Ion/molecule reactions of protonated diglycine: an electrospray ionization flow tube reactor experiment

Reactions of protonated diglycine, GLY(2)H(+), with methanol, ammonia, and a series of methylamines were studied under thermal conditions with a combination of an electrospray ion source and a how tube reactor. The major primary reaction product in all of the systems studied is the complex formed between the ionic and neutral reagents in a ternary association reaction involving the helium carrier gas and oxygen or nitrogen molecules as collisionally stabilizing species. Effective binary rate constants were determined experimentally and compared with calculated ion dipole collision rate constants. Proton transfer was observed from GLY(2)H(+) to trimethylamine but not to any of the other reagents studied. Secondary products observed include formation of protonated mixed trimers of GLY(2), with two amine molecules. In the case of methanol, a secondary product is the protonated mixed dimer of GLY(2), and dimethylether. The results will be, discussed in the light of the mechanisms of hydrogen-deuterium (H-D) exchange of GLY(2)H(+) with deuterated isotopomers of methanol and ammonia studied previously by various groups. (Int J Mass Spectrom 179/180 (1998) 165-171) (C) 1998 Elsevier Science B.V.