ION-MOLECULE REACTIONS OF CIS-CYCLOPROPANE AND TRANS-CYCLOPROPANE DERIVATIVES WITH METHANE, ACETONE AND VINYL-ACETATE UNDER CHEMICAL-IONIZATION CONDITIONS

Ion-molecule reactions of four isomeric cyclopropane derivatives were investigated under chemical ionization(CI) conditions, using methane, acetone and vinyl acetate as reagent gases, The methane positive-ion C I mass spectra of each of two isomer pairs 1,2 and 3,4 are identical, and so are the collision-induced dissociation (CTD) spectra of the pro tonated molecules of each of the two isomer pairs, The protonation rea ctions for the isomer pairs 1,2 and 3,4 occurred on the sites of the c arboxyl groups and the R groups, respectively, Differences between iso mers 1 and 2 are observed in their acetone (A) positive-ion CI mass sp ectra and in the CID spectra of their adduct ions ([M+H+A](+)), The ad duct ions of compounds 2, 3 and 4 with protonated acetone and with pro tonated acetone dimer are observed in their CI mass spectra, However, only the adduct ions of compound 1 with protonated acetone appear in i ts CI mass spectrum, The protonated dimers of each of the four compoun ds are found in their vinyl acetate positive-ion CI mass spectra, and the CID spectra of these dimers for isomers 1 and 2 can also reflect t heir stereostructural difference. (C) 1998 John Wiley & Sons, Ltd.