Gas phase reactions between acetylene radical cation and water. energies, structures and formation mechanism of C2H3O+ and C2H4O+* ions.
Reactions of the acetylene radical cation (C2H2(+*)) with H2O were investigated using ion mobility mass spectrometry. The primary products are the C2H3O(+) and C2H4O(+*) ions, produced with an overall rate coefficient k(300 K) = 2(+/-0.6) x 10(-11) cm(3) s(-1) that increases with decreasing temperature. The C2H4O(+*) (adduct) vs C2H3O(+) (H loss) ratio also increases with decreasing temperature, and with increasing third-body pressure. Ab initio calculations on the products showed seven stable C2H3O(+) isomers and eleven stable C2H4O(+*) isomers. In the C2H4O(+*) adduct channel, the reactivity and energetics suggest that the adduct is the H2C=CHOH(+*) (vinyl alcohol) ion. In the C2H3O(+) channel, the H loss occurs exclusively from water. The C2H3O(+) product ion undergoes slow deprotonation by water to form H(+)(H2O)n clusters. The reactivity, combined with energetics, suggests that the protonated ketene CH2COH(+) is the most likely observed C2H3O(+) ion probably with some contribution from the cyclic c-CH2CHO(+) ion.
Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006, USA.
Paul O
PO
Momoh
Enli
E
Xie
Samuel A
SA
Abrash
Michael
M
Meot-Ner Mautner
M Samy
MS
El-Shall