragmentation occurred by similar routes for all complexes considered (Table 28). 

Isomerization and fragmentation selectivities over the other acidic Pt-zeolite catalysts (Pt-HY and Pt-NaHY [13] as well as on a mixtiu e of HY and Pt/SiOo [15]) have been found to be roughly equal. The highest abimdance of 2,3DMB among the Cg products over Pt-HZSM (Table 1) indicated that the importance of acid catalyzed isomerization route was most important over this catalyst. 

With the first fragment union successfully completed, the transition from the Smith approach to the Paterson route was now required in order to arrive at the final C7.24 coupling partner. This necessitates the elaboration of both termini to introduce the (Z)-enal and the terminal (Z)-diene unit and introduction of the pendant carbamate moiety. Table 4 shows the results for the yields of 7 at various scales. 

Furthermore, the analysis of polyaromatic fractions following the reaction (M3 products) showed that these molecules had relatively lower MW, shorter chains and were more aromatic. The results of this woik confirm that side chain fragmentation and hydrogenation/dehydrogenation reactions are major routes in the thermal cracking of heavy oils and bitumen (see Tables 9-10). 

What can be said about characteristic fragments in the lower mass region Is there information on aromatic building blocks or even ions formed through rearrangements (McLafferty, retro-Diels-Alder) Also the application of MS/MS with the registration of product ion spectra from major ions is a successful route for structure elucidation. Here tables with plausible explanations of fragment ions are helpful (see Table 3.6). 

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