The dissociation reactions of protonated amino alcohols were examined in a quadrupole ion trap mass spectrometer. Multi-stage collision-induced dissociation techniques were used to characterize the ions and their fragments and to assist in the determination of the dissociation mechanisms. In addition, semi-empirical calculations were used to rationalize the results on the basis of the thermodynamics of the reactions in question. The reaction of special interest was the double elimination of water and ammonia. For this high-energy process, it is shown that the initial deamination step is the thermodynamically favored one in most cases. The enthalpies of formation for the various precursor and product ions and also those for some of the reaction intermediates were estimated using molecular modelling and semi-empirical calculation methods. The values obtained indicated that the minimum endothermicity of the sequential deamination-dehydration reaction ranges from 209 to 460 kJ mol-' for the compounds studied here. Moreover, protonation at the amine site was found to be energetically favored by 38-192 kJ mol-' over protonation at the hydroxyl site.

Polyethylene glycols react with CH30CH2+ ions from dimethyl ether to form ( M + 131 + products. The [M + 131' ions are stabilized by intramolecular interactions involving the internal ether oxygen atoms and the terminal methylene group. Collisionally activated dissociation (CAD), including MS" and deuterium labeling experiments show that fragmentation reactions involving intramolecular cyclization are predominant. Scrambling of hydrogen and deuterium atoms in the ion-molecule reaction products is not indicated. The CAD spectra of the [ M + 131 + ions provide unambiguous assignment of the glycol size.

The influence of functional group interactions on the bimolecular and dissociation reactions of diols were examined in a quadrupole ion trap mass spectrometer. Reactions of dimethyl ether ions with diols resulted in formation of (M + H)(+) ions and (M + 13)(+) ions (by net methyne addition). The product distribution depended on the relative separation of the hydroxyl groups within each diol, with the more proximate diols producing the greatest abundance of (M + 13)(+) ions compared to (M + H)(+) ions. The enhancement of the formation of (M + 13)(+) ions is attributed to the capability for electrostatic interactions between the hydroxyl groups and the electropositive methylene group of the methoxymethylene reagent ion. The enhancement is most significant for diols that can adopt five- or to a lesser extent six-membered ring transition states (i.e, any 1,2 or 1,3 diol). Collision-activated dissociation (CAD) techniques, including both sequential activation experiments (MS (n) ) and comparison of CAD spectra for model compounds, suggest that the (M + 13)(+) ions are protonated cyclic diethers.

Collisionally activated intermolecular dehydration reactions of proton-bound alkenol dimers and proton-boundalkenol-dimethyl ether adducts were examined in both a triple quadrupole mass spectrometer and a quadrupole ion trap mass spectrometer. Ion-molecule reactions of protonated dimethyl ether (DME) with allyl alcohol, Ibuten-l-01 and 4-penten-1-01 (M) produced the ions [ M + HI +, I2M + HI +, [ M + H + DMEI' and [ M + H + DME -H,O] +. Collisionally activated dissociation was used to characterize the structures of the product ions, and energy-minimized structures and heats of formation of ions were calculated by molecular mechanics and semiempirical computational methods. The loosely bound [ M + H + DMEl' ions rearrange and dissociate by an intermolecular dehydration reaction to form [ M + H + DME -H,OI + ions, with methylated ether stuctures. These [ M + H + DME -H,O] + ions dissociate predominantly via direct cleavage of the ether linkage. Comparisons of the bimolecular and dissociation reactions of the alkenols were made with those of simple alcohols, diols and alkenes to demonstrate that the presence of the carbon-carbon double bond specifically assists in many of the observed processes.

The reactions of dimethyl ether ions with neutral amino alcohols were examined in both a quadrupole ion trap mass spectrometer and a triple quadrupole mass spectrometer. These ion-molecule reactions produced two types of ions: the protonated species [M+l](+) and a more complex product at [M+13](+). The abundance of the [M+13](+) ions relative to that of the [M+1](+) ions decreases with increasing formal interfunctional distance. Multistage collision-activated dissociation techniques were used to characterize the [M+13](+) product ions, their reactivities, and the mechanisms for their formation and dissociation. In addition, molecular semiempirical calculation methods were used to probe the thermochemistry of these reactions. Reaction at the amino alcohol nitrogen site is favored, and the resulting [M+13](+) addition products may cyclize for additional stabilization. Comparisons were made among the behavior of related compounds, such as alcohols, diols, amines, and diamines. The alcohols reacted only to form the protonated species, but the diols, amines, and diamines all formed significant amounts of [M+13](+) ions or related dissociation products.