Detailed spectroscopic studies have been carried out on the alkaloid d-pilocarpine as free base and after quaternization. Characteristic changes in the NMR, IR and UV spectroscopic properties have been established following quaternization. The respective mass spectra have been analysed, and characteristic fragmentation patterns are described. The amidic nature of d-pilocarpinehydroxamic acid has been confirmed by JR, NMR and mass spectrometric measurement.

The mass spectra of α‐, β‐ and γ‐pyridine aldoximes and the respective O‐methyl ethers were studied. The mass spectral behaviour of α‐pyridine aldoxime is characterized by the elimination of NO, while the molecular ion of the γ‐isomer expels H2 CN. In the case of the β‐isomer the formation of the m/e 67 ion (C4H5N) in a concerted process is the main feature. In the α‐pyridine aldoxime methyl ether, in sharp contrast to the hydroxy analog, the M‐30 peak was found to be due to the elimination of CH2O, the expulsion of NO being absent. The mechanism of the fragmentation reactions is discussed, the conclusion drawn being based on the high resolution measurements as well as on the spectra of the respective deuterioanalogs and on the metastable transitions.

The H-D exchange of methylene protons in a side-chain when situated between a positively charged N-atom (a-CH,) and a ketone function was studied in various pilocarpinium (N-methyl imidazolium) and hydroximinomethyl pyridiniums using NMR measurements. Structural factors which determine the course of the exchange are reported, and the role of the solvent was examined. Mass-spectra of nondeuteria ted and deu teriated 4-hydro ximinomethyI-I-phenacyI-pyridinium chloride confirmed the fast exchange of the a-CH,. An alternative H-D exchange of the C, -H in the imidazolium moiety of certain pilocarpinium compounds without a ketone in the N-chain was detected. Mechanisms for the two types of exchanges involving an ylid as intermediate and attack of a deuteron were proposed.

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Das Imidazolylmethyl‐lacton (I) liefert die Salze (II) bzw. (III).