Effects of functional group interactions on the bimolecular and dissociation reactions of diols

Abstract

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.

Stereochemical differentiation of cyclic glycols by ion-molecule reactions in a quadrupole mass spectrometer using dimethyl ether acetonitrile and 2-S-pyrrolidinemethanol

“…PCI with DME has been applied to a wide of variety of classes of organic compounds, including alcohols22 and diols 23,. 24 Plasma in the ion source was mainly constituted of protonated DME ( m/z 47 [(CH 3 ) 2 OH] + ) and deprotonated DME or methoxymethylene cation ( m/z 45 (CH 3 O = CH 2 ) + ). Other ions were at m/z 61 and 93 which corresponded, respectively, to [(CH 3 ) 2 OCH 3 ] + and [DME…H…DME] + (Fig.…”

Comparison of gas‐phase basicities and ion–molecule reactions of aminobenzoic acids

“…Another group reported the cyclization enthalpy resulting from proton bridging between two interacting amine groups to range from -5 to -17 kcal mol-' depending on the geometry of the hydrogen bond. l 6 Additionally, from measurements on the proton-transfer equilibria of a series of polyethers, it was found that basic molecules that could participate in multi-coordination of a proton have enhanced proton affinities but suffer a decrease in entropy owing to the enforced organization of the polyether structures." For instance, the enthalpy of the intramolecular hydrogen bond in protonated polyethers has been determined to between -7 and -25 kcal mo1-I.…”

Dimethyl ether chemical ionization mass spectrometry

“…with unsaturated alcohols (14), diols (15), diol ethers (16), and polyethylene glycols (17). For ally1 alcohol, 3- 291') were observed.…”