[CH₃COH]˙⁺, the central intermediate in the isomerization–dissociation reactions of ionized vinyl alcohol

Abstract

In complete agreement with experimental results ab initio molecular orbital calculations predict that ionized hydroxy(methyl)carbene, [CH,COH] +, does not only exist as a stable C,H,O*+ isomer but also serves as the key intermediate in the isomerization-dissociation processes of the cation radical of gaseous vinyl alcohol.

Dissociative photoionization of CH3C(O)CH2 to C2H5+

“…We investigated the cationic surface computationally, revealing a mechanism by which, even upon 10.5 eV photoionization, the parent CH 3 C(O)CH 2 radical could dissociatively ionize to C 2 H 5 + + CO; this occurred via an isomerization and subsequent dissociation on the cationic surface. This mechanism is quite different from other situations where, at low enough energies, photoionization could result in detection at the parent mass-tocharge ratio [13][14][15]. In our case, there is no local minimum at the CH 3 C(O)CH 2 + cation's isomer, so a near-barrierless isomerization occurs.…”

“…Others exhibit dissociative ionization when there is a local minimum near the vertical geometry, but the internal energy of the cation is sufficiently high to allow isomerization on the cationic surface and subsequent dissociation (see Refs. [13][14][15] for a few examples). Dissociative ionization at very low photoionization energies, as investigated here, is much less common.…”

Fragmentation of 1- and 3-methoxypropene ions another part of the C4H8O+•potential energy surface

“…(Such arrangements are known to involve an appre ciable energy barrier; e.g., the CH 2CHOH+ ' to CH 3COH +' transformation requtres s 240 k] mol " ! [22].) As will be seen in the continuing discussion , this ion plays an important role on the potential energy surface shown in Figure 1, and so we will next describe the mass spectral characteristics of ionized I-methoxypropene, 2.…”

Vibrational and collision energy effects on the reaction of CH3CHO+ with methanol

“…[2][3][4][5][6] Collision partners can substantially lower the barriers, however, and van der Rest et al 7 have recently reported an elegant experimental and theoretical study of the catalyzed keto-enol isomerization in thermal energy collisions with methanol. [2][3][4][5][6] Collision partners can substantially lower the barriers, however, and van der Rest et al 7 have recently reported an elegant experimental and theoretical study of the catalyzed keto-enol isomerization in thermal energy collisions with methanol.…”