Correlations between the Stereochemistry and the Chemical Ionization Spectra of Epimeric 3,4-Dimethyl-1,2-cyclopentanediols

The eight epimeric 3,4-dimethyl-l,2-cyclopentanediols have been investigated as bistrimethylsilyl (TMS) ethers and as diacetates by means of isobutane chemical ionization (CI). Correlations between stereochemistry and CI spectra appear to be limited in the case of the TMS ethers. All eight diacetates, however, can be unequivocally identified from their isobutane CI spectra.

Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und n-Pentylbenzol in der Gasphase / Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes

The investigation of several 13carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations.